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 th

INSAT BASED DATA COLLECTION SYSTEM 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 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 Central Water Commission Snow& Avalanche Establishment India Meteorological Department Central Water Commission Snow& Avalanche Establishment NIOT State Agencies

CHARACTERISTICS OF THE TRANSMITTER (DCP) 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)

DRT TRANSPONDER CHARACTERISTICS Rx. Frequency Range : 402.75Mhz. 100KHz. Rx. G/T : - 19.0dB/ K Receive Polarization : Circular(RHCP for METSAT &LHCP for INSAT 3A) Down link frequency : 4505 MHz (Nominal) Transmit Polarization : Linear EIRP (EOC) :18dBW

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 : 10dBW Antenna gain (including cable loss) : -3dBi Tx. EIRP : 7dBW Max. Slant range to satellite (at 5 deg. Ele) : 41130 Km Uplink path loss : 177 dB Satellite G/T : -19dB/K : EIRP - path loss + G/T+K Uplink C/No : 39.6dBHz DOWN LINK: Down link freq. : 4505Mhz Down link path loss : 197.0dB Satellite EIRP : -1dBW Down link path loss : 197.0db G/T of earth station (3m) : 17dB/K Down link C/No : EIRP - Path loss+ G/T+k : 47.6dBHz Total C/No : 39.5dBHz Required C/No : 34dBHz Link Margin : 5.5dB

DATA COLLECTION FROM DATA BUOY THROUGH INSAT UHF(402MHz) C-BAND(4.5GHz) Data from Sensors 3.8m Data Acquisition (CPU) UHF TRANSMITTER (10W) LNA RF D/C BURST DEMOD (BPSK) To data processing system of NIOT GPS 70MHz IF 300b/s DATA COLLECTION FROM DATA BUOY THROUGH INSAT

Block Schematics of INSAT UHF Transmitter 402MHz Message Generator Power Amplifier (10W) Data from CPU BPSK Modulator 300bbps (1/2 rate) 4.8Kbaud Frequency Synthesizer (UHF) Block Schematics of INSAT UHF Transmitter

BURST FORMAT OF TRANSMISSION   F (8) MID (16) IINFORMATION  (320) CRC DATA FORMAT CR BTR UW       256 64 64 UP TO 752 SYMBOLS 1.68Sec sec CR Carrier Recovery BTR Bit Timing Recovery UW Unique Word SCRAMBLED AND ½ RATE CODED  

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

TEST RESULT OF SATELLITE LOOP TX power   C/No (dBHz) Packets % PEP Rx / Tx 1W 32.3 80/100 0.2 1.25W 33.3 90/100 0.1 1.5W 34.3 96/100, 95/100, 0.04 96/100 2.5W 36.3 98/100 0.02 9W 41.8

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

DATA BUOYS WITH INSAT COMMUNICATION INDIA Pipvav Off Paradip Mumbai Bay of Bengal Arabian Sea Machillipatnam DS1 Goa NIOT Mangalore Chennai SW6 DS3 Tuticorin 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

MSS Terminal Specification 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 - TRANSMITTER Buoy fitted with MSS transmitter is ready for deployment.

Block Schematics of Alert Transmitter         GPS Receiver Message Generator BPSK Modulator Power Amplifier Emergency Switch Frequency Synthesizer Battery

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