Polarimetric, combined, short pulse scatterometer-radiometer system at 15GHz for platform and vessel…

Polarimetric, combined, short pulse Polarimetric, combined, short pulse scatterometer-radiometer system at 15GHz scatterometer-radiometer system at 15GHz

for platform and vessel applicationfor platform and vessel application

A.K.Arakelyan, A.A.Arakelyan, S.A.Darbinyan, A.K.Arakelyan, A.A.Arakelyan, S.A.Darbinyan, M.L.Grigoryan, I.K.Hakobyan, A.K.Hambaryan, M.L.Grigoryan, I.K.Hakobyan, A.K.Hambaryan, V.V.Karyan, G.G.Hovhannisyan, T.N.Poghosyan, V.V.Karyan, G.G.Hovhannisyan, T.N.Poghosyan,

N.G.Poghosyan and S.F.CliffordN.G.Poghosyan and S.F.Clifford

ECOSERV Remote Observation Centre Co. ECOSERV Remote Observation Centre Co. Ltd.Ltd.

2 G. Njdeh Str., #24, Yerevan, 375006, ARMENIA2 G. Njdeh Str., #24, Yerevan, 375006, ARMENIAPhone: (374 10) 421 877/425 088; Fax: (374 10) 421 877 Phone: (374 10) 421 877/425 088; Fax: (374 10) 421 877

emails: [email protected]; [email protected]: [email protected]; [email protected]

AbstractAbstractIn this presentation a KIn this presentation a Kuu-band, dual-channel, -band, dual-channel, polarimetric, combined, short pulse (~25ns) polarimetric, combined, short pulse (~25ns) scatterometer-radiometer system is described, scatterometer-radiometer system is described, for short and middle distance application (from for short and middle distance application (from 6m up to 300m), for polarimetric (vv, vh, hh, 6m up to 300m), for polarimetric (vv, vh, hh, hv), spatio-temporally coincident microwave hv), spatio-temporally coincident microwave active-passive measurements of water surface, active-passive measurements of water surface, soil, snow and vegetation parameters.soil, snow and vegetation parameters.

The minimum operational range of the The minimum operational range of the scatterometer is ~6m.scatterometer is ~6m.

A KA Kuu-BAND SCATTEROMETER--BAND SCATTEROMETER-RADIOMETER SYSTEMRADIOMETER SYSTEM

The principal requirements for a The principal requirements for a development of the system weredevelopment of the system were::

Functional and constructive combining both Functional and constructive combining both microwave active and passive means of sensing microwave active and passive means of sensing as a single microwave device, providing as a single microwave device, providing simultaneous operational peculiarities.simultaneous operational peculiarities.

Coherent-pulse construction of the Coherent-pulse construction of the scatterometer’s functional scheme, provided scatterometer’s functional scheme, provided high level of decoupling between transmitting high level of decoupling between transmitting and receiving sections, allowed realize short and receiving sections, allowed realize short range operational potential beginning from 6m.range operational potential beginning from 6m.

Transmission of signals at a specified Transmission of signals at a specified (vertical or horizontal) polarization and (vertical or horizontal) polarization and receiving both co- and cross polarized receiving both co- and cross polarized components of backscattered radar signal.components of backscattered radar signal.

Possibility for application of developed Possibility for application of developed principles and methods for signal’s forming principles and methods for signal’s forming and processing for aero-space based and processing for aero-space based prototype of the system.prototype of the system.

Time division channeling of scatterometer and Time division channeling of scatterometer and radiometer functioning was used for the radiometer functioning was used for the system’s functional scheme development, to system’s functional scheme development, to provide their swimmingly interaction. provide their swimmingly interaction.

Such a construction allows improve relative Such a construction allows improve relative accuracy of measurements by cross polarized accuracy of measurements by cross polarized signals, simplify calibration procedure, and signals, simplify calibration procedure, and reduce complicity and the value of the system, reduce complicity and the value of the system, by using microwave and intermediate frequency by using microwave and intermediate frequency modules of the system as common modules, for modules of the system as common modules, for both scatterometer and radiometer channels.both scatterometer and radiometer channels.

Radar Reception at vv and vh pol.


Time for Receivers Protection


1ms

1ms

Pulse Transmission at v pol.

10 pulses of 25ns

100mks


Radiometric reception at v and h pol.

The

Pulse

Dur

atio

n is

30ns

1mks



10mks




Pulse Transmission at h pol.Radar Reception at hh and hv pol.



