Time-Frequency Analysis of Radar Backscattered Signals using Phase Coupled Frequencies Extracted from Time-Varying Bispectrum Estimates

A new approach to time-frequency analysis of radar echo responses obtained from moving objects is represented. The suggested approach is based on the extraction of phase-coupled harmonics from time-varying bispectrum estimates of transient sequences separated from the total radar backscattered signal by a sliding window. A coherent, homodyne, and continuous-wave radar has been employed for measuring multi-component, non-stationary, and nonlinear frequency modulated signals backscattered by moving objects. The experimental study underpinned with the theoretical assumptions of the suggested approach has demonstrated clean recovery of time-varying phase-coupled frequencies for test targets like a swinging metallic sphere or a walking human. The obtained time-frequency distributions of phase-coupled harmonics can be recommended as a new information feature in automatic radar target recognition systems.