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 N₂ during t₂ at t=τ, where t₂ is equal to t₁ which is the interval required for N₁=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 0.015sec_-1 in the case of a delay time of τ=1sec. For τ ?? 2sec, it becomes smaller than 0.008sec_-1. The delay time τ is set to a value chosen among 1, 2, 4, 8, 16 and 32sec, 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.