International Telecommunication Union

Abstract:

The determination of the minimum signal level required for satisfactory radio reception in the absence of other unwanted radio signals necessitates a knowledge of the noise with which the wanted signal must complete.

There are a particular number of types of noise which may influence reception, although, with a particular circuit, usually only one type will predominate. Broadly, the noise can be divided into two categories depending on whether it originates in the receiving system or externally to the antenna. The internal noise is due to antenna and transmission line losses, or is generated in the receiver itself. It has the characteristics of thermal noise, and, in many cases, its effects on signal reception can be determined mathematically with a high degree of precision.

External noise can be divided into several types; each having its own characteristics. The most usual types are of atmospheric, galactic, and man-made origin. All these types are considered here, but since atmospheric noise usually predominates at frequencies below about 30 Mc/s, this Report deals primarily with this type and with its influence on the reception of signals.

The purpose of this report is to present values of noise power and of other noise parameters, and to show, by examples, the method of using these in the evaluation of the probable performance of a radio circuit.

Keywords: interference; propagation prediction; predictions; statistical analysis; radio frequency interference (RFI); radio transmission; distribution (property); graphs (charts); atmospherics; man-made radiofrequency interference; Switzerland; periodic variations

Disclaimer: Certain commercial equipment, components, and software may be identified in this report to specify adequately the technical aspects of the reported results. In no case does such identification imply recommendation or endorsement by the National Telecommunications and Information Administration, nor does it imply that the equipment or software identified is necessarily the best available for the particular application or uses.

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