David Middleton

Abstract: A general statistical-physical model of man-made radio noise processes appearing in the input stages of a typical receiver is described analytically. The first-order statistics of the se random processes are developed in detail for narrow-band reception. These include, principally, the first order probability densities and probability distributions for a) a purely impulsive (poisson) process, and b) an additive mixture of a gauss background noise and impulsive sources. Particular attention is given to the basic waveforms of the emissions. in the course of propagation. including such critical geometric and kinematic factors as the beam patterns of source and receiver, mutual location, Doppler, far-field conditions, and the physical density of the sources, which are assumed independent and poisson distributed in space over a domain A. Apart from specific analytic relations. the most important general result s are that these first-order distributions are analytically tractable and canonical. They are not so complex as to be unusable in communication theory applications; they incorporate in an explicit way the controlling physical parameters and mechanisms which determine the actual radiated and received processes; and finally, they are formally invariant of the particular source location and density, waveform emission, propagation mode, etc., as long as the received disturbance is narrow-band, at least as it is passed by the initial stages of the typical receiver. The desired first-order distributions are represented by an asymptotic development, with additional terms dependent on the fourth and higher moments of the basic interference waveform, which in turn progressively affect the behavior at the larger amplitudes. This first report constitutes an initial step in a program to provide workable analytical models of the general nongaussian channel ubiquitous in practical communications applications. Specifically treated here are the important classes of interference with bandwidths comparable to (or less than) the effective aperture-RF-IF bandwidth of the receiver, the common situation in the case of communication interference.

Keywords: man-made radio noise; radio noise models; Statistical communications theory

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