Staggered Coprime Pulse Repetition Frequencies Synthetic Aperture Radar (SCopSAR)

High-Resolution Wide-Swath Synthetic Aperture
Radar (HRWS-SAR) imaging is highly desirable since it allows
covering large areas during a short visit time. In this paper,
SCopSAR is propsed. It divides the time during which a scatterer
is illuminated by the antenna beam-pattern into two halves where,
in each half, pulses are transmitted at the rate of one of two
sub-Nyquist Pulse Repetition Frequencies (PRFs). Such PRFs
are related to the Nyquist PRF using two coprime sub-sampling
factors. This allows extending the maximum swath width that
can be imaged by a number of times that equals the smaller
sub-sampling factor at the expense of a reduction in the azimuth
resolution by half. It further allows for a reduction in the amount
of data to be stored and communicated. SCopSAR is an imaging
modality suitable for scenes that contain a small number of bright
scatterers over a dark background which, for instance, is the
case when imaging ships in a calm sea background. Compared
to the techniques recently proposed in the literature, SCopSAR
simplifies the Radar requirements since it uses only one carrier
frequency, one waveform, and one channel. Simulations and real
ERS-2 satellite raw data are used to validate the theoretical
findings presented in this paper.