The optimum dynamic parameters of digital rate meter algorithms

The definition of the "Quality," Q, of a count-rate meter algorithm is introduced as the reciprocal of the algorithm's (tau x epsilon) product, where tau is the response time of the algorithm to a sudden change in the average count rate and where epsilon is the fractional standard deviation of the steady-state measurement of a constant average count-rate pulse stream. Analytical expressions for tau and epsilon of digital rate meter algorithms are used to calculate maximum values of Q for both linear and exponential algorithms. The values of the basic algorithm parameters necessary to achieve these minimum (tau x epsilon) products are derived for both algorithms. The use of these values results in algorithms that have relatively short response times and, simultaneously, relatively small steady-state errors. (C) 1997 American Institute of Physics.