cs: 9 · 2014. 7. 9. · conversion andnomenclature, that isused indescribing thedata formats, andthen sp~cif.bsthe lay-out ofthe Source Packet structure, includingthe contents ofthe

ENVISAT-1

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4 MEASUREMENT DATA FORMAT DEFINITION

ESA/ENVISAT-1 Management: J. Louet Date:

Prepared by: Date: cs: P.9

Checked by: Date:

Product Assurance: M. Degenhardt Date:

l]~Project Management: Dr. K.-P. Bartholoma

Distribution. See Distribution List

ENVISAT-1

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Project:

UOC NO.:

Issue: Date: 30104.9954-2Sheet:

Volume 4 Change Record

lsSUE I R.Ev. I DATE I SHEET I DESCRIPTION OF CHANGE ti

Draft I 0 I 27 05.94 All Draft issue of the document

0 I 28 04.95 All New issue of the document

2 I 0 I 29.03 96 All Changes have been implemented in order to get in ~ineWiththe

updates of the other volumes Implementation of D(:R 00-DR-

DOR-SY-0250 incorporated as per DCN PO-DN-DPR-SY-

0070\I

3 I 0 I 1401 97 I All I New issue of the document

4 I 0 I 30 04 98 I All I Application IDs changed for MERIS and MIPASI

5 I 0 I 30 04.99 I All I Clarification on MWR specific Source Sequence C~m1tl

implementation

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Volume 4 Register of Changes

Pages Revision/Date Pages Revision/Date

A B c D E F A B c D E F

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4-14-24-34-44-54-64-74-84-9 .4-104-114-124-134-144-154-164-174-184-194-20

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Volume 4 Table of Contents

4MEASUREMENT DATA FORMAT DEFINITION

4.1 Data Format Overview ...4 1.1Measurement Data Format Overview4.1.2 PPF AuxiliaryData Format Overview. . . ..

4.2 Measurement Data Format Specification .4.2.1 Measurement Data Convention andNomenclature.4 2 2 Source Packet Data Format..

4 2 2.1 Source Packet Overview .....4.2 2.2 Packet Header

4.2.2 2.1 Overviewof the Packet Header Structure4 2.Z.2 2 Packet Identification4.2 2.2.3 Packet SequenceControl4.2.2 2.4 Packet Length

4 2 2.3 Data FieldHeader . . .4.2 2 4 Source Data Field4.2.2.5 Packet Error Control Field

.. 4-l

. 4-74-7

.. 4-8

.. 4-10. 4-10

······ 4-11,1

.. 4-124-12.4-13

..... .4-214-224-224-24. 4-24

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4-5Sheet:

Figure 4 .2 2.1-1, illustrates the overall PGICD document concept and the relationship to Volume4.

Preface to Volume 4

ENVISAT-1 PAYLOAD

TO

GROUND SEGMENT ICD

VolumeO· Title Page and Document Register of changes

Volume l · Introduction

Volume 2. Documentation

Volume3 System Description

Volume4: Measurement.Data Format Definition

Volume 5. Measurement Data Definition and FormatDescription for ASAR

Volume 6: Measurement Data Definition and FormatDescription for GOMOS

Volume?: Measurement Data Definition and FormatDescription for MERIS

Volume 8: Measurement Data Definition and FormatDescription for MIPAS

Volume 9 Measurement Data Definition and FormatDescription for MWR

Volume lO Measurement Data Definition and FormatDescription for RA-2

Volume 11· Measurement Data Definition and FormatDescription for AATSR

Volume 12. Measurement Data Definition and FormatDescription for DORI,S

Volume 13: deleted

Volume 14 Measurement Data Definition and FormatDescription for SClAMACHY

Volume 15 PPF/PMC Auxiliary Data Format Description

Appendix A' Print-out of PlMDD Files

Appendix B: Acronyms List

Figure 4.2.2.1-1: Volume4 in the PGICD Structure

-,

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Volume 4 provides an overview of the measurement data format (i e Source Packets) which isapplicable to both the ESA Developed and Announcement of Opportunity Instruments. Themeasurement data format definition section begins with an explanation of the bit num~eri~gconversion and nomenclature, that is used in describing the data formats, and then sp~cif.bs thelay-out of the Source Packet structure, including the contents of the Source Packet Headbr andthe description of the Source Packet Data Field.

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4.1 Data Format Overview

4.1.l Measurement Data Format Overview

The measurement data (i.e low, medium and high rate) acquired by all ENVISAT-1 instruments

are packed into Source Packets.

LOW AND MEDIUM RATE DATA

For low and medium rate data, the instrument transfers the Source Packets to the HSM forfurther formatting and transmission to the ground

The HSM formats the Source Packets into VCDUs and CADUs, and multiplexes the CADUs intoa real-time or recorder dump data streams A description of the formatting and multiplexing,which is performed by the HSM can be found in Volume 3, Section 3 4.3 of this document.

The specification (i e definition and lay-out) of the Source Packet format and, specifically, thecontents of the Packet Header are provided in the Section 4 2

The on-board generation of the measurement data, the packetisation process and the definitionand description of the data parameters within the Source Packets' Data Field Header, Source DataField and Packet Error Control Field is described in Volumes S through 14 on an instrument perinstrument basis.

HIGH RATE DATA

For the ASAR high rate data, the High Rate Data Format is used in addition to the Source

Packets The High Rate Data Format is, essentially, the same VCDU/CADU format that isapplied to the Source Packets in the HSM However, the formatting process is performedcompletely within ASAR

The High Rate Data Format structure, on-board generation process and definition of parameterswithin the High Rate Data Format are addressed in Volume 5, Section 5 5

The type of measurement data format used by each instrument, per operations mode, are providedin Table 4.2 2 2.1-1


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The layout of the measurement data format and the High Rate Data Format, as define1 in thePGICD, is independent of whether the X-Band or Ka-Band transmission assembly is urd

I

4.1.2 PPF Auxiliary Data Format Overview

PPF generates, as part of the its nominal activities, a set of Auxiliary Data that is included, by theHSM, in the measurement data stream The Auxiliary Data set consists of ancillary data ~ndHouseKeeping (HK) data from the

Instrument I Operations Mode I Data Format--Image I CADU

ASAR IWide Swath CADll

Alternating Polarisation CADU

External Characterisation CADU

Wave Source Packet

Global Monitoring Source Packet

Module Stepping I Source Packet

GOMOS All Source Packet

MERIS All Source Packet

MIPAS All Source Packet

MWR All Source Packet

RA-2 All Source Packet

AATSR All Source Packet

DORIS All Source Packet

SCIAMACHY All Source Packet

PMC All Source Packet

Table 4 2 2 2. l-I . ENVJSAT-1 MeasurementData Formats per Instrument I

Iii

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• ServiceModule,• PMC, and• Instruments

The ancillarydata consists of the orbit and attitude state vectors, the time of validityof the statevectors, the time of the next Equatorial crossing, and various event flags

The PPF, like the instruments, uses Source Packets to package the auxiliarydata set TheseSource Packets are then transferred to the HSM

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4.2 Measurement Data Format Specification !

IIn interpreting the data formats, defined in the PGICD, the following Bit Numb~nglCohven(ionand Bit-Field Nomenclature shall be used. I

I

BIT NUMBERING CONVENTION

I

The convention used to identify each bit, in a forward-ordered N-bit field, is shown it Fi,ure4 2.2.1-1 The first bit in the field to be transmitted (i e the most left-justified bit in t e fjgure) ··,defined as "Bit O" The following bit is called "Bit l" and so on up to "Bit N- l"

4.2.1 Measurement Data Convention and Nomenclature

Bit Oi +Bitl

Bit n-I

[]] N - Bit Data Field DLFirst Bit Transmitted = MSB

Figure 4.2.2. l-2 Bit Numbering Convention

When the field is used to express a binary value, such as a counter, the most significa~t *t (N'~)shall be the first transmitted bit of the field (i e "Bit O")

BIT FIELD NOMENCLATURE

Data fields are often divided into 8-bit groups which conform to the Bit Numbering ~ontventibn.In accordance with modern communication practice, the following definitions are used i.the

I

PGICD.

ByteWord

= 8-bits16-bits (=2 Bytes)=

The numbering convention for identifying each byte or word in a forward-ordered Ntby,e/wqrdfield is shown in Figure 4.2.2.1-3

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Byte/Word n-1

1~yte/Word 1

I I -IN - BX!_e/WordData Field

~ost SignificantByte/Word

Figure 4.2.2 1-3 Byte/Word Numbering Convention

4.2.2 Source Packet Data Format

4.2.2.1 Source Packet Overview

The Source Packet format is utilised for the packaging of all measurement data

Packet Identification

Packet Header Packet Sequence Control

Packet Length

Data Field Header

P<1cketData Field Source Data Field

Pocket Error Control (optional)

Figure 4 2 2 1-1 Source Packet Data Format Layout

As shown in Figure 4 2 2.1-1, the Source Packet consist of a Packet Header, and a Packet DataField.

The Packet Header contains general information about the data contained in the Source Packetand has a fixed length

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The Packet Data Field contains the source data and any auxiliary data which are specific uo thei

I

II .

The detailed layout of the Packet Header is provided in Section 4 2 2 2 An overview !ofthestructure and constraint associated with the Data Field Header, Source Data Field, and the PacketError Control Field is provided in Sections 4 2 2 3 through 4 2 2 S

generating source on board the spacecraft and has a variable length

The detail structure and content of the Data Field Header, Source Data Field, and thelPa¢ketI

Error Control Field is addressed in Volumes S through 14, on an instrument per instrument basis.

4.2.2.2 Packet Header

4.2.2.2.1 Overview of the Packet Header Structure

The Packet Header has a fixed length of 48 bits (6 bytes) and contains standardised controlinformation

As shown in Figure 4.2 2 1-2, the Packet Header consists of

the Packet Identification Field,the Packet Sequence Control Field, andthe Packet Length Field•

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TheData Field Header Flag (DATA_FLD_HD_FLG) is a one bit field that indicates thepresence ( = l) or absence ( = 0) of a Data Field Header in the Packet Data Field All ENVISAT-

~I I Source Packets will contain a Data Field Header.~"'0~OL-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~-

Packet Header (48 Bits)

Packet Identification (2 Bytes) I Packet Sequence Control Packet(2 Bytes) Length

(2 Bytes)I

Packet Packet Data Application Segmentation SourceVersion Type Field Process ID Flags SequenceNumber Header Count

Flag

3 bits I I bit I 1 bit I 11 bits I 2 bits I 14 bits

Figure 4.2.2. l-2 Source Packet Format Structure

4.2.2.2.2 Packet Identification

The Packet Identification is a 16 bits field which consists of the following parameters

•

Packet Version NumberPacket Type

Data Field Header FlagApplication Process ldentifier

The Packet Version Number (PCK_ VERSION) is a three bit field that describes the version of theCCSDS Source Packet Standard The Packet Version Number is defined as

PCK_ VERSION= 4 (HEX)

The Packet Type (PACKET_ TYPE) is a one bit field which is set to zero (0) for telemetry and toone (1) for tele-command All ENVISA T-1 Source Packets will be used for telemetry purposes.

Thus, the Packet Type field is defined as

PACKET TYPE = O

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Thus, the Data Field Header Flag is defined as

DATA_FLD_HD_FLAG= 1

The Application Process Identifier (APP_ID) is an eleven bit field that uniquely ident,fie~ both

the instrument and the particular application process (i e instrument measurement m~de)iwhich isI

responsible for the generation of the source data

An application process is defined by a given instrument mode delivering measurement data via:aparticular virtual channel

As depicted in Figure 4 2 2 2 1-1, the first six bits of the Application Process Identifier eontainsthe Virtual Channel Identifier and the next five bits reflect the operations mode.

Bit Number

9 100 6. 72 4 5 83

Instruments' Virtual Channel Identifies Instruments' Operational Mode

Figure 4.2 2 2.1- l Application Process Identifier Bit Field Structure

(~·:.,\

The Application Process Identifiers for each EDI and their specific measurement modes are givenin Table 4.2.2 2 2-1 The Application Process Identifiers and the specific measurement modesfor each AO Instrument are given in Table 4 2 2 2.2-2

--

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Instrument Application Process Identifier Description

Binary Value HEX I

Value

VCID Ops Mode

ASAR 101011 11000 578 WaveMode

101011 01011 568 Global Monitoring Mode

101011 01101 56D Module Stepping Mode

110000 10100 614 Image Mode

110000 llOll 61B Wide Swath Mode

110000 001 l l 607 Alternating Polarisation Mode ( Co-Polar)

110000 01000 608 Alternating Polarisation Mode (Cross-Polar H)

110000 01101 600 Alternating Polarisation Mode ( Cross-Polar V)

110000 00010 602 External Characterisation Mode

110000 10001 611 Test Mode

GOMOS 100100 00000 480 All Operational Modes

I

MERIS 000101 00000 OAO Full Spatial Resolution Data - Fully Processed - IDirect and Averaging Mode I

I

000101 00001 OAI Full Spatial Resolution Data - Fully Processed -i

Stabilisation Mode (Full & Reduced Resolution)i000101 00100 OA4 Full Spatial Resolution Data - Raw Data -

Direct and Averaging Mode000101 00101 OA5 Full Spatial Resolution Data - Raw Data -

Stabilisation Mode (Full & Reduced Resolution) iI

000110 00000 oco Reduced Spatial Resolution Data - Fully Processed -Direct and Averaging Mode

I

OOOllO 00001 OCL ReducedSpatial Resolution Data - Fully Processed -I

StabilisationMode (Full & Reduced Resolution)I000110 00010 OC2 Reduced Spatial Resolution - Full Processed Data III

Avcraging Mode I

J

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i

'

!


Binary Value HEXValue

VCID Ops Mode

000110 00011 OC3 Reduced Spatial Resolution Data - Fully ProcICSSC ~- I'

Stabilisation Mode (Reduced Resolution) i

000110 00100 OC4 Reduced Spatial Resolution Data - Raw Dataj - II

'Direct and Averaging Mode 'i

000110 00101 ocs Reduced Spatial Resolution Data - Raw Data/- IStabilisation Mode (Full & Reduced Resolution) i

000110 00110 OC6 Reduced Spatial Resolution Data - Raw Data - i

Averaging Mode l )Reduced Spatial Resolurion Data - Raw Dau. - '000110 00111 OC7

Stabilisation Mode (Reduced Resolution) :'

l000110 OH>OO OC8 Reduced FOV Data - Raw Data -

Averaging Mode i000110 01001 OC9 Reduced FOV Data - Raw Data -

Stabilisation Mode (Reduced FOV) 'I000110 10000 ODO Spectral Calibration Sequence !

'On Board Calibration Mode I ;

!10001 lO 10001 001 Spectral Calibration Sequence

On Ground Calibration Mode:

0001 JO IOOIO 002 Dark Current Calibration SequenceOn Board Calibration Mode I ! ;

000110 IOOl I om Dark Current Calibration Sequence I

!

On Ground Calibration Mode '

000110 10100 004 Absolute Radiometric Gain Sequence - Diffl I 1 -.On Board Calibration Mode I i

0001 JO 10101 005 Absolute Radiometric Gain Sequence - DitrJ I1

On Ground Calibration Mode'000110 10110 OD6 Absolute Radiometric Gain Sequence - Diff 2 1.

On Board Calibration Mode I i i

000110 lO I I I OD7 Absolute Radiometric Gain Sequence - Di~ 2 !On Ground Calibration Mode i

OOOlJO 11000 008 Spectral Calibration Sequence - without Dark <).rrent

correction

IOn Board Calibration Mode i

000110 11010 ODA Absolute Radiometric Gain Sequence - Diff l *ithouti

Dark Current correction

On Board Calibration Mode i0001 JO 11IOO ODC Absolute Radiometric Gain Sequence - Di~ 2 tithmtt

Dark Current correction ·

On Board Calibration Mode

'

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Binary Value HEX

Value

VCID Ops Mode

-

MIPAS 100111 00000 4EO Nominal Output (Nominal Scan Sequence)

10011l 00001 4El Nominal Output (Nominal Scan Sequence - offset

calibration)

100111 00010 4E2 Nominal Output (Nominal Scan Sequence-Black Body

calibration)

100111 00011 4E3 Nominal Output (Special Event Scan Sequence)

100111 00100 4E4 Nominal Output (Special Event Scan Sequence-offset

calibration)

100111 00101 4E5 Nominal Output (Commanded Deep Space Calibration)

100111 00110 4E6 Nominal Output (Commanded Black Body Calibration)

100111 10000 4FO Raw Output (Nominal Scan Sequence)

JOO111 10001 4FI Raw Output (Nominal Scan Sequence - offset

calibration)

100111 10010 4F2 Raw Output (Nominal Scan Sequence-Black Body

calibration)

lOOll I 1001l 4F3 Raw Output (Special Event Scan Sequence)

100111 10100 4F4 RawOutput (Special Event Scan Sequence-offset

calibration)

IOOlll IOIOI 4F5 RawOutput (Commanded Deep Space Calibration)

100111 lOl 10 4F6 Raw Output (Commanded Black Body Calibration)

100111 10111 4F7 Transitory Sweep (Raw)

100111 01111 4EF LOS Calibration Mode

100111 OlJOO 4EC SPE SelfTest Mode

0 100l l l 0011 l 4E7 Transitory Sweep (Nominal)~..•s0

"'"'0

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:

I! I

Instrument Application Process Identifier Description !J

Binary Value HEXValue

VCID Ops Mode i

!

- Ii

MWR 100010 10001 451 Nominal Measurement Mode'

II

RA-2 001001 11001 139 Acquisition/Tracking Mode i :I I

001001 10100 134 RF BITE Mode ' I

iI

001001 11010 13A Digital BITE Mode :..001001 10101 135 IF Calibration Mode

: i

'- Table 4.2.2.2.2-1 : Application Process Identifiers and Operational Mode per ~DI

'

'""

.L ______j__ __ ___; -

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Binary Value HEX

Value

VCID Ops Mode -

AATSR 100001 00000 420 Measurement Mode

DORIS 101000 IOIOI 515 Doppler Packets in Measurement Mode

101000 I 1001 519 Navigation Packets in Measurement Mode

SCIAMACHY 001010 00000 140 Measurement Category 0

001010 00001 141 Measurement Category I

OOIOIO 00010 142 Measurement Category 2

OOIOJO 00011 143 Measurement Category 3

001010 00100 144 Measurement Category 4

001010 OOIOI 145 Measurement Category 5

001010 001 JO 146 Measurement Category (1

OOIOIO 00111 147 Measurement Category 7



001010 01010 14A Measurement Category I0

001010 OIOl I 148 Measurement Category I I

OOIOIO 01100 14C Measurement Category 12

001010 01 IOI 140 Measurement Category 13

001010 Ol no 14E Measurement Category 14

001010 01111 14F Measurement Category 15


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;

i

I A I. . J> Id . • D . . I !nstrument pp 1cation rocess ent1her escnpuon i

Binary Value HEX

Value

VCID Ops Mode1

,

I '00I010 I000I 151 Measurement Category 17 _ '

1

001010 IOOIO 152 Measurement Category 18 I 1

1

I

l

00IOIO 10011 I53 MeasurementCategory 19 . J

00 I0 I0 I0 I00 154 Measurement Category 20 I I00I0 IO I0 IOI 155 Measurement Category 21 I ! 1

!00I0 I0 I0110 156 Measurement Category 22

1i

i !0010I0 10111 157 Measurement Category 23 ,

! '00 I0 IO II 000 158 Measurement Category 24 i

l .OOIOIO 11001 159 Measurement Category 25 . !

00I0 IO 110I0 I5A Measurement Category 26 I 1 ,

00 I0 I0 11011 158 Measurement Category 27 j I ,i ;

00 I0 I0 I 1100 I5C Measurement Category 281

: ,

!

OOIOIO 11101 15D Measurement Category 29 1

I I I~00 I0 I0 111 l0 I5E Measurement Categ,ory JO , I

' T

0010IO I 111I I5F Measurement Category JI I J

i !

I i

Table 4.2.2.2.2-2: · Application Process Identifiers and Operational Mof e ~er AOInstrument • !

I I

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4.2.2.2.3 Packet Sequence Control

The Packet Sequence Control is a 16 bits field which provide the sequence control information forthe Source Packet The field is divided into two parts, the Segmentation Flag and the SourceSequence Count

The structure of the Packet Sequence Control Field is shown in Figure 4 2.2 2 2-1.

Bit Number

0 2 3 I 4 85 6 7 9 I 10 I 11 12 13 14 15

Segmentation

FlagSource Segmentation Counter

Figure 4 2.2.2 2-1 Packet Sequence Control Bit Field Structure

The Segmentation Flag (SEG FLAG) occupies the two most significant bits of the 16-bits field. If- .a Source Packet is converted into one, two, or more telemetry packets, the Segmentation Flag isset as follows·

Parameter Interpretation

SEG_FLAG == l(HEX)SEG_FLAG == O(HEX)SEG FLAG == 2(HEX)SEG_FLAG == 3(HEX)

First segmentContinuation segmentLast segmentUnsegmented

For ENVISAT-1, all Source Packets are unsegmented the Segmentation Flag is defied as

SEG_FLAG == 3(HEX)

The Source Sequence Count (SEQ_ COUNT) occupies the remaining 14-bits and is a wraparound sequential count (Modulo 16 384) of each source packet generated by each particularapplication process

The Source Sequence Count is used by the Ground Segment to reconstruct the correct SourcePacket sequence.

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The Source Sequence Count field starts with a valueI

SEQ COUNT = 0, lif the instrument (except ~ see chapter 9 2) starts a new operating mode, and in ' rements by"l" for each Source Packet that is generated When the value reaches

SEQ COUNT= 16383

the count wraps around

4.2.2.2A Packet Length

The Packet Length (PCK_LEN) is a 16 bit field which contains the length of the Packet DataField minus one The maximum length of the Packet Data field is specified at 65,53~ bytes

The actual size of the Source Packet is implicitly six bytes longer, since the standard ~8-~itsPacket Header always precedes the Packet Data Field. Thus, the maximum size oft~e SourcePacket, the Packet Header plus the Packet Data Field, is

Packet Header 6 BytesPacket Data Field 65.536 Bytes

65,542 Bytes

The minimum size of the Source Packet is defined as 1008 bytes which is equivalentlto ·""',PCK_LEN = 1001 bytes The minimum size is driven by to the length of the Virtual Channel L ••LaUnits (VCDUs) that are generated by the HSM.

The Packet Length for each instrument and its operation modes is addressed in Volumes 5'through 14, on an instrument per instrument basis

4.2.2.3 DataField Heat/er

The Data Field Header provides a means for inserting any auxiliary data which are necessary forthe interpretation of the source data As defined in Section 4 2 2 2 2, all ENVISAT~ 1 Source

!

Packets will contain a Data Field Header The length of the Data Field Header shallfalways be aniintegral multiples of bytes

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The Data Field Header,as shown in Figure 4 2 2.3-1. shall contain the

• Data Field Header Length• Instrument Mode Definition• ICU On-Board Time• Instrument Redundancy Definition Vector• Other Auxiliary data

Data Field Header RemarksArea Size

Data Field Header Length 16hits Defines the number of bytes used for the Data Field Header •

Instrument Mode Definition 16 bits I Defines the instrument mode in which the data were acquired

ICU On-Board Time Code variable I Identifies the measurement time of the data in the source packet The

ICU Time Code format shall use an integer number of bytes, depending

on the instrument

Redundancy Definition Vector variable I Specifics which redundant instrument unit/assembly is to be used or

selected when required .(fBC)

Other Auxiliary Data variable I Additional auxiliary data that are needed to interpret or process the

measurement data

Table 4.2 2 3-1. Data Field Header Layout

The Data Field Header length (DAT A_FLD_HD_LEN) is a 16-bits field which defines thelength of the Data Field Header Detailed information of this field is given in the instrumentspecific volumes

The Instrument Mode Definition (INSTRUMENT MODE) is a 16-bits field which defines theoperating mode that is generated.

