1. 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

2. 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.

3. INSAT DRT coverage

4. 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

5. PRESENT DCP Central Water Commission Snow& Avalanche Establishment
India Meteorological Department
Central Water Commission
Snow& Avalanche Establishment
NIOT
State Agencies

6. 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)

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

8. 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.

9. Satellite Link calculation
UP LINK:
Up link frequency : MHz.  
Tx power : 10dBW
Antenna gain (including cable loss) : -3dBi
Tx. EIRP : 7dBW
Max. Slant range to satellite (at 5 deg. Ele) : 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

10. 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

11. 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

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

13. 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

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

15. 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.

16. INSAT Transmitter and Antenna for data buoys

17. 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

18. 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 platform/ hour/carrier.

19. TRACKING SYSTEM

20. 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 D)
Transmission
3 Packets/message randomized – Aloha mode.
1 Packet / Message - TDMA mode
Transmission time
4 sec (Max) / Message
Frequency band
to 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

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

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

24. Thank you