Encoder-decoder device for selective signaling

Claim 1

A COMBINATION ENCODER-DECODER DEVICE FOR USE IN SELECTIVE SIGNALING TWO-WAY RADIO APPARATUS, WHICH APPARATUS UTILIZES A TONE SIGNAL FOR TRANSMITTER OPERATION AND IS RESPONSIVE TO A CONTROL SIGNAL FOR RECEIVER OPERATION, SAID DEVICE INCLUDING IN COMBINATION, AN AMPLIFIER HAVING INPUT AND OUTPUT CONDUCTORS, AN ELECTRO-MECHANICAL FREQUENCY RESPONSIVE UNIT INCLUDING A DRIVING COIL, A SENSING COIL AND MECHANICAL VIBRATORY MEANS COUPLING SAID DRIVING COIL TO SAID SENSING COIL AND RESPONSIVE TO A PREDETERMINED FREQUENCY, MEANS CONNECTING SAID OUTPUT CONDUCTOR OF SAID AMPLIFIER TO SAID DRIVING COIL, MEANS RESPONSIVE TO VIBRATION OF SAID VIBRATORY MEANS AT THE PREDETERMINED FREQUENCY UPON ENERGIZATION OF SAID DRIVING COIL BY A TONE SIGNAL OF THE PREDETERMINED FREQUENCY FROM SAID AMPLIFIER TO PRODUCE A CONTROL SIGNAL FOR THE RADIO APPARATUS, AND SWITCH MEANS SELECTIVELY OPERABLE TO COUPLE SAID SENSING COIL TO SAID INPUT CONDUCTOR OF SAID AMPLIFIER TO CAUSE SAID DEVICE TO OSCILLATE AT THE PREDETERMINED FREQUENCY AND PRODUCE A TONE SIGNAL FOR THE APPARATUS.