Moving Target Indication Radar Architectures for Tactical Targets in Foliage

A novel architecture employing optimized space-time-frequency processing to meet the seemingly disparate requirements imposed by FOPEN SAR and MTI is presented. Two primary techniques are discussed: (a) simultaneous, long-dwell multibeam receive processing and (b) wideband, udorandomly hopped frequency employ multiple, wideband antenna elements each with a low-cost, wideband, digital receiver and heterogeneous digital signal processing to simultaneously perform SAR imaging and MTI detection. A low frequency, wideband LFM waveform is synthesized by using a narrower band, pseudorandom, hopped waveform simultaneously supporting SAR and MTI. The architecture provides for rejection of radio frequency interference prevalent at low frequencies and for space-time adaptive processing, jointly optimizing MTI clutter/interference rejection. Displaced locations of VHF/UHF receivers for direction finding and sidelobe control are also supported. Since the narrowband, hopped frequency waveform requires narrowband transmissions for discrete, interleaved time slots; frequency multiplexing can be used as a spectral management tool to interleave other receive-only functions such as SIGNIT. Additionally, the multi-beam receive architecture inherently supports bistatic operation since it already employs multiple receive beams to instantaneously provide wide angular sector MTI coverage. ISI will follow its commercialization plan that created the ImageExpress tm product from an earlier SBIR program.