Spectral Analysis of a PAM-FM Signal

A PAM-FM telemetry system has been analyzed when the various sensors or telemetering transducers each monitor a stationary Gaussian random process (GRP). Each GRP sensor output is band limited and instantaneously sampled at the optimum rate. This optimum frequency is the minimum sampling rate that causes no signal distortion due to aliasing in the frequency domain. A maximum number of sensors are accommodated with timedivision multiplexing so that the composite PAM multiplexed signal is also assumed to be a Gaussian random process. This PAM multiplexed signal is then considered to be the input modulating signal to an FM transmission system. A FORTRAN computer program has been used to obtain the resulting PAM-FM output spectral distributions for various mean square values of the PAM multiplexed signal.