GB867552A - Improvements in or relating to the measurement of time delay in an electrical signaltransmission - Google Patents

Abstract

867,552. Circuit delay-time measurements. WAYNE KERR LABORATORIES Ltd., and GOURIET, G. G. Feb. 25, 1960 [June 23, 1959], No. 21519/59. Class 37. Apparatus for measuring the time-delay inherent in an electrical system comprises a pulse generator 10 feeding a train of short duration pulses to the system 13 under test, a sawtoothwaveform generator 18 synchronized to the train of pulses, and means 15 for multiplying together the respective outputs of the system 13 and generator 18 to provide a D.C. output, the Specification showing that the datum level of the sawtooth waveform gives an indication of the. delay introduced by system 13 when the average output of 15 is zero. The device 15 may be a balanced ring modulator or a device employing the Hall effect, and its output may be supplied to a slow-acting direct-voltage or current meter 22 to indicate the mean output. In operating a preferred embodiment of the apparatus, pulses from generator 10, after passing through a network 11 introducing a short time delay to ensure that the linear portion of the sawtooth waveform is reached by the time the pulse reaches system 13, are applied directly to device 15 via switches 12, 14, and the datum level of the sawtooth waveform is adjusted by varying resistor 23, potentiometer 20 being set to a zero calibration mark, until meter 22 indicates zero. The datum level at this juncture corresponds to the mean epoch of the input pulse. Pulses are nextsupplied to the system 13 and potentiometer 20 is adjusted to alter the datum level until meter 22 again indicates zero. The setting of potentiometer 20 then represents the difference between the mean epoch of the input pulse and the mean epoch of the output signal of system 13, i.e. the delay introduced:by system 13. This method of measuring the time delay is said to be independent of frequency and the shape of the input pulses. In another preferred embodiment, Fig. 2 (not shown), the output of 15 is supplied to a high-gain amplifier the output of which controls the datum level of the sawtooth waveform. The feedback system thus provided is self-balancing, and the feed-back voltage from the amplifier is a measure of the time delay introduced by system 13.