Advanced Synthetic Aperture Radar (SAR) Waveforms

SAR systems covering large swath widths suffer from range ambiguities when using high duty cycle radar signals having standard SAR waveforms. Range ambiguities can be eliminated by transmitting nonstandard orthogonal waveforms. Analysis and simulations will be carried out to determine the performance of different orthogonal waveforms in terms of minimizing SAR image sidelobe levels and limiting range ambiguities. In addition, a limited amount of data collected using selected orthogonal waveforms will be analyzed in this trade-off study. Many SAR applications of interest require the use of wideband radar signals to obtain the desired range resolution. If standard SAR processing technologies are used then the range of waveforms that can be easily processed is limited. To eliminate this limit it is proposed that two Essex processors be used in series for SAR image formation: ImSyn¿, with the wideband range-Doppler imager (RDI) as a preprocessor for ImSyn. RDI is waveform independent, and accepts analog radar signals so that high speed A/D converters are not needed. ImSyn computes the DFT, hence does not require interpolation of data two a rectangular grid. The implications of using RDI and ImSyn in series will be analyzed and a top level design of such a configuration carried out.