Scatterometric and Radiometric Channels Scatterometric and Radiometric Channels OperationOperation Time DiagramTime Diagram

(short distance application from 6m up to 100m)(short distance application from 6m up to 100m)

Scatterometric andScatterometric and Radiometric Channels Radiometric Channels OperationOperation Time Diagram Time Diagram

(application range from 50m to 300m and more)(application range from 50m to 300m and more)

Pulse Transmission at v pol.Pulse Transmission at v pol.





1ms

1ms


100mks


The

Pulse

Dur

atio

n is

100n

s


Pulse Transmission at h pol.

3mks


Time for Receivers Protection Radiometric reception at v and h pol.

Radar Reception at hh and hv pol.

Time for Receivers Protection Radiometric reception at v and h pol.

100ns

Of cause, time-division channeling of Of cause, time-division channeling of stterometer and radiometer functioning has its stterometer and radiometer functioning has its shortage connected with a reduction of shortage connected with a reduction of backscattered signals accumulation (storage) backscattered signals accumulation (storage) efficiency and with a reduction of radiometers’ efficiency and with a reduction of radiometers’ integration times. integration times.

However, for stationary and low speed platform However, for stationary and low speed platform application this fact is not sufficient, if the main application this fact is not sufficient, if the main requirement for the system’s operation is its requirement for the system’s operation is its work stability and the accuracy of the work stability and the accuracy of the measured data.measured data.

3 2 3

4

7

22

27

8 8

10 10

9

8

11 11

20

14 12 12

10

13 13

14 14 17 17

15 18 18 15

16 16

23

26

32

14 30

31

1

14

6

7

25

21

14

29

9

8

1

2 h-pol. v-pol.

5

22

9

8

6

5

28

19

24

10

9

1 – Antenna 2 – Orthomode Transducer 3 – Circulator 4 – Polarization Switch SPDT 5 – Protector 6 – Antenna Switch/Modulator 7 – Four-Port Directional Coupler 8 – Attenuator 9 – Noise Source10 – Isolator11 – Low Noise Amplifier12 – Mixer13 – IF Pre-Amplifier14 – 3-dB Splitter15 – Radiometer IF Amplifier16 – Synchronous Detector & Integrator17 – Radar IF Amplifier18 – Phase Detector and Sample/Hold19 – Reference Oscillator20 – Pulse Modulator21 – Microwave Oscillator (Heterodyne)22 – Directional Coupler23 –Power Pre-Amplifier24 – UP-Converter25 – Band Pass Filter26 – Power Amplifier27 – Sq. Detector28 – LF Amplifier29 – Sample/Hold30 – Check Indicator31 – Synchronizer32 – Solver and Recorder

A block diagram of KA block diagram of Kuu-band -band ((~15GHz~15GHz)) scatterometerscatterometer-radiometerradiometer

The main technical characteristics of The main technical characteristics of developed microwave devicesdeveloped microwave devices

ParametersParameters RadiometerRadiometer ScatterometerScatterometerFrequency BandFrequency Band ~15GHz~15GHz ~15GHz~15GHzPolarizationPolarization v and hv and h vv; vh or hh; hvvv; vh or hh; hvTwo ParabolicTwo Parabolic

AntennasAntennasGains / SidelobesGains / Sidelobes

26cm Dish/8cm Focus and 26cm Dish/8cm Focus and 50cm/13cm 50cm/13cm

25dB / -20dB and 32dB / -25dB / -20dB and 32dB / -23dB23dB

Antenna Beam WidthAntenna Beam Width ~6~6oo andand ~3~3oo

Cross-Polarization Cross-Polarization Isolation Isolation Better than -25 dBBetter than -25 dB

Receiver’s BandwidthReceiver’s Bandwidth ~10 %~10 % ~3%~3%Receiver’s Noise Receiver’s Noise

FactorFactor 350 K350 K ~2.5 dB~2.5 dB

Sensitivity at 1s Sensitivity at 1s ~0.15K~0.15K ~ – 126dB/W~ – 126dB/W

The main technical characteristics of The main technical characteristics of developed microwave devices (developed microwave devices (cont cont

……))ParameterParameter RadiometeRadiomete

rr ScatterometerScatterometer

Absolute Accuracy of Absolute Accuracy of MeasurementsMeasurements ~2 K~2 K ~1.5 dB~1.5 dB

Radar Pulse DurationRadar Pulse Duration ~25 ns~25 nsRadar Pulse PowerRadar Pulse Power ~65 mW~65 mWMinimal Operational Minimal Operational RangeRange ~6m~6m

Weight & DimensionsWeight & Dimensions ~15 kg / 500 x 380 x ~15 kg / 500 x 380 x 340mm340mm33

Power ConsumptionPower Consumption ~200 W~200 W

CONCLUSIONCONCLUSION Thus, a KThus, a Kuu-band, dual-channel, polarimetric, combined -band, dual-channel, polarimetric, combined

scatterometer-radiometer system is developed and realized. scatterometer-radiometer system is developed and realized.

