Adaptive cosine transform coding for compression of Mars-96 ELISMA instrument data

Abstract Mars-96 ELISMA is a scientific project designed to measure the electric and magnetic fields around Mars when the Russian spacecraft Mars-96 orbits the planet. The data rate of the on-board ELISMA instruments will reach a figure which is about five times the telemetry rate allocated to them. To overcome this problem, a coding was designed to compress the data for the telemetry. This coding combines an adaptive cosine transform with marginal analysis. Data from the instruments are divided into blocks with each block converted by the cosine transform into coefficients. The marginal analysis method is performed on the coefficients to achieve a bit allocation vector specifying the level of the subsequent Lloyd-Max quantization of the coefficients. This paper describes the coding algorithm and also shows simulation results for the compression of geophysical data.