The chapter begins with definition of angle modulation and derives important relations between phase modulation (PM) and frequency modulation(FM). The theoretical development is first carried out for single tone modulating signal which includes definition of modulation index, bandwidth, spectrum and phasor representation. This is followed up by discussion where modulating signal is arbitrary in nature and modulation can be narrowband or wideband. Different types of FM generation schemes are discussed with Armstrong’s system taken up as a case study. The demodulator discussion, besides traditional ones refers to Integrated Circuit based techniques. The way to get PM modulators and demodulators from its FM counterpart is also discussed. The relative immunity of FM and PM signals to weak interference is highlighted through an example. Finally, we present a detailed scheme of FM stereophonic broadcasting and MATLAB simulation experiments.
