Low Probability of Intercept/Low Probability of Detection (LPI/LPD) and Radio Frequency Interference (RFI) Mitigation Techniques

RFI and signal security are indelibly intertwined in military FOPEN radar systems. RFI is a dual problem for FOPEN radars: on transmit, the radar signal interferes with other friendly systems operating in the same band; on receive, these systems' signals interfere with radar operations. A common solution to dealing with both RFI manifestations is to notch the RFI signal. However, a piori knowledge of the spectral characteristics of the friendlies in the region, which is acquired by a "sniff" mode or is available before radar operations, is crucial. Furthermore, notching distorts the received signal, degrading the performance of the radar, if not corrected for. TSC proposes an LPI/LPD waveform design to alleviate the RFI problem with minimal distortion when RFI information is available, while providing signal security. When information is unavailable, RFI is detected, notched, and autoregressive filtering applied to recover the target signals. TSC has investigated and developed a variety of LPI/LPD waveforms in the past, and applied AR techniques to recover corrupted SAR and other radar signals. During Phase I, TSC will investigate the feasibility of these RFI mitigation techniques, and develop tools and plans for Phase II demonstration tests utilizing a GeoSAR UHF transmitter in TSC's possession.