DYNAMIC BANDWIDTH OF PHASE-MODULATED SIGNALS.

A method of signal representation is introduced which simplifies the analysis and provides a better understanding of systems using phase-modulated signals. To replace time function and spectrum, the concept of instantaneous frequency is supplemented by that of dynamic bandwidth. Instantaneous frequency indicates in which part of the spectrum the signal energy is concentrated at a particular time, whereas dynamic bandwidth measures the degree of concentration. The combination of both concepts reveals the nature of a phase-modulated signal in a manner in better agreement with physical intuition than time function and frequency spectrum. A signal with arbitrary phase modulation can be thought of as a succession of elementary constant-carrier pulses of varying duration or, in the frequency domain, as a succession of spectral bands with linear phase and varying widths. It is shown that this approach permits one to write down results that would take a complicated analysis if conventional methods were used. Author