Synthetic aperture radar processing using a nonuniform pulse repetition interval

Due to recent development of the theory related to non- uniform Pulse Repetition Intervals (PRI) for pulse doppler radars, it has become feasible to combine the multiple pulse integration of Synthetic Aperture Radar (SAR) with the temporal agility of non-uniform PRI's. This combination can bring to the traditional SAR system the benefits of both strong resistance to countermeasures and interception, and high sensitivity. A significant problem which must be addressed in synthetic aperture radars is the possible smearing of the azimuth dimension of the image due to doppler sidelobes which are too high. This issue is even more serious with a non-uniform PRI waveform. In a traditional SAR the sidelobes are controlled with signal processing techniques such as amplitude weighting. However, these simpler techniques are not adequate for non-uniform PRI waveforms. One method for increasing the sidelobe rejection capability of these waveforms requires the use of a processor which consists of time varying linear digital filters. One way to design such a filter is through the use of interpolation based techniques.