Remote indicating device

Claim 1

A REMOTE CONDITION MEASURING APPARATUS COMPRISING A SIGNAL TRANSMITTING ELEMENT HAVING A SIGNAL MODIFICATION CHARACTERISTIC WHICH VARIES ACCORDING TO A KNOWN RELATIONSHIP WITH THE MAGNITUDE OF SAID CONDITION, A SIGNAL RECEIVING MEANS, A PAIR OF CLOSELY SPACED SUBSTANTIALLY IDENTICAL SIGNAL TRANSMISSION PATHS EACH HAVING ONE END CONNECTED TO SAID RECEIVING MEANS, THE REMAINING END OF ONE OF SAID TRANSMISSION PATHS BEING CONNECTED TO THE OUTPUT OF SAID SIGNAL TRANSMITTING ELEMENT, MEANS FOR APPLYING ACOUSTIC PULSE SIGNALS TO THE INPUT OF SAID SIGNAL TRANSMITTING ELEMENT AND TO THE REMAINING END OF THE OTHER OF SAID TRANSMISSION PATHS ACCORDING TO A KNOWN RELATIONSHIP, AN ACOUSTIC REFLECTING TERMINATION IN SAID TRANSMITTING ELEMENT TO REVERSE THE DIRECTION OF PROPAGATION OF THE ACOUSTIC PULSES THEREIN, AND MEANS ASSOCIATED WITH SAID RECEIVING MEANS FOR ASCERTAINING THE RELATIONSHIP BETWEEN THE SIGNALS RECEIVED ALONG EACH OF SAID TRANSMISSION PATHS.