# US 4,392,749 A · Instrument for determining coincidence and elapse time between independent sources of random sequential events > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 4,392,749 A - Document ID: US4392749A - Status: Granted - Kind: A - Application number: 06/282,191 - Filed: 1981-07-10 - Granted: 1983-07-12 - Earliest claimed: 1981-07-10 - Assignees: The United States of America as represented by the Administrator of the National Aeronautics and Space Administration - Inventors: James I. Clemmons, Jr. - Web page: https://patentgrep.com/patent/US4392749A ## CPC - G01P 5/26: by measuring the direct influence of the streaming fluid on the properties of a detecting optical wave - G01F 1/661: using light - G01R 29/027: Indicating that a pulse characteristic is either above or below a predetermined value or within or beyond a predetermined range of values - G04F 10/00: Apparatus for measuring unknown time intervals by electric means - G01P: MEASURING LINEAR OR ANGULAR SPEED, ACCELERATION, DECELERATION, OR SHOCK; INDICATING PRESENCE, ABSENCE, OR DIRECTION, OF MOVEMENT (measuring or recording blood flow A61B5/02, A61B8/06; monitoring speed or deceleration of electrically-propelled vehicles B60L3/00; vehicle lighting systems adapted to indicate speed B60Q1/54; determining position or course in navigation, measuring ground distance in geodesy or surveying G01C; combined measuring devices for measuring two or more variables of movement G01C23/00; measuring velocity of sound G01H; measuring velocity of light G01J7/00; measuring direction or velocity of solid objects by reception or emission of radiowaves or other waves and based on propagation effects, e.g. Doppler effect, propagation time, direction of propagation, G01S; measuring speed of nuclear radiation G01T; measuring acceleration of gravity G01V; {measuring or recording the speed of trains B61L23/00; speed indicators incorporated in motor vehicles B60K35/00; measuring frequency or phase G01R; traffic control G08G}) - G01F: MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME - G01R: MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES (indicating correct tuning of resonant circuits H03J3/12) - G04F: TIME-INTERVAL MEASURING (measuring pulse characteristics G01R, e.g. G01R29/02; in radar or like systems G01S) ## Abstract An instrument that receives pulses from a primary external source and one or more secondary external sources and determines when there is coincidence between the primary and one of the secondary sources. The instrument generates a finite time window (coincidence aperture) during which coincidence is defined to have occurred. The time intervals between coincidence apertures in which coincidences occur are measured. ## Claims ### Claim 1 An instrument for determining coincidence between a primary external source of pulses and one or more other external sources of pulses comprising: means receiving said primary external source of pulses for generating a start pulse, a reset pulse and a coincidence aperture pulse each time a primary external source pulse is received; means receiving said coincidence aperture pulse and the pulses from said other external sources of pulses for producing a coincidence pulse each time a pulse from said other external sources of pulses coincides with said coincidence aperture pulse; and means receiving said start pulses, said reset pulses and said coincidence pulses for measuring the time intervals between coincidences. ### Claim 2 (depends on 1) An instrument according to claim 1 wherein said means for generating a start pulse, a reset pulse and a coincidence aperture pulse includes a time base oscillator for generating a constant frequency pulse source. ### Claim 3 (depends on 2) An instrument according to claim 2 wherein said start and said coincidence aperture pulse begin at the time of the primary external source pulse and said reset pulse occurs after the end of said coincidence aperture pulse. ### Claim 4 (depends on 3) An instrument according to claim 3 wherein said means for measuring the time intervals between coincidences comprises first and second counters connected to said time base oscillator and means receiving said start pulses, reset pulses and coincidence pulses for controlling said first and second counters such that they alternate in providing counts of the constant frequency pulse source between the start pulses in which there are coincidences during the corresponding aperture pulses. ### Claim 5 (depends on 4) An instrument according to claim 4 wherein said means for controlling said first and second counters includes means for activating the counter that was not counting upon the receipt of a start pulse and means for inactivating and resetting the counter that started counting the last time there was coincidence upon the receipt of a coincidence pulse and a reset pulse and for inactivating resetting the other counter upon the receipt of a reset pulse without a coincidence pulse. ### Claim 6 (depends on 5) An instrument according to claim 5 wherein said means for controlling said first and second counters includes means for temporarily storing the count on the counter that was counting upon the receipt of a start pulse. ### Claim 7 (depends on 6) An instrument according to claim 6 wherein said means for controlling said first and second counters includes means responsive to said coincidence pulses for indicating whether or not the temporarily stored pulses are valid.