Abstract: A programmable tone decoder for standard bell system DTMF tone pairs is presented which comprises an integrated DTMF receiver and a means for programming a sequence of digits which are compared to the output of the DTMF receiver. The decoding means provides an output for an exact comparison of the complete sequence, the output being indicative of the reception of a proper telephone code sequence.

Abstract: An automatic radio telephone encoder/decoder including a microcomputer programmed to decode incoming dial codes and generate outgoing radio telephone functions and dial codes in response to received signals or keypad activation is presented in combination with control circuitry activated by the microcomputer which is maintained in an off condition except when called upon to perform encoding or decoding functions by a keyboard input means or signals received by the radio telephone.

Abstract: A tone decoder for the sixteen standard Bell System DTMF tone pairs is presented which is comprised of first and second tone detectors adapted to provide logic signals in response to detection of predetermined frequencies. The logic signals are processed by a counter which is incremented by simultaneous logic signals from the first and second tone detectors and which controls a switch adapted to change the frequencies to which the tone detectors are responsive.

Abstract: A digitally synthesized tone encoder and automatic number identification generator for a radio-telephone is presented herein. The system includes a tone burst generator for producing two audio tones simultaneously in response to either a keypad input or sequencing of a multiplexer providing a single-pole eight-throw switching function in response to the incrementing of a counter.

Abstract: Presented herein is a sub-miniature radio telephone decoder which through a unique arrangement of integrated circuits adapted to create frequency detectors and counters provide the means whereby a radio telephone receiver is held in a muted state until a predetermined 600/1500 MTS code representing a phone number is decoded. When the predetermined code has been detected, the decoder unmutes the receiver and activates an audio signal. The functions are accomplished by first and second frequency detectors responsive to 600 Hz and 1500 Hz tones in combination with means to count frequency shifts between the two tones and interpret sets of shifts as digits of a predetermined telephone code.