GB937454A - Improvements relating to electronic apparatus for indicating variations in the lengths of time intervals between pulses - Google Patents

Abstract

937,454. Phase detectors. ASSOCIATED ELECTRICAL INDUSTRIES Ltd. Nov. 29, 1961 [Nov. 16, 1960], No. 39367/60. Drawings to Specification. Class 40 (5). The variation of the time intervals between successive 2<SP>n</SP>th pulse of a pulse series is measured by applying the pulses in succession to n frequency division-by-two bi-stable circuits with outputs differentiated (and only pulses of one polarity selected) and the final pulses applied to a bi-stable output circuit whose mark/space ratio (measured as the average D.C. output of one state) indicates the ratio of the time intervals between successive 2<SP>n</SP>th pulses of the pulse train. A reference pulse train may precede groups of the pulses, especially if the groups do not contain precisely 2<SP>n</SP> pulses, and may be added into one of the inputs of the pulses to each side of the frequency dividers and output circuit, e.g. through cathode followers and an adding circuit, so that each of all the bi-stable circuits is switched to a predetermined state at the commencement of the group. The system may be in part duplicated so that variations in the time interval between different 2<SP>n</SP>th pulses of the group are measured, by selecting a differentiated output from another side of a bistable frequency divider. To this end a multivibrator may alternately switch the two outputs to a recording pen. The outputs from each side. respectively, of the final bi-stable circuit may be differentially combined and amplified by a differential amplifier which at the same time averages its two inputs to produce a D.C. output indicating in magnitude and polarity the ratio of the time intervals between successive 2<SP>n</SP>th pulses and whether this ratio is greater or less than unity. Specification 937,453 is referred to.