Advances in Onboard Data Reduction Methods for Next-Generation Synthetic Aperture Radar Systems

For present and future spaceborne synthetic aperture radar (SAR) missions, an increasing volume of onboard data is going to be required, due to the employment of large bandwidths, multiple polarizations, and large swath widths, which lead to hard requirements in terms of onboard memory and downlink capacity. This paper presents novel methods for data volume reduction in the context of multi-azimuth channel (MAC) SAR and staggered SAR, which allow for high-resolution imaging of a wide swath by means of different system architectures. In particular, for such systems, a pulse repetition frequency (PRF) typically higher than the processed Doppler bandwidth is selected. The resulting oversampling and correlation properties of the azimuth SAR raw signal can be exploited by applying an efficient encoding and quantization of the SAR raw data in order to reduce the onboard volume of data. Simulation results show that the proposed methods allow for a significant reduction of the data volume to be downlinked to the ground at the cost of a modest increase of onboard computational effort