The developed system allows investigate peculiarities of The developed system allows investigate peculiarities of relationships between power (amplitude) and phase relationships between power (amplitude) and phase characteristics of the backscattered radar signal and between characteristics of the backscattered radar signal and between power characteristics of backscattered radar and emitted proper power characteristics of backscattered radar and emitted proper radio thermal signals of the observed surface or object, at various radio thermal signals of the observed surface or object, at various polarizations, under test-control laboratory and field conditions. polarizations, under test-control laboratory and field conditions.

The system may be used as a detector and identifier and will The system may be used as a detector and identifier and will allow to detect and to classify at least 32 types of anomalies, allow to detect and to classify at least 32 types of anomalies, originating on the background due to the changes of the originating on the background due to the changes of the observed surface geo-physical and biochemical parameters. observed surface geo-physical and biochemical parameters.

AcknowledgementsAcknowledgementsThe described scatterometer-radiometer system The described scatterometer-radiometer system was developed, manufactured and assembled in was developed, manufactured and assembled in Armenia by ECOSERV Remote Observation Armenia by ECOSERV Remote Observation Centre Co. Ltd., under the framework of the Centre Co. Ltd., under the framework of the Project ARG2-579-YE-04 of the US Civilian Project ARG2-579-YE-04 of the US Civilian Research and Development Foundation (CRDF Research and Development Foundation (CRDF NSMP) in collaboration with Cortana NSMP) in collaboration with Cortana Corporation.Corporation.

Authors express their gratitude to CRDF and Authors express their gratitude to CRDF and Cortana Corporation for their financial support Cortana Corporation for their financial support of the planned works fulfillment.of the planned works fulfillment.

Thank you !Thank you !

At that, the work while of the system is divided by 1ms time cycles, in which 1% of time period is At that, the work while of the system is divided by 1ms time cycles, in which 1% of time period is used for transmission of 10 pulses and for reception, sequentially after each transmission, co- and used for transmission of 10 pulses and for reception, sequentially after each transmission, co- and cross polarized components of 10 backscattered scatterometric signals. 9% of the time period or cross polarized components of 10 backscattered scatterometric signals. 9% of the time period or cycle is used to protect the inputs of the radiometric receivers from the impact of the transmitter. cycle is used to protect the inputs of the radiometric receivers from the impact of the transmitter. And the remain of the time (90% of the work period) is used for reception proper radio thermal And the remain of the time (90% of the work period) is used for reception proper radio thermal signals of the observed surface at v and h polarizations.signals of the observed surface at v and h polarizations. The polarization of the transmitted signals may be changed periodically or by pre-assigned order, The polarization of the transmitted signals may be changed periodically or by pre-assigned order, manually, from the system’s management control panel.manually, from the system’s management control panel.

The input of the system includes a parabolic antenna, an ortho-mode transducer (polarization The input of the system includes a parabolic antenna, an ortho-mode transducer (polarization splitter), two decoupling Y-circulators, a polarization switcher and two antenna switchers or splitter), two decoupling Y-circulators, a polarization switcher and two antenna switchers or modulators.modulators.

The scatterometer was built in compliance with a structure of entire internal coherence system. The scatterometer was built in compliance with a structure of entire internal coherence system.

The microwave oscillator’s (heterodyne) signal at ~5.35GHz is used for generation transmitter’s The microwave oscillator’s (heterodyne) signal at ~5.35GHz is used for generation transmitter’s signals in up-converter, and is used as a local heterodyne signal for feeding the mixers of the signals in up-converter, and is used as a local heterodyne signal for feeding the mixers of the receivers. receivers.

As a source for a reference signal for the up-converter and for a phase detectors, a high stable high As a source for a reference signal for the up-converter and for a phase detectors, a high stable high frequency oscillator is used at 250MHz.frequency oscillator is used at 250MHz.

Transmitter’s pulse signals, as an envelope of 10 pulses with a duration of 30ns each, are formed Transmitter’s pulse signals, as an envelope of 10 pulses with a duration of 30ns each, are formed by the pulse modulator from the continuous signals of the reference oscillator. The modulation by the pulse modulator from the continuous signals of the reference oscillator. The modulation frequency is 1MHz, and the repetition frequency of the envelope is 1KHz, at a modulation depth frequency is 1MHz, and the repetition frequency of the envelope is 1KHz, at a modulation depth ~100dB.~100dB.

