Nonlinear radar via intermodulation of FM noise waveform pairs

Abstract

To take advantage of the unique scattering responses associated with nonlinear radar, the predominant approach involves the detection of target-induced harmonics elicited by the interrogation of a single spectrally pure waveform (often a tone). In contrast, we consider the impact of using a pair of high-dimensional waveforms to realize a novel nonlinear intermodulation approach. The interrogating waveforms in this case are two unique sets of FM noise waveforms that also permit the high incident power necessary to induce a nonlinear response. Both waveforms reside in the resonant region of the device under test, with their intermodulated response signal made sufficiently separable from the second-order harmonics of each individual waveform in the same band by virtue of very high dimensionality. This framework, collectively denoted as shared-spectrum pseudorandom intermodulation (SSPRInt), is demonstrated via simulation and experimentally in a loopback configuration.