Earth Stations

ISRO was responsible for the installation and maintenance of the earth sta­tions and also the design, installation, and maintenance of the augmented com­munity receivers. The earth stations and the DRS formed the ground segment of the network. While NASA provided the satellite, the ground segment was indigenously manufactured by ISRO with little help from foreign countries. The earth stations helped transmit signals to the satellite, the satellite received these signals, amplified them, and transmitted them back to earth where they were received by custom-made television sets that were suitably tuned.

Four earth stations located in Ahmedabad, Delhi, Amritsar, and Nagpur were utilized for the SITE project. The central earth station that transmitted the bulk of the programs using the 15-meter parabolic antenna was located in Ahmedabad. The second earth station, a 10-meter parabolic antenna located in Delhi, helped in telecasting national programs—Republic Day, Independence Day, and addresses from the prime minister and president. It also served as a backup facility if the central station in Ahmedabad were to face any techni­cal glitches. The third earth station was located in central India in Nagpur. It housed the “monopulse beacon” instrument. The ATS-6 satellite had the capa­bility of “homing in” to a beacon station located to keep the satellite accurately oriented if its internal pointing systems failed. This was one of the important back up modes to ensure the ongoing functionality of the ATS-6 spacecraft.