The ICU On-Board Time Code (ICU_ OBT) is a variable-bit length field which identifies the timereference for the Source Packet The resolution is instrument dependent Therefore, the specificlay-out of the ICU On-Board Time Code field is addressed in Volumes 5 through 14 thisdocument

j

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The Redundancy Definition Vector (REOUND _VECTOR) is contained in a variable-bits lengthi

field.

The=:Auxil~aryData Field is a var~able.length bit field that is u~ed for ins~rtingt.i.in1rmal···ionthat ts needed to interpret the data contained m the Source Packet Smee these infor , at on ateinstrument dependent, the layout and definition of the field is provided in Volumes 5 hr ugh 14of this document

4.2.2.4 Source Data Field

The Source Data field contains the measurement data which are generated by the int. rumentThe Source Data field has a variable length which is given as an integer multiple ofb · e~.Th~.·layout of the Source Data field are instrument specific and are provided in the instrume t sd>ecifi ~

I ~

Volumes 5 through 14 · ·

4.2.2.5 Packet Error ControlFie/ti

The Packet Error Control field is optional field that is used to verify the integrity of ~he tompleteI ~·

Source Packet structure Whether this field is used is discussed in the specific instrument Volumes

5 through 14 If the field is used, the coding procedure is addressed in detail

Dornier ombH 0oc.No: PO-ID-DOR-SY-0032.•......•. ~ n...... 'ln nA oo···~

ENVISAT-1 Sheet S-1

,•.'!

; .

()I

',:1,

Prepared by: S. Schiltz ;11/ltN\ Date: t.~-.vJChecked by: D. Demuth Date:

Product Assurance: M. Degenhardt Date:

Instrument Contractor.

i ) I Project Management: Dr. K.-P. Bartholoma f~ Date· /. IJF,9'/ ._ESA/ENVISAT-1 Management: J. louet Date:

;

Distribution: See Distribution List

Copying of this document, and giving it to others and the use or communication of the contents thereof, are forbidden without express authority. Offenders are liable to the payment of damages All rights

are r--.ied in the event of the grant of a patent or the registration of a utility model or design

g~s8 ----------------------------------------------'------------------------------------

Volume 5 Change Record

Issue I Rev. I Date I Sheet I Description of Change

Draft 0 27 05.94 All Draft issue of the document.1 0 28.04.95 All New issue of the document2 0 29 03.96 All Implementationof DCR PO-DR-DOR-SY-0286, and

related review comments (ref. PO-DOR-0516/96)incorporated as per DCN PO-DN-DOR-SY-0070

3 I 0 I 1401.97 15-29,5-41, update reflecting changes in the document ,,ASAR

I I I I5-43, 5-47, Interpretation of Source Packet Data", PO-TN-MMS-

·~ 15-52,5-64, SR-0248, issueBJ) 5-78, 5-79,

5-810

5-73 Clarificationof r (for compression ratio) in formula5-106 'IA' pattern during Pre-Op and LR modes

4 I 0 I 30.04.98 I All Implementationof OCR PO-DR-DOR-SY-0674 andrelated review comments (ref PO-MMS-SR-2598/97)Section numberingcorrectedModule Stepping performed on V or H not bothSamplingFrequency in examplemodifiedto 19 208MhzDigitalFiltering Section removedCyclePacket Count Sequence added to timeline

• description-»,\, I Q = 5, P <= 14 inWide SwathMode timeline)) Description on ResamplingFactor detailed

Example for CalibrationRow Numbering addedAntennaBeam Set Number in periodic calibrationsource packet of Wave Mode modified .

ICyclepacket count from 0 to 3 repeating 80 times

;1 ITBD data rates Wave and GlobalMonitoringModeremoved

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Volume 5 Table of Contents

5 MEASUREMENT DATA DEFINITION AND FORMAT DESCRIPTION FORASAR _ 5-1

5.1 Measurement Data Generation Description ···~·············5-25.1.1 Introduction 5-2

5.1.1.l Summaryof ASARObjectives................ . 5-25.1. 1.2 Summary of;ASAR·MeasurementPrinciples. .... .. . .. ... 5-2

5 1.1.2.1 Measurement;Principle. '.•· ..•..i . . . . 5-25 l 1.2 2 Calibration Principle . . ... . . .... . .. .. . . .. ... 5-55.1. l.2 3 Related DesignFeatures.. .. . . . . . . . . . .. . 5-6

S.1 1 3 Summaryof ASARPerformance .. . .. . . 5-85.1.2 OperationalModes .. .. .. . . .. .. .... . . . . .. . . 5-9

5.1.2. l Overview . ..... .. . ... . . . . . . ..... . . 5-95. l.2.2 lmage Mode. . . .. .. . . . .. ..5-10· 5.1.2.2 l Objectives.~.......... .. .. .. . . . 5-105.1.2 2 2 Execution......... . . 5-10

5.1.2.3 Wide Swath Mode.. . .. .. . . . . 5-105.1 2 3.1 Objectives..... . . . . . . .. . .S-105 1.2.3.2 Execution .. . . .. . . . .. .. .. .. . 5-10

5.1.2 4 WaveMode........... . .. . 5-115 l.2.4. l Objectives . . ... ... ..... ....... ........... .... ..... ..... . . .. . ...... 5-11S.1.2.4.2 Execution.............. . . . . . . . 5-11

5.1.2.5 AlternatingPolarisationMode (Copolar, Cross-polar Hand Cross-polar V)5-115.1 2.5. l Objectives.. . . . 5-115.1.2.5.2 Execution.......... . . . . . . . . . .5-11

5.1.2 6 GlobalMonitoring Mode...... .. . 5-125.1.2.6. l Objectives.. . T" . .. .. . .. . . 5-125.1.2.6.2 Execution .. . . .. . .. . . . .. . 5-12

5 l 2.7 External CharacterisationMode . .. .. . . .. 5-125 1.2 7 1Objectives... . . . . .. .. . . . . . . 5-125.1.2 7 2 Execution.. . . .. . .. . . . . . . . .. . 5-12

5.1.2.8 Module Stepping Mode . . . . . . . 5-135. l.2.8 lObjectives .. . . . .. . . . 5-135.128 2 Execution . . . . . . . . . . . . . . 5-13

5.1.2 9 Test Mode....... . . . . . . . . . .. . . 5-135:1.2:9.1 Objectives......... . .. . . . . . 5-135.1.2.9.2 Execution............. .. 5-13

5.1.3 Operations Constraints .. . . .. . . . 5-145.1.4 Acquisitionof Observation/CalibrationData .. . 5-15

5.1.4 l Pulse Generation 5-195.1.4.1 1Chirp Waveform. . . .. .. 5-195.1.4. l 2 Offset ChirpWaveform., . .. . .. .. . 5-195 1.4.1.3 Predistorted ChirpWaveform.... . .. .. . . . . 5-205.1.4. l.4 ChirpSelection . ::......... .. . . . 5-215 1.4.l .5 Modulationonto IF............ ...... ..... .... ......... ........ ..... .. .... . 5-215.1.4. l 6 Upconversionto RF..... .. . .. . .. ...5-22

5.1.4 2 Antenna........... . .. . .. . 5-225.1.4 2.1 RF SignalRouting ·...... .. . . .. .. .. .. . 5-22

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5.1.4.2.2Phase and AmplitudeSetting 5- 25.1 4.3 ReceiverChain......... .. ... . . . .. . . . . . 5- 4

5.1.4.3 l Downconversionto IF..... . . .. .. . S- 45.1.4.32 Demodulationto Baseband .. . .. .. . .. . . .. .. .. ·1·5-4S.1.4.33 ADC... . . . . . . ..~ 5- 5

5 l .4.4 Digital Data Processing . ·. . . ........ ... ... ..... . . ... . ... . ... .....• 5- 75.1 4.4. l deleted .. . . . . . . ,..5- 75. l .4 4 2 Data Resampling . . ... ...... .. . . ... .... . ..... . . .. . ....... ,.5~~5.1.4.4.3 Quantisatio..n . . . . . .. . .. . . ,..5-j28

5.1.5 Generation of Measurement Data for the Image Mode...... . .. ,..51325.1.5.1 Image Mode On-Board.DataProcessmg..................... . .,»: • •••••••••• j .• 5-/32

5.1.5.l 1 Pulse Generation...... .. r .. 5i325.1.5.1.2 Antenna.... .. . . .. . . f •• 5+335.1.S.1.3 Summary of Receive ChainCharacteristics.. . . si34 ) )

S. l .5.2 Source Pack~t Ge~eration for the ImageMode .. .. 5t355.1.5 2.1 Mode Time-Line for the ImageMode .. 5,355 1.5.2.2 Generation of Source Packets . ..... . .. . . ~O

5. l.6 Generation of Measurement Data for the Wide Swath Mode . . .. . .. . . .sk 15. l.6 l Wide Swath Mode On-Board Data Processing....... . .. .. ~41

5. l 6.1.1 Pulse Generation . ... ............. . ........ . . ... . ..... . . .. .. . .g_41

;::::::i~:::;,~fR~ci~~·ch;;i~Ch~.;.ct~~ii~~:::::::: ::. . . ·::. . :.: i:J~i5 1.6.2 Source Packet Generation for the Wide SwathMode..... .. . ...$-44

5.1.6 2.1 Mode Time-Line for the Wide Swath Mode ..$-445.\.6.2.2 Generation of Source Packets... . $-46

5.1 7 Generation of Measurement Data for the Wave Mode .. .. S-475.1 7.1 Wave Mode On-Board Data Processing... . . . .. . ..S-47

5.1 7 1.1 Pulse Generation. . . . . . . .. 5-475.1.7.1.2 Antenna . . .. . . .. .. .. . . .. .. . .. . ~-485.1.7. l.3 Summary of ReceiveChainCharacteristics. . . ... . . .. . . :S-49

5.1.7.2 Source Packet Generation for the WaveMode........ . . .S-505.1.7.2. l Mode Time-Line for the WaveMode.... . . '. 5-55.l.7.2.2 Generation of Source Packets ......... .......... . . . .... . . .. ..... .. 5-S1

5.1.8 Generation of Measurement Data for the GlobalMonitoringMode 5-525 1.8.l GlobalMonitoring Mode On-Board Data Processing .. .. 5-52

S.l.S 1.l Pu\se Generation....................... .. 5-525.1.8.1.2Antenna.. .. . . . . .. 5-535 1 8 l.3 Summary of ReceiveChainCharacteristics.... .. .. . .5-54

5 1:8.2SourcePacket Generationfor theGlobalMonitoringMode . 5-555.l.8.2.1 Mode Time-Linefor the GlobalMonitoringMode.. .. . .: 5-555.l.8.2.2 Generation of Source Packets............... . . 5-56

5.1.9 Generation of Measurement Data for the AlternatingPolarisation Mode S-585.1.9. l Alternating PolarisationMode On-Board Data Processing.. . . S-58

5.1.9.1.IPulse Generation..... .. . . . .. . ..5-585.1.9.1.2 Antenna... .. . .. .. . . . . . .. 5-595 1.9.l.3 Summary of ReceiveChainCharacteristics. . . .. .. .. . .. . 5-60

5.1 9.2 Source Packet Generation for the AlternatingPolarisationMode . . ..5-615.l.9 2 l Mode Time-Linefor the AlternatingPolarisationMode . ..... ... . ..5-61S l.9.2.2 Generation of Source Packets.. ..... . .. . . ..... . . . .. . .. .5-63

5.1 10Generation of Measurement Data for the External Characterisation Mode ..S-645. l. l0. l External CharacterisationMode On-Board Data Processing .... ... 5-64

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5.1.10 .1. l Pulse Generation........ .. .......................... . . ....... . ...... . 5-645.1.10.1.2 Antenna.... .. .. .. 5-655.1.10.1.3 Summary of Receive Chain Characteristics .. . . . . . 5-66

5. l.10.2 Source Packet Generation for the External Characterisation Mode. . .... 5-675 I. I0.2.1 Mode Time-Line for the External Characterisation Mode .. . 5-675 I I0.2.2 Generation of Source Packets ....... . . .. . .. . .. 5-68

5 1.11 Generation of Measurement Data for the Module Stepping Mode .. .. 5-695.1.11.1 Module Stepping Mode On-Board Data Processing. . . . . · . . .. ..5-695. l .11.2 Source Packet Generation for' the Module Stepping Mode.. . .. 5-69

5.1. l l.2 1Mode Time-Line for:the·ModultfStepping Mode 5-695.1. l l.2.2 Generation of Sourbe Pac~ets : : :......... .. .. S-70

5.1.12 Generation of Measurement Data for the Test Mode..... ....... .. 5-715.1 12.1 Test Mode On-Board Data Processing 5-71S. l.12.2 Source Packet Generation for the Test Mode .. . . .. . 5-71

S. 1.12.2. I Mode Time-Line for the Test Mode .... . ...... ..... ..... .. 5-715.1. 12.2.2 Generation of Source Packets..... . . .. .. . . 5-71

5.2 Source Packet Format of the Image Mode.......... .. . . . . . .. .. .5-725.2. l Overview .. .. .. . 5-725.2 2 Description of the Packet Header.. . . .. .. .. . . . .. . 5-725.2.3 Description of Data Field Header............. . .. .. . .5-75

5.2.3.1 Data Field Header Length. .. .. .. . . . . .5-765.2.3.2 Mode Identifier. . .. . .. .. .. .. . .. . 5-765.2 3.3 On-Board Time .. . . . 5-76

· 5 2 3.4 Redundancy Definition Vector.. . . . . ..... . . . .. .. . .... . 5-765 2.3 5 Mode Packet Count........ ....... ..... ... . ... . .... ... . . . 5-775 2.3.6 Antenna Beam Set Number ... . .. . . . ... . .. . ..5-775.2.3.7 Compression Ratio . .. . . . . . . .... 5-775.2.3 8 ECHO Flag . . . . .. .. . . . . . 5-775.2.3.9 Noise Flag .. •.... .. . .. . . . . . . .. .. . . . 5-775.2 3 I0 Calibration Flag .. ..... ... .. . . ...... . . ......... ..... .. . ..... ....... ...... .5-775.2.3 11 Calibration Type.......... . .. . . . . 5-785.2.3 12 Cycle Packet Count..... . . . 5-785.2.3.13 Pulse Repetition Interval . . .. .. .. . . 5-785.2.3.14 Window Start Time........... . .. .. . 5-785.2.3.15 Window Length . . . . 5-795 2.3.16 Upconverter Level.... . .. . . . . 5-795 2.3.17 Downconverter Level .. .... ...... . ...... .... .... ..... . ... . 5-805.2·3. IS"Tx Polarisation.... . .. . .. .. . .. . . 5-80

, 5 .2 3.19 Rx Polarisation ... . .... ....... ....... . ... ... . .. . ..... ..... . .. . ... .5-805.2.3.20 Calibration Row Number.. . . . . .. .. . . . 5-805.2.3.21 Tx Pulse Length . . .. .5-805.2.3.22 Beam Adjustment Delta... . .. . .. . . . . 5-815 2.3 .23 Chirp Pulse Bandwidth .. . ........ . ......... . ... .... . . .. .. . ... . .. .5-815.2.3.24 Auxiliary Tx Monitor Level...... . . .. . . 5-815.2.3.25 Resampling Factor · ... .. ..... .. . . .. . .. . .. . . .5-82

5 2.4 Description of the Source Data Field . . ::. .. . 5-835.2.5 Description of the Packet Error Control Field . .. . . ... . .. . 5-84

5.3 Source Packet Format of the Wide Swath Mode5.3 I Overview... .. . . .. . .

5-85. . ...... 5-85

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5.3.2 Description of the Packet Header .. . . . . .. .. .. .. . . 5155.3.2 1 Packet Length. . . . .. . .. . 5 85

5.3.3 Description of Data Field Header...... . 5 865.3.4 Description of the Source Data Field................. . . ... 5 865.3.5 Description of the Packet Error Control Field ······················t··586

s.~~o¥«f~:.~.~.~~..~.~.~~.~~v~.M_o.d~..::::::::::::::::.:··:::·:::::::::::·:::::..:::::::::::::::L~fs~5.4.2 I>~riP,tion of the Packet Header................. . . . 5t875.4.3..Descrip'tion of Data Field Header................. . .. . . . 5i88.· ' . . . I5.4.4Desc~pt!on of the Source Data Field·······:.. .. .. . .. . . . .. .

1.5r88

5.4.5 Description of the Packet Error Control Field i ••• 51-90

5.5 Source Packet Format of the Global Monitoring Mode . 5~91 J

5.5.l Overview....................... .. . . 5i-9l )5.5.2 Description of the Packet Header...................... .. . .. .. . 5!-915.5.3 Description ofData Field Header....... . . . .. . .. . . ; . S-925.5.4 Description of the Source Data Field. . . . . . .. . . . , S-925.5.5 Description of the Packet Error Control Field.. . . .. . . l S-93

5.6 Source Packet Format of the Alternating Polarisation Mode .5 6.1 Overview ..5.6.2 Description of the Packet Header .5.6.3 Description of Data Field Header............ . .. . . .5.6.4 Description of the Source Data Field .5.6.5 Description of the Packet Error Control Field .

S-94S-94

...$-94. 5-95

. S-95······· , $-95

5.7 Source Packet Format of the External Characterisation Mode $-965.7.1 Overview..... . . l S-965.7.2 Description of the Packet Header . . . . . :.. 5-965.7.3 Description of Data Field Header....... .. . . . .. . .~-975.7.4 Description of the Source Data Field . .. . . . .. .. .. . . 5-975.7.5 Description of the Packet Error Control Field.... .. ....... ..... ....... . . .. 5-97

5.8 Source Packet Format of the Module Stepping Mode .5.8.1 Overview... . . . .. . . . .5 8.2 Description of the Packet Header . . . . . .5.8.3 Description of Data Field Header .5.8.4 Description of the Source Data Field .5.8.5 Description of the Packet Error Control Field .

5.9 Source Packet Format of the Test Mode .

5-98.5-98

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. . 5-99..S-99

...'.5-99

S-100

5.10 Description of the High Rate Data Format... ..... ... . . .. . .. ... ..$-1015.10 l On-Board Generation of the High Rate Data Format. .. .. .. . . .. . .. $-IO J5.10.2 Virtual Channel Data Unit (VCDU) S-101

5.10.2.1 VCDU Primary Header.. .. . . . $-1025. I0.2.2 VCDU Data Field.... . . ... ........ . . ...... ........ .. .. .. ... . $-1035.10.2.3 VCDU Trailer...... .. . .. . . ...S-104

5.10.3 Channel Access Data Unit (CADU) .. .. . . $-1045.10.3 .1 Synchronisation Marker... .... .. ... . . . ... ... . .. 5-104

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5.10 3.2 Scrambling Procedurer. . .. .. . 5..;IOS5.10 4 Idle VCDUs ,.. . . .. . .. 5-1065.10.S High Rate Data Downloading ,;,;.; 5-1065. I0.6 Data Handling Procedure for Mode Transitions 5-107

5.11 ASAR Data Rates 5-1085.11. l Data Rate Summary ,.....................................................•..................... 5-1085.11.2 ImageMOde s.,C.:t.: : :..•... l':..... .. .. ·,;:;·..:_"0•••,,, .5-1095.11.3 Wide SMwadthM?~e .).i.').'; '.;:.::: ':: . . . <····;;;.,::~~:·k:.·'.'.·:.;55if105.1L4 Wave . o. ':.. ···.:::v·~·'"''.'.9'Jl·::.:>'.'.' ; 1••••••••• ;1105.11.S Globaf.Momtonl'lg·,Mode...•;·, · :... .. .. .. . . . s..1115.11.6 Altematin1fPolansa~iol1iMode'<.'.:'.'.:.. .. . s.:1135.11.7 External Characterisation·Mode............ . 5-114S.11.8 Module Stepping Mode...... .. . .. .. S-114

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ENVISAT-1 PAYLOAD

TO

GROUND SEGMENT ICD

VolumeO.

Volume 1:

Volume 2:

Volume J.

Volume4

Volume 5·

Volume6:

Volume 7·

Volume 8.

Volume9:

Volume 10·

Volume l l:

Volume 12·,

--- Volume 13·

Volume 14·

Volume 15.

Appendix A

Appendix B.

Title Page and Document Register of changes

Introduction

Documentation

SystemDescription

Measurement Data Format Definition

Measurei:p.entPata Definition aod Format .:Dcscril>ti<JllforASA:RMeasurement Data Definition and FormatDescription for GOMOSMeasurement Data Definition and FormatDescription for MERISMeasurement Data Definition and FormatDescription for MIPASMeasurementData Definition and FormatDescription for MWRMeasurement Data Definition and FormatDescription for RA-2Measurement Data Definition and FormatDescription for AATSRMeasnrement Data Definition and FormatDescription for DORISdeleted

Measurement Data Definition and FormatDescription for SCIAMACHYPPF/PMCAuxiliary Data Format Description

Print-out of PIMDD Files

Acronyms·List

Figure 5-1 Volume S in the PGICD Structure

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Volumes 1through4 and Volume 5 are applicable to ASAR and forms part of the ASAR ICDData Package. As such, the contents of these Volumes need to be verifiedduring ASAR tests.

Volumes 1 through 4 provide introductory information, the list of applicable and referencedocuments, a description of the ENVISAT-1 System, and the general definition of themeasurement data format, respectively. ·

Volume 5, describes the on-board generation of the ASAR measurement data ~4.provides thedefinition of the source packet structure.that is used. The definition of the measurement ~ataparameters, which are contained in the Data Field Header and the Source Data:Fi~ld,.and·thedefinition of the Packet Error Control Field (if used by the instrument), are provided for eachoperating mode

ACKNOWLEDGEMENT

Volume 5 was generated from inputs (i e documents, technical notes, timelines)provided byMatra Marconi Space These inputs are listed in the PGICD, Volume 2, section 2 2.2

We wish to thank Matra Marconi for their timely responses in providing answers andclarification to our questions and comments

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s.i.r Introduction/. l . i; ,y,\ ...~~·-.-,:}..{{~.\ 1.··

S.1.1.l Summary of ASAR Objeetives'..r..:,;

The objectives of ASAR are very similarto those of ERS-1 and ERS-2. The.main task.is/.t~~

:, ~~ni;~i~~~;~~~~~~.~f~~~~~AJ~;;~~~~'rp~:~~.:':::~~ili~~~~:~~v~~r.m~j~~

Monitoring of the bio-mass all around the Earth, especiallymonitoring of de-forestation ih ttjelarge primev~lforests i~ the equatorial regions, will allow initiation of c:ountermeasures~d ! )better modelhng of the influence on the greenhouse effect and global ,~hmate. )

Desertification an~ distribution of humidity, the change of water levels, flooded areas and t~·extent ~fth~ i~.~ps .'.~p~nd:the North and Sout~ poles are oth~r m~jorfactorswhic~need ob~·moin,tot.ed..·•-m ?f~er.'.m.~•mprovetheun~erstand1ng\o~glob~lclimatic ~hanges.SAR·1m~.·e 1will also further improve the understandmgof ocean dynamics and the mteraction betweenoceans and the atmosphere, as well as the effect of man made and natural processes on thecoastal zones.

I

The major advantage of using an ASAR for Earth observation tasks is its capabilityof tajkin~images during day or night and independent of weather conditions and cloud coverage. Th~weather independent observation capabilityof ASAR is of vital importants for disaster I lassessment. Disasters, such as floods and big oil spills,usually occur during adverse weatherconditions which dramatically reduces the usefullnessof optical sensors.

