Transmission data reduction by coding data acquired at satellites flying in close formation

摘要

The Synthetic Aperture Radar obtains the information of moving target on the earth surface using MTI (Moving Target Indication) technique, which is a differentiation of the earth surface image data acquired successively, either at two antennas mounted on one satellite, or at two satellites flying in close formation. In the latter case, the differentiation operation is normally applied in the ground station, and each satellite needs to transmit the acquired voluminous data to the ground station independently, consuming broad downlink bandwidths. The earth surface image data acquired at the two satellites have a strong correlation since the static background image data other than the moving targets are essentially the same except for the noise factors. We focus on this fact and claim that the transmission data should be reduced by taking off the redundancy of the two data and sending the differential parts only. In this paper, we first explain the coding theory discussion related to this redundancy suppression. We discuss source, channel and network coding, and also the Slepian-Wolf theorem for two correlated sources. Then, we propose a coding and compressing scheme for a simplified model. Next, we generalize it to apply to a more realistic model and present a procedure of the proposed scheme.