Remote interrogator-responder signal-ling system communications channel apparatus

Claim 1

AN INTERROGATOR-RESPONDER SIGNALLING SYSTEM, COMPRISING IN COMBINATION: AN INTERROGATOR UNIT FOR PROVIDING AN INTERROGATOR SIGNAL COMPRISING AN INTERROGATOR CARRIER HAVING A FIRST GROUP OF DISCRETE SIDEBAND FREQUENCIES EACH DIFFERING IN FREQUENCY FROM SAID INTERROGATOR CARRIER BY A RESPECTIVE ONE OF A FIRST GROUP OF FREQUENCIES; A PLURALITY OF RESPONDER DEVICES, EACH OF SAID RESPONDER DEVICES BEING CAPABLE OF MOTION RELATIVE TO SAID INTERROGATOR UNIT AND OPERABLE UPON APPROACH TO SAID INTERROGATOR WITHIN A CERTAIN DISTANCE TO PROVIDE A CODED RESPONSE SIGNAL COMPRISING A RESPONSE CARRIER HAVING A SECOND GROUP OF DISCRETE SIDEBAND FREQUENCIES EACH DIFFERING IN FREQUENCY FROM SAID RESPONSE CARRIER BY ONE OF SAID FREQUENCIES OF SAID FIRST GROUP OF FREQUENCIES; A RESPONSE RECEIVER UNIT LOCATED WITHIN SAID CERTAIN DISTANCE FROM SAID INTERROGATOR, TUNED TO RECEIVE SAID RESPONSE SIGNAL AND OPERATIVE TO DEMODULATE SAID RESPONSE SIGNAL TO PROVIDE COMPLEX WAVE CONTAINING COMPONENTS OF CERTAIN OF SAID FIRST GROUP OF FREQUENCIES; A COMMUNICATIONS CHANNEL CONNECTED TO CARRY SAID COMPLEX WAVE TO A REMOTE LOCATION; A SECONDARY CARRIER FREQUENCY OSCILLATOR LOCATED AT SAID REMOTE LOCATION AND OPERATIVE TO PROVIDE A SECONDARY CARRIER; A MODULATOR CIRCUIT CONNECTED TO SAID COMMUNICATIONS CHANNEL AND SAID SECONDARY CARRIER FREQUENCY OSCILLATOR AND OPERATIVE TO MODULATE SAID SECONDARY CARRIER WITH SAID COMPLEX WAVE TO PROVIDE A SECONDARY MODULATED SIGNAL HAVING AT LEAST ONE DIFFERENT SIDEBAND FOR EACH OF SAID COMPONENTS OF SAID COMPLEX WAVE; AND A PLURALITY OF FREQUENCY SELECTIVE DETECTOR MEANS CORRESPONDING IN NUMBER TO SAID FIRST GROUP OF FREQUENCIES LOCATED AT SAID REMOTE LOCATION AND CONNECTED TO RECEIVE SAID SECONDARY MODULATED SIGNAL, EACH OF SAID DETECTOR MEANS BEING ARRANGED TO SELECT AND DETECT A DIFFERENT SIDEBAND COMPONENT OF SAID SECONDARY MODULATED SIGNAL, THEREBY TO PROVIDE COLLECTIVELY A PARALLEL DIGITAL CODED SIGNAL.