5.1.1.2 Summaryof ASAR Measurement Principles

5.1.1.2 1 Measurement Principle

The ASAR will produce a two-dimensional image ofa strip of ground (i e the scene), {vhic;histo the side of the PPF flight path, at high resolution, with orthogonal axes defined in th~ rangeand azimuth direction '

The range resolution of a pulsed radar system is limitedfundamentallyby the bandwidth o( thetransmitted pulse The wider the bandwidth the better the range resolution A wide bandwjdthcan be achievedby a short duration pulse However, the shorter the pulse the lower wip b4 thetransmitted energy (for a fixed peak power limitation)and the poorer will be the signal'to noiseratio and hence the radiometric resolution. '

To preserve the radiometric resolution a long transmit pulse is desirable. If the transmittedsignal can be encoded in time during the long pulse, then high range resolution can also b~obtained, since any point on the return echo is then uniquely labelled The technique adoptedby ASAR is to use a long linear frequencymodulated pulse (or chirp) The length of the pulse

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is defined to be consistent with the requirement for the signal to noise ratio, and the chirpbandwidth is defined by the required range resolution. After the received signal has beencompressed the range resolution will be optimised without loss of radiometric resolution.

The azimuth resolution of a real aperture radar system is a function of the antenna length, (thelarger the antenna the better the resolution) It can be shown that a space-borne real apertureradar giving a useful azimuth resolution for points on the earth's surface will require animpractically large antenna. Aperture synthesis offers a means of greatly improving the azimuthresolution.

>:··.'The principle of th,eSA,R depends 09 ·theJse :,ol;.C<>herentradiation together with preciseknowledge ofthe'~t and receive point of the radar pulse For a given target as theplatform moves, the distance from the radar to the target (ie the slant range) changescontinuously, hence the electrical distance changes (ie the number of wavelengths in the twoway path changes)

The significant feature of the ASAR instrument is the active phased array antenna, whichallows independent control of the phase and amplitude of the transmitted radiators fromdifferent regions 'of the antenna surface. It also provides independent weighting of the receivedsignal to eachof these regions. This offers great flexibility in the generations and control of theradar beam, giving the ASAR instrument the capability to operate in a number of differentmodes These modes use two principal method of taking measurements That is, the ASARinstrument may operate as a conventional stripmap SAR or as a ScanSAR

When operating as a stripmap SAR the phased array antenna gives it the flexibility to select theimaging swath by changing the beam incidence angle and the elevation beamwidth. In addition,the appropriate PRF required to ensure acceptable ambiguity performance and to suppressunwanted nadir returns is selected. 'Two modes, using the stripmap technique, are defined forASAR. The first mode is called image mode and the second is called wave mode.

When operating the ASAR instrument as a ScanSAR, the constraint of a narrow swathimposed by the ambiguity limitation can be overcome By the use of an antenna beam, which iselectronically steerable in elevation, it is possible to achieve swath widening. Radar images canthen be synthesized by scanning the beam-look angle and sequentially synthesizing images forthe different beam positions The area imaged from each particular beam is said to form asub-swath. The principle of ScanSAR operation is to share the radar operational time betweentwo or more separate sub-swaths in such a way as to obtain full image coverage of each

ASAR operates according to the ScanSAR principle, as described above, in the wide-swathmode and global 'monitoring mode. These use five pre-determined overlapping antenna beamswhich cover the wide-swath.

An additional ASAR measurement mode, called alternating polarisation mode, which employsa modified ScanSAR technique has also been defined. Instead of scanning between differentelevation sub-swaths, it scans between two polarisations combinations (HH and VV, VV andVH, HH and HV), within a single swath (which is pre-selected as for image and wave modes).

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5.1.1.2.2 CalibrationPrinciple

Calibration is performed by the followingfunctions:

Internal Calibration

An internal calibration loop is built into the ASARequipment The loop includes a set of 640connections made to the Hand V transmit outputs (receive inputs) of each module These are'Combinedthrough a passive network to provide a single connection to the central electronicsThe loop is used to couple transmit pulses at the module outputs into the main receiver chain,and to inject pulses through the modules along the normal receive path Pulses are also routedaround the central electronics. The modules are excited sequentiallyone row at a time acrossthe array for both transmit and receive From the amplitude and phase of these pulses anestimate of the instrument gain at a single reference point can be calculated Observed drifts ofthis estimate may be used to correct for instrumentgain instability

In support of the internal calibration scheme, the modules are activelycontrolled using atemperature compensation scheme. This is includedto maintain the antenna beam patterns attheirground characterised values.

The instrument also provides noise sampleswhich can be used to correct for the noisecontribution in the image

External Characterisation

External Characterisation is a specificactivity, requiringa dedicated ground receiver,performed at commencement of ASAR operations and thereafter at regular time intervalsMeasurements are made of the relativeamplitude and phase of a sequence of transmit pulses tothe ground receiver from each ow of modules in tum Simultaneouslythe transmit pulsesequence is coupled into the main receiver chainby the calibration loop . Measurements aremade of the relative amplitude and phase of the ground received and coupled pulse sequenceare used to determinethe antenna mechanical(TBC}pointing error in elevation, and forcharacterisation of the paths through the calibration loop and from the loop connection to theantenna radiating face.

External Calibration

External calibration is a specific activity, performed at commencement of ASAR operationsand thereafter al regular time intervals, to calibrate the instrument against known ground targettransponders. Three ground transponders are observed in imagemode in different swaths withdifferent polarisationson different passes of the satellite. A few observations are made in wideswath and global monitoring modes The transponder output image magnitudeobservationsmay be used to estimate the overall calibration scalingfactor for the system

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ENVISAT-1

5.1 1.2.3 Related Design Features

The ASAR consists of the following major sub-assemblies and distribution subsystem:

The Antenna Sub-Assembly (ASA), which is a deployable planar phase ¥raycontaining distributed transmit/receive modules which perform the transmit and rfe1yeamplification and beam forming functions for the instrument I I

, I ;

The Central.·..Electro.nics Sub-.As...sem·b·l·y·.v (·C..ESA}, which provides control., data.·~·..•d.\irt.Jgand power ir)~erfaceswith the P,ayloaq $eryice Modules in the Platform, generat th6transmitra,d,ar waveform, and samples ~d. digitises the received radar echoes 1 · •

The lnstru~ent Distribution Subsystem, which performs the interface between th~ tvt'osubassemblies and the interconnections within the CESA

The ASA is subdivided into the Antenna Service Subsystem, the Tile Subsystem and the i 1

Antenna Power Subsystem. The Antenna Service Subsystem provides all the services necessarvfor the proper operation of the antenna. The Antenna Power Subsystem provides power i

switching a~d monitoring of the. active ~ntenna. The.Ti~e Subsxstem applies phase chan~s 4ndpower amplification to the RF signal pnor to transnussron A highly attenuated return e o !signal will be received from the earth The Tile Subsystem will also apply phase changes! andamplification of this echo signal I •

))

The CESA consists of the following subsystems

RF SubsystemControl SubsystemData SubsystemCentral Electronics Power Subsystem

r Digital Bus Unit

The RF Subsystem performs frequency generation for instrument timing and radar sign~l i • •generation, it receives, filters and amplifies the radar signals. The Control Subsystem p~ovikl.es 'Tthe command and control interface to the satellite; it also provides the operational cont ol ofthe various subsystems during the operational modes The Data Subsystem generates t e qhirpsignal, detects the echo signal, digitises the resultant baseband signal and provides the '1tetfaceto the payload data handling equipment. ·

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5.1.1.3 Summaryof ASAR Performance., ,•-. y ·. '.J t'' _; ·(

. . ~Table 5.1.1.3-1 gives an overview on the ASAR performance derived from the measure entsand prediction given in SRcRD12, issue H (Dec 1994f The values in the table are given .orinformation only. ··· ' · "··· · ·· · · · ·

Ima~~'""'""'.j,.~aye'· ~I·~~~h" ·' I;:,~lW~.ti,c>n•I~;,~~~~gParameter unit

Spatial

rlesolutioli ,:Peak Sidel.obe aJ0ng.track : idB.~7~·-!26:6~0.;:?~ 20.~~2<fs·( 20.s- 20~·Ratio ·~rosstrack· 'dB · ·20.s-207 . .. ,21.. ::22.9... 22 o-25. l 20.5-20 1· . ,Spurious ia~~ng·t~¢k'·dB-."\... ;~72 ;. ~: " 2~ 1~272 :; 21.1 · · 21 1> )Sidelobe Ratio ' " .··' , · '· ·.. · ·

20.5

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AJnbigtlify ' Ialorigfrack I 'dB I 23.8•29 6 '·l·26 8-29 6 I 26'9.:.28r "120' 1:.279Ratio PointTargets

~67~26.9

~2.~3o.6Tacross track I dB 22 3-40 5 I28.9-40 s I22.3-30.6 I23.8-35.4along track 21 9.:24.3 I 22.8-24.3 I 23 8-25.9 I 18.9-24.2dBAmbiguity

9.2-35 9 · I 8 8-35.9 I9 2-21.8 I9 2-35 9 9.2-il 8 iRatio Distrib. Iacross track IdBTargets . below

cso minNoise Imargin ldBEquivalentSjgma, actual dBm~I

Radiometric Resolution dBRadiometric Accuracy dBRadiometric Stability dBSwathWidth kmVignette Length km

Width kmSwath ; degPositionLocalisation along track kmAccuracy across track kmAlongTrack Interval kmCross Polarisation dB

0.5-8 l 110q-16.2:l

0.7-8 3 0.8-22 2 66-8.9

-25 0. to -28 I to-21.9 -22.6l.44-1 64 l 52-1 95124-l 33 1.28-1.40032-0 35 0.34-0.37

4064 95-5 04 95-5 015.145 2

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o 05-0 12 Io 05-0 12 Io 05-0.10 Io 05-0 12100 -

23.3-24 o I 23 3-24.0 I23.4-24.0 I 23.3-24.0 23J4-24.(l'

Table S 1.1 3-1: Summaryof A~.ARPerformance

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5.1.2 Operational Modes

5.1.2. l Overview

The ASAR modes are divided into Support and Operation Modes

The Support Modes are, essentially, states which are established in order to achieve ormaintain the desired instrument conditions prior to entering an Operation Mode. The PreOperation Mode (i.e. one of the Support Modes) will be entered whenever the instrumentswitches from one Operation Mode to another Operation Mode.

The Operation Modes are grouped into the following categories.

- Measurement Modes- Calibration Modes- Auxiliary Modes

The Measurement Modes provide the required ASAR operation according to the commandedrequirements.

The Calibration Modes allow the external characterisation of the instrument during theoverflight of the ground receivers.

The Auxiliary Modes provide means for health/test checks and on-ground verification.

Table 5 1.2 1-1 lists the Operation Modes, their relation to the mode groups and themeasurement data rate

Mode Name Mode Group Measurement Data Rate

ImageMeasurement Mode High Rate

Wide Swath High Rate

Wave Low Rate

Global Monitoring Low Rate

Alternating Polarisation High Rate. ,External Characterisation Calibration Mode High Rate

Mod~le SteppingAuxiliary Mode Low Rate

Test High Rate

Table 5 1 2 1-1 ASAR Operation Modes

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5.1.2.2 ImageMode

5.1.2 2.1 ObjectivesI

The ASAR system is required to provide high quality, high resolution images of the m~r,scene

.TheI~age ~ode provides 30m x 3~~ resolution images of l00 km x 100 km in si¥; Thfswath is required to be selectable within a 500 km band. · . 1

S 1.2 2.2 Execution

The ASAR operates as an imagingradar according to the synthetic aperture radar (ASAi) )principle. It collects data from a swath of nominally100km wide to the right of the sadite )ground track, forminga continuous strip in the flight direction of the satellite.

The !111agingis.perfo~ed by transmitting a _continuouss_eriesof pulses and acquiring th~required echo information after the appropnate return tnp delay i

5.1.2.3 Wide SwathMode

5 1.2.3 l Objectives

ln order to allow imaging over a wider swath than the lOOkmdefined for the ImageMode.lasecond mode has been defined which allows relaxationof the resolution to 1SOmx 1SO~ inorder to ensure a 400 km swath width ·

5.1.2 3 2 Execution

In Wide Swath mode the ASAR operates as an imagingradar according to the ScanSA)Rprinciple. The 400 km swath is divided into a series of smaller subswaths and each sub~wathisimaged for long enough to form a single look before proceeding to the next swath in thesequence. The return time to each subswath is set so as to ensure that the along track imagingis continuous. T-hestrips relating to each subswath can then be merged together in the groundprocessor to form a single wide swath image ·

For each subswath there is a burst of transmissionsfollowed by a short quiescent period whilstthe echoes from the last transmit pulses are received Then transmissions switch to the nextsubswath. ·

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5.1.2.4 Wave Mode

5.1.2.4.1 Objectives

The WaveMode is, effectively, a" sampled" ImageMode, which reduces the data productionrate thus allowingon-board storage of data on the platform tape recorders

.It allows the acquisition of 5 km x 5 km "Wave Vignettes" at regular along track intervals ofabout 100 km. The wave vignette is positioned anywherewithin an ImageMode swath Up totwo positions may be defined for each mode, with each position freely selectable either in oneswath or in different swaths. The two vignette positions are imaged alternatelyat 100 km ·.intervals (thus forming a 200 km separation between successive vignettes in one position).

5.1.2 4.2 Execution

The Wave Mode operates by transmitting bursts of about 3000 pulses, corresponding to animaged length of 5 km The pulses are sampled in the same manner as ImageMode except thatonly a small section of the received echo window is utilized This portion corresponds to aswath width of 5 km.

5.1.2.5 Alternating Polarisation Mode (Copolar. Cross-polar Hand Cross-polar V)


The AlternatingPolarisation Mode is a variation of the Image Mode providinghigh resolutionimages in two polarisations continuously over any of the Image mode swaths

5.1.2 5 2 Execution

During Copolar Alternating Polarisation Mode.the radar operates in horizontallypolarisedtransmit and receive blocks interleavedby verticallypolarised transmit and receive blocks. Inorder to achieve this a scanSAR technique is appliedwhere there are two "subswaths", namelythe horizontallyand vertically polarised blocks. The size of the blocks is selected to ensurecontinuous coverage for each polarisation and hence information from both polarisations isavailableto the user for each imaged area

In the Cross-polar modes. the transmit pulses are allH or all V polarisation,with the receivechain operating alternatively inH and V as in the Copolar mode

Dornier GmbH ' . Date:!0oc No: PO-ID-DOR-$Y-0032

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5.1.2.6 GlobalMonitoring Mode


S.l.2.7 External CharacterisationMode

5.1 2.7.1 Objectives

The external characterisation mode provides absolute calibrationmeasurements during!theoverflight of a ground receiver. I

S.l.2 7.2 Execution

The measurements start with a set-up period comprisinga coded sequence to initiate data]recording in the ground receiver, followed by a transmissionwhich is recorded and usqrl.•t~extract the underlyingcarrier Onlyone column of the antenna array is used for this se--u~period. This provides a wider footprint which allows a longer time to acquire lock.

1

For a single cycle of the mode, each row is transmitted in a predefined pseudo-randomsequence using-unmodulatedpulses. The cycle is repeated during the 0.5 second satelliteoverflight time of the ground receiver 1

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5.1.2.8 Module Stepping Mode ·

5.1.2 8.1 Objectives

5.1 2 8.2 Execution

) Each of the 320 modules is cycled in a pseudo-random sequence, firstlyusing the auxiliary) I receiver to couple the transmit pulse back through to the ADC and secondlyusing the auxiliary

transmitter to couple the pulse back through the main receiver This is performed for thevertical or horizontal polarisation chain.

The Module SteppingMode provides an internal health checking facilityon an indi.vidualmodule basis The calibration paths to and from the antenna are used for this, al~~:Oiighmeasurements are not intended to provide calibration information The purpo~qf~h,e mode is.primarilyto identify~y malf.'Jn~tioningmodules to allow them to be switcfied~<>tf;iftj~ss~uj.and to identifymodul~ for'\~~~~~~i~r&fl~n offsets are to be applied '.·:;·<_:; ·;/· . ' · ·

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5.1.2.9 Test Mode

5.1 2.9 1 Objectives

The Test Mode is used only during the ASAR on-ground verificationprocesses

5 l.2.9.2 Execution

The execution of this mode is dependent on the test in operation.

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Doc. No.: PO-ID-DOR-SY-0032\ ~mierGmbH Issue: 5 Date: JO 04 9q

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5.1.3 Operations Constraints

TBD

The transmit pulse characteristics are set within the Data Equipment by coefficients in a DigitalChirp Generator which supplies In-phase (I) and Quadrature (Q) components. The signal isgenerated between I kHz and the selected bandwidth as a linear up-chirp over the chosen pulsewidth which is modulated onto an Intermediate Frequency (IF) from the oscillator within the

) I RF Subsystem The output of the Data Subsystem is a composite "chirp" of rising frequencycentred on the IF carrier. Pre-distortion of the chirp can be achieved by modifying thecoefficients placed into the chirp generator in order to compensate for some instrument errors.

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ENVISAT-1

5.1.4 Acquisition of Observation/Calibration Data

The ASAR Instrument is controlled by its Control Subsystem (CSS), which provides thecommand and control interface to the satellite The CSS also provides the operational controlof the ASAR equipments during the operational modes.

Using the data supplied from the ground in conjunction with the pre-programmed operationcharacteristics the Control Subsystem sets up the appropriate control, timing characteristics(e.g. pulse repetition frequencies and sample window timings) and data information (e.g.transmit pulse and beam characteristics) which are required for the selected mode.

These operation characteristics are maintained and managed using the following set ofParameter Tables

Beam Data Table;Image and Alternating Polarisation Modes Parameter Table;Wide Swath Mode Parameter Table,Wave Mode Parameter Table;Global Monitoring Mode Parameter Table,External Calibration Mode Parameter Table,Module Stepping Mode Parameter Table

The use and interpretation of the information in the Parameter Tables is the key to theacquisition of the ASAR measurements and calibration data.

Acquisition of Observation Data

The signal is then passed to the RF Subsystem where it is mixed with the local oscillatorfrequency to generate the RF signal centred on 5 331 GHz.

The upconverted signal is then routed via the Calibration/Switch Equipment to the antennasignal feed waveguide At the antenna the signal is divided within the waveguide network,firstly by 1.5 to feed each of the 5 panels on the antenna and secondly by 1 4 to feed the fourTiles on each panel.

The TR Modules apply phase and gain changes to the signal in accordance with thebeamforming characteristics, including compensation for temperature effects The signal is thenpower amplified and passed via one of two feeds (V or H) to the Tile radiator panel

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ENVISAT-t

Pulse Generation ! II !

Chirp Modulation Upconversion I

1--t H.··Generation onto IF to RF

4 CAU 1-tSWITCH t :

~- Equipment i... ~nt~nna1·

.--- - ----------- -· --- .. ----·- ---- ----------·-Receive Chain

Digital Data - ADC ~- Demodulation ~ Downconversion1-1 '-

Processing to Baseband to IF

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Figure 5.1.4-1: ASAR Functional Overview

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Echo signals are received through the same antenna array, passing to the TR Modules for lownoise amplification and phase and gain changes which determine the receive beam shape. Theoutputs from each module are routed at RF via the corporate feed and antenna RF distributionsystem which acts as a combiner, effectively adding signal inputs coherently and noise inputsincoherently. ·

The signal is passed to the demodulator where it is divided into two channels for mixing withthe respective I and Q components of the IF carrier.

Then the I and Q baseband components are digitised following anti-aliasing filtering The datais packaged into a pre-determined configuration, with auxiliary data, and passed to the DataManagement System of the payload.

Acguisition of Calibration Data

The precise details of the operation of the internal calibration scheme depend on the modebeing used. but in essence, the technique is common. The aim is to characterise the active partof the antenna on a row by row basis for both transmit and receive using special calibrationpulses and the calibration loop, and also to characterise central electronics gain drift

In outline the calibration scheme operated as follows:

The aim is to measure the characteristics of one row of modules with minimal interferencefrom signals from other modules. Each module shares a power supply with three othermodules. In order to avoid the potential problem of the transmit characteristics of a rowvarying due to different power supply loading, rows are driven by the calibration pulses ingroups of four corresponding to the power supply demarcations For each calibration pulsethere is one 'wanted' row out of the four driven whose characteristics are to be measured. Themodules within the wanted row take the amplitude and phase settings appropriate to normal

. operation of the mode and swath being used.

The phases of the modules in the unwanted rows are set so that their combined signal out ofthe calibration loop is nominally zero The amplitude setting on each of the unwanted rows isset to its normal operating value to produce the same power supply loading as in normaloperation. -,

Pulse 1 (sense wanted row transmission)

For a particular PRI. the modules in the wanted row and the three unwanted rowsusing the same power supply are set up as described above, while all other modules areturned off A pulse (referred to as Pulse I) is sent to the antenna along the normaltransmit path and the combined output of the calibration loop produced by the wantedrow is fed into the auxiliary (TBC) receiver chain and digitised at the receiver output.The combined output also contains a residual contribution from the three unwantedrows, due to imperfect cancellation arising from module setting errors.

The Pulse 1 output is influenced by the central electronics transmit and receivecharacteristics as well as the characteristics of the wanted row of modules on transmit

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\ Dornier -GmbHProject:


Pulse JA (sense unwanted row transmission)'"

During the next PRI (TBC) all nfodules are turned off except for those in the threeunwanted rows, which retain the phase and amplitude ~~t_i9gsused above.anda pulse(referred to as Pulse IA) is sent to the antenna alongthe normal transmit'path."Theco~~ined ou~.putoft~~ cal~J>r~iW~:l~p~prod~ced by.t~eunwanted rows i.~f,~}nto theauxiliary receiver cham (TBC)·anddigitised at the receiver output. . ·:·,.\'' "·

This provides a,,m~~r~.·~Qh~ ~~id~~Icontributionfrom the unwantedtq~s to .Pulse.. . '·.t· ·:'" ''.!:.·'·:~{{·~·~·;'~,:::1·;,-1::.1 ,..; ..:·;1··, ". .:;·i.;:.; .: .; -~.:... ,..) ...~WAtt~.'."·.

.,Pulse 2 (sense wanted row receivers)·1

During a different PRI, a copy of the transmit pulse (referred to as Pulse 2) is injectedinto the ca"ibq~tionloop network from the central electronics. This pulse is received bythe modules iil the wanted row which have their normal receive settings, and passesalong the.n.u1ij!1 ASAR receive path to the ADC All other modules are turned off duringthis measu,rem~nt

The Pulse 2 output is influencedby the central electronics transmit and receivecharacteristics as well as the characteristics of the wanted row of modules on receive

Pulse 3 (route around central electronics)

During a different PRI, a precise copy of the transmit pulse (referred to as Pulse 3} isrouted around the majority of the central electronics transmit and receive circuits, andis digitised at the ADC. The path excludes the final transmit gain stage, and the frontend receiver gain stage in the central electronics.

This provides an independent measurement of the central electronics.•

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5.1.4.1 Pulse Generation

5.1.4.1. l ChirpWaveform

The ASAR utilises a pulse waveformof a linear frequencymodulated pulse with risingfrequency, i.e an up-chirp. · .

All chirps needed by a mode are calculated at the beginning of this mode ASAR is ca~e ~calculating and storing up to 5 chirps, (one per subswath). 1

The ideal chirp waveform is givenby the formula.

S(t) = exp (jnut") -T,12 s t ~T,12

where

µis the FM rate of the chirp [Hz] defined as:

µ=BITp

TP is the pulse length [ls] definedas

T i: T IfP L . .~om

with

TL= the pulse length [clock intervals]f!klm= Radar SamplingRate [MHz]

Bis the pulsebandwidth [MHz] defined as

withN8 = the S-bit chirp bandwidth codeword

S.1.4.l.2 Offset ChirpWaveform

In modes where an offset frequencyis included the ideal pulse waveform becomes

- T PI) SI S T" I 2

wheref01T is the centre frequency offset.

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5.1.4.1.3 Predistorted Chirp Waveform

The generated pulse waveform entering the modulation chain is given as

S' (t) = S(t)g{t) .. -T,12 s t <5.T,12

with the predistortion function

with na=np=2.

