Based on the terrain observation by progressive scans (TOPS) mode, an efficient
full-aperture image formation algorithm for focusing wide-swath spaceborne TOPS data is proposed.
First, to overcome the Doppler frequency spectrum aliasing caused by azimuth antenna steering,
the range-independent derotation operation is adopted, and the signal properties after derotation
are derived in detail. Then, the azimuth deramp operation is performed to resolve image folding
in azimuth. The traditional dermap function will introduce a time shift, resulting in appearance
of ghost targets and azimuth resolution reduction at the scene edge, especially in the wide-swath
coverage case. To avoid this, a novel solution is provided using a modified range-dependent deramp
function combined with the chirp-z transform. Moreover, range scaling and azimuth scaling are
performed to provide the same azimuth and range sampling interval for all sub-swaths, instead of the
interpolation operation for the sub-swath image mosaic. Simulation results are provided to validate
the proposed algorithm.
CORE (COnnecting REpositories)
CORE (COnnecting REpositories)