Adaptive Comb Waveform Design for Reverberation Suppression

Comb waveforms possess the ability to strongly sup-press reverberation over a controllable range of Doppler shifts. This ability is measured by the Q-function, the Doppler marginal of the waveform’s Ambiguity Function (AF). In addition to Q-function shape, it is generally desirable for comb waveforms to be constant modulus to facilitate efficient transmission on practical acoustic projector systems. Additionally, it is also desirable for waveforms to possess an Auto-Correlation Function (ACF) with reasonably low sidelobes to facilitate distinguishing a weak target in the presence of a strong one. These three design considerations conflict with one another and previous comb waveform designs to date have not achieved all three simultaneously. This paper investigates whether the Multi-Tone Sinusoidal Frequency Modulated (MTSFM) waveform can simultaneously achieve all three of these design criteria. The MTSFM waveform’s instantaneous phase is represented as a finite Fourier series. The Fourier coeffcients are utilized as a discrete set of parameters that are adapted to design constant modulus comb waveforms with a desirable Q-Function shape as well as reasonably low ACF sidelobes.