The predistortion coefficients Iii and Bi are commandable via macrocomand The coefficientswill be selected in order to compensate for the amplitude error, which is introduced bygenerating the chirp using discrete signal samples, with values held by the Digital to AnalogueConverter (DAC) during chirp sample intervals. This gives rise to the 'holding' effect shown infigure 5.1.4.1.3-1.

The predistorted chirp is shown in figure 5 1.4 1.3-2

-2

0Time in PuIse (us)

20

Figure 5.1.4 1.3-1. Distorted Chirp in Time Domain (Generated at 38.4 MHz)

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/ Figure 5.1.4.1.3-2. Pre-distorted Chirp in Time Domain (Generated at 38.4 MHz)

-5.1.4.1.4 Chirp Selection

After selection of a chirp, the coefficients are stored in the chirp generator unit and, on receipt of apulse trigger control, they are clocked out at a rate equal to twice the sampling frequency Thedigital samples clocked out of the chirp generator are converted to analog with any n~essaryfiltering to. ensare smoothing of the quantisation effects The resultant signals are the I :and Qcomponents of a chirp at baseband The chirp bandwidth at lF will be in the range ,O4 MHz to 16 MHz, the precise value is given by the Chirp Pulse Bandwidth codeword in thesource packet Data Field Header

5.1.4. l 5 Modulation onto IF

The baseband chirp l and Q component signals are each low pass filtered to remove unwantedfrequency components before being modulated onto the lF by mixing with the output of thefrequency generator and then added, thus producing the chirp signal centred on lF (TBD)

The signal at IF is then be amplified to a level suitable for supply to the upconversion process

• IIL_ ==

~)

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Dornier GmbH TDoc. No: _PO-ID-DOR-~~-~?~~

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5.1.4.1.6 Upconversion to RF

The upconversion process mixes the IF signal with a local oscillator frequency derived from thesame frequency generator to provide an RF signal at the desired transmission frequency. Theupconverter provides a controlled gain amplification which is set via the control function of theASAR instrument. The level of the gain amplification is provided with the measurement data. Thelevel of upconverter output has to be set to maintain a constant input to the antenna throughout the

. .mission and over the'teffiperature ranges experienced around the orbit.

5.1.4.2 Antenna

5.1.4.2.1 RF Signal Routing

·The RF signal routed to the antenna has to be distributed to the transmit receive modules. In orderto ensure that the signals received at each of the TR modules are nominally identical, compensationfor the different path lengths to each module is provided within the distribution network

The distribution of RF signals on the antenna has to effectively provide a 1:320 division ratio. Thisis broken down into three logical stages:

al 5 division to feed each of the 5 mechanical panelsa I :4 division to feed each of the four tiles on a paneland a I ·I6 division to feed each of the 16 modules on a tile.

On receive, the same distribution network is used to combine the echo outputs from each of themodules adding the echo signals coherently and the noise signals incoherently.

5 1.4.2.2 Phase and Amplitude Setting

Phase and amplitude of each of the TR modules are set to provide the requested beamfonningcapability of the antenna. Each swath has a different excitation requirement determined by the beamdirection and shape in elevation.

The beam data are stored within a table held in the Central Electronics, as outlined in Figure5.1.4 2 2-l.

From this figure it can be seen that

the Beam Data Table contains 'several Antenna Beam Setseach Antenna Beam Set contains one ore several Antenna Beamseach Antenna Beam contains 20 Tile Beams one beam for each Tileeach Tile Beam consists of 16Beam data words one for each TR module

--···-·-·---·---·--·-~·---~------

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uate:

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T\l.E 1 PANEL A+ITILE 2 PANEL A I

SE.AM0 •

IT\l.E 3 PANELEuIlll.E 4P ANEL E TIInu: , PANELA1 SE.AMDATA WORD FORMODU

TILE 2 PANELA I BEAM DATA WORDFORMOOU

BEAM 1:BEAM DATA WORDFORMODU

T\LE J PANEL EI BEAM DATA WORDFORMODU :3

TILE 4 PANEL E T BEAM DATA WORD FORMOO ::'BEAM DATA WORDFORMOOU ,_5

BEAM DATA WORD FORMODU ': 6

SIBEAM DATA WORD FORMOOU :7

\ BEAM DATA WORD FORMODU =aBEAM DATA WORDFORMOD i:9

jTIL.E1 PANEL A ~ \BEAM OATA WORD FORMOO = 1

BE.AMDATA WORDFORMOO L.E1

!TILE 2 PANELA I. SE.AMDATA WORD FORMOD LE 1

BEAM N(i}-1 ·

T\l.E 3 PANEL E t 1 \1 BEAM DATA WORD FOR MODULE15

T [ H(1) I N(O)N(3) I H(2)

N(ml IN(m-1)ANTENNABE.AMSETO

enQc:0~..,..0N

\

jTIL.E4 PANEL E T!TILE 1 PANEL A 1\!11LE 2 P AMEL A 1 l

\l: aEAMN(i):

T1LE3PANELE 1·TILE 4 PANEL E f

I ANTENNA\ 3EAM SETm

'..LI !• SE.AMDAT A WORD:

• o 1 2 1 a 9 10 15

PHASECODEWORD

LSBMSB

Note: BeamCountN is: 1 s; N s 64

Size oi Beam Seti is:. ,S = 16 • 20 • N(i) Words

The sum oi all the beam set lengths N(i) shall be:

Figure 5.1.4.2 2-1 Beam Data Table

Issue: '\

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))


5.1.4.3 Receiver Chain

5.1.4 3.1 Downconversion to IF

The receive chain provides filtering ensuring that interfering signals are suppressed to the desiredlevel.

The radar signal is downconverted from RF to IF.

Variable gain control is provided by use of a programmable stepped attenuator giving a0-31 dB range for lifetime and temperature effects. The level of the attenuator is provided with themeasurement data.

5.1.4.3.2 Demodulation to Baseband

After IF filtering and amplification, the signal will be divided into two paths one of which will have a90 deg. phase shift applied to establish In-Phase (I) and Quadrature (Q) channels.

Each channel will be mixed down to baseband, low pass filtered to the desired bandwidth and thensampled with an analog to digital converter at the same rate as that used for the chirp generation.

For all modes except Global Monitoring, a Sth order elliptic filter is implemented to achieve apassband of 0-8 5MHz and a steep roll-off whilst retaining close to linear phase in-band

In Global Monitoring mode a 4th order elliptic filter is provided to achieve a passband of0-0.S MHz.

The I and Q signals differ by about 212 in phase such that the Quadrature signal Q lags the In-phasesignal I by 212. In the receive chain an orthogonality error may be introduced. Thus I and Q can berepresented by

l(t) = R(t) cos[ <l>(t)]Q(t) = R(t) sin [<ll(L) + ~<l>]

where ;-

R(I) is the instantaneous amplitude of the IF signal at time t.

0(t) is the phase difference between the IF signal and the local oscillator at time t

~0 is the orthogonality error

Dornier ombHItoe. t>.-' PO-ID-DOk-!1\'-00. 32I issue: 5 Date: ~0.04.99

Proiect: Sheet: 5-25ENVlSAT-1

5.1.4.3.3 ADC +

The ADCs used to quantise the I and Q channel signals for ASAR produce 8 bits sampl_j[ in theoffset binary format. The ADC quantisation is illustrated in Figure 5.1.4.3.3-1·. i

i

The codeword assigned as the I or Q sample output, illustrated in Figure S.1.4.3 3-1 is such ~at

;Sn-I ~VIN < Sn,1~n~127,VIN <Sn.s, ~VIN <Sn+i~-121~ns;-1,V,N < S_1211;1~n::;;127

T,,Ti211

Codeword =~T ·.n

T_l28

where7~ are the selectable codewordsSn are the input voltage thresholds used for codeword selectionViN is the analogue input voltage

The thresholds are centred about zero volts such that So = 0 V nominal

The input power and voltage levels for a particular sample are related by the following equation!

where

Pi is the sample power levelvi is the sample voltage level·Psai is the ADC saturation power levelVsai is the ADC saturation voltage level

The power at which both I and Q ADCs simultaneously saturate has a nominal value of-10 dBm.

This equates to an individual ADC saturation level of-JO dBm+ IOloglO[O 5]=-13.0 dlsm.;

\I)

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Codeword11111111

a:~s0

"'g

11111110

11111101

10000010

10000001T3T2T1~~~,--.,r--~,-.-,___,,,~~-.-,-r-1

S-127 S-125 5-123-- S-3 S-1

10000000

01111111S123 5125 S127

01111110

T.1241 00000100

T.12s 00000011

T.126 I 00000010

T.121 1 00000001

T.1;a 00000000

Figure 5.1 4.3 3-1.. ADC Characteristics

;

The errors inherent in the non-ideal ADC will produce a non-linear relationship between the outputsample code and the corresponding input voltage level, Ti with additional errors due to gainimbalance and DC offset

Non-Linearity

The deviation of the output values from the ideal ones for both Iand Q Channels

I

Dornier GmbH IDoc. No.: PO-ID-DO~-~Y-0~32Issue: e Date: I 1n n~ oo

IISheet: 5-27ENVISAT-1

Gain imbalance ;< ··<·· .·.··.·l . ' .

The gain of the I and Q channel is giy~ byth~ slope of the best fit straight line through theoutput value versus input level f6r thfl and Q channels respectively. The gain imbalancethe Iand Q is the difference in the slopes of the two lines produced for Iand Q

Gain Imbalance = 20 log10(S') ·.·. SQ .

where s, and Sv a~ethe slopes oftheJ'.an<J.Q.~hs respectively.~--. , '.V' ? «: ';~>'.t;·.:-, .·· ·. ·. >

DC Offset : . 1

The DC offset for.each..o..f~he,1 and Q ch~nbls is given by the intersection C1and ~of th~ bstraight line (through J~~graph of output; value versus input level for the I and Q ~hrespectively) witJl:the coded olltp'ut voltage axis (see Figure 5.1.4 3 3-1)

' /:·. .

fit )els )

Ichanne·:·/.;.;D(·:·:ouset= ·[-. Ci ]···.* .100%··· · · : .· ·w• · 127.5

Q channel DC offset = [~] * 100%127.5

5 .1.4 .4 Digital Data ProcessingI

The data transmission rate requirements for the instrument restricts the quantity of data th4tcan be collected for transmission in each mode In order to maintain the instrument Iperformance the raw digitised data is processed in such a way as to reduce the amount lof

1transmitted data whilst accommodating the specified dynamic range 1 i ~

For example given the parameters

Maximum Data Rate= 97.5 Mb/sSampling Frequency =:: 19208 MHzEcho Window Length= 300 µsPRF=2050Hz

, Iimplies that 5762 samples are to be transmitted in 488 us, corresponding to a rate of :12* 106 samples/sec. This limits the sample length to 8 bits (i.e. 4 bits land 4 bits Q), ~ t~atthe raw digitised 16bit data samples (8-bits I and 8-bits Q) need to be processed to redudetheir length.

5 1.4 .4. I deleted

-- -- - _l -

Quantisation when used in 'the sense hereafter, is identified to represent the post-ADC datacompression functions.

J Quantisation takes place after any filtering and resampling performed for the dataI

The data compression techniques used by ASAR is described in the following section in termsof the sample and codeword formats given in Figure 5 I 4 4 3-l

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5.1.4 4.2 Data Resampling

The resampling function reduces the effective sampling rate by transmitting one in every Nsamples. The resampling factor N is a programmed integer in the range 1 to 64.

·s.t 4.4.3 Quantisation

0 1 2 3 4 5 6 7

1s I DI I 02 I 03 I 04 IDS I 06 I 01 I 8-bit sampleMSB LSB

0 1 2 3

js I Cl IC2 I CJ I 4-bit codewordMSB LSB

0 I 2) I js I Cl I C2 I 3-bit codeword

MSB LSB

0 1

1s I Cl I 2-bit codewordMSB LSB

;

Figure 5 I 4 4.3-1. Bit Identification for 8-bit Samples and Codewords

5.1.4.4.3.1 Quantisation - Averaging Mode

For Averaging Mode the 8-bit samples output by the I and Q channel ADCs are compressedusing the Flexible Block Adaptive Quantiser (FBAQ) in the following manner.

a Each 8 bit sample is converted from offset binary format to sign-magnitude formatThe transformation from offset binary format to sign-magnitude format is given by

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S,,;gn-magni111t1e = INV [S<!D"...,,~,"""']

;s<!D"•t-bi"""' = 0~Soffw1-bint1f)'= I

whereS is the sample sign bitD is the sample magnitude (D lD2D3D4DSD6D7)INV[ x] is a function inverting the bits in x

b.

I

I

The FBAQ divides the data from a sample window into a number of blocks oflerigtH W16 bit words (each containing an 8-bit I sample and an 8-bit Q sample), plus a Iremainder block. W depends on the compression ratio selected, see Table 5.1.4 4.3~1.

8/4 I 8/3 8/2

4 3 2

256 64 64

63 I 84 126

I~12 I~1264

7

Compression Ratio

Output Codeword Length (bits)

Number of quantisers, q

Length of sample data compressed as one block, W(16 bit words)

3 scaling factor, S

Number of QTLs defining symmetric quantiser

Table 5.1 4 4 3-1 Averaging Mode Parameter Definition

c. The following operations are performed on each block of data :

1. For blocks of length W words a quantiser is selected using a QuantiserSelection Code (QSC). The QSC is calculated, by taking the running total.of land Q moduli for the W sample words of data in a block divided by the scalingfactor S for the chosen compression ratio, according to:'

where3 is the QSC

11. For residual blocks the QSC for the previous block is used to select a quantiser

111. Each 8-bit sample is compressed to a 4-bit, 3-bit or 2-bit codeword, dependingon the compression ratio chosen, by comparison with the QTLs of the selectedquantiser according to the following equations

s..0.;;0

~0

J Jv.v-..,,

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8/4 Compression

{

0002CIC2C3 = m

1112

;D < QTL(QSC,O);Q1L(QSC,m- I)~ D < QTL(QSC,m),O «m s 6~D ~ QTL(QSC,6)

8/3 Compression

SJ-bi, = SS-bi,

{

00~

ClC2 == m112

;D < Q1L(QSC,O),Q11J(QSC,m- l) s D <QTL(QSC,m),O <ms 2

, lJ ~ Q1l(QSC,2)

8/2 Compression

•.c.;2_,,;, = sc~-bit

;D <QTL(QSC,O),D ;;::QTL(QSC ,0)

whereDis the magnitude 01020304050607 of the 8-bit sampleQTL(QSC,x) is the x'" Quantisation Threshold Level (QTL) in thequantiser selected by QSC for the given compression ratio

iv . The Block ID code given by

l:(IIl 1 IQI) IRII

where R = 64 for 8/4 CompressionR = 128 for 8/3 and 8/2 Compression

is appended to the beginning of the compressed data block

The output codewords are therefore expressed in sign-magnitude format.

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5.1.4.4.3.2 Quantisation - Sign +Magnitude Mode [Fixed Exponent] '

For Sign +Magnitude Mode [FixedExponent) the 8-bit samples output by the I and Q c I:annelADCs are compressed in the followingmanner. . ~

l"'l"Ol8Ct:

ENVISAT-1Sheet:

a. Each 8 bit sample is converted from offset binary format to sign-magnitudeformat.For the transformation from offset binary format to sign-magnitudeformat see seetidn5.1.4.4.3. l. I

b. An 8 bit sample is converted into a 4 bit codeword according to

S4-bil = Sil-bit

C'lC2C3 = {/JSIJ6/J711\,

/JlD2DJD4DSD6D1 <00001112

DlD2D3D4DSD6D1~00001112

) I

Thus the output codeword is expressed in sign-magnitudeformat.

5.1.4.4.3.3 Full 8 bit Quantisation

For Full 8 bit Quantisation the sample is not compressed and the ADC output remainsuntouched in offset binary format

;

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A functional overview on the acquisition of the observation/calibration data is given in section5.1.4 and Figure 5.1.4-1 ·

-In the following sections summary tables on the related ASAR parameters together with somenominal values and ranges are given, for additional information on the nominal values andranges refer to SR_RD 11.

For the interpretation of the measurement data the information provided in the source packetstogether with the measurement data and the parameter characterised on ground (ref.SR_RDIO) have to be used

An overview on the pulse characteristics for the transmit and calibration pulses in Image Modeis given in Table S.1.S.l-1

IENVISAT-1

5.1.5 Generation of Measurement Data for the Image Mode

S.1.S.1 Image Mode On-Board Data Processing

5 I .5. I . I Pulse Generation

The generation of the pulses is described in section S l 4 l

Parameter nominal value/ I reference/remarkrange

f••m IRadar Sampling Rate 192 MHz characterised on groundCI RADAR SAMPLING RATE

RF IRadar Frequency I 5.331 GHz I~har~cteriscd~n ground -_Cl9_RADAR_FREQUENCY

Tp I Pulse Length 116µsto corresponding to a TX duty ratio of 2.5%41.3 µs to 6 512%, can be derived from TL

TL IPulse Length providedwith the measurementdata,[samplingclock ref section 5 2 3.20intervals)

B IChirp Bandwidth Is- 16MHz I characterised on ground,C23 CHIRP BW- - -

Ns I Chirp Bandwidth providedwith the measurementdata,Codeword ref section 5 2 3.22

foir IBasebandOffset na no offset frequency included in imageFrequency modeI

Upconverter Level O - 7 5 dB providedwith the measurementdata, ref.section 5 2 3 16

Table 5 l.5.1-1 Summary of Pulse Characteristics

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I

5.1 5 1.2 Antenna ' I ~

For a description on the antenna refer to section 5 1 4.2. An overview on the beam dataparameter for the Image Mode is given in Table 5.1.5 1-2;

provided with the measurement data, rer.section 5 2.3 6characterised on ground, TBD

characterised on-ground per swath,C25 ANTENNA PATTERNS- - -

characterised on-groundC25_ANTENNA _PATTERNS

Parameter nominal I reference/remarkvalue/range

Number ofBeam.S,~~s : I., ,_1··~: L~..be~?1.~.~tper swath r1·

I

Beam set number

RelationBeam set number - Swath

1 - ISl2-IS23 - IS34- IS45 - ISS6- IS67 - IS7

Table 5 I 5. I-2· Summary of Beam Data Parameter

))

I

I ·tit.

Antenna Elevation Pattern

Antenna Azimuth Pattern

I

l

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5.1.5.1.3 Summary of Receive Chain Characteristics

The receive chain is described in section 5 I .4.3 An overview on the receiver characteristics isgiven in Table 5.1.5.1-3

Parameter nominal reference/remarkvalue/range

Downconverter Level 0- 31 dB provided with the measurement data, refsection 5.2 3.17

Non-orthogonality between I & ± 50 characterised on-groundQ,60 _C35_I/Q_PHASE _ERROR

ADC input voltage thresholds, characterised on-ground, TBDS0, n=-127, .. 127

Gain Imbalance <0.25dB characterised on-ground_C34_1/Q_RATIO

DC Offset ±4% characterised on-ground_C33_I/Q_OFFSET

Resampling Factor I provided with the measurement data, refsection 5 2 3 24

Quantisation Echo AV 8/4 AV= Averaging Mode,Scheme compression ratio is provided with the

measurement data, ref section 5.2.3 7

Noise FE 8/4 FE 8/4 =Sign+ Magnitude Mode [FixedExponent]

Initial Cal FQ 8[8 FQ 8/8 = Full 8-bit Quantisation

Periodic Cal FQ 8/8 FQ 8/8 = Full 8-bit Quantisation

Quantisation Transition levels characterised on-ground, _C41(QTL)

Table 5 l 5 1-3 Summary of Receive Chain Characteristics

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S.l.S.2 Source Packet Generation for the Image Mode

5.1.5 2.1 Mode Time-Line for the Image Mode

The Image Mode provides continuous coverage over a single swath nominally l 00 km wid~For nominal operation seven swaths (i e. IS I through IS7) are defined which provide the i_required performance over a 500 km region. The imaging is performed by transmitting a 'continuous series of pulses and acquiring the required echo information after the appropri~ereturn trip delay The mode timelines are summarized in Figure 5.1.5.2-1. I

II

After transition to lmage Mode an initialisation sequence is performed, comprising astabilisation period, noise measurements and initial calibration sequence

Following the initial noise/calibration sequence, the echo measurement commences. The . ! ) 'continuous echo measurements are interrupted after every 1023 PRI for one PRI, which i$used to download calibration data. The calibration sequence occupies four PRls within the1024 PRI cycle but of these only one echo is corrupted

. :r----1:iL-J

0·1:\ .Ol Ip

STABtUSATION '...1X OF1=(R PRI)

,.~...,z•la• is':1: :i:. . . .

. d. d. d. 0:..,•....: ; : : : :~--·:I It !CJD I I

..:1:

CALIBRATIONSl!QUENCE (4 PRI)

PULSE TRANSMITION

SI .i CAL DATA TRANSMISSION '~ (1PRI) :

Figure S l 5.2-l · Image Mode Summary Timeline

'l f\ f\A f\f\

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Image mode continues. uninterrupted. until the receipt of a macro-command to enter anothermode. The current cycle is completed, another noise measurement is made - similar to that atthe beginning of the mode, before the instrument begins its transition to Pre-Operation mode.

Initial Noise/Calibration Sequence

This sequence starts with a transmitter off period, i.e. the transmission is interrupted for up to16 pulse repetition intervals (PRls). allowing the echoes to die away before making noise·measurements as part of the initial calibration cycle.

During this sequence, all 32 rows of the antenna are calibrated by using the different calibrationpulses as described in section 5.1.4. Following the noise acquisition (duration 8 PRis), pulse 2measurements are made for each of the 32 rows of the antenna Then a reference path (pulse 3)measurement is made. Finally pulse land IA measurements are made for each of the 32 rows.The initial calibration sequence is illustrated in Figure 5.1 5.2-2.

32nd row•........• lst rowIsl row•........• 32nd row4 • •

Noise Measurement(8 PRI) D·D

+--P2--+ P3+--- PlaPI---+

rnInitial·Cal Sequence(97 PRI)

__...I Pill

Figure S l.S 2-2· Initial Noise/Calibration Sequence

The default calibration row sequence is given in Table S l 5 2-l This pseudo random sequenceused to step through the Antenna rows is the same for both initial and periodic calibration Thesequence may fie modifiable by patching

The initial calibration sequence is performed with Cal Order 0, for definition see description forperiodic calibration and Figure S. I .S.2-3

Dornier GmbH

ENVISAT-1

order row

1 0

2 4

3 8

4 12

5 16

6 20

7 24

8 289 IlO 5

order row11 912 13

13 17

14 2115 2516 29,17 218 619 1020 14

order row21 18

22 22

23 26

24 3025 326 7

27 1128 15 {29 1930 23

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l

Sheet: 5-37

order row31 27

32 31

Table 5.1.52-1: Default CalibrationRow Sequence

Echo Measurement

The detailed timing for the echo measurement sequence as seen in the data subsystem i~shown in Figure S 1 S 2-3 The associated timingvalues are shown in Table S 1 S 2-1.

1 signal propagation time

OST

•12 ---;

RX echo ofTX pulse n-R

.__ -r-_.,_ - - - - - - I I I

I SWST

I l"~tSWL -...

Figure 5.1 5.2-3: Timing for Echo Measurements

The figure shows timing for a pulse repetition interval (PRI), the PRis are repeated in

,) )

Dornier GmbH 1Doc. No.: PO-ID-DOR-SY-0032Issue: 4\ Date: 10 04 QQ

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ENVISAT-1

accordance with the mode timeline shown in Figure 5 .1.5 2- l .

