Digital Period Meter

Abstract

This paper describes a new type of digital reactor period meter utilizing integrated circuits. The period is calculated from the number of counts N 2 during t 2 at t=τ, where t 2 is equal to t 1 which is the interval required for N 1=104 at t=0. Its output is the digital inverse period signal. The statistical error is delimited by fixing the number of counts instead of the counting interval. The absolute error is about 0.015 sec−1 in the case of a delay time of τ = 1 sec. For τ≧2 sec, it becomes smaller than 0.008 sec−1. The delay time τ is set to a value chosen among 1, 2, 4, 8, 16 and 32 sec, depending upon the count rate. The period meter contains about 250 integrated circuits, of which approximately 80 circuits are used for display and auxiliary functions not directly related to the primary purpose of period calculation.