Digital Computer Simulation of a Frequency-Shift Keying System

A digital computer simulation of a noise-free frequency-shift keying (FSK) data system is described. This system consists of a frequency modulator, a send and receive bandpass filter, a limiter, and a frequency demodulator. The simulation is used to study the performance of the system in terms of telegraph distortion for various filters and demodulators. The accumulated spectral density of the modulated Q 9S test signal is examined. The modeling of the system and the processing of the test signal are discussed.