ABSTRACT
This chapter aims to treat the nature of atmospherics, i.e., the relationships between atmospheric noise and telecommunication systems. It defines the receiving system operating noise factor and shows how the internal and external noises must be combined. The chapter then provides estimates of the minimum (and maximum) environmental noise levels likely at any location on the earth's surface. It summarizes the effects of atmospheric noise on system performance and also provides various means of improving system performance in impulsive noise. The chapter presents a summary of mathematical models for the atmospheric-noise process, because quite often proper system design requires more information about the process than can be obtained by measurement alone. It concentrates on the statistics of the envelope process. In general, for system analysis, the required statistics that determine performance are either the envelope statistics directly or are obtainable from the envelope and phase statistics.
