Proximity warning device

Claim 1

TRANSPONDER RANGING APPARATUS FOR TERRAIN CLEARANCE PURPOSES COMPRISING AN AIRCRAFT-LOCATED INTERROGATOR AND A GROUND-LOCATED RESPONDER INCLUDING: IN SAID INTERROGATOR, A PULSE SOURCE, A FIRST HEIGHT SENSITIVE DEVICE, A FIRST HEIGHT DELAY CONTROLLED BY SAID FIRST HEIGHT SENSITIVE DEVICE, AND A FIRST TRANSMITTER, MEANS PASSING A PULSE FROM SAID PULSE SOURCE TO SAID FIRST TRANSMITTER THROUGH AND IN PARALLEL TO SAID FIRST HEIGHT DELAY WHEREBY A PULSE PAIR IS GENERATED AS AN INTERROGATION SIGNAL, SUCH PULSE PAIR BEING SEPARATED BY A TIME CONTROLLED BY THE HEIGHT SENSITIVE DEVICE; IN SAID RESPONDER, A FIRST RECEIVER, A SECOND HEIGHT SENSITIVE DEVICE, A SECOND HEIGHT DELAY CONTROLLED BY SAID SECOND HEIGHT SENSITIVE DEVICE, MEANS PASSING A RESPONSE SIGNAL FROM SAID FIRST RECEIVER TO SAID SECOND HEIGHT DELAY, A FIRST HEIGHT GATE, MEANS PASSING THE DELAYED SIGNAL FROM SAID SECOND HEIGHT DELAY TO SAID FIRST HEIGHT GATE, MEANS PASSING A RESPONSE SIGNAL FROM SAID SECOND RECEIVER TO SAID FIRST HEIGHT GATE WHEREBY A SINGLE RESPONSE PULSE IS GENERATED, A SERIES-CONNECTED FIRST FIXED DELAY, THIRD HEIGHT DELAY AND SECOND TRANSMITTER, SUCH THIRD HEIGHT DELAY BEING CONTROLLED BY SAID SECOND HEIGHT SENSITIVE DEVICE, MEANS PASSING SAID SINGLE RESPONSE PULSE TO SAID SECOND TRANSMITTER DIRECTLY, VIA SAID FIRST FIXED DELAY AND VIA SAID FIRST FIXED DELAY AND THIRD HEIGHT DELAY IN SERIES, THEREBY TO FORM A THREE-PULSE RESPONSE SIGNAL; IN SAID INTERROGATOR, A SECOND RECEIVER, A SECOND FIXED DELAY HAVING A DELAY EQUIVALENT TO SAID FIRST FIXED DELAY, A BEACON COINCIDENCE GATE, MEANS FEEDING A RESPONSE SIGNAL FROM SAID SECOND RECEIVER TO SAID BEACON COINCIDENCE GATE DIRECTLY AND VIA SAID SECOND FIXED DELAY, A FOURTH HEIGHT DELAY FED BY THE OUTPUT FROM SAID BEACON COINCIDENCE GATE, SAID FOURTH HEIGHT DELAY BEING CONTROLLED BY SAID FIRST HEIGHT SENSITIVE DEVICE, MEANS CONNECTED TO THE OUTPUT OF SAID FORUTH HEIGHT DELAY TO GENERATE A LONG PULSE CHARACTERISTIC OF THE RANGE OF HEIGHTS TO BE RECEIVED, A SECOND HEIGHT COINCIDENCE GATE FED BY SAID LONG PULSE AND ALSO BY THE OUTPUT OF SAID SECOND RECEIVER WHEREBY AN OUTPUT PULSE FROM SAID SECOND HEIGHT COINCIDENCE GATE CORRESPONDS TO A DANGEROUS SITUATION.