Time-frequency approach to radar detection, imaging, and classification

This is an editorial paper for a special issue in an application area of time-frequency signal processing.. (Additional details can be found in the comprehensive book on Time-Frequency Signal Analysis and Processing (see http://www.elsevier.com/locate/isbn/0080443354). In addition, the most recent upgrade of the original software package that calculates Time-Frequency Distributions and Instantaneous Frequency estimators can be downloaded from the web site: www.time-frequency.net. This was the first software developed in the field, and it was first released publicly in 1987 at the 1st ISSPA conference held in Brisbane, Australia, and then continuously updated).One of the central problems in exploiting the radar data is the analysis of atime series. The problem at hand is how to extract the information present in the data and use it to its full potential. Traditionally, radar signals have been analysed in either the time or the frequency domain. The Fourier transform is at the heart of a wide range of techniques that are generally used in radardata analysis and processing. However, the change of frequency content withtime is one of the main features we generally observe in radar data. As a result of this change of frequency content with time, radar signals belong to the class of non-stationary signals. The analysis of nonstationary signals requires a technique that extends the notion of a global frequency spectrum to a localfrequency description. Joint time-frequency analysis using time-frequencytransforms has improved the analysis of non-stationary signals by revealingtime-varying information embedded in signals.Institution of Engineering and Technolog