Parameter nominal value/ reference/remark.PRIrange

PRF Pulse Repetition 1580 - 2150 Hz minimum,maximum and incrementFrequency characterised on ground

C7 PRF MODES- - -PRI Pulse Repetition l/PRF provided with the measurement data,

Interval ref. section 5.2 3.13

Tp Pulse Length 116µs- provided with the measurement data in41 3 µs terms of sampling clock intervals,

ref section 5 2.3 20

dtl Tx path delay the sum dt I+dt2 is characterized on

dt2 Rx path delay ground, CJ RANGE GATE BIAS- - - -SWST Sampling Window provided with the measurement data in

Start Time terms of sampling clock intervals, refsection 5 2.3.14

SVTT Sampling Window provided with the measurement data inLength terms of sampling clock intervals, ref.

section 5 2 3. 15

R Swath Rank 9-14 characterised on ground,C6 SWATH RANK- - -

OBT On-Board Time provided with the measurement data, ref.section 5.2 3 3

Table 5.1 5 2-2 Overview on Timing Parameter

Periodic Calibration

During each 1024 PRJ cycle a single row calibration update is made The calibration rownumber is provided with the measurement data, ref section 5 2 3 19.

A typical calibration sequence is shown in Figure 5.1 5 2-4. Information on the pulse types aregiven in section 5. l 4.

The Calibration Order, which can be either l or 0, defines whether the CAL pulse is before orafter the echo sample window For periodic calibration both Calibration Order 0 and I may beused

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4 ..,.... ~ !l!lll ~ mm ••••• rll!!!. ;

..••

:,>~.'".'.

iI/

• ..:.~ '·~·-V·::;.~~-~··_;~:.:~~~J!'·i'*:~.--;·,,.·:···· ·i~:_:~l·:.. pmi1 .... -~-!-~~ . Ml• ; ..·., ·: .~,,. . , CAJ.llM1'10NSIGtl!laCCAIJIRA1IOHORDIR•dt

;.. ';)~.-:.:·:'.~!.~~Jt~:i<:1<:"~:·,.~)·,(·'··'l_;.!... . . : ·' ··.CAL ,.,, '. " ,/'*r,\ I ';CAL,,, .' .CAL'~!, ~· l'UUa,, ,flULIE__J_., :1x ·'• ..,

I !--'-~-. ...!X.,. 1

:~I .II RX l l RX j l RXI ECHO : : ECHO ! J. I ECHO

~ ~ i 1

"".I pm . pm ..:.. PB!•••••• ••• •••~

RXECHO

RXECHO

'CAL'PULRI

,-D.?

l \i ir :

RXICHO

..;...

••

RXECHO

••,. ·-' -·· . '' '.'.'. . Ci*J PERIODIC CAIJBRAl'ION SEQUENCE (CAU8RA110H OIUJEft • 1)

Figure 5.1 5.2-4. Typical Calibration Sequence

_l -· J

/.\

)

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5.1.5.2.2 Generation of Source Packets

In Image Mode source packets are generated for

echo data:initial calibration·periodic calibration:

one source packet per sampling windowone source packet per sampling windowone source packet per calibration sequence (i.e. four samplingwindows)one source packet per sampling windownoise data:

Considering the timelines this leads to the sequence of source packets shown inTable 5.1.5.2-3

Number of source Source packet contents

packets Source Data Type Cycle PacketCount

8 llOISC 0-7

97 initial calibration 8-104

1023 echo 0-1022

1 periodic calibration 1023

I023 echo 0-1022

1 periodic calibration 1023

... . . ...1023 echo 0-1022.I periodic calibration 1023

8 noise 0-7

Table 5 I 5 2-3. Sequence of source packets for Image Mode

;

·1 Doc. No.: PO-ID-DO~-S~ -0002IC>Qo••• • ' noot<>• I 'lh n/I,Q(\ISheet: 5-41

Dornier GmbH

t'l'Of8Ct:

ENVISAT-1 I

In the following sections summary tables on the related ASAR parameters together wit~ some 'nominal values and ranges are given, for additional information on the nominal values 3'dranges refer to SR_RD 11. . 1

For the interpretation of the measurement data the information provided in the source lcletstogether with the measurement data and the parameter characterised on ground (ref. T 1 )

SR RD I0) have to be used. r )- I

II

III

5.1.6 Generation of Measurement Data for the Wide Swath Mode

5.1.6.1 Wide Swath Mode On-Board Data Processing

I

A function~l overview on the acquisition of the observation/calibration data is given in sfcti(>n5.1.4 and Figure 5.1.4-1

5 1.6.1.1 Pulse Generation III

The generation of the pulses is described in section 5. 1.4 .1. An overview on the pulse f Jcharacteristics for the transmit and calibration pulses in Wide Swath Mode is given in 1J'are5.1.6.1-1 I

I

I- I nominalParameter

value/ range

fsam IRadar Sampling Rate 19.2 MHz

RF IRadar Frequency S 331 GHz

Tp IPulse Length I l 1 6 µs to4 l 3 µs

-----

reference/remark

Icharacterised on ground I _ /. !

_Cl_RADAR_SAMPLINq_~TEj

characterised on ground 1

_c19_RADAR_ FREQUE*e

corresponding to a TX duty r~io of2.5% to 6 512% :

Pulse Length [sampling clockintervals]

provide~ with the measurefi e't data,ref section 5.2 3 20 1 1

I IChirp Bandwidth 3 - 16MHz characterised on ground, j

C23 CHIRP BW '- - -B

NB I Chirp Bandwidth Codeword provided with the measurement data,ref. section 5 2.3.22 '

n.a no offset frequency included Jn wide-swath mode ' 1

I

fotr IBaseband Offset Frequency

Upconverter Level provided with the measurement data,ref section 5.2 3 16 I : '

' I•

0-7SdB

Table 5 1.6 1-I · Summary of Pulse Characteristics

I

----- --

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f.. I

I

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Projeet: ENVISAT-1 I I=~::_42'"'-•-· ·rn f\A nn

5.1.6 1.2 Antenna

For a description on the antenna refer to section 5.1.4.2. An overview on the beam dataparameter for the Wide Swath Mode is given in Table 5.1.6 1-2.


Number of Beam Sets 1-6 (5] 1-6 subswaths, [nominal 5 subswaths]

Number of beam per beam 2 I for transmit and 1 for receiveset

Beam set number provided with the measurement data, refsection 5.2 3 6

Relation 15 - SS 1 characterised on groundBeam set number - Swath 16 - SS2

17 - SS318 - SS419 - SSS

Antenna. ..:.levation Pattern characterised on-ground per swath,C25 ANTENNA PATTERNS- - -

Antenna Azimuth Pattern characterised on-groundC25 ANTENNA PATTERNS- - -

Table 5 1.6.1-2· Summary ofBeam Data Parameter

Dornier GmbHDoc. No: PO-ID-DO~-S~-Oq:J2

I I I 1n o4/Q~~'1.; I 1~-1; !

ENVISAT-l ::>-"U i

II

5.1.6.1.3 Summary of Receive Chain Characteristics Ii

The receive chain is described in section 5 1.4 3 An overview on the receiver characteris ICSISgiven in Table 5.1.6.1-3

i

Parameter nominal reference/remark Ii

value/range

Downconverter Level '' 0-31 dB . provided with the measurement data, 1ef.section 5.2.3.17

Non-orthogonality between ± 50 characterised on-groundI & Q, ~" _C35_I/Q__PHASE_ERROR

ADC input voltage thresholds, characterised on-ground, TBD ))s., n=-127, .. 127

Gain Imbalance <0.25dB characterised on-ground !

_C34_UQ__RATIO IDC Offset ±4% characterised on-ground I

_C33_UQ_OFFSETResampling Factor I provided with the measurement data, rel

section 5 2 3 24

Quantisation Echo AV 8/4 AV= Averaging Mode, I

IScheme compression ratio is provided with tiaemeasurement data, ref section S 2 3 7

Noise FE 8/4 FE 8/4 = Sign +Magnitude Mode [l 'ixedExponent]

IInitial Cal FQ 878 FQ 8/8 = Full 8-bit Quantisation I

I

~Periodic Cal FQ 8/8 FQ 8/8 = Full 8-bit Quantisation

Quantisation Transition levels characterised on-ground, _C4 I,TBI)(QTL) I

Table S.1.6 1-3. Summary of Receive Chain Characteristics; I

'

' I.. I

II'Il

I !!

II i

i

Doc. No: Pu-ID-i.JO.K-S Y.-0032Issue: 5 Data: 30.04.99Sheet:, 5-44

Dornier GmbH

ENVISAT·l

5.1.6.2 Source Packet Generation for the Wide SwathMode

5.1.6.2.1 Mode Time-Line for the·Wide Swath Mode·.·.

The Wide SwathMode provides continuous coverage over a swath nominally400 kmwideThis swath is divided into up to·6 subswaths ranging from 60 to 100km Using the ScanSAR,technique ASAR transmits bursts of pulses to each of the subswaths in tum such that on returnto any subswath a continuous along track image is formed. The mode timeline lssummarizedin Figure 5 1 6.2-1. r. ··;.·..· · i ·· '; • ·

After transition to Wide Swath Mode and a ~tabilisationperiod, the initialnoise and calibrationsequence is performed During this sequence all 32 rows of the antenna are calibrated for eachof the subswaihs by use of the calibration pulses. The 105PRI sequence for each subswath isthe same as tM,tusedfor the imagemode with gaps between sequences to allow for echoes todie away before cc>inmencirigthe next subswath. An overview on the Wide Swath Modetimeline parameter.is given in Table 5 1 6.2-1 ·

I - ' , ._-. <. . .. I~--,.~~-·,': :'·~·,_

Following initial'~libratioli.the echo measurement sequence com~ences. For each subswaththere is a burst of transmissions followed by a short quiescent period whilst the echoes fromthe last transmit pulses are received. Then transmissionswitch to the next subswath in thecycle.

The calibrationmeasurements are contained in four PRJ at the end of each subswathtransmission burst. Once the return from the calibrationmeasurements have died away,R (rank)-2 noise measurement are made before the returns from the first transmissionson thenext subswath arrive.

01) receipt of a macrocommand to move to another mode, the instrumentwill complete therepetition cycle that is already underway

Operation is defined in up to 6 subswaths Each repetition cycle mayuse a subswath one ormore times with a sequence limitof twelve subswaths

For details on the timing and calibration sequences refer to the description for the ImageMode, section S.l 5.2

Parameter - nominalvalue/ rangeSubswath'order within cycle characterised on ground,

_C9_WS_TIMELININGNumber of echoes per subswath (M) 37 - 54 (TBC)Number of PRis per subswathSwath Rank (R)

Table 5 l 6.2- l. ·WideSwathMode TimelineParameter

Dornier GmbH

ENVISAT-1

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~ - m •• : E • .,a.. 3: ~ - :;, l! ~ .. c :lo s ~"E: a·~ E- 0 ••• ., - ••. •cc= a:::i: •••••.•0 0. _. u •.c.,- : ~-ti "i ·= 0=iii= o.!! =:; • z~ c i II( o c ~o• ~ iii •.•• z -~ •...

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I~:Dornier GmbHProject:

ENVISAT-1 5-46

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5.1.6.2 2 Generation of Source Packets

In Wide Swath Mode source packets are generated for

one source packet per sampling windowone source packet per sampling windowone source packet per calibration sequence (i e. four samplingwindows)one source packet per sampling window

echo data:initial calibration:periodic calibration

noise data:

The sequence of the source packets is shown in Table 5 I 6.2-2

Number of Source packet contentspackets Data Type Cycle Packet Count

8 noise 0-7 subswath l Initial97 initial calibration 8-104 noise/calibration8 noise 0-7 subswath 2 sequence97 initial calibration 8-104

...8 noise 0-7 subswath Q97 ' initial calibration 8-104 (Q= 5)R1-2 noise O-(R1-3) Isl subswath I lst cycleM, echo {R1-2)-(M1+R1-3)l periodic calibration (M1+R1-2)

R1-2 noise O-(Rr3) I 2nd subswathM1 echo (Rr2)-(M2+Ri-3)I periodic calibration (M2+Ri-2)

Ro-2 noise O-(Rp-3) I P-th subswathMp echo (Rp-'2)-(M,,+Rp-3) I (P>=Q, P<=l4)l periodic calibration (M,.+Rp-2)

...Ri-2 noise O-(R1-3) l l st subswath I last cycleMr echo {R1-2)-(M1+R1-3)l periodic calibration {M1+R1-2)

R1-2 noise O-(R2-3) I 2nd subswathM2 echo (R2·2)-(M'.!+R:i-3)

irperiodiccalibration (M2+Rr2)...

Ri,-2 noise O-(Rp-3) I P-th subswathMp echo (Rp·2)-(M1,+R1,-3)l periodic calibration (Mp+R.,-2)

Table 5.1 6 2-2 Sequence of source packets for Wide Swath Mode

Dornier GmbHl'"l'OjE!C\:


5.1.7 Generation of Measurement Data for the Wave Mode

5.1.7.1 Wave Mode On-Board Data Processing

A functional overview on the acquisitionof the observation/calibrationdata is given in Section5 .1 4 and Figure 5. I 4-1.

·in the following sections summary tables on the related ASAR parameters together wiuascenenominal values and ranges are given, for additional informationon the nominalvaluesranges refer to SR_RD11

For the interpretation of the measurement data the informationprovided in the source t' c,etstogether with the measurement data and the parameters characterised on ground (ref . ) )SR_RDIO) have to be used

5.1 7.1.1 Pulse Generation

The generation of the pulses is described in section S I 4. I.

An overview on the pulse characteristics for the transmit and calibration pulses inWavFModeis given in Table 5 I 7.1-1 I -1

IParameter swath nominal value/ reference/remark I I !

rangeI I

fsam Radar Sampling Rate 19 2 MHz characterised on ground -~· i

_Cl_RADAR_SAMPLING_ ~TE

RF Radar Frequency 5.331 GHz characterised on ground +~

_C 19_RADAR_FREQUENC

Tp Pulse Length II 6µs to corresponding to a TX duty raiio c If 2.5 Vo41 3 µs to 8.0%, can be derived from 1"L

i

TL Pulse Length provided with the measuremen da a, i[sampling clock ref. section 5.2 3 20intervals} '- '

! :B Chirp Bandwidth 8 - 16 MHz characterised on ground, I !

C23 CHIRP BW- - - I'Ne Chirp Bandwidth provided with the measurement da~. !

Codeword ref section 5 2.3.22I I '

fotr Baseband Offset off~et f~equency included onlyiforl 'Frequency calibration CW pulse . l

', I

Upconverter Level 0 - 7 S dB .. provided with the measureme9t d;a. refsection 5 2.3 16 1 ,

I I'

! ! '

Table 5 I 7 1-1. Summaryof Pulse Characterisatics

II

[~o;;ierGmbH I \0oc."' Po:ID-ooR-sv-0012Project: '- - -- 1" ~-•- "'" nA nn


5 .1.7.1.2 Antenna

For a description on the antenna refer to section 5 1 4.2. An overview on the beam dataparameter for the Wave Mode is given in Table 5.1.7.1-2.


Number of Beam Sets 3 l beam set per swath + 1 cal beamset

Number of beam, per beam 2 transmit and receiveset

Beam set number provided with the measurementdata, ref section 5 2.3 6

Relation 0 - Chirped Cal characterised on groundBeam set number - Swath 8 - ISi

9 - IS2IO- IS311 - IS412 - ISS13 - IS614 - IS7

Antenna Elevation Pattern characterised on-ground per swath,C25 ANTENNA PATTERNS- - -


Table 5.1.7 1-2· Summary of Beam Data Parameter

;

~-

II Dornier ambH

!I '

Doc. No.: PO-iD-uOt·-~!~ -00.Y.Li

Issue: 5 Date: 3Kl04 99''"'I""'- •.• I ISheet: 5-49 I

iENVISAT-1

I

5 .1. 7. I 3 Summaryof ReceiveChainCharacteristics

The receive chain is described in section 5.1.4 3given in Table 5.1.7 1-3.

·1

An overview on the receiver characteri,icslis

I.


rI

Downconverter Level 0-31 dB providedwith the measurement data, ~f.section 5 2.3.17 I

I

characterised on-ground_C35_I/Q_PHASE_ERROR

Non-orthogonality between I& I± 5°Q,~0

I

ADC input voltage thresholds,Sa, n=-127, ...127

characterised on-ground, TBD

characterised on-groundC34 I/Q RATIO- - -

< 0 25dBGain ImbalanceI

DC Offset ±4% characterised on-groundCJJ l/Q OFFSET- - - I

Resampling Factor(calibration (CW))

12 provided with the measurement data, ref''section 5.2.3 24 ·

Quantisation I EchoScheme

AV 8/2 AV=AveragingMode, I1

compression ratio is provided with tilemeasurement data, ref section 5 2 3.7

lFE 8/4Noise FE 8/4 = Sign+Magnitude Mode [Rxe~

Exponent] ·

FQ 8/8•

FQ 8/8 = Full 8-bit QuantisationCal (CW)Cal (chirp) FQ 8/8 FQ 8/8 = Full 8-bit Quantisation

Quantisation Transition levels(QTL)

characterised on-ground, _C4 l

Table 5.1.7 l-3: Summaryof ReceiveChainCharacteristics

;

~.0N0~~0'----------~~~~~~~~~----~~~~~~~--~~--~--~--~--~~------~~--------------~--~--~

l

IDoc. No.: PO-ID-DOR-SY-0032issue: C\ Date: 1n n.4 oo

Dornier GmbH


5.l.7.2 Source Packet Generation for the Wave Mode

5. l.7.2.1 Mode Time-Line for the Wave Mode

The Wave Mode is defined i~:sectlon 5·l.2 4.The Wave Mode timeline is summarized in Figure 5 I. 7 2-1After transition to waJe M()a~·1~~cfa1st~i>11r~atioriperfod, an initi~f~oiseiria(~ibr~ion ·

- =::;;:~:~·~.t~·~w~M~~~ff'~&t~~;r~g:~~~e~;:~i~~i~dwi~t:~~:f.t°edpulses are 'generated The data·from'these allows on-ground correction of within pulse phaseand amplitude errors introduced 'by the ASAR Instrument. ' . ··- ~. ' ' . . ..

The initial calibration sequenceis followed immediately by a burst of transmissions coveringthe Skm along track vignette distance A 'quiescent period is used to transfer the data via thelow rate data interface

TheWaV~Jl,\ode·r~peat\cycle comprises oftwosubcycle, where the above sequence isperformed first for one swath, and then for another

Initial noise/calibration sequences are repeated at the start of each subcycle

On receipt of a macrocommand to go to another mode, the current wave cycle is truncated.

Parameter nominal value/ rangeNumber of pulses per vignette 2368 - 3288 (fB,C). \ characterised on ground

(multiple of 8) _C8_WAVE_MODE _TIMELININGSwath Rank (R) 9-14 characterised on ground,

. '. ". ' -C6_SWATH_RANK

•Table 5 I 7 2- J · Wave Mode Timeline Parameter

Rc1>elition cvcle- suhl.'VcleI (sw~th A) subcvcle2 l•wath1n -Transition to PRE-OP - ,,__-Transition to Wave Mode -Stabilisation D ]Calibration (chirped) (2 PRI) 0 D

; DKeyeles Part of

Tx o« (R PRI) • D I cycle

Noise Measuremenl ( 8 PRI) 0 0Calibration (CW) (97 PRI) D 0Transmit Pulses ( M PRI) I Ml I CMilNo echoes (R PRI) IJITJ IfillEchoMeasurement ( M PRI) I Ml I [MC]Quiescent Period I I..

Figure S I 7 2-1 ASAR Wave Mode Summary Timeline

Dornier GmbH IDoc No.: PO-ID-DOR-$Y-0032''""•••. c n..t... ~" "" nn

11'qect: I I SMet:I

ENVISAT-1 5-51 I I

I!

5 .1.7.2.2 Generation of Source Packets

In Wave Mode source packets are generated for '

echo data: one source packet per 8 samplingwindowcalibration (CW)· one source packet for the 97 calibration samplingwindowscalibration (chirp): one source packet containing3 calibration samplingwindowsnoise data. one source packet 8 noise samplingwindows

The sequence of the source packets is shown in Table 5 1 7 2-2.

Number of Source packet contents Isource packets Source Data Type Cycle Packet !

Count I

l calibration (2 PRls) 0 1st subcycle lst cycle ) J

l noise (8 PRls} 0

I calibration sequence I I

(97 PRls)/

M1/8 echo (8 PRls) 0 -(M1/8-I)

l calibration (2 PRls) 0 2nd subcyclc

l noise (8 PRls) 0I

calibration sequenceI

l l I

(97 PRis)

M1/8 echo (8 PRis) O-(M2/8-l)

l calibration (2 PRis) 0 lsl subcycle 2nd cycle

l noise (8 PRls) 0

l calibration sequence I(97 PRls)

~M1/8 echo (8 PRls) 0 - (M1/8-I)

1 calibration (2 PRls) 0 2nd subcycle

I noise (8 PRls) 0

I calibration sequence 1(91 PRls) i

. M1/8 echo (8 PRls) O-(M2/8-I) I.:

last cycle (truncated) r

'

Table 5.1.7 2-2· Sequence of source packets for Wave Mode i

..

I

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Dornier GmbH 1Doc. No.: PO-ID-DOR-SY-0032Issue: " Date: :rn 04 9<>

Sheet: 5-52l-'l'019Ct:

ENVISAT-1

5.1.8 Generation of Measurement Data for the Global Monitoring Mode

5.1.8.1 Global Monitoring Mode On-Board Data Processing

A functional overview on the acquisition of the observation/calibration data is given in section5.1.4 and Figure 5.1.4-1.

·In the following sections summary tables on the related ASAR parameters together with somenominal values and ranges are given, foradditional information on the nominal values andranges refer to SR_RD 11. ·

For the interpretation of the measurement data the information provided in the source packetstogether with the measurement data and the parameters characterised on ground (ref.SR_RD 10) have to be used

5.1.8.1. 1 Pulse Generation

The generation of the pulses is described in section S 1 4.1.

An overview on the pulse characteristics for the transmit and calibration pulses in GlobalMonitoring Mode is given in Table 5 l 8 1-1_.

Parameter nominal reference/remarkvalue/ range

fsam Radar Sampling 19.2 MHz characterised on groundRate Cl RADAR SAMPLING RATE- - - -

RF Radar Frequency 5.331 GHz characterised on ground. _C 19_RADAR _FREQUENCY

Tr Pulse Length l l 6 µs to corresponding to a TX duty ratio of41 3 µs 2 5% to 6 5 12%, can be derived from TL

TL Pulse Length provided with the measurement data,[sampling clock ref. section 5.2 3 20intervals]

B Chirp Bandwidth 0.3 - 0 7 MHz characterised on ground,; C23 CHIRP BW- - -

Ns Chirp Bandwidth provided with the measurement data,Codeword ref section 5 2.3 22

fotr Baseband Offset n.a no offset frequency included in GlobalFrequency Monitoring mode (TBC)

Upconverter Level O - (.5 dB provided with the measurement data, refsection 5 2.3 16..

Table S. l.8.1-I ·Summary of Pulse Characterisatics

g~~0~~0'--~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~-

Dornier GmbH 0oc No.' PO-li.J-00~-s'f..whIssue: 5 Date: I J~.04.99

I .Sheet: 5-53ENVISAT-1

5.1.8.1.2 Antenna · __ •.: '.··

For a description on the antenna refer to section 5 l 4 2 An overview on the beam dataparameter for the Global Monitoring, ,M9~e is given in Table 5 .l 8 1-2.

Parameter -;''<>~ll'-:t,,.;f., I r~fe,~~~ce/remarkvalue/range ' " ' ' . ' , ,

Number of Beam Sets .... ; ..~·J,~.I~l....),,beam setper subswath," ) !;• '.',(''." '. <'./;'.\" "[' dtninaf5; sub'swathsl ' ' '•'.·· '·" , . ifnHl'!·Jt.mu,r~}l~bn,..? .ft!-''""' ''1." .- 1.,.,i.-:-.v,,·.·'.,. t·,. ,:, ;.. ~,,

N b f b &.:..: ' .. . "'2'·'·. -. . . ' 'um er o earn per oeam '·: .·::·.:.,.", · ·.;>Jfi~~<-set :«1! • . ._

Beam set number (. \ .•...•.• , ! '. ·[provided with the.measurementdata. ref section 5 2 3.6

20 - SSI21 - SS222 - SS323 - SS424 - SSS

characterised on groundRelationBeam set number - Swath

Antenna Elevation Pattern characterised on-ground per swath.C25 ANTENNA PATTERNS- - -


Table 5.1 8 1-2· Summary of Beam Data Parameter

,-···

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i-----··--·---·--·--------- 1~No: _PO-ID-DOR-~~ ~O~~=Project:

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Sheet. 5-54

5 1.8.1.3 Summary of Receive Chain Characteristics

The receive chain is described in section 5 1.4 3 An overview on the receiver characteristics isgiven in Table 5.1.8.1-3.


