Telemetry, Tracking and Command Systems of Spacecraft

Abstract

The Telemetry, Tracking and Command (TT&C) Systems of a spacecraft provides the most vital telecommunication link between a satellite and ground station. The TT&C systems provide the uplink for command, downlink for monitoring the various health parameters through telemetry and much needed tracking information for the satellite for monitoring its position in orbit. The link is provided using a ground station and onboard telecommand & tracking data receiving systems, onboard decoder and telemetry transmitter. The TT&C link of a satellite is of prime importance, right from the time of its launch to the end of the mission. The uplink and downlink frequencies could be in VHF/S/X/Ku or Ka bands depending on the mission requirements, system development status and facilities available. The development, testing and fabrication of these systems are quite involved, tricky and difficult. It requires a lot of expertise to develop them. A brief description and specifications mainly related to their developments in ISRO have been presented in this paper.

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S Pal

S Pal an alumnus of BITS, Pilani and IISc, Bangalore is presently Outstanding Scientist & Deputy Director, Digital & Communication Area, ISRO Satellite Centre, Bangalore. He joined Indian Space Research Organization (ISRO) in 1971, after a brief tenure at TIFR. Dr Pal is responsible for starting Antenna & Microwave activities in the ISRO Satellite Centre at the inception. He has been responsible for the development & fabrication of all spacecraft related telecommunication systems for India's all satellites starting with Aryabhatata to present day IRS & INSAT series of spacecraft. He has been consultant to: (i) INMARSAT/ICO (UK) for LEOSAT definitions, responsible for the development of Satellite Hand Held Telephone Antenna System for ICO (UK) & (ii) ITU for defining Regional African Satellite Communication System. Presently he is Chairman of Information Infrastructure Working Group of Ministry of Information Technology.

Dr Pal is a Distinguished Fellow of IETE, Fellow of INAE, INASc, Sr Member, elected Fellow of IEEE (USA), MAMTA (USA), MASI has received several awards, including NRDC awards for various developments and inventions. Besides, he holds Indian, European & International patents for his various inventions.

Dr Pal has published more than 135 papers in international and national Journals of repute.