An overview of XSAT data downlink and image processing system design and development

Abstract

To produce images from a raw data bitstream from Earth observation satellites, a multi step process is employed. It includes reception via X-band antenna, down conversion, demodulation, disambiguation and frame formatting, error correction if any, data descrambling, image generation and timing recovery, radiometric and geometric correction, and finally archiving and distribution. Apart from antenna and demodulator hardware subsystems, XSAT's data ground station's design and development was an in-house effort at CRISP, National University of Singapore. In this paper, we present the design and operation of the various components of the XSAT data ground station. This includes the software based QPSK disambiguation algorithm, the image processing software for normalization and formatting, archival and distribution architecture and the automation process to increase operational efficiency.