A simple scheme for enhanced reassignment of the smoothed pseudo Wigner-Ville representation of noisy signals

The reassignment procedure has often been employed to improve readability of some time-frequency representations (TFRs). When processing noisy signals, the problem of sensitivity of the technique to noise is encountered. A simple modification of the reassignment method is proposed, based on a thresholding operation. Specifically, by preventing the reassignment of the distribution coefficients below the noise dependent threshold and replacing them with zeros, the enhanced signatures on the time-frequency plane are obtained. This method is compared with other techniques, such as the reassigned spectrogram (RSP) and the supervised reassigned spectrogram (SRSP). An experimental test of these algorithms as the instantaneous frequency (IF) estimators for a chirp signal have shown that our method improves the accuracy of the estimation for heavy noise.