ISRO Satellite Centre (ISAC), Bengaluru, is the lead centre for conceptualisation, design, development, fabrication, integration and testing of complex satellite technology. Spacecraft Checkout Group of ISAC is responsible for integrated spacecraft testing to ensure the flight worthiness of the spacecraft built at ISAC. During the testing, ground systems will communicate to spacecraft via the same uplink and downlink signals, as in space. The spacecraft typically use ISRO formats for telemetry and telecommand (downlink and uplink), for which indigenous equipment are being used. However, the interplanetary spacecraft use an international standard known as CCSDS - Consultative Committee for Space Data Systems. Presently equipment are being imported for telemetry reception and telecommand transmission requirements.

As part of ‘Make in India’ campaign, indigenous development of Telemetry & Telecommand Processor (TTCP) was taken up by ISRO and successfully realised. This processor replaces the expensive imported equipment. This will be used in Integrated Spacecraft Testing of Low Earth Orbit, Geostationary Orbit and Interplanetary Spacecraft. This system is configurable to meet uplink and downlink requirements of both CCSDS and ISRO standards. Multiple Clients can remotely access this system for data and monitoring. Productionisation of this system will be initiated with the help of Indian industry.

The system was developed on an FPGA (Field Programmable Gate Array) platform taking advantage of System On Chip (SOC) features. Telemetry & Telecommand sections were realised as separate hardware. Telemetry input can be received at 70 MHz Intermediate Frequency (IF) and Pulse Code Modulation (PCM) level. Telecommand outputs are available at PCM, Frequency Shift Keying (PSK) / Phase Shift Keying (FSK) and 70 MHz IF. All the features of TTCP are programmable remotely, using the soft-core processor onboard FPGA. A computer with server software is used for configuration management, remote monitoring, Telemetry data streaming, Telecommand echo and secured access for Telecommand & Control from multiple remote clients. This system is an amalgamation of diverse software, hardware devices and digital signal processing techniques which work in tandem to provide the required functionalities.

This indigenously developed Processor was successfully deployed for the first time in checkout of GSAT-19, which is scheduled to be launched shortly.

Telemetry & Telecommand Processor (TTCP)