Measurement of the Peak Field Strength of a Narrow Band Atmospheric

Abstract

At tropical latitudes, the principal source of interference in the frequency range, 0·1–10 MHz, is the burst form of atmospheric radio noise. The structure of a burst shows several approximately rectangular pulses of duration in the msec, range. The influence of the noise on data communication can only be examined when the value of the amplitude of the highest pulse of this type is known. The equivalent field strength of the source of such a pulse in the corresponding narrow band atmospheric is, therefore, defined as its peak field strength. On the basis of this definition, the design of the output unit of the noise meter for measuring this peak field strength is examined. The appropriate charging and discharging time constants are 1 and 160 msec, respectively. Calibration suggested is in terms of the peak field strength of continuous waves. The entire problem has been examined on the basis of an idealized statistically valid representation of the burst form of the noise and the structure of a noise burst. Although the paper is concerned with a specific problem, the principles and procedures emerging from the discussion may find wider application.