MF and HF Band Atmospheric Radio Noise Data for India

Abstract

Communication Engineers expect at least 90 per cent of the time satisfactory service in a short period of time like five minutes. Hence, the highest amplitude noise present for 10 per cent of the time or less is of relevance to the system designer. The mean value of this noise as a source of interference to voice communication is called the noise level, N. N can be converted into average amplitude, RMS amplitude or expressed in terms of the peak amplitudes prevailing over such average or RMS amplitudes by use of suitable statistically assessed conversion factors. Hence, the basic parameter utilized in the report is N. Its seasonal median values and short and long term standard deviations are furnished as data. N is furnished for a 1 kHz bandwidth at 1 MHz with suitable conversion factors for converting data for other bandwidths and other frequencies in the range 0·3–30 MHz. With the use of this data, the desirable signal to noise ratio for different types of services have been derived and furnished as data. In order to facilitate extensive use of the data, the physical principles underlying the evaluation are briefly described at the outset.