Abstract:

One of the major advantages of expressing signal of interest in terms of Wigner--Ville distribution is that one can see how energy of signal varies with regard to time and frequency. On the other hand, a major drawback of this method is that it also displays ``signal interference,'' therefore one has to have a priori knowledge about the signal. Otherwise, one cannot distinguish true and false information from the distribution. This paper addresses the idea to reduce such signal interferences. The idea simply comes from a hypothesis that there could be a domain on which the interference could be more realizable than the time-frequency axis, which is the Wigner--Ville domain. In fact, there can be four different quadrants. The ambiguity function of the Wigner--Ville distribution is examined, which can be regarded as the mirror image of the distribution. What was found is rather useful---the interferences which appear in the Wigner--Ville distribution tend to be located at the center of the ambiguity function domain. Several simple signals were examined. Based on this theoretical analysis, attempts were made to develop a kind of window that can effectively eliminate the interferences, which is, in fact, a ``rotating window'' in ambiguity function domain. Several numerical simulations reasonably confirm the proposed idea. Various acoustic and vibration signals are now under investigation to demonstrate the ability of the method. [See NOISE-CON Proceedings for full paper.]