In the proposed algorithm,
the range-independent de-rotation operation is employed to overcome the spectrum aliasing problem,
and the signal properties after de-rotation are derived in detail. Moreover, a modified range-dependent
deramp function is proposed to accommodate the time shift, and the chirp-z transform is utilized
for correcting geometry distortions caused by the range-dependent deramp operation. Furthermore,
range scaling and azimuth scaling are performed, providing the same pixel sampling interval for all
sub-swath images in both range and azimuth dimensions respectively, which avoids interpolation for
the sub-swath image