查看文章

We present a review of the diversity of concepts and motivations for improving the concentration and resolution of timefrequencydistributions (TFDs) along the individual components of the multi-component signals. The central idea has been to obtain a distribution that represents the signal’s energy concentration simultaneously in time and frequency without blur andcrosscomponents so that closely spaced components can be easily distinguished. The objective is the precise description of spectralcontent of a signal with respect to time, so that first, necessary mathematical and physical principles may be developed, andsecond, accurate understanding of a time-varying spectrum may become possible. The fundamentals in this area of research havebeen found developing steadily, with significant advances in the recent past.