Advanced SAR Waveforms

Current long range SAR systems are performance limited by slant range ambiguity problems and need wide instantaneous bandwidths to obtain high resolution SAR images. These SAR systems push the leading edge on all technology fronts, hence they are complex and expensive. The proposed HopFreq SAR solves the slant range ambiguity problem by using hopped frequency waveforms. The HopFreq SAR's frequency in changed pulse to pulse across N center frequencies (effective bandwidth), and a particular center frequency is not repeated for N pulses. The HopFreq SAR's effective PRI (at any one frequency) is increase by a factor of N relative to conventional SAR waveforms. Since the unambiguous slant range is proportional to the effective PRI, the HopFreq SAR's unambiguous range will be N times the conventional chirped SAR unambiguous range. HopFreq SAR achieves equivalent high range resolution by processing a burst of N pulses. (gives large effective bandwidth) and the proposed implementation uses simple waveforms, commercial (slow speed and inexpensive) A/D converters and DSP boards, while solving the unambiguous range problem associated with conventional SAR.