Patent GB-1086302-A (GB)
Title: Improvements in or relating to time measuring apparatus
Inventor: CHADNEY DONOVAN COLIN
IPC: G04F10/00
Filed: 1964-02-19
Abstract: 1,086,302. Measuring short time intervals. GENERAL ELECTRIC CO. Ltd. May 7, 1965 [Feb. 19, 1964], No. 6925/64. Heading G1U. [Also in Division H3] An apparatus for producing an output signal representative of the time which elapses between a selected pair of pulses, not being successive pulses, in a pulse sequence comprises a circuit responding to the individual pulses of the sequence which generates a timing signal initiated by the occurrence of the first and terminated by the occurrence of the second of the selected pulses, an arrangement responding to the timing signal for producing a continuous change in a control signal for a period corresponding to the length of the timing signal and an output arrangement for generating a signal having a value depending upon the total change in the control signal. In an arrangement for measuring the time between the trailing edge of a first pulse and the leading edge of a third pulse in a sequence of pulses, the pulse sequence is applied via a filter and preamplifier to a splitting circuit 3 which divides the pulses at their mean amplitude level, the time period under measurement being related to this level. The positive going parts (with respect to the mean amplitude) of the pulses are passed directly to a summing circuit 5 while the negative going parts are amplified and inverted, thereafter being passed to the summing circuit. The output from this circuit consists of a series of negative going spikes whose positions correspond to the times at which the pulse edges cross the mean amplitude position. These are fed to a pulse generator 6 which produces equivalent positive going pulses which are passed to a diode pump circuit 7. In this circuit the charge on a capacitor is built up as each pulse enters the circuit until a defined number of pulses has been applied after which a diode reset arrangement 8 causes the capacitor to discharge. The output from the diode pump is thus a staircase waveform with each step corresponding to the position of an input pulse. This is passed to a clipping circuit which is designed to pass only that part of the signal above a certain level. In this example the level is fixed so that it is exceeded by the second input pulse to the pump circuit (which corresponds to the trailing edge of the first pulse at the system input). The reset circuit 8 is designed to reset the pump at the fifth input pulse to the pump, (which corresponds to the leading edge of the third pulse at the system input). The output from the clipping circuit is thus a pulse whose length corresponds to the time to be determined. This pulse is passed via a delay 16 to a ramp generator 11, which produces a linearly increasing voltage for as long as the pulse is applied to it. The peak voltage is detected by a detector 12, which is reset prior to the operation by a short pulse derived from the undelayed output of the clipping circuit. After smoothing the detected voltage is passed to indicating arrangements which show the time required. Certain of the circuits may be combined Fig. 2 (not shown) and detailed circuitry is described (see Division H3).