Analytical Expression for the Impact of Velocity Variations on Azimuth Ambiguity Suppression in Digital Beamforming SAR

Kurzfassung

Airborne SAR demonstrators are employed to validate digital beamforming (DBF) techniques and support the development of high-resolution wide-swath (HRWS) operational modes for spaceborne SAR missions. These systems process data from multiple apertures displaced in azimuth using a bank of reconstruction filters based on signal models. However, the models have to assume a constant velocity, which does not hold in airborne SAR systems. The focus of this work is to develop an analytical expression to predict the impact of velocity variations on the suppression of azimuth ambiguities. The proposed expression provides an analytical prediction of the azimuth ambiguity-to-signal ratio (AASR) as a function of the velocity error. The expression is validated using point target simulations. Finally, its potential application to estimate an optimal reconstruction block size is discussed and evaluated.