Echo ranging display system

Claim 1

A RANGE MEASUREMENT SYSTEM FOR USE IN PULSE ECHO SEARCH APPARATUS WHEREIN THE TIME INTERVAL BETWEEN A TRANSMITTED SEARCH SIGNAL AND A RECEIVED ECHO SIGNAL IS A FUNCTION OF RANGE COMPRISING, A PLURALITY OF ELECTRONIC COUNTERS, EACH HAVING A STORAGE REGISTER WITH A PLURALITY OF STABLE VOLTAGE STATES, INDICATOR MEANS TO DISPLAY VISUALLY EACH OF SAID STABLE STATES, A FIRST OF SAID COUNTERS HAVING AN INPUT FOR EVENTS TO BE COUNTED, THE REMAINING COUNTERS BEING SERIALLY INTERCOUPLED TO MEASURE COMPLETE CYCLES OF DIFFERENT ONES OF SAID STTORAGE REGISTERS INCLUDING THAT OF SAID FIRST COUNTER, A SEPARATE SINGLE POLE MULTITAP SWITCH COUPLED TO EACH OF SAID REGISTERS SO THAT THE SIGNAL VOLTAGE EXCLUSIVELY ASSOCIATED WITH EACH STABLE STATE APPEARS AT A SEPARATE TAP, A COINCIDENCE GATE MEANS HAVING A SEPARATE INPUT COUPLED TO THE COMMON POLE OF EACH OF SAID SWITCHES FOR GENERATING AN INDEX SIGNAL WHEN SAID SIGNAL VOLTAGES APPEAR SIMULTANEOUSLY AT SAID COMMON POLES, A TIMED GENERATOR OF CLOCK SIGNALS, A BISTABLE GATE COUPLING SAID TIMED GENERATOR TO SAID INPUT RESPONCOUNTER, SAID BISTABLE GATE HAVING AN "ON" INPUT RESPONSIVE TO SAID TRANSMITTED ECHO PULSE TO OPEN SAID GATE AND AN "OFF" INPUT COUPLED TO SAID COINCIDENCE CIRCUIT TO CLOSE SAID GATE IN RESPONSE TO SAID INDEX PULSE, AND A MIXING CIRCUIT MEANS COUPLED TO SAID COINCIDENCE GATE TO COMBINE SAID INDEX SIGNAL WITH SAID RECEIVED ECHO SIGNAL.