On-board Antenna Tracking System for HTS Satellites: ISRO’s First In-Orbit Success on GSAT-19

This paper presents ISRO’s and India’s first successful development and validation of a space borne Antenna Tracking System technology on its experimental HTS satellite GSAT-19. Onboard tracking system demonstration is an enabling technology for a High Throughput Satellite (HTS) program as it is essential to maintain beam coverage of high-gain sharp multiple beam antennas locked to specific coverage zones on the ground to ensure edge-of-coverage gains and variations in spite of spacecraft roll & pitch stability residues. The tracking system senses such fine angular offsets and generates proportional DC error voltages that are used to apply the required correction to the antenna axes through appropriate drive motors. The system has been designed & tested for the tracking accuracy better than 0.01°. The technology has been successfully developed and proven for the first time on an ISRO satellite, paving the way for full-fledged follow-on HTS satellites (GSAT-11, GSAT-20 etc).