Mitigation of Clutter Modulation in Cognitive Radar for Spectrum Sharing Applications

Congestion in the frequency spectrum is an ever-growing issue for current and future radar systems due to the increasing number of commercial wireless devices and technologies. Both communications devices and radar continue to demand access to greater swaths of bandwidth, but do not coexist well. The cognitive radio and radar communities have investigated solutions to this problem through the use of dynamic spectrum access (DSA) and spectrum sharing (SS). For radar, the pulse-agility required to effectively share the spectrum with other rapidly changing signals complicates coherent integration due to the variation in the transmitted waveform. In particular, when non-identical pulses are processed with standard Fourier-based range-Doppler (RD) processing for moving target indication, a modulation / distortion effect is induced. The Richardson-Lucy deconvolution algorithm, an image processing technique, is implemented in a software-defined radar (SDRadar) system to remove the undesired modulation from the RD images. The approach is then verified via an over-the-air experiment where the SDRadar must share a radio frequency (RF) band with a communications device and detect a moving target simultaneously.