'Institute of Electrical and Electronics Engineers (IEEE)'
Abstract
In an along-track interferometric SAR system, the discrete sampling of
moving target signals can give rise to two types of ambiguity: Doppler
ambiguity, and interferometric angle ambiguity. These ambiguities lead to
ambiguities in target velocity estimation.
Range cell migration of moving targets is unambiguous in target velocity.
Hence, it can be used for resolving the ambiguities in target velocity
estimation mentioned above. The wave number domain algorithm as well as
the chirp scaling algorithm is adapted to moving target signals. In order to
focus moving target signals with arbitrary velocities both approaches are
extended to arbitrary Doppler frequency ands. Moving target signals
distributed over two neighbouring PRF bands are especially difficult to detect
and analyze because the sgnal splits into two parts. It is shown that the two
parts appear at different positions in the SAR image and have different ATI
phases. They show up as two weaker targets since the energy is split
between them. It is demonstrated how the two targets can be identified as
possibly the same target, and how they can be properly focussed by
adaptation of the SAR focussing algorithms
