This chapter starts the introductory tutorial that constitutes Part I of the book. It provides the basic insights needed to understand time-frequency (t, f) fundamental principles, techniques, methods, and algorithms; it also provides the background material required to do the (t, f) toolbox tutorial in Chapter 17. Time-frequency signal processing (TFSP) is a set of signal processing (SP) methods, techniques, and algorithms in which the two natural variables time (t) and frequency (f) are used concurrently. This contrasts with traditional SP methods in which either time t or frequency f is used exclusively and independently of the other. TFSP has become a standard digital signal processing (DSP) technology with applications found in all traditional areas of DSP and beyond. This chapter presents the essential concepts on which the field of TFSP is built. It uses simple language, describes the most important concepts in qualitative terms and illustrates them with examples. An understanding of these basic (t, f) concepts and terminology is a prerequisite for comprehending, mastering, and using the more specialized methods reported in the other chapters.
The choice of the contents, style, and organization of this chapter is motivated by the desire to
provide a nonspecialist with:
• a bridge or stepping stone to the key fundamental (t, f) concepts presented in Chapter 1;
• a step-by-step approach to conceptually grasp the complexities of the field and be able to represent
a signal in a 2D (t, f) space;
• a framework that relates general and generic TFSP principles to those more specific methods and
techniques applicable in typical situations;
• a presentation of TFSP using examples that are familiar to students, engineers, and researchers in
• an insight into key characteristic features that are (t, f) specific, such as instantaneous frequency
(IF), spectral delay (SD), and instantaneous bandwidth.
Finally, a brief overview of the following chapters is provided at the end of this chapter.