2.    ALGORITHM DESCRIPTION

The basic RD algorithm is generally used to process continuous data. In this case, the phase of any target is preserved at the peak of the impulse response, and is a ramp function across the impulse response, with the slope of the ramp being a function of the Doppler centroid. A key point to note here is that all targets exhibit the same frequency versus time characteristics, since each target is swept by the same antenna beam in which the target is illuminated continuously. Therefore, ignoring the azimuth variation of the Doppler centroid, all targets in the same range gate occupy the same range of frequencies in the Doppler spectrum. As a result, each compressed target has the same phase ramp in the continuous mode.

• 2.1    Spectrum of ScanSAR Targets
• 2.2    The Modified RD Algorithm