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INSAT SATELLITE BASED DATA COLLECTION & TRACKING SYSTEM FOR

OCEAN DATA BUOYS

S. N. Satashia, Prem Kumar, M. Jeyamani &

Tata Sudhakar

Space Application Centre Ahmedabad & NIOT Chennai

BY

Tata Sudhakar

National Institute of Ocean Technology, Chennai

• The system uses Data Relay Transponder(DRT) of the Satellites

• The satellite receives transmission from data buoy in UHF band(402MHz) and retransmits to ground station in C band(4.5GHz).

• There are two satellites having DRT transponders INSAT 3A at location 93.5E and METSAT (KALPANA) satellite at location 74E.

INSAT BASED DATA COLLECTION SYSTEM

INSAT DRT coverage

FEATURES OF THE INSAT SATELLITES

INSAT 3A

C band Transponder :12

Ext C band Transponder :6

Ku band Transponder :6

DRT&SAS&R Transponders :1

Met Transmitter(VHRR&CCD) :1

METSAT(KALPANA)

DRT & SAS&R Transponder :1

Met Transmitter(VHRR) :1

PRESENT DCP

• India Meteorological Department

• Central Water Commission

• Snow& Avalanche Establishment

• NIOT

• State Agencies

• Transmit power 10W (Typ.)

• Transmit at 4.8Kbps in random mode in allotted

time window.

• Uses Directional antenna of gain 11dB (Typ.)

• Uses 3.8m Ground Receive station (Hub)

CHARACTERISTICS OF THE

TRANSMITTER (DCP)

Rx. Frequency Range : 402.75Mhz. 100KHz.Rx. G/T : - 19.0dB/ KReceive Polarization : Circular(RHCP for METSAT

&LHCP for INSAT 3A)Down link frequency : 4505 MHz (Nominal)Transmit Polarization : LinearEIRP (EOC) :18dBW

DRT TRANSPONDER CHARACTERISTICS

Satellite Link Design for Data Buoys

• The Transmit power from the data buoy is 10W.

• The transmit data rate is 300bps.

• Forward Error Correction Coding (convolution Coding) for the satellite channel is employed.

•Packet Error rate Probability(PEP)is kept as 0.01.

•Time Division Multiple Access(TDMA) transmission protocol employed with time synchronized to GPS received time.

Satellite Link calculation  

UP LINK:

Up link frequency : 402.710MHz.  Tx power : 10dBWAntenna gain (including cable loss) : -3dBiTx. EIRP : 7dBWMax. Slant range to satellite (at 5 deg. Ele) : 41130 KmUplink path loss : 177 dBSatellite G/T : -19dB/K

: EIRP - path loss + G/T+K Uplink C/No : 39.6dBHz DOWN LINK: Down link freq. : 4505MhzDown link path loss : 197.0dBSatellite EIRP : -1dBWDown link path loss : 197.0dbG/T of earth station (3m) : 17dB/KDown link C/No : EIRP - Path loss+ G/T+k

: 47.6dBHzTotal C/No : 39.5dBHzRequired C/No : 34dBHzLink Margin : 5.5dB

UHF TRANSMITTER

(10W)

DATA COLLECTION FROM DATA BUOY THROUGH INSAT

UHF(402MHz)

Data Acquisition

(CPU)

GPS

Data from Sensors

LNA RFD/C

BURSTDEMOD(BPSK)

70MHz IF 300b/s

C-BAND(4.5GHz)

To data processing system of NIOT

3.8m

INSAT

Message Generator

Frequency Synthesizer

(UHF)

Power Amplifier

(10W)

BPSKModulator

Data from CPU

Block Schematics of INSAT UHF Transmitter

4.8Kbaud

402MHz

300bbps (1/2 rate)

  

 

F(8)

 MID(16)

 IINFORMATION 

(320)

 CRC(16)

 F

(8)

  

DATA FORMAT

BURST FORMAT OF TRANSMISSION

CR BTR UW  

 

1.68Sec sec

256 64 64 UP TO 752 SYMBOLS

SCRAMBLED AND ½ RATE CODED

CR Carrier Recovery

BTR Bit Timing Recovery

UW Unique Word

Specification of Receive station(HUB)

 Receive frequency :4505MHzG/T of Receive station (3.8m) : 22dB/KIF Input to BPSK demodulator :70MHz (nominal)Output data rate & level : 300b/s, RS 232Output data frame format (Demod) : HDLCInput to data processing unit :4800baud

TEST RESULT OF SATELLITE LOOP

TX power 

C/No

(dBHz)

Packets % PEPRx / Tx

1W 32.3 80/100 0.2 

1.25W 33.3 90/100 0.1 

1.5W 34.3 96/100, 95/100, 0.0496/100

2.5W 36.3 98/100 0.02 

9W 41.8 98/100 0.02 

1. THE EXPERIMENT RESULTS SHOW THAT INSAT SUPPORTS DATA BUOY COMMUNICATION WITH ADEQUATE MARGIN

2. OCCASIONAL LOSS OF DATA DUE TO INTERFERENCE FROM OTHER GROUND SYSTEM IS TAKEN CARE OF BY DIFFERENTIAL CODING and REPEAT TRANSMISSION.

INSAT Transmitter and Antenna for data buoys

INDIA

Arabian SeaBay of Bengal

SW6

DS1

DS3

Chennai

Machillipatnam

Mangalore

Tuticorin

Goa

Mumbai

NIOT

Pipvav

Off Paradip

DATA BUOYS WITH INSAT COMMUNICATION

Data Buoy with Insat communication

Buoy with Insat Position reporting system

NIOT Hub and INSAT DRT capacity

A hub station has been commissioned at NIOT in association with SAC Ahmedabad to establish the INSAT link for buoy communication.

Successfully carried out the preliminary tests

INSAT (METSAT & INSAT 3A) can handle communication up to 1200 platform/ hour/carrier.

TRACKING SYSTEM

Information Rate 300 BPS

Format HDLC

Message Length 40 Characters (Max)

Error Protection 16 bit CRC

Error correction rate

600 BPS

Modulation BPSK, bust

External Data RS-232 Interface (GPS,NMEA - 0183D)

Transmission 3 Packets/message randomized – Aloha mode.

1 Packet / Message - TDMA mode

Transmission time 4 sec (Max) / Message

Frequency band 2677.56 to 2678.56 MHz

Freq. Uncertainty ± 2.7 KHz Max.

Antenna Coverage ± 45°

Tx EiRp 9 dBW (min.)

Power Supply Li - Ion -12 V DC, 600 mAh, Rechargeable Battery

Temperature 0 to + 50° C

MSS Terminal SpecificationMSS Terminal Specification

Buoy fitted with MSS transmitter is ready for deployment.

MSS - TRANSMITTERMSS - TRANSMITTER

Message Generator

Frequency Synthesizer

Power Amplifier

BPSKModulator

GPS Receiver

Emergency Switch

Battery

        

 

  

Block Schematics of Alert Transmitter

Thank you