A Priori Doppler-Shaped MMSE Range-Doppler Estimation for Pulse Agile Radar

Pulse-agile radar suffers from a degraded signal-to-interference-plus-noise ratio (SINR) due to a form of selfinterference known as range-sidelobe modulation (RSM). The minimum mean square error (MMSE) estimator is able to suppress RSM at the cost of mismatch loss (MML). Additional fast-frequency spectral tapering allows mitigation of MML at the cost of super-resolution; however, the trade space between MML incurred by the MMSE estimator and RSM suppression is dictated by the passband variance of the waveform power spectral density. Waveforms that are not optimized on a pulse-to-pulse basis (here, called unoptimized waveforms), which may be desirable on low-cost transmit platforms due to their lower computational cost to generate, are characterized by higher variance in the passband, limiting how well the MMSE estimator can mitigate MML. High pulse repetition frequency (PRF) radars with large unambiguous Doppler spaces can utilize an intelligent Doppler shaping of the a priori scattering covariance matrix in the MMSE estimator for improved mitigation of MML, and further suppression of the noise-plus-interference floor, increasing detection capability. A computationally efficient formulation of this modified MMSE estimator is proposed, and the efficacy is demonstrated on open-air experimental data.