Downconverter Level 0 - 3 1 dB I provided with the measurement data, refsection 5.2 3.17

Non-orthogonality between I& I± 5°Q,Li0

characterised on-ground_C35 _l/Q_PHASE_ERROR

ADC input voltage thresholds,S0, n=-127, 127

characterised on-ground, TBD

Gain Imbalance I <O 2SdB characterised on-groundC34 l/Q RATIO- - -

DC Offset

Resampling Factor(resampling for echo,calibration and noise)

±4% characterised on-ground_C33_I/Q_ OFFSET

Quantisation IEchoScheme

17 - 36 provided with the measurement data, refsection 5.2.3 24

Noise

AV 8/4 AV= Averaging Mode,compression ratio is provided with themeasurement data, ref section 5.2 3.7

Initial Cal

Periodic Cal I FQ 8/8

FE 8/4 FE 8/4 = Sign +Magnitude Mode [FixedExponent]

Quantisation Transition levels(QTL)

FQ 8{8 FQ 8/8 = Full 8-bit Quantisation

FQ 8/8 = Full 8-bit Quantisation

characterised on-ground.. C41 .

Table 5 I 8 1-3 Summary of Receive Chain Characteristics

\ Do;;.ier GmbHProject:

ENVISAT-1

\

0oc No.: PO-ID-DOR-~Y-0032..,.,,•••. c Date: 1H\t\A oo

Sheet: 5-55

5.1.8.2 Source PacketGenerationfor the GlobalMonitoringMode

5.1.8.2. l ModeTime-Linefor the GlobalMonitoringModeI

The Glob~!~onit~ring ~ode. P.rovidescontinuous alon~ track samplingac~ossa 400 *·• wideswath. This rs achieved m a similarmanner as for the Wide Swath Mode usmg a ScanS '..technique.The same subswaths as defined for Wide Swath Mode will be usedThe timeline for Global Monitoring Mode is summarized in Figure 5.l. 8 2-1. The initial/noiselcalibra~.iort~u~~~ js as described for the Wide Swath Mode !

As for the Wide Swath Mode the timeline is defined as a cycle during which the sub-s!ths areimaged. However. for the Global MonitoringMode that cycle is made up of four sub-c cle .During each sub-cycle, every sub-swath is visitedonce for a short burst of transmission . The ). ,i

dwell time on each sub-swath is determined by a number of pulses required for a look d-fhetime interval for all the associated returns to be collected An overview on the GlobalMonitoring Mode timeline parameter is given in Table 5 I 8.2-1

I

. I .

For the first subcycle only. of each repetition cycle, calibration and noise measurementsar~made The calibration sequence is as defined for the Wide Swath Mode. 1

On receipt of a rnacrocomrr•.•11dto go to another mode, the current repetition cycle iscompleted.For details on the timing and calibration sequences refer to the description for the lma$eMode, section 5 1.5.2

Parameter nominalvalue/ range l

Number of echoes per subswath (M) 6-10 (TBC) characterised on grouncNumber of PRls per subswath 16-23 (TBC) _C11_GM_TIMEL~I ~GSwath Rank (R) 9-14 characterisedon grdunc

_C6_SWATH_RANK i ~Number of subcycles per cycle 2-15 [default= 4} I

J

Number of subswaths per subcycle 1-14 [default= 5] I II

Table 5.1 8.2-1 Global MonitoringMode TimelineParameter

;

Dornier GmbH

ENVISAT-l Sheet: 5-56

MONITORING'MCllD'GLOllAL llEl'£AT FOR

ALL~An:1~

:IUlllQIDT:~:

TRANISITIOHTOPR&..QP DTRANSIS110NTOG MON D . . IU8C'tCLa I. ..STABIUSATIOH(4ZOPRI) 0TXOFF(RPAI) o :aNOISEMEASUREMENT(8 PRI) d::......INITIALCAUBRA110HSEQUENCE : : 0 ,~PRI) • • '• • • .11(11 ISClt 111111

TXPULSES (INPAIFOR SUBCYCL.£t : : D D DII PRIOfR SUBC"ICLE2:2) ,) I I HOECHOES • • 0 ~ 0

J ECHOllEASURSEMT : . ~ : : 0 0 0\ INTERSWAlHGAP • • G [!] 0

CALllRA110NSl!OUENCE(4PRI) . • • : 0 0 0(ONLYFORSUBCYCLEt OFOOOCYC:U:S) • •NQIK llEASUAllENt' (1PRI) : • • • o· i 01 01(ONLYFOR SUllCYCLE1 OFEVENCYCLES): ' '

J

•••••D00D

:; ~:.•. ~I!.• c.t •.,.. " ·-·-..

po

Notes· 1 SS( I) refers to the 1"1subswath in the sequence

2 n is the number of subswaths per subcycle

Figure 5 I 8 2 - I Global Monitoring Mode Summary Timeline

one source packet per M(SSn) sampling windowsone source packet per 97 sampling windowsone source packet per calibration sequence (i e. four samplingwindows)one source packet per sampling window

5.1.8.2.2 Generation of Source Packets

In Global Monitoring Mode source packets are generated for

echo datainitial calibration:periodic calibration-

;

noise data:

The sequence of the source packets is shown in Table 5. 1.8 2-2.

Dornier ambHDoc No: PO-ID-DO"tJ-s~ -0032

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Issue: 5 Date: ' 3( .04.99......•-..~ I ISheet=ENVISAT-1 5-57I

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i Number Source packet contentsof packets data type cycle packet

count

8 noise 0-7 subswath I Initial Noise/Calibration SequenceI initial cal (97 PRI) 88 noise 0-7 subswath 2

1 initial cal (97 PRI) 8...

8 noise 0-7 subswath Q ' ' \.~1 initial cal (97 PRI) 8 (Q=S)

I periodic calibration 0 1st subswath I"'subcycle 111 cycle(odd)1 echo (M1 PRI) I )1 periodic calibration 0 2'M1subswath )I echo (M2 PRI) I

...1 periodic calibration 0 ptt'subswath1 echo (M,, PRI) I !

I echo (M1 PRI) 0 111 subswath 2'Kl subcycle

l echo (M2 PRI) 0 2"'1 subswath'- ..

l echo (Mp PR() 0 p11'subswath

l echo (M1 PRl) 0 l'1 subswat h S'" subcycle... I

1 echo (M1,PRI) 0 p111subswath I1 noise 0 1•t subswath Ist subcycle 2°..i cycle (ev~n)1 echo (M1 PRI) I

~I noise 0 2"d subswath

...I

'...

l periodic cal/noise 0 111subswath I11 subcycle N°' cycleecho (M1 PRl)

I1 l (odd/evea)!

l periodic cal/noise 0 p11'subswath1 echo (M1 PRI) I

I

l echo (M1 PR!) 0 I" subswath S11' subcycle !

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..I

l echo (Mp PRI) 0 p'"subswath !

Table 5 l .8.2-2. Sequenc.e of source packets for Global Monitoring Mode !s..0;;;0

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5.1.9 Generation of Measurement Data for the Alternating Polarisation Mode

5.1.9. l Alternating Polarisation Mode On-Board Data Processing

A functional overview on the acquisition of the observation/calibration data is given in section5.1.4 and Figure 5.1 4-1

In the following sections summary tables on the related ASAR parameters together with some-nominal values and ranges are given, for additional information on the nominal values andranges refer to SR_RD 11.For the interpretation of the measurement data the information provided in the source packetstogether with the measurement data and the parameters characterised on ground (ref.SR_RDIO) have to be used.

5.1.9.1. I Pulse Generation

The generation of the pulses is described in section S 1.4.1

An overview on the pulse characteristics for the transmit and calibration pulses in AJternatingPolarisation Mode is given in Table S I 9 1-1.

parameter nominal reference/remarkvalue/ range

fsam Radar Sampling 19.2 MHz characterised on groundRate Cl RADAR SAMPLING RATE- - - -

RF Radar Frequency S 331 GHz characterised on ground_Cl 9_RADAR_FREQUENCY.

Tp Pulse Length I l.6 µs to corresponding to a TX duty ratio of4 l.3 µs 2.5% to 6.512%, can be derived from TL

TL Pulse Length provided with the measurement data,[sampling clock ref section 5 2.3 20intervals]

B Chirp Bandwidth 8- 16 MHz characterised on ground,; _C23_CHIRP_ BW

NB Chirp Bandwidth provided with the measurement data,Codeword ref section 5.2 3 22

fotr Baseband Offset n.a no offset frequency included in imageFrequency· mode

Upconverter Level 0 - 7.5 dB provided with the measurement data, refsection 5.2 3.16

Table S.1 9 .1-1: Summary of Pulse Characteristics

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5.1.9.1.2 Antenna ' t • 1,\'.f.1 ..• 1 ·; (\ ',<

(''·' I nofoinat: . I Ireference/remarkvalue/range

Parameter

Number orB~mpef~~~'l'. ..set ··· · · ··'""·"·

I bealD'set per swath, 4 bCarri)ets.wit ..;rel~'iant·,v{1'\~i~'5,~ttingg~~e~t~1: · . Iinternall}'·:··'<Y''::I'"'· · ;:,,-.1>;;,\•\':''1'..'Wan~mlf'and1receive ·' · :'l'·

For a description on the antennarefer tosection 5.L4.2 An overview on the beam dataparameter for the Alternating Polarisation Mode is given in Table 5 J 9 1-2

Beam set number provided with the measurement data,ref. section 5.2 3.6

RelationBeam set number - Swath

1 - ISI2 - IS23 -lS34 - IS4S - ISS6 '~67 - IS7

characterised on ground, TBD

Antenna Elevation Pattern characterised on-ground per swath,C25 ANTENNA PATTERNS- - -

Antenna AzimuthPattern characterised on-groundC25 ANTENNA PATTERNS- - -

Table S I 9.1-2: Summaryof Beam Data Parameter

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5. l. 9 1.3 ,.Summary of Receive Chain Characteristics

The receive chain is described in section 5.1.4.3 An overview on the receiver characteristics isgiven in Table 5.1.9.1-3.


Downconverter Level 0-31 dB provided with the measurement data. refsection 5.2 3 17

' . t ,'-..~

Non-orthogonality. between I & ± 50 characterised on-groundQ,L\0 _C35_I/Q_PHASE _ERROR

ADC input voltage thresholds, characterised on-ground, TBDS.., n=-127, ... 127

Gain Imbalance <0.25dB characterised on-ground_C34_ I/Q_RA TIO

PC Offset ±4% characterised on-groundC33 I/Q OFFSET- - -

Resampling Factor I provided with the measurement data, ref.section 5 2.3.24

Quantisation Echo AV8/4 AV= Averaging Mode,Scheme compression ratio is provided with the

measurement data, ref section 5.2 3 7

Noise FE 8/4 FE 8/4 = Sign +Magnitude Mode [FixedExponent]

Initial Cal FQ 8/8 FQ 8/8 = Full 8-bit Quantisation

Periodic Cal FQ 8/8 FQ 8/8 = Full 8-bit Quantisation

Quantisation Transition levels characterised on-ground, _C4 I(QTL)

Table S. l 9.1-3: Summary of Receive Chain Characteristics

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5.1.9.2 Source Packet Generation for the AlternatingPolarisation Mode

5.1.9.2.1 Mode Time-Line for the Alternating PolarisationMode

The Alternating Polarisation Mode is described in section 5 1.2.5.The timeline for Alternating PolarisationMode is summarized in Figure 5 .1.9 2-2.

Following the t~ans.itionto AlternatingPolarisationMode, a stab._i1is~tionp.e..n..·od and.a trt'., smit'off' penod, noise measurements are made on VV and ffii polarisations. '(hen, each. 'polarisation is passed through an initialcalibration sequence similar to Image Mode : •The echo measurement is made within repetition cyclescontaining two bursts oftransmi sidnson each of the polarisations As the same PRFswill apply to both polarisations, thereis oneed to incur gaps in the timeline to collect echoes prior to switching to the next block islthecase inWide Swath Mode. The only break in the sequence is a calibration sequence as f rImage Mode. On alternate cycles VV or HH calibrationmeasurements are made, which lldwsthe cycle to be disrupted as little as possible !In the Cross-polar H mode, the transmit pulses are all horizontally polarised The receiv~chainoperates inH and V polarisation - exactly as for the co-polar mode This mode will protuchalf of the data in cross-polar form (HV) and half in co-polar form (HH).

1

In the Cross-polar V mode, all the transmission is in vertical polarisation, the receive ch~inasin co-polar mode, and the data will be in VH and VY form. I

On receipt of a macrocommand to go to another mode, the current cycle is completed. I

For details on the timing and calibration sequences refer to the description for the lmagfMode, section 5 l.5.2.

Parameter nominalvalue/ rangeNumber of echoes per burst.at each 194 - 297 (TBC) characterised on gro nd i

1polarisation (M) _Cl 0_AP_TIMEL 1IN tfSwath Rank (R) 9-14 characterised on gro . ""

_C6_SWATH_ Il!m:m===--==============================-+=~F==..S!

Table S l 9 2-1: Alternating PolarisationMode TimelineParameter

Dornier GmbH


--C'ICU ,-·-- 'i":

-·.u. _1 0

II

·~0::o.0. if

~Do

n-o.n'--'

TXOff(RPAI)

NOISE .li&ASCIAIEMENT'VV(I PAI)

NOISE MeASUREMENT Hit (IPRll

INl1W. CAUBAA110N VVC17PAI• 1NULi. PAI)

0: ' Qn ' u: r1 '

INl1W. CAUBAATION HitC17PAI• 1NULLM)

CAUBAATIOH 5&QUINCE I&""'>llULS£ TRANSMISSION !SEE NOTE) ,.;..,,_i_,_,~i-l•..!-1-i

Ell-1-1-j-i-ll-1-1CAL DATA TAAHSMISSIONii TO POKT (1 PAI) : g 8

Notes: 1. In Co-polar mode, the transmit pulses are V and Has shown.

2. In Cross-polar H mode, the transmit pulses are all H.

3. In Cross-polar V mode, the transmit pulses are all V.

Figure 5 I. 9.2-1 · AJternating Polarisation Mode Summary Timelines

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5.1.10.l.2 Antenna

For a description on the antenna refer to section 5 1.4.2. An overview on the beam dataparameter for the External CharacterisationMode is given in Table 5.1.10.1-2.


'

Number of Beam Sets 2 1 set for initial sequence, 1 for rowsteppi~g sequence

Number of beam per beam 1 transmit only ,;:

setBeam set number providedwith the measurement data, ref.

section 5.2.3 6Beam set numbers 25,26 characterised on groundAntenna Elevation Pattern characterised on-ground per swath,

-C25_ANTENNA_PATTERNSAntenna Azimuth Pattern characterised on-ground

C25 ANTENNA PATTERNS- - -

Table 5.1.10.1-2: Summaryof BeamData Parameter

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5 .1.1o.1.3 Summary of Receive Chain Characteristics

The receive chain is described in section 5 I .4. 3. An overview on the receiver characteristics isgiven in Table 5.1. IO ·1-3 ' ·

Parameter · Inominal I reference/remark ··value/range .

ADC input voltage thresholds,s., n=-127, ... 127

cha'racter~sC<f_<on-~o~nd,Ta)). ' (' ' ..~'• •{.''•

Gain Imbalance <0.25dB ch~racterjsed on-ground. C34 U.Q_RATIO .· .-1 •.., -' · ti .•. ··'

±4% 1(:1jaracterised-on-ground~C33~.J/Q~OFFSET

oc·otrset

Resampling Factor provided with the measurement data, refsection 5.2.3 24

QuantisationScheme

Echo n a.

Noise i n.a

initial Cal I n a.Periodic Cal I FQ 8/8 FQ 8/8 = Full 8-bit Quantisation

.Quantisation Transition levels(QTL)

characterised on-ground, _C41

Table S. l .10. l -3: Summary of Receive Chain Characteristics .

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5.1.10.2 Source Packet Generation for the External Characterisation Mode

5.1.10.2. l Mode Time-Line for the External Characterisation ModeII

The External Characterisation Mode provides absolute calibration measurements by Itransmitting on each row of the antenna according to a predefined pseudo-random sequ.n.Additionally some internal calibration measurements are made simultaneously in order tfprovide comparative values. I

The timelinefor External Characterisation Mode is summarized in Figure 5 I. I0.2-1. I

Following the transition to External Characterisation Mode. a set-up period is executed Icomprising a coded sequence to initiate data recording in the ground receiver This is fr!no'ltledby a single column transmission. l'For a single cycle of the mode. each row is transmitted in a pseudo-random sequence u~inunmodulated pulses The cycle is repeated 42 times centred about the calculated satell~'toverflight time of the ground receiver. During the eye.le.occurring at the calculated ov rflithttime, the calibration loop in the ASAR is used to couple transmit pulses at an offset fr uencyinto the main receiver. which are then sampled in a calibration window. 1 ,

)'

After completion of the sequence a single column operation is executed and the instru~en1 willautonomously switch down to Pre-Operation Mode '

Parameter nominal value/ rangeNumber of cycles 43 characterised on groi nd11----:------:-~~~--,---,.---+---------1_C 17_EC_ TIMELl1' IN tJ ;Row Stepping Order within Cycle 1-32 '

Table S. I I0 2-1 External Characterisation Mode Timeline Parameter•

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STQUIA1ION

ROWSfl!f PIG<JPERA110H. .

ROWOPERA11NG0, 4, I, 12, 11, 20. 24, 21. 1, 5, 1---21, 2- 30.3 -31

Figure S. I . I0 2-1 : ASAR External Characterisation Mode Summary Timeline

5.1. l 0.2.2 Generation of Source Packets

In External Characterisation Mode 32 source packets each containing calibration data for onecalibration sampling window are generated (Cycle Packet Count 0 - 31).

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5.1.11 Generation of Measurement Data for the Module Stepping Mode

5.1.11.1 Module Stepping Mode On-Board Data Processing

The Module Stepping Mode provides an internal health check facility on an individual modhlebasis. The calibration paths to and from the antenna are used for this, although measureme ••tsare not intended to provide calibration information The purpose of the mode is primarily t1

identify any malfunctioning modules to allow them to be switched off if necessary, and toidentify modules for which calibration offsets are to be applied.

S.1.11.2 Source Packet Generation for the Module Stepping Mode

S 1.11.2. I Mode Time-Line for the Module Stepping Mode

The timeline for the Module Stepping Mode is summarized in Figure S.l l l. 2.:.1

The mode is entered with a sequence which exercises all four TR Modules associated wit'particular Tile Power Supply. This sequence is repeated a number of times to permitstabilization, and during the last of these cycles, the - .•xiliary receiver is used to coupletransmit pulse back to the ADC followed by the auxiliary transmitter to couple the pulse naethrough the main receiver. This sequence is performed for all the eight power supplies in •column and then for all the columns. This is performed for the complete antenna using V prpolarisation. ·

D. . .. . .·oCYCLIC OPERATION

iI DOWN LOAD at.TA To1toifT ·' ••.•-----•... I I II •

Ut lX2 U2TX t

TX a lllAllln,AUXRX·IU• AUXn, llAINU

Figure 5. l. l l 2-1: ASAR Module Stepping Mode Summary Timeline

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The module stepping sequence is definedby means of a Row sequence of32 and a Columnsequence of 10. The row sequence is nominallythe same as for row stepping in External·Characterisation Mode The column sequence is changed at a 32 PRI count so that all 32modules are used before the column number is changed.On completion of the sequence, the instrument autonomously switches down to Pre-OperationMode.

5 .1.11.2.2 Generation.of Source Packets

"InModule Stepping Mode 320 source packets each containing calibrationdata for twosamplingwindows are generated (Cycle Packet Count ranging from 0 to 3, repeating 80times).

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5.1.12 Generation of Measurement Data for the Test Mode

5.1.12.1 Test Mode On-Board Data Processing

The Test Mode provides instrument flexibility for on-ground testing, it is used only during meASAR on-ground verification processes. It will allow the operator to select auxiliary or mai_transmit and receive paths by command, as well as selecting any combination of ·filtering,resampling and quantisation within a variable window (start time and length). T}1emode will also have selectable PRF and pulse characteristics. ·Precise set-ups used within the Test Mode depends on the detailed definitions of the=

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5.1.12.2 Source Packet Generation for the Test Mode ) I

5.1.12.2 I Mode Time-Line for the Test Mode

The precise timeline for the mode is dependent on the test in operation

5.1 12.2 2 Generation of Source Packets

The generation of source packets is dependent on the test in operation.

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5.2 Source Packet Formatoftl~e Image Mode

5.2.l Overview

The measurement data are formatted in source packets according to the generat layoutdescribed in Volume 4.

5.2.2 D~sc~iptitiriof tbe Packet Header

The packet header has a common format for all instruments The overall structure of thispacket header format is described in Volume 4, section • : 2

The contents of the• Application Process Identifier• Packet Length

contained in the packet header are instrument dependent.

Application Process Identifier

APP ID=Operational Mode = 14 (HEX)

• ' ' ...).>..·; : . .

,The Source Packets consist oft~ree main parts, which are detailed in the following ~tions:

• Packet Header.(length{i~.H~es);,·, .: .:..··.· . .·..• Data field Header (leng!Rdd 'bytes)'.·• Source Data Field (variable length)

·1. I The Packet Error Control field is not applicable for ASARI

Virtual Channel Identifier= 30 (HEX)I I 0 I I I 0 0I I I I 0 I 0 I 0 0

MSB LSB

Packet Length

The field Packet Length (PCK _LEN) gives the number of bytes of the packet data field minusone.

The length of the packet data field is dependent on- the number of sample windows included in the source packet- the sample window length and- the data processing applied to the samples

In addition the following conditions have to be met ..- the source packet ends on word boundary, i e the length of the source packet has to beeven.

- the source packet has a minimum length of 1008 byte.

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Th~ formulae provided below give the source packet length for the various data processi1g·options. •

A. Resampled data length for a samplewindowI

A = HIN1l:SIF) (1)

B. Length of sample window data field

t, AveragingMode

a = 2 *A *r (2)

(3)b = L!N1l al63]

,a= b * 63c={~-63*b+l ,a:t:h*63

(4)

d 0"" 2 *HIN7lc/2]-c (S)

(6)B =- 6./ * b + c + d

11. Sign+ Magnitude (Fixed Exponent) Mode

e = 2 * HIN11A I 2)-A (7)

(8)B =A+ e

111. Full 8-bit Quantisation

B = 2*A (9)

C. Length of source data field

,for n " B> l008-(H1 +H2)

,for 11* 8-5, l008-(H1 +H2)(IO)

D. Length of packet data field

(11)

E. Length of source packet

E = D + Hi (12)

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whereS is the echo/cal/noise samplewindow length, ref. section S.2 3. lSF is the resampling factor, ref. section 5.2.3 25r is the compression ratio selected for averaging mode, ref. section

5.2.3 7, (r=0.5 for 8/4 compression, r=0.25 for 8/2 compression)a is the length of the compressed data for a sample window in bytesb is the number of complete data blocks formed in AveragingMode per sample

window ·c is the length of a remainderblock, if present, in bytesd is the lengthof the samplewindowpaddingattached to the end of the Averaging

Mode compresseddata inbytese is the lengthof the samplewindowpaddingattachedto the end of the Sign+

MagnitudeMode compresseddata inbytesH1 is the Data FieldHeader length in bytes (= 30)H2 is the Packet Header length in bytes(= 6)n is the number of samplewindows placed in a source packet, ref section

5.1.x 2 2A is the length of the resampledsamplewindow in 16-bitsamplesB is the length of the samplewindow data field in bytesC is the length of the source data field in bytesD is the length of the packet data field in bytesE is the length of the source packet in bytesLINT[x] is the lower integer of the two between which a number liesHINT[x] is the higher integer of the two between which a number lies

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5.2.3 Descriptionor D•ta i:'itldHea,der . 1Thecontentsof theDam ~i~IJ,~~~'i~,~~~ict-4 inTable~.23.:1. ~e ~etailed.definitio.01the contents of the data field he_ader~l~:mentscan be found m the following sections. I

DATA FIELD HEADERDATAAREA': AREA SIZE REMARKSII. . {\'-·(' :. -_ .. - . ·.-.

