Simulation Study of Multi-Channel RADARSAT-2 GMTI

摘要

Accurate ground moving target indication (GMTI) and target parameter estimation can be achieved only after sufficient suppression of interfering stationary clutter, particularly for space-based SARs with typically small exo- clutter regions. In its simplest form, this is accomplished using two radar receiver channels, such as the dual receive antenna mode of RADARSAT-2's Moving Object Detection EXperiment (MODEX). In this mode of operation, the full antenna is broken up into two sub-apertures with two parallel receivers to create two independent phase centers. It is well known, however, that a two- aperture approach to GMTI is sub-optimum and that target parameter estimation is often compromised by clutter interference or poor signal-to-clutter ratios. Two degrees-of-freedom are simply not enough to simultaneously suppress the clutter and to accurately estimate the target s properties, such as velocity and location. The investigation, described in this Technical Memorandum, explores several concepts of increasing the spatial diversity for RADARSAT-2, which allows the two-channel SAR system to operate like a three or four channel radar. Owing to the very flexible programming capabilities of the RADARSAT-2 antenna, this can either be accomplished by the toggling of the transmitter between subsequent pulses or via clever transmitter/receiver excitation schemes. A trade-off analysis between number of channels, phase center separations, and PRF limitations is presented for a system based on RADARSAT-2 MODEX parameters.