GB730598A - Improvements in or relating to electrical timing arrangements - Google Patents

Abstract

730,598. Measuring short time intervals electrically. CINEMA-TELEVISION, Ltd. Aug. 21, 1953 [Aug. 22, 1952], No. 21115/52. Class 40 (1). Apparatus for measuring the duration of a time interval comprises means for counting the number of pulses from a first, crystal-controlled oscillator during that interval, and adding the algebraic sum of the pulses from a second, higher frequency oscillator for periods determined by the start of the interval and the first counted pulse from the first oscillator, and the end of the interval and the last counted pulse from the first oscillator. As shown, (Fig. 1), start and stop signals open and close respectively a gating circuit 2 to pass a series of pulses from a crystal-controlled oscillator 1 of known frequency to a counting circuit 3. The start signal also opens a gate 6 to pass pulses from a higher frequency oscillator 5 to a counter 8 until gate 6 is closed by the first pulse from oscillator 1 passed by gate 2. The stop signal also opens a gate 7 to pass pulses from oscillator 5 to a counter 9 until gate 7 is closed by the next pulse from oscillator 1. The algebraic sum of counts 8, 9 determined in unit 10, is added to count 3 to give the duration of the time interval between the start and stop signals. In another embodiment, Fig. 1 (Prov.), pulses from an oscillator 4 are again passed through a gate 3 to a counter 5, and in addition coincidence timing devices 7, 9 of the type described in Specification 729,931 measure the time between the start signal and the first pulse from oscillator 4 passing through gate 3, and the time between the last pulse from oscillator 4 through gate 3 and the stop signal. The algebraic sum of the counts in 5, 7 and 9 gives the duration of the time interval.