Data Field Header Length 16 bits see section 5.2.3 l.:·.,.

,,16 bits· . ·'. »,see section 5 2.3.2ModelD . "1:..1 ·,.,;\):.

0t!li.•'/i~{f,,·,

' ··' ·, !

On ~~a~~,:Tim~;.,/'; . ·, I ..; -. '.~ .' ,' . ' ·-'.,....•.. '··.· ,•) ;_, 1i'~section 5 2.3.3{{:~~ ;•.::L . ·' ·.i : .: ·

' ,}''40 bJlS.i;,,,, .•t ;-~; ·-~.".

, . ,,J,s , '·, \ •\' ... ' ·~. -.. ·:.. :; .·.•.···.

' (..... -, ,, . .,. ..Spare Field ;._:·{~·,; ' :J; ~I.';,i I ;_-,J;' .s bits

. ' ·.. ·;''' )11•

Mode Packet Count ; -:i 24 bits .see section 5.2.3 5 IAntenna Beam Set Number· ·· ,· r,. ·····' · · 6 bits see section 5 2.3.6 I )

Compression Ratio , . 2 bits see section 5.2.3.7 f

Echo Flag· ''.··:,.. ' . ·,·'"

,-, •' I bit . .: 'see section 5.2 3.8INoise Flag I bit see section 5 2 3.9

1

Cal Flag I bit see section 5.2.3 10/

Cal Type l bit see section 5 2.3.111

Cycle Packet Count 12 bits see section 5 2 3.12

Pulse Repetition Interval 16 bits see section 5 2.3.13/

Window Sta11Time 16 bits see section 5.2.3 14

.Window Length • 16 bits see section 5.2.3.15

Upconverter Level 4 bits see section 5.2.3. l<l11,~

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Downconverter Level 5 bits see section 5.2.3. l'tTx Polarisation l bit see section 5 .2 3. I

Rx Polarisation 1 bit see section 5.2 3 I~

Calibration Row Number S bits see section 5.2 3 20i

Tx Pulse Length 10 bits see section 5 2 3.2

Beam Adjustment Delta 6 bits see section 5 2 3.2~ '

Chirp Pulse Bandwidth 8 bits.

see section 5 2.3 23 !

Auxiliary Tx Monitor Level 8 bits see section 5.2 3 2~ I;

''

Resampling Factor . 2 I '16 bits see section 5 2.3. ;5 I,,

Table 5 2.3-1 Source Packet Data Field Header

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5.2.3.1 Data Field Header Length

The ASAR has a fixed data field header length of 30 bytes. The data field header length is setto length in bytes minus one, i.e.

Data Field Header Length = ID(HEX) =

lo lo lo lo lo lo lo lo lo lo lo I• 11 11 Io I 1 IMSB LSB

5.2.3.2 Mode Identifier

The Mode Identifier indicates the mode in which the data in the source packet were aquiredFor the Image Mode the mode identifier is set to

Mode ID=

I spare Io Io Io Io I I I I54(HE~

I I I I lololololoMSB LSB

S.2.3.3 On-Board Time

The On-Board time is a wrap around counter indicating the time at which the first sampledwindow in the source data was acquired (ref OBT in Figure 5 1.5.2-3)

The parameter is defined in 40 bits, with the LSB corresponding to an interval ofI •

- sec r~I 5. 26 us)2'6

According to the requirements the accuracy of the relation between OBT (coded in the header)and the UTC time is better than 200 sThe accuracy which can actually be achieved will be detailed when available

5.2.3.4 Redundancy Definition Vector

n/a for ASAR

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5.2.3.5 Mode Packet Count j,

This counter is a 24 bits wrap around counter, sequentially incremented for each source~··actetwhich applies to the current mode. The counter is incremented independent of the conte tssource packets, i e. there are no separate counters for echo, noise and calibration data ecounter is reset to 0 on entry into an operation mode j

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IThis 6 bit value has to be interpreted as an unsigned integer, indicating the antenna beat sto which the packet data apply (ref. section 5 1.4.2)

Up to 6 different values are used during a mode depending on the swath to which the s4urndata applies (for Image mode there is I beam set per mode) ,

Note: The Periodic (Chirp) Calibration Source Packet in Wave Mode contains one of~lalthough Antenna Beam Set 0 is used

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.5.2.3.6 Antenna Beam Set Number

5.2.3.7 Compression Ratio

This parameter is a 2bit value indicating the compression ratio used in Quantisation -Averaging Mode (ref section S.1.4.4.3)

For the interpretation of the value see Table S.2.3.7-1.

MSB LSB

8/4 compression 0 08/4 compression 0 1

8/3 compression I 0•

8/2 compression I I

Table 5.2 3 7- l Compression Ratio Idenitifiersl

Note. The processing mode (Full 8-bit, averaging or sign+ magnitude) cannot be infer~d fl.omthe source packet alone (TBC) It depends on mode and source data type, for the AS"-R "]baseline refer to the sections 5.1 x. l 3. 1 I

5.2.3.8 ECHO. Flag

A single bit flag which is set to 1 if the packet contains echo data, 0 otherwise

5.2.3.9 Noise Flag

A single bit flag which is set to l if the packet contains noise data, 0 otherwise

S.2.3.10 Calibration Flag

A single bit flag which is set to I if the packet contains calibration data, 0 otherwise 1

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5.2.3.11 Calibration Type

A single bit flag indicating the type of the calibration data contained in the source data field,when the calibration flag is set.

The flag is set to

1 if the packet contains periodic calibration data0 if the packet contains initial calibration data.

5.2.3.12 Cycle Packet Count

This counter is a 12 bits wrap around counter, sequentially incremented for each sourcepacket.

It is reset on receipt of a 'Select Beam·Set' ICB cpommand with the Rx bit set to 1, whichcorresponds to the following events:

• start of a mode• start of a cycle• change of the subswath• change of the polarisation• change of pulse shape (CW or chirp)

For the mode dependent sequences of the cycle packet counts ref sections 5 I x 2 2

5.2.3.13 Pulse Repetition Interval

This 16 bits codeword describes the length of the Pulse Repetition Interval (PRI = 1/PRF(Pulse Repetition Frequency), ref Figure 5 I 5 2-3 and Table 5.1.5.2-2)

The LSB corresponds to one sample clock interval which is the reciprocal of the radarsampling rate Therefore the PRI can be calculated as

P/U =N

where PRI is the Pulse Repetition Interval in seconds

N is the PRI codeword

fsam0is the radar sampling rate (ref Table 5.1.5.1-1)

5.2.3.14 Window Start Time

This 16 bits codeword gives the echo sampling window start time (SWST) relative to theleading edge of the preceding transmit pulse (ref Figure 5.1.5 2-3 ).

The codeword is to be interpreted as unsigned integer.' with the LSB corresponding to onesample clock interval.

NSWST =i.:

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where SWL is the sampling window length in seconds

N is the SWL codewordfsam is the radar sampling rate (ref Table 5 I .5.1-1) I I

I I

~

' 1

Upto 18 different values are used during a mode depending on the swath and data type o f

w.hich the source data applies. The field will contain either the Echo, Calibration or Noite .•...'.'depending on the type of data containedjn the source packet, as indicated by the Echo, :Calibration and Noise Flags. 1 1

! lAI l Tr-

5.2.3.16 Upconverter Level I1

This four bit codeword indicates the upconverter gain level set in the instrument (ref I ,

5.1416). I IThe codew~rd bas to be interpreted as 'an unsigned integer. with the LSB correspondinf t1

0.5 dB nominal I !G . N . I Iam= - nomma

2where Gain is the upconverter gain in dB

N is the upconverter codeword

£1~VIi:)" 1-1

where SWST is the sampling window start time in seconds

N is the SWST codeword

fsam is the radar sampling rate (ref. Table 5.l. S l-I)

Upto 6 different values are used depending on the swath to which the source data applie.•.

These are updated periodically round orbit, at nominally 1S seconds intervals

5.2.3.15 Window Length

This 16 bits codeword describes the sample window length (SWL) of the data in the sourcepacket in sample clock intervals (ref Figure 5 I S 2-3)The codeword has to be interpreted as unsigned integer, with the LSB corresponding to ]onsample clock interval.

SWL Nr:

The actual values Gain(N) are provided as characterisation parameter

This parameter will be invariant duri~g a mode, but can take any of the selectable vatu9s.

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S.2.3.17 Downconverter Level

This five bit codeword indicates the downconverter attenuation level set in the instrument (refS.l.4.3.1).The codeword has to be interpreted as an unsigned integer, with the LSB corresponding to

l dB nominal.Attenuation = N nominal

where Attenuation is the downconverter attenuation in dB

N is the downconverter codeword

The actual values Attenuation(N) are provided as characterisation parameter

This parameter will be invariant during a mode, but can take any of the selectable values.

S.2.3.18 Tx Polarisation

This 1 bit indicates the transmit signal polarisation used for the source packet data. Its valuesis:

I for Vertical polarisation0 for Horizontal polarisation

S.2.3. l 9 Rx Polarisation

This 1 bit indicates the receive signal polarisation used for the source packet data. Its values is:

1 for Vertical polarisation0 for Horizontal polarisation

S.2.3.20 Calibration Row Number

The S bits codeword indicates the antenna row to which Periodic Calibration data applies forImage, Wide Swath, Wave, Global Monitoring and Alternating Polarisation modes (ref sectionS.1.4 and 5,. l .5--2. I)The codeword has to be interpreted as an unsigned integer, the range is 0 to 3 l.

This parameter will be stepped through a pseudo random sequence during a mode, ref. Table5.1.5.2-1. The calibrated row only changes at the end of a cycle, e g in AlternatingPolarisation Mode row=O for HH and VY in the first cycle, row=4 for HH and VY in thesecond cycle.etc

5.2.3.21 Tx Pulse Length

The Tx pulse length in sample clock intervals (ref section S 1.4 l l and Figure 5.1 5.2-3)comprises 10bits describing the length of the pulse transmitted for the returning signal storedin the source packet

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The codeword has to be interpreted as.a.nu.n.signed integer. with the LSB corresponding tj'. osample clock interval.

1

, . ,, ·:r;)'~!-·~_1r····"d· .•..~· -;'.· -.

T = _L_ !, f' ' llfllM

where TP is the Tx pulse length in seconds

T 1.. is the Tx pulse length codeword .&..is the radar sampliij~~\(refl'TableS:l.S.M) '" n , ' ' , iJf,ti!Ji1,' J

Upto 6 d~tferent values are u.s~··"·)dun.;J18 '8. p~de<1ependingon1the'swalh'tll Whieh #~data apphes. ·,· · •···· · · · · I .

II

5.2.3.22 Beam AdjustmentD.elta;,.-_:· · .. -:-:-_,.,

The BeamAdi~SIJW'•!.·9"1tacomprises six bits describing the delta phase shift applied to th~Antenna el~\l!;ltlO~\patt~r.n:for the source packet data ·· .; . . <, '

1

'

-. . ; ·-.-· .'.·The codeword has to be interpreted as an unsigned integer

s =(N-32}*3601 4096

where BA is the phase offset in degreeN is the beam adjustment delta codeword

Upto 6 different values are used depending on the swath to which the source data applies. ~hevalue may be updated around orbit

5.2.3.23 Chirp Pulse Bandwidth

This 8 bits codeword indicates the pulse bandwidth used for the generation of the Tx pulsetransmitted to get the returning signal that is stored in the source packet (ref sectionS 1.4.1 I).The codeword has to be interpreted as an unsigned integer. with

16 *JO"B = *N; 255

where B is the chirp pulse bandwidth in HzN is the chirp pulse bandwidth codeword

Upto 6 different values are used during a mode depending on the swath to which the sourcedata applies.

5.2.3.24 Auxiliary Tx Monitor Level

This 8 bit value indicates the Auxiliary Tx Monitor level measured on the Aux Tx path. II

The RF SIS power values corresponding to the Auxiliary Tx Monitorlevel setting are providedas characterisation parameter. · ·

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5.2.3.25 Resampling Factor

This 16 bit word to be interpreted as an unsigned integer gives the resampling factor applied tothe data in the source packet (ref section 5.1 4.4 2), when resampling is performed on thedata The range of the resampling factor is 0 to 64 (i.e only the least significant byte containsrelevant information, the most significant byte contains spare bits set to 0).

Note·a) The resampling factor is normally set to 0 when there is no resampling factor given for the- swath(s) (i.e. for Image. Alternating Polarisation, Wide Swath, External Characterisation

and Module Stepping Mode)b) The resampling factor does not indicate, whether the resampling is performed or bypassed,

i.e. the resampling factor may contain a value different from Ior 0, even if the data are notresampled. The validity of the resampling factor cannot be infered from the source packetalone. The resampling control depends on mode and source data type For the ASARbaseline refer to the section 5.1 x 1.3.Example· For Wave Mode the resampling factor 12 is used only for initial calibration data,for echo, noise and periodic calibration no resampling is performed; but the value of theResampling Factor Field is 12 in all source packets (echo, noise and calibration).

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f I

5.2.4 Description of the Source Data Field

I

The Source Data Field of a source packet in the imagemode contains either• echo data or• calibration data (initial calibration) or• calibration data (periodic calibration)_or• noise data

Which data are in the source data field is indicated in the Data FieldHeader by the appropriateflag.

Echo data

The echo data contained in the Source Data Field correspond to exactly one samplingwihddwThe data are formatted according to the Quantisation - Averagingmode, ref. section5.1.4.4.3. l.

First Block 64 bytes 8 bits Block ID code

4 bits I-channel codeword of I" sample

4 bits Q-channel codeword of ISl sample

4 bits I-channel codeword of 2na sample

4 bits Q-channel codeword of 2•ia sample---

4 bits I-channel codeword of 63'3 sample

4 bits Q-channel codeword of 63 sample

. I 8 bits Block ID code

4 bits I-channel codeword of 64'' sample

4 bits IQ-channel codeword of 64°1sample

Second Block 64 bytes

N°' (last) Block m+ I bytes, if m is I 8 bits Block ID code

even

odd 4 bits I-channel codeword of ((N-1)*63+ 1)111 ~mple;

m+2 bytes, if m is I 4 bits Q-channel codeword of ((N-1)*63+1)0'~jle

mc= 63 4 bits I-channel codeword of ((N-1 )*6J+m)u' !!ample

4 bits Q-channel codeword of ((N-1 )*63+m)0' m le

d bytes d•H spare bits (d calculated according t<lsection5.2 2 equation (5))

1

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Calibration Data

The calibration data contained in the Source Data Field correspond to• exactly one sampling window in case of initial calibration• four sampling windows in case of periodic calibration

The data are formatted according to Full 8-Bit Quantisation

The Source Data Field for initial calibration can be given by the following

No Bits 8 8 8 8

po IQO I 11 I Q 1 I ...... .. .... ..8 8

l1<q-1) IQ(q-1) Iand the Source Data Field for periodic calibration can be given by

No Bits 8 8 8 8 8 8ll(q-1> IQl(q-t) I120 1020 1121 14(q-I) IQ4(q-1)110 IQIO 1111 IQll

first sampling window second sampling window fourth sampling window

where q is the number of calibration samples per sampling window (ref sampling windowlength)

Noise Data

The noise data contained in the Source Data Field of a source packet correspond to exactlyone sampling window.

The data are formatted according to the Quantisation - Sign +Magnitude Mode (FixedExponent), ref section 5.1.4 4 3.2

No Bits 44 4 4 4 4 e

I l(q~l) I Q{q-1) I sparewhere q is the number of noise samples (ref. sampling window length) and e is calculated asgiven in 5.2.2-(7).

General

Where necessary, spare bits are attached, in order to get a source packet of at least I008 bytes

5.2.5 Description of the Packet Error Control Field

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5.3 Source Packet Format of the Wide Swath Mode

5.3. l OverviewIi

The measurement data are formatted in source packets according to the general layout [described in Volume 4. /_The Source Packets consist of three main parts, which are detailed in the following secticfi.s:

• Packet Header (length 6 bytes) /• Data Field Header (length 30 bytes) ·• Source Data Field (variable length)

The Packet Error Control field is not applicable for ASAR

I!

5.3.2 Description of the Packet Header /

The packet header has a common format for all instruments. The overall structure ofthi~packet header format is described in Volume 4, section 4.2.2 I

iThe contents of the• Application Process Identifier• Packet Length

contained in the packet header are instrument dependent.Application Process IdentifierAPP ID=

' -Virtual Channel ID"' 30 (HEX) Operational Modes = IB(HEX)

0 0 0 0 0MSB LSB

5.3.2.1 Packet Length i

The field Packet Length (PCK_LEN) gives the number of bytes of the packet data fie~one. I

; I

The length of the packet data field is dependent on

• the number of sample windows included in the source packet• the sample window length and• the data processing applied to the samples

For the calculation of the packet length see section 5.2:2

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5.3.3 Description of Data Fietd Header,.:;.. ;') f'J t..·.·.:-:-,..··)'

The data field header has a common format for all modes. The overall structure of this datafield header format is described in section 5.2.3.

For the Wide Swath Mode the mode identifier is set to'. ,. ' ' '. :" '.- ..:-.···.d ···,.·, . .

ModeID =

spare~o 10 10ToMSB

\ .J: .·,·:.'


The Source Data Field of a source packet in the Wide Swath mode contains either• echo data or• initial calibration data or• periodic calibration data or• noise data

Which data are in the source data field is indicated in the Data FieldHeader by the appropriateflagsThe source data are organised as in the ImageMode, ref section 5 2 4


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5.4 Source Packet Format of the Wave Mode

5.4. l Overview

The measurement data are formatted in source packets according to the general layoutdescribed in Volume 4.The Source Packets consist of three main parts, which are detailed in the following sectiqns.

• Packet Header (length 6 bytes)• Data Field Header (length 30 bytes)• Source Data Field (variable length)


5.4.2 Description of the Packet Header

The packet header has a common format for all instruments. The overall structure of thipacket header format is described in Volume 4, section 4.2.2.

The contents of the following parameter• Application Process Identifier• Packet Length

is instrument dependentApplication Process Identifier·

APP lD =

Virtual Channel ID= 2B (HEX) Operational Modes 18 (HEX)

IPacket Len~ ; I I IThe field Packet Length (PCK _LEN) gives the number of bytes of the packet data field 4inuslone.

1j ·

It

0 0 0 0 0

MSB LSB

The length of the packet data field is dependent onthe number of sample windows included in the source packetthe sample window length andthe data processing applied to the samples

For the calculation of the packet length see section 5.2.2.

-OWlI .

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Which data are in the source data field is indicated in the Data Field Header.

Echo data

) I The echo data contained in the Source Data Field of a source packet correspond to eightsampling windows

The data are formatted according to the Quantisation - Averaging mode (8/2 compression),ref section S 1.4.4.3 I

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5.4.3 Description of Data Field Header

The data field header has a common format for all modes. The overall structure of this datafield header format is described in section 5.2 3.

Mode Identifier

For the WaveMode the mode identifier is set toMode ID=·. .·

( spare

I · · I 1 Io IoI o ·I o I o I o I o I oMSB LSB


The Source Data Field of a source packet in the Wave Mode contains either• echo data or• calibration data or• noise data

;

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1• First Block 64 bytessampling 2 bits I-channel codeword of I" samplewindow 2 bits Q-cbannel codeword of 1"sample I'

2 bits I-channel codeword of 2'1Qsample2 bits Q-chanuel codeword of 2""sample I

I... !

2 bits I-channel codeword of 126111sample2 bits Q-cbannel codeword of 126UIsample

Second 64 bytes 8 bits Block ID CodeBlock 2 bits I-channel codeword of 127"' sample

2 bits Q-channel codeword of 127"'sample rI

..... 'J)

N°'(1ast) c+d bytes 8 bits Block ID code'Block (ref equation 2 bits I-channel codeword of ((N- l)* 126+lt' sample

(4) and (5) of ..section 5.2.2) 2 bits Q-channcl codeword of ((N-1)*126+m)°'sample

8*d spare bits2na First Block 64 bytes &bits Block ID code I

sampling 2 bits I-channel codeword of 111sample Iwindow 2 bits Q-channel codeword of I11sample

Igm ... I !sampling W'(last) c+d bytes I

I..window Block (ref. equation 2 bits I-channel codeword of ((N-l)* 126+m)'"sample I

(4) and (5) of 2 bits Q-channel codeword of({N-l)*l26+m)111sam1 le Isection 5.2 2) 8*d spare bits '

...•Calibration Data

The calibration data contained in the Source Data Field correspond to

• 97 sampling windows in case of the calibration using the CW pulse• ..three sampling windows in case of the calibration using the chirp

I

The data are formatted according to Full 8-Bit Quantisation.I

i

I

!

first calibration window 2'K'window lastwindow'

'NoBits 8 8 8 8 8 8 8 8 .. .. 8i

~!

10 QO II QI l(q-1) Q(q-1) IO QO l(q-1~ ~(Q-p

where q is the number of calibration samples (after resampling).

I

'

I I ' II ' I

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The noise data contained in the Source Data Field of a source packet correspond to eight sampl

ENVISAT-1

Noise Data

where q is the number of samples in one noise sampling windowe is as calculated in equation (7) in section 5.2 2

General

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Where necessary spare bits are attached in order to get a source packet of at least 1008bytes

f1

I 5.4.5 Description of the Packet Error Control Field

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5.5 Source Packet Format of the Global Monitoring Mode 1I

5.5.1 Overview II

The measurement data are formatted in source packets according to the general layout i

described in Volume 4. I

The Source Packets consist of three main parts, which are detailed in the following secti~ns·

Packet Header (length 6 bytes) !

Data Field·Header (length 30 bytes)Source Data Field (variable length)

The Packet Error Control field is not applicable for ASAR.


The packet header has a common format for all instruments. The overall structure ofthilpacket header format is described in Volume 4, section 4 2 2 iThe contents of the following parameters

Application Process IdentifierPacket Length

is instrument dependent.


APP ID=

Virtual Channel ID = 28 <HEX Ooerational Modes = OB<I-IEl I 0 11 I 0 11 0 11 I 0 11MSB

;

Packet Lengthi

The field Packet Length (PCK_LEN) gives the number of bytes of the packet data field 1~inusone.


the number of sample windows included in the source packetthe sample window length and · .. ·the data processing applied to the samples

For the calculation of the packet length.see section 5 2.2.

B

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5.5.3 Description of Data Field Reader

The data field header has a common format for all modes. The overall structure of'this datafield header format is described in section 5.2.3. ..·

Mode Identifier·.,.:/,:,._,..,,..-:/.:;:.';,,</..:..(·./(,,, ·..',;·:. : -

For the Global Monitoring Mode the mode identifier is.set to.' '. { '- I ~ ' ' 1, ,'I -. -; '

Mode ID

S{!areI 0 I I I 0 I i0 I0 I 0 0 I 0 I ,I 0

MSB LSB


The Source Data Field of a source packet in the wave mode contains either

echo data orcalibration data ornoise data

Which data are in the source data field is indicated in the Data Field Header by the appropriateflags.

