Development of Onboard Signal Processor for ISRO’s GNSS-Remote Sensing Instrument

The advent of Global Navigation Satellite Systems (GNSS) unlocked innovative applications in remote sensing and Earth observation. Among these, GNSS Reflectometry (GNSS-R) stands out as a powerful technique, enabling precise measurements of various Earth surface parameters, such as soil moisture, sea surface roughness, etc. This paper outlines the architecture details and development of GNSS remote sensing receiver and digital subsystem in particular developed for ISRO’s first on-board GNSS reflectometry mission. The system comprises of Antennae, RF front-end, digital signal processing unit for data archival and onboard processing, and a communication interface for integration with GNSS receivers and spacecraft subsystems.