Receiver’s switcher SP3T is used as well as a modulator for a radiometer. It protects the receivers input from the transmitter pulse signal and carrier Receiver’s switcher SP3T is used as well as a modulator for a radiometer. It protects the receivers input from the transmitter pulse signal and carrier leakage as well.leakage as well.

The first two positions of polarization switchers SP3T are used for realization of transmitted and received signals polarizations. The first two positions of polarization switchers SP3T are used for realization of transmitted and received signals polarizations.

The third positions of polarization switchers SP3T and the second position of SPDT switcher are used for switching-on the loops for internal calibration The third positions of polarization switchers SP3T and the second position of SPDT switcher are used for switching-on the loops for internal calibration of scatterometric and radiometric channels of the system.of scatterometric and radiometric channels of the system.

The output signals of the up-converter, through the band pass filter, come to the The output signals of the up-converter, through the band pass filter, come to the main (power) amplifier and are emitted at a specified polarization. main (power) amplifier and are emitted at a specified polarization.

Received co- and cross polarized components of the backscattered signals are Received co- and cross polarized components of the backscattered signals are converted by the receivers mixers into intermediate frequency (IF) signals and feeds converted by the receivers mixers into intermediate frequency (IF) signals and feeds the inputs of the IF pre-amplifiers. the inputs of the IF pre-amplifiers.

The output of the pre-amplifiers is divided in two parts, which feed inputs of The output of the pre-amplifiers is divided in two parts, which feed inputs of scatterometric and radiometric channels IF amplifiers. scatterometric and radiometric channels IF amplifiers.

The input of scatterometer channel’s IF Amplifier connects with the mixer only The input of scatterometer channel’s IF Amplifier connects with the mixer only during scatterometer operation while. during scatterometer operation while.

Amplified signals, at a central frequency 250MHz and a bandwidth ±50MH, come to Amplified signals, at a central frequency 250MHz and a bandwidth ±50MH, come to the input of phase detector, from the outputs of which I-Q quadrature components, the input of phase detector, from the outputs of which I-Q quadrature components, through the sample and hold, come to the input of the ADC (analog digital converter) through the sample and hold, come to the input of the ADC (analog digital converter) and are saved by PC for real time (preliminary) and further (detail) processing. and are saved by PC for real time (preliminary) and further (detail) processing.

Fetch (sampling) time is equal 20ns, and the sampling instant corresponds to the Fetch (sampling) time is equal 20ns, and the sampling instant corresponds to the commencement of the receiving of backscattered signals. commencement of the receiving of backscattered signals.

The Dicke radiometers use two reference noise temperature levels in the The Dicke radiometers use two reference noise temperature levels in the section of their equivalent loads. Such a construction provides gain and section of their equivalent loads. Such a construction provides gain and noise insensibility and allow carry out continuous calibration. noise insensibility and allow carry out continuous calibration.

During radiometers’ work period, the receivers’ inputs, by turns of 1KHz During radiometers’ work period, the receivers’ inputs, by turns of 1KHz frequency, connects to appropriate antenna outputs and to the frequency, connects to appropriate antenna outputs and to the equivalent load sections outputs (switched of Modulators) by means of equivalent load sections outputs (switched of Modulators) by means of the antenna switcher. Switching times to antenna and to equivalent load the antenna switcher. Switching times to antenna and to equivalent load are equal and constitutes a half of the radiometer modulation time. are equal and constitutes a half of the radiometer modulation time.

Input noise signals for the equivalent load section, for creation of a Input noise signals for the equivalent load section, for creation of a necessary pilot signal, has a modulation frequency 2KHz. necessary pilot signal, has a modulation frequency 2KHz. It is generated by a noise It is generated by a noise generator developed on the basis of 1A404a varactor, worked at an avalanche breakdown condition.generator developed on the basis of 1A404a varactor, worked at an avalanche breakdown condition.

Modulated noise signals, converted in the mixer and gain in the Modulated noise signals, converted in the mixer and gain in the radiometer IF amplifier, through a synchronous detector and integrator radiometer IF amplifier, through a synchronous detector and integrator come to the input of the ADC and in parallel with the scatterometer come to the input of the ADC and in parallel with the scatterometer signals are saved by PC. signals are saved by PC.

For radiometric receiver’s internal calibration the second noise generator For radiometric receiver’s internal calibration the second noise generator is used, is used, developed as well on the basis of the 1A404a varactor, worked at an avalanche breakdown condition.developed as well on the basis of the 1A404a varactor, worked at an avalanche breakdown condition.

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Polarimetric, combined, short pulse scatterometer-radiometer system at 15GHz for platform and vessel…