A data volume reduction strategy based on on-board Doppler filtering

Abstract

High-resolution wide-swath (HRWS) synthetic aperture radar (SAR) systems based on digital beamforming (DBF) in elevation are very attractive for the observation of dynamic processes on the Earth’s surface. However, due to their resolutions and swath widths, HRWS systems are inherently associated with a huge data volume. Furthermore, a pulse repetition frequency (PRF) much higher than the required processed Doppler bandwidth is often desirable to comply with azimuth ambiguity requirements. The data volume can be significantly reduced, if on-board Doppler filtering and decimation are performed before downlinking the data. This paper presents different criteria for the design of the low-pass filter and shows that a finite impulse response (FIR) filter with a relatively small number of taps is sufficient to completely suppress the additional ambiguous components and recover the original impulse response, provided that a compensation of the filter transfer function is performed within the processing. This strategy is also applicable to staggered-SAR systems, where on-board Doppler filtering and resampling can be jointly implemented.