Echo data

The echo data contained in the Source Data Field of a source packet correspond to Msampling windows, where M depends on the subswath, ref section 5. l 8 2 I

. 'The data are formatted according to the Quantisation - Averaging Mode, each samplingwindow is formatted as the echo data in image mode, ref. section 5.2 4

Calibration Data

The calibration data contained in the·Source Data Field of a source packet correspond to

97 sampling windows in case of initial calibrationfour sampling windows in case of periodic calibration

The data are formatted according to Full 8-Bit Quantisation, ref calibration data in WaveMode, section 5.4 4

Dornier ombH Doc. No.: -0*32Issue: e Date: i .


Noise DataI

The noise data contained in the Source Data Field of a source packet correspond to exacflyone samplingwindow. I

The data are formatted according to the Quantisation - Sign +MagnitudeMode (Fixed I

Exponent) as noise data in ImageMode, ref section 5 2.4. I

General I IWhere necessary spare bits are attached in order to get a source packet of at least I008 'yt+

I I


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5.6 Source Packet Format of the Alternating Polarisation Mode

5.6.1 Overview

The measurement data are formatted in source packets according to the general layoutdescribed in Volume 4.

The Source Packets consist of three main parts, which are detailed in the following sections:

Packet Header (length 6 bytes)Data Field Header (length 30 bytes)Source Data Field (variable length)

The Packet Error Control field is not applicable for ASAR.


The packet header has a common format for all instruments The overall structure of thispacket header format is described in Volume 4, section 4 2.2.

The contents of the


contained in the packet header are instrument dependent.


APP ID=

Virtual Channel ID = 30 (HEX) Operational ModesCo-polar I I 0 0 0 0 0 0 ' I ICross-polar H I I 0 0 0 0 0 l 0 0 0Cross-polar V l I 0 0 0 0 0 I I 0 1

MSB LSB

Packet Length

The field Packet Len~th (PCK _LEN) gives the number of bytes of the packet data field minusone.

The length of the packet data field is·dependent on..

the number of sample windows included in the source packetthe sample window length andthe data processing applied to the samples

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The data field header has a common format for all modes. The overall structure of this d~tafield header format is ~es~ri~e,~~~,~ectio~,~..2.~., ,;., . ·. \I

For the calculation of the packet length see section 5 2.2...,,

5.6.3 Description of Data Field Header

Mode Identifier

For the Alternating Polarisation Mode the mode identifier is set to

I

I

' I · 1

The Source Data Field of a source packet in the Alternating Polarisation Mode containJ eitl er ,__1

~

. . I r 1

echo data orinitial calibration data orperiodic calibration data ornoise data

5.6A Description of the Source Data Field

Which data' arein the source data field is indicated in the Data Field Header by the appropfiateflags'

The data are formatted as described for Image Mode, ref section 5 2 4


n/a for ASAR

Packet Header (length 6 bytes)Data Field Header (length 30 bytes)

-~ I - Source Data Field (variable length)

' ) I The Packet Error Control field is not applicable for ASAR.

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5.7 Source Packet Format of the External Characterisation Mode

5.7.l Overview


The Source Packets consist of three main parts, which are detailed in the following sections


The packet header has a common format for all instruments The overall structure of thispacket header format is described in Volume 4, section 4 2 2

The contents of the


contained in the packet header are instrument dependent..Application Process Identifier

APP ID=

Virtual Channel ID= 30(HEX Ooerational Modes = 02(HEXI I I I O I 0 I 0 010 I 0101110

MSB LSB

Packet Length

The field Packet Length (PCK_LEN) gives the number of bytes of the packet data field minusone.


the number of sample windows included in the source packetthe sample window length andthe data processing applied to the samples

For the calculation of the packet length see section 5 2 2

.. -·· ·--- -·-----------··

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0 0SB

S.7.3 Description of Data Field Header

The data field header has a common format for all modes The overall structure of this d~tafield header format is described in section 5 2.3. I

Mode Identifier

For the External Characterisation Mode the mode identifier is set to

ModeID =

MSB0 I o 0 0 0 00

S.7.4 Description of the Source Data Field

The Source Data Field of a source packet in the External Characterisation mode containscalibration data corresponding to one sampling window. i

i IThe data are formatted in Full 8-Bit Quantisation, as the calibration data in Image Mode, rtf.section 5 2.4. i 1

'I lWhere necessary spare bits are attached in order to get a source packet of at least I00~ bYfes.

S.7.5 Description of the Packet Error Control Field

n/a for ASAR


~J I The Packet Error Control field is not applicable for ASAR)

1() ().100

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5.8 Source Packet Format of the Module Stepping Mode

5.8.l Overview


The Source Packets consist of three main parts, which are detailed in the following sections·


The packet header has a common format for all instruments The overall structure of thispacket header format is described in Volume 4, section 4 2 2.

The contents of the

Application Process ldentifierPacket Length

contained in the packet header are instrument dependent


APP ID=

Virtual Channel lD = 28(HEX) Ooerational Modes = ODfflEXI I 0 I I I 0 O I I I I I O I l

MSB LSB

Packet Length

The field Packet Length (PCK_LEN) gives the number of bytes of the packet data field minusone.


the number of sample windows included in the source packetthe sample window length and ··the data processing applied to the samples

For the calculation of the packet length see section 5.2.2.

------------ ·--- --

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Mode Identifier

5.8.3 Description of Data Field Header .The data field header has a common format for all modes The overall structure of this d~tafield header format is described in section 5 2 3

I

I

For the Module Stepping Mode the mode identifier is set to

ModeID =

~()___LJ) 0 0CD(HEX)

0 I 0 I I IIT 0 I 0MSB

0


The Source Data Field of a source packet in the module stepping mode contains calibrationdata corresponding to two sampling windows 1

The data are formatted according to Full 8-Bit Quantisation

Where necessary spare bits are attached in order to get a source packet of at least Ioosr+I •


n/a for ASAR

) ' Mode Identifier

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5.9 Source Packet Format of the Test Mode

The measurement data are formatted in source packets according to the general layoutdescribed in Volume 4

The Source Packets consist of three main parts, which are detailed in the following sections·



The Test Mode is used only during the on-ground verification processes. The precise set-upsused within the Test Mode, and as a result the precise format of the source packets, dependon the detailed definitions of the tests

The source packets of the Test Mode can be identified via the following Application Processand Mode Identifiers.


APP ID=

Virtual Channel ID = 30 (HEX) Ooerational Modes = 11(HEXI I l I O I O I O 0111010101 l

MSB LSB

For the Test Mode the mode identifier is set to

Mode ID =

'Eil 0Fl(HE~se_are

0 I 0 I 0 I 0 o I ii I i I o I oO I OMSB LSB

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5.10 Description of the High;,R:~te·DataFormat,

5.10.l On-Board Generation of the High Rate Data Format

For operational modes which require data to be transferred on the high rate data interfacf. mesource packets are further formatted into Channel Access Data Units (CADUs) I

I

1VCD_Us1·Packets ,

Figure 5.10. 1-1 Functional Overview in High Rate Formatter Module!

As shown in figure 5. 10. 1-1 the formatting of the source packets containing high rate datacontains three main functions·

Generation ofVCDUs·The source packets are packed into equal length VCDUs (ref section S 10 2). !

Generation of CADUs : " i

CADUs are generated by scrambling the VCDU bit pattern and prefixing the scrambled :sequence with a synchronization pattern. When no measurement data are gener*e~. iidleJ.A.i • .

VCDUs are included (ref. section 5.10.3). 11 .,......,..

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High Rate Data Downloading:The CADUs are transmitted as two bit-wise multiplexed data streams (ref sectionS.10.S).

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5.10.2 Virtual Channel Data Unit (VCDU)I ,

The purpose of the VCDU format is to encapsulate variable length source packet data withinfixed length packages Additionally the VCDU format provides security features, such 1asvirtual channel ID and error control fields. 1

The VCDU format summarized in Table 5 I0 2-1 consists of the following main parts

VCDU Primary Header (8 bytes)VCDU Data Field (1010 bytes) ..VCDU Trailer (2 bytes)

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Primary Header (8 bytes) VCDU ldentification (2 bytes) Version Number (2 bits)

SIC Identification (8 bits)

Virtual Channel Id (6 bits)

Virtual Channel Data Unit Counter (3 bytes)

Signalling Field (I byte) Replay Flag (I bit)

Spare (7 bits); .

VCDU Header Error Control (2 bytes)

Data Field ( l 0 l 0 bytes) Protocol Data Unit Header(2 Spare (S bits)bytes)

First Header Pointer (11 bits)

Data Unit Zone (1008 bytes)

Trailer (2 bytes) Error Control Field (2 bytes)

Table S I0.2-1: VCDU Layout

S.10.2.1 VCDU Primary Header

The VCDU Primary Header contains the following fields:

VCDU Identification Field

Version Spacecraft ID = C7 (HEX) • Virtual Channel ID = 30 (HEX)Number0 I I I I I 10 10 10 11 I 1 11 I I I 10 10 lo loMSB LSB

VCDU Counter

The VCD\J counter is a 24 bit wrap around counter which counts the VCDU's. The counter isreset when the CESA is powered off. The counter is not incremented for idle VCDU's.

VCDU Signalling Field

Replay Reserved spares set to "all zeros"Fla~

0 0 I 0 I 0 I 0 I 0 I 0 I 0MSB LSB

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VCDU Header Error Control Field

The VCDU-ID (16 bits) and the Signalling Field (8 bits) are protected by an error detectihgand correcting code, where parity symbols are contained within this 16-bit field. rFor generating the VCDU header error control field a shortened Reed-Solomon (10,6) c~delisused. The parameters of the selected code are as follows

"J = 4" bits per Reed-Solomon (R-S) symbol

"E = 2" symbol error correction capability within a R-S code word.

The field generator polynomial is·

F(x) x4 + x + l,over GF(2)

The code generator polynomial is.

g(x) = (x+a") (x+a') (x+a8) (x+a"), over GF(24)

where F(a)=O, a6=1 IOO, a7=101 I, a8=0101, a9=1010

also:g(x) = x4 + a3x3 + ax2 + a'x + 1, over GF(24)

where a0 = 0001, a3 = 1000, a= 0010

5.10.2.2 VCDU Data Field

The VCDU data field has a length of I0 I 0 bytes, it consists of the following parts:

Protocol Data Unit HeaderData Unit Zone

Protocol Data Unit Header

The POU-Header consists of S spare bits and the First Header Pointer ( 11 bits) The F~rst !Header Pointer is used for localisation of the source packet header in the VCDU data ~el~The value assigned to the First Header Pointer is ·

1

all l's, i.e. 11l 1111 1111 (binary) if there is no source packet start boundary i~ thtVCDU, i.e. if the VCDU doe~ not contain the first byte of a source packet. I

or

the index of the byte within the Data Unit Zone, which contains the first byte of thrsource packet counting from 0, i e if the data unit zone starts with a new sourte Ipacket, the First Header Pointer is 0. 1

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Data Unit Zone

The Data Unit Zone contains the data from the source packets

Source packets exceeding l008 bytes are transmitted in several VCDU's

Incomplete data unit zones are not filled with dummy data, but continue with data from thenext source packet (gapless).

5.10.2.3 VCDU Trailer

The VCDU Trailer contains a 16-bit cyclic redundancy code which provides a capability forerror detection.

The cyclic redundancy code is generated over the whole VCDU excluding the VCDU traileritself The generator polynomial is·

g(x)=x16 + x12 + x5 + I

The encoder is initialized to the "all ones" state for each VCDU

5.10.3 Channel Access Data Unit (CADU)

Each VCDU is packaged as a CADU T.he CADU layout is given in the Table 5.10.3-1

CADU (1024 bytes) Synchronization Marker (4 bytes)scrambled VCDU (1020 bytes)

Table 5 10.3-l: CADU Layout

5.10.3.1 Synchronisation Marker

The synchronization marker bit pattern is IACFFC ID (HEX)

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5.10.3.2 ScramblingProcedure ,

The scrambled VCDU bit sequence is obtained by multiplying the original VCDU seque.lewith a pseudo random sequence The same pseudo random sequence is applied to each ~C

The pseudo random noise (PRN) is produced by the polynomial

h(x) = x8 + x7 + x5 + x3 + l

The PRN generator is initializedto an "all ones" state prior to convolution with the firstVCDU bit and is updated to each subsequent state prior to each successiveVCDU bit

The first 40 symbolsof the PRN sequence are as follows:

MSB l 1110100000011001001

1111100011100000IOIO

) )

The MSB is the first symbol of the sequence and is "exclusivelyOR'ed" with the MSB mth~first VCDU byte. '

Figure 5.10.3-1 shows a model of the bit scramblingoperation:

x7 I x6 I x5 I x4 I x3 I x2 I xt I xO shill register

scrambled VCDU hilsequence as inserted -inCADU

VCDI l bit sequence-- (1020*8 hits)

Figure 5.10.3-l: Scramblingof VCDU

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5.10.4 Idle VCDUs

In order to keep a constant output dafifrate. idle VCDUs are inserted to the data stream, if noVCDUs containing measurement data are available

Every idle VCDU has exactly the same bit'pattern. It conforms with the normal :VCDU formatwith the following settings: '

··:.i..:·

VCDU Identification Field

·Virtual.Channel .JDi9 lFi(Hex),. . .,. ' ' .VersionNumber

0 10 00 I IMSB LSB

VCDU Counter,

The VCDU counter is set constant to 0.

Signalling Field

The Signalling Field is set to 00 (HEX), as in a normal VCDU, ref section 5.10 2 I.

VCDU Header Error Control Field' ' . .. .

Generated using a shortened Reed-Solomon (10,6) code, as described in section 5 10.2 l

Protocol Data Unit Header

First Header Pointer= "all ones minus I", i e0 0 0 \ I\ \I \\ \\ \\ ll \\ 0

LSB

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Data' Unit Zone

The data unit zone is completely filled with zeroes, i.e. every byte is set to 00 (HEX).

VCDU Trailer

Generated using a cyclic redundancy code, as described in section 5.10 2.3

5.10.5 High Rate Data Downloading

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The MSB (bit 0) is transmitted down the HR data I-channel

III• I

Least significant ~t ~t .,I , i

The high rate data in the form of CADUs are transmitted as two bit-wise multiplexed datastreams, defined as a single virtual channel. This is shown in Figure 5 I0 5-1 r

Most significant bit sent first.1

CADUData lo I 1 12 p 14 Is 16 17 101611017 11018 11019 11020 11021 I 1 ~I!

~ ~ 110201~

~ ~ ~ ~ i

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H-R Data I ~ (!] ~ (!]

~ @]~Ione clock cycleH-RDataQ F

H-R Data transfer scheme showing bitwise multiplexing,i.e. alternate bits sent down I&Q channels

Figure 5 I0.5-1 Bit-wise Multiplexing for H-R Data Transmission

5.10.6 Data Handling Procedure for Mode Transitions

Entering a High Rate Mode

When commanded to enter a high rate mode the data handling function starts the transmissionofCADUs (containing idle VCDUs) at least I second before the first valid packet is 1

transmitted.

Leaving a High Rate Mode

At the end of a High Rate Mode (i e after finalisation of the source packet generation 1 1

according to the mode tirneline, ref sections 5 1.x 2 1) an additional source packet (cohta'1ingnoise) is generated

All data which can be formatted into complete CADUs are transmitted Any remainingsampled data are cleared from the memories of the data handling function This means iqheend of the last source packet (i e. the additional dummy source packet) does not completely fillthe VCDU Data Field, the corresponding VCDU is discarded

HR-Interface during Pre-Op and Low Rate Modes

During Pre-Op and LR modes a fixed ' IA' pattern is sent at the HR interface provided le H1ltsync 50 MHz clock is received When entering or leaving a High Rate Mode (i e going om'1 A' to Idle CADUs or vice versa) a few bytes of' all ones' or 'all zeroes' may be trans itted.

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5.11 ASARData Rates

5.11.l Data Rate Summary

The source packet generation frequency and source packet length for ASAR depend on severalparameters which are commandable and therefore may be varying In table 5 I I . 1-1 an,overview on the data transmission rates and the maximum of the average data generation ratesare given The ~verageis calculated for the duration of a mode (e g considering the gapsbetween downloading of the wave mode data )

Transmission Rate Maximum Average SourcePacket Generation Rate

linage Mode. I00 Mbit/sec 98 5 Mbit/secWideswath Mode I00 Mb it/sec 98 S Mbit/secWave Mode O900 Mbit/sec 0 9 Mbit/secGlobal Monitoring 0 900 Mbit/sec 0.9 Mbit/secAlternating Polarisation Mode I00 Mbit/sec 98 5 Mbit/secExternal Characterisation Mode I00 Mbit/sec 98 5 Mbit/secModule Stepping Mode 0 900 Mbit/sec 0 9 Mbit/sec

Table S 11. 1-1· Data Rate Summary

Details on the data generation rates are given in the following sections It has to be noted thatthe values given below are the nominal values corresponding to the baseline of the time whenthis document was generated. The ranges may still change

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5.11.2 Image Mode

The data rates for the Image Mode are given in Table 5.11.2-1 In Image Mode (apart from~gap ofR pulses after the initial calibration period) the source packet generation frequency i

correponds to the Pulse Repetition Frequency (PRF), there is one source packet generated p'rsampling window. For details refer to the mode time lines described in section 5.1.5.2.1. i

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ISi IS2 ISJ IS4 ISS IS6 IS7Source Packet Generation Frequency [Hz] I

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PRF mm 1678 1645 2071 1668 2048 1684 2035max 1678 1645 2096 1680 2082 1698 2070

Source Packet Length [bytes] I

Echo min 4708 5604 5348 6628 5412 6308 5348imax 5156 6052 5860 7268 5860 6948 586q

Initial mm 1008 1008 1008 1008 1008 1008 10081Calibration max 1528 1558 1246 1536 1258 1522 1266Periodic mm 2332 2372 1876 2324 1884 2300 1892Calibration max 6004 6124 4876 6036 4924 5980 495~Noise mm 4636 5518 5266 6526 5328 6210 5266

max 5076 5958 5770 7156 5770 6840 5770Data Transmission Rate = I00 Mbit/s (CADUs including idle VCDUs, ref. section 5 I0) I

Table 5 l 1.2-l Image Mode Data Rates

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5.11.3 Wide Swath Mode

The data rates for the Wideswath Mode are given in Table 5 11.3-1 Similar as in image modethere is one source packet generated per sampling window. Therefore the PRF can be taken asa measure for the source packet generation frequency For details on the mode timelines referto section 5.1.6 2 I.

I I SSI I SS2 I SS3 I SS4 I SSSSource Packet Generation Frequency [Hz]PRF Imin 1658 2069 1667 2046 1683

max 1662 2096 1679 2082 1698Source Packet Length [bytes]Echo I min 6628 5348 6628 5412 6308

max 7268 5860 7268 5860 6948Initial mm 1008 1008 1008 1008 1008calibration max 1544 1246 1536 1258 1522Periodic mm 2348 1876 2324 1884 2300calibration max 6068 4876 6036 4924 5980Noise min 6526 5266 6526 5328 6210

max 7156 5770 7156 5770 6840Data Transmission Rate = 100 Mbit/s (CADUs including idle VCDUs, ref section S.10)

Table 5.11.3-1 :.Wide Swath Mode Data Rates

5.11.4 Wave Mode

In Wave Mode transmission and acquisition may be done in parallel. Nevertheless the data forone complete vignette are acquired, formatted and stored before starting the transmission (refFigure 5.11.4-1).

WaveAcquire

WaveDownload

start transmission subevcle I start transmission subcycle I

Figure 5 I I .4-1 ..Wave Mode Data Transmission Scheme

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The source packets containing echo data are generated with a frequency of I source packet per8 PRI during the acquisition period In addition there is one source packet containing noise andtwo source packets containing calibration for each subcycle For details on the mode timelinesrefer to section S.1.7 2. 1

ISl IS2 IS3 IS4 ISS IS6 IS7 !

Source Packet Generation FrequencyNumber of echo nominal 299 297 381 315 393 331 j97packets per cycle i

Cycle repeat time [s] nominal 15067 15072 15082 15093 15.106 15.117 15 1]31IAcquisition [s] nominal 1.426 1444 l 472 l.511 1.535 1572 15 131 lSource Packet Length [bytes] IEcho min 2216 2396 2320 2756 2644 2968 2844

max 4772 5008 4424 5344 4760 5532 4976Calibration (CW) min 7020 7214 5662 7020 5662 7020 566i

max 22346 22734 18078 22540 18272 22346 184~16Calibration (chirp) min 1008 1008 1008 1008 1008 1008 1008

Imax 1434 1464 1170 1444 1182 1430 1188 I

INoise mm 4316 4676 4524 5380 5156 5804 5556 I

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max 9348 9820 8668 10484 9324 10852 9756 i

IData Transmission Rate= 0.900 Mbit/s (excluding the gaps between downloading) I

Table 5 11.4-1 Wave Mode Data Rates

5.11.5 Global Monitoring Mode

In Global Monitoring Mode transmission and acquisition is done in parallel Nevertheless acomplete cycle is stored before starting transmission (ref. Figure 5 11.5-1)

Cycle n Cycle n+l

Acquisition

Transmission

7~7-Acquir~cJ;"';';-

tstart transmission

Figure 5.11.5-1 · Global Monitoring Mode Data Transmission Scheme

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The maximum data generation rate per cycle is shown in table 5.1 J 5-1. For details on themode timelines refer to section 5 1.8.2.1.

SSI SS2 SS3 SS4 SSSNumber of Source Packets per CycleEcho packets per subcycle I 1 I l lSubcycles per cycle 4 4 4 4 4Cal I noise packets per cycle I I I I 1Source Packet Length [bytes]Echo min 2370 1732 1576 1494 1254

max 3012 2124 1724 1806 1564Calibration/Noise 1008 1008 1008 1008 1008Maximum Cycle Data Generation RateTotal data per cycle (bytes] 53800Cycle Repeat Time [msec] 478.530

Table 5 11 5- 1 Global Monitoring Mode Data Rates

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'5.11.6 Alternating Polarisation Mode

The data rates for the Alternating Polarisation Mode are given in Table 5.11 6-1 Similar as inImage Mode the source packet generation frequency correponds to the Pulse RepetitionFrequency (PRF), there is one source packet generated per sampling window For details referto the mode time lines described in section 5.1.9.2. l

ISi IS2 IS3 IS4 IS5 IS6 IS7Source Packet Generation Frequency [Hz]PRF mm 1678 1645 2071 1668 2048 1684 2035

max 1678 1645 2096 1680 2082 1698 2070Source Packet Length [bytes]Echo mm 4708 5604 5348 6628 5412 6308 5348

max 5156 6052 5860 7268 5860 6948 5860Initial calibration mm 1008 1008 !008 1008 1008 1008 1008

max 1528 1558 1246 1536 1258 1522 1266Periodic calibration mm 2332 2372 1876 2324 1884 2300 1892

max 6004 6124 4876 6036 4924 5980 49$6-

Noise mm 4636 5518 5266 6526 5328 6210 5266max 5076 5958 5770 7156 5770 6840 5770

Data Transmission Rate = l00 Mbit/s (CADUs including idle VCDUs, ref section 5.10)

Table 5. l I 6-1 . Alternating Polartisation Mode Data Rates.

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5.11. 7 External Characterisation Mode

Source Packet Generation Frequency [Hz]PRF 2799.951Source Packet Length [bytes]Calibration 1574

Table 5. 11 7-1 : External Characterisation Mode Data Rates

S.11.8 Module Stepping Mode

Source Packet Generation FrequencyNumber of packets per sequence 320Download Time to HSM [sec] 89Source Packet Length [bytes]Calibration 3112

Table 5.11 8-1 Module Stepping Mode Data Rates

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Documents

cs: 9 · 2014. 7. 9. · conversion andnomenclature, that isused indescribing thedata formats, andthen sp~cif.bsthe lay-out ofthe Source Packet structure, includingthe contents ofthe