Atmospheric Radio Noise Intensities in the Northern & Eastern Regions of India

Abstract

Some of the already measured values of atmospheric radio noise· field strengths (ARN-FS) for Delhi (28°35'N, 77°05'E) and Gauhati (26°10'N, 91°40'E) have been utilized, with a modified form of the available mathematical expression, to calculate the expected ARN·FS for a number of frequencies in the range 0.3-20·0 MHz for different time blocks and seasons. The ARN-FS values thus calculated have been compared graphically with the measured values and also with those predicted in CCIR Report No. 322. They are found to be almost of the same order of magnitude and form, for all frequencies, times and seasons except that the predicted noise shows very low values in some lower hf bands of frequencies during daytime. It is pointed out that the basis for prediction at these frequencies during daytime is not quite what it should be to account for the actual conditions for propagation of ARN over the Indian landmass. Besides, in view of the fact that both the predicted and calculated ARN-FS are almost within acceptable limits for all other frequencies and times, the method of calculation outlined here is considered to be quite convenient to estimate ARN-FS existing in the northern and eastern regions of India under actual conditions, for practical applications.