Tape editing aid

Claim 1

IN COMBINATION WITH A RECORDING SYSTEM OF THE CLASS HAVING A MAGNETIC TAPE MOVABLE PAST A RECORDING HEAD FOR RECORDING A PRIMARY SIGNAL HAVING PERIODIC INTERRUPTIONS, SAID SYSTEM INCLUDING MEANS FOR RECEIVING A PAIR OF INPUT SIGNALS AND COMPARING THE PHASES OF SAID INPUT SIGNALS TO VARY THE SPEED OF SAID TAPE AS A FUNCTION OF THE PHASE DIFFERENCE BETWEEN SAID INPUT SIGNALS, THE COMBINATION COMPRISING: A PLURALITY OF INDEX MARKS PRE-PRINTED AT REGULAR INTERVALS ON SAID TAPE; A MASK HAVING A SLIT FORMED THEREIN AND MOUNTED ALONGSIDE SAID TAPE WITH SAID SLIT SPACED FROM SAID RECORDING HEAD OF A DISTANCE CORRESPONDING TO A MULTIPLE OF SAID INTERVALS; A PHOTOELECTRIC CELL MOUNTED TO VIEW SAID INDEX MARKS IN PASSAGE BEFORE SAID SLIT AND FUNCTIONING TO PRODUCE A FIRST PULSE AT THE INSTANT EACH INDEX MARKS PASSES SAID SLIT, SAID PHOTOELECTRIC CELL BEING CONNECTED TO SAID SIGNAL COMPARING MEANS TO SUPPLY SAID FIRST PULSES THERETO AS ONE OF SAID PAIR OF INPUT SIGNALS; AND PULSE FORMING MEANS CONNECTED TO RECEIVE SAID PRIMARY SIGNAL AND TO PRODUCE A SECOND PULSE AT THE INSTANT EACH OF SAID INTERRUPTIONS IS RECEIVED BY SAID PULSE FORMING MEANS AND BY SAID HEAD FOR RECORDING ON SAID TAPE, SAID PULSE FORMING MEANS BEING CONNECTED TO SAID COMPARING MEANS TO SUPPLY SAID SECOND PULSES THERETO AS THE OTHER OF SAID PAIR OF INPUT SIGNALS; WHEREBY SAID TAPE SPEED IS VARIED IN ACCORDANCE WITH THE PHASE DIFFERENCE BETWEEN SAID FIRST AND SECOND PULSES SO AS TO BRING AND TO MAINTAIN SAID FIRST AND SECOND PULSES IN SYNCHRONOUS PHASE RELATION, THEREBY INSURING THAT SAID PRIMARY SIGNAL INTERRUPTIONS ARE EACH RECORDED PRECISELY AT CORRESPONDING INDEX MARKS ON SAID TAPE.