GB723240A - Improvements in or relating to means for measuring time intervals - Google Patents

Abstract

723,240. Measuring pulse time intervals. NATIONAL RESEARCH DEVELOPMENT CORPORATION. March 3, 1953 [March 3, 1952], No. 5471/52. Class 37. Apparatus for sorting a series of pulses according to their time displacement from a reference pulse, comprises means for repeating the reference pulse at one recurrence frequency, means for repeating the series to be sorted at a different recurrence frequency and means for detecting coincidences between the two sets of repeated pulses. By this means the time scale of the series of pulses is expanded. As shown, Fig. 1, the reference or A-pulse is fed from the A detector 9 via the A injector 4 to a circulating system 1 comprising a delay line 5 having a delay of # + d#. The A-pulse also opens a gate 10 to admit the following pulse series from the B detector 12 via the B injector 7 to a circulating system 2 comprising a delay line 8 having a delay of #. Pulses from the circulating system 1 are fed to a shaper 13 which lengthens them to a length d# and thence to a coincidence circuit 17 also fed from the circulating system 2 After each circulation the A-pulse will coincide 18a ... 18d which are opened in turn by a control circuit 19 stepped by successive A- pulses received from the circulating system 1. Each initial A-pulse from the detector 9 operates a mark-space generator 23 which operates blocking devices 21, 22 to remove all circulating pulses present due to any preceding timing operation. In a modification, Fig. 3 (not shown), a common delay line of length # is used for both A- and B-pulses which are of opposite polarity for enabling the A- and B-injector circuits to recognize them, the A- injector circuit comprising an additional delay line of length d#. To avoid possible interference and consequent neutralizing of A- and B-pulses in the delay line the initial series of B-pulses is fed in through a small delay line of length X and as soon as a coincidence in respect of a B-pulse has been recorded that pulse is removed from the delay line. The A- input to the coincidence circuit is fed via a compensating delay line of length X. In a further modification, Fig. 4, not only a common delay line 44 but also a common injector 43 is used. As shown, the A-pulses from the detector 46 are fed as negative pulses by an injector 41 into the circulating system having a circulating period #. The A-pulses are also fed with a small delay Y to an injector 43 which injects the pulses as positive pulses. The B- pulses are fed from the detector 50 with a delay X > Y) to the injector 43 whcih also injects these pulses as positive pulses. The diode with a successively later portion of the time scale of the B series and if a B-pulse occurs in one of these portions it is fed to an appropriate one of the counters 20a ... 20d via gates switches 48, 49 together with the control circuit 54 operate on receipt of a negative A-pulse in such a manner that the diode 48 opens for the next positive A pulse only, after which the diode 49 opens to pass the succeeding B pulses. The positive A pulse is therefore subject to an additional delay d# in each 'circulation. The output from the injector 43 is applied to a shaper and separator circuit 56 containing two diode switches and a control circuit similar to 48, 49, 54, which passes the A-pulse through a line having a delay X-Y and the B pulses directly to a coincidence detector 57. Coincidences are counted and B-pulses removed on registration as previously described.