Abridgment of behavior of radio receiving systems to signals and to interference

Abstract

This paper develops a point of view and method by means of which it is possible to arrive at many of the transient effects occurring in radio systems by a consideration of steady-state properties alone. The scheme is to replace the voltages in radio receiving systems due to interference and signals by a group of generators having the correct voltages and frequencies. These generators can be thought of as having been in the circuit for an indefinitely long time, so that only the steady-state response of the system need be considered. The generators which replace the voltages induced in an antenna by interrupted continuous wave stations, by spark telegraph stations, by telephone stations and by static are worked out. The desirable properties of radio receiving systems for receiving various types of signals through interference are arrived at and an ideal system is described which may be used as a standard of reference for judging the merits of any actual frequency selecting system. It is shown that this ideal system reduces the interference from all sources to the smallest possible value which can be obtained in a system which makes use of frequency selection to reduce interference. The paper thus arrives at the degree to which interference can be mitigated by frequency-selection methods. In order to illustrate the method of treating actual systems, calculations are given for a simple series receiver. The interference caused by transmitting stations of various types and by static is discussed and the factors determining such interference are pointed out.