Spaceborne DINSAR monitoring with weekly revisit time with TOPSAR

Abstract:
The paper focuses on the design of a LEO spaceborne SAR sensor, intended mainly for differential interferometric monitoring, and achieving a global coverage with weekly revisit time. A cost-effective design should lead to a compact antenna, in the order of 4 x 2 m, while attaining the required swath coverage of about 400 km on the ground. Such a system could not be feasible in conventional STRIPMAP mode, due to the known relation between the maximum of the range swath coverage and the antenna length in azimuth. However, we this bound can be relaxed by exploiting two different modes, namely ScanSAR and TOPSAR, both of them able to trade azimuth resolution for coverage. The paper discusses the fundamental relations that govern the antenna area, the azimuth resolution, the swath widh, and Noise Equivalent Σ Zero (NESZ) performances, in the framework of these burst mode acquisitions. Thereafter the design of scan timeline is shortly reviewed for both TOPS and ScanSAR. Finally, the design of a weekly revisit time system in both modes is provided as example and comparison is made on performances in terms of ambiguities and NESZ.