Abstract: A dual purpose integrated circuit device which can be utilized both as an encoder for providing digital signals according to a preselected code and as a decoder for comparing a received signal with an internally generated digitally coded signal. The device includes a plurality of input/output ports for making an electrical connection between