System and method for detecting and characterizing vibrating targets

Abstract

A method and system for processing radar return signals reflected from a vibrating target to determine the actual vibration frequency and to isolate a characteristic vibration of the vibrating target, including an oscillation signature function (OSF). A radar signal processor receives a stabilized phase history which includes frequency components, namely an FM sideband corresponding to a modulation imparted upon a reflected radar return signal by the vibrating target. The radar signal processor detects the FM sideband and determines a candidate vibration frequency. The stabilized phase history is filtered at a phase rotation based on the candidate vibration frequency to isolate the OSF and to determine the actual vibration frequency. To distinguish the nearly identical frequency spectra produced by vibrating targets which vibrate at multiples of the radar system folding frequency, the stabilized input signal is further filtered at phase rotations corresponding to the candidate vibration frequency plus or minus multiples of the radar system folding frequency. By comparing the characteristic vibration or oscillation signature function with known information, the type of vibrating target, the identity of the vibrating target, and/or the state of the vibrating target can be determined. Further, the radar system can detect the actual vibration frequency and characteristic vibration of vibrating targets directly from the stabilized phase history prior to performing any image processing.