Abstract: A method of determining the rate of change of frequency of a plurality of randomly occurring events begins by counting the number of random events which occur within a plurality of predetermined sampling intervals to obtain a plurality of count values, each corresponding to one of the sampling intervals. These count values are stored in a memory table and the count values which correspond to the most recent set of N of the sampling intervals is summed to obtain a first accumulated count. A second accumulated count is obtained by summing the count values which correspond to a second set of N of the sampling intervals, preceding the most recent set. The rate of change of event frequency is then calculated by dividing the logarithm of (S.sub.1 /S.sub.2) by the number N. The value of the number N is dynamically adjusted for subsequent calculations based on the incoming frequency of random events.

Abstract: A method of counting a plurality of pulses representative of randomly occurring events includes the steps of counting the number of pulses, having an amplitude exceeding a first threshold amplitude, which occur during a predetermined sampling period to obtain a first count and counting the number of pulses, having an amplitude exceeding a second threshold amplitude, which occur during the sampling period to obtain a second count. The second count is compared to a predetermined number and the counts for that sampling period are rejected if the second count is too large. If the second count is not too large, the true count is calculated by subtracting the second count from the first count. This counting procedure is repeated for a preselected number of successive sampling periods. After the final sampling period, all of the true counts are added to obtain an accumulated count and the accumulated count is multiplied by a scaling factor to obtain an output count.