Extraction of information from a time-frequency image Up to this point, we have examined the main solutions proposed to the problem of representing a non-stationary signal in the time-frequency plane. We now consider the problem of the interpretation of the time-frequency image which describes the evolution with time of the frequency content of the signal. Even if they all tend to the same goal, each representation has to be interpreted differently, according to its own properties. For example, some of them present important interference terms, other are only positive, other are perfectly localized on particular signals...So the extraction of information has to be done with care, from the knowledge of these properties. We give in the following some general guide lines to profit from a time-frequency image.
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