Short-Term Time Characteristics of Atmospheric Radio Noise Above Different Thresholds

Short-term time characteristics of burst and quasi- continuous forms of atmospheric radio noise were investigated at Bangalore at a number of frequencies in the range 100 kHz-9 MHz and over a 300-Hz-16-kHz range of bandwidth. It was found that for all frequencies, bandwidths, and threshold levels the duration and spacing follow log-normal distributions. The duration of a pulse above a particular threshold is statistically independent of its spacing from an adjacent pulse. Further, the average duration varies approximately linearly with the threshold level. These results are expected to be of use in planning digital communications where atmospheric noise is the limiting factor in reception capability.