Nonlinear Radar via Intermodulation of Jointly Optimized FM Noise Waveform Pairs

It was recently shown that a new form of nonlinear radar can be achieved using pairs of separately optimized FM noise waveforms, where the optimization serves to provide useful spectral shaping of each waveform. Here the utility of jointly designing these separately transmitted waveforms according to their resulting intermodulation response is explored. This formulation relies on gradient descent optimization of an intermodulation-based cost function that is defined in the context of physically realizable polyphase-coded FM (PCFM) waveforms. The result is evaluated both in simulation and experimentally via a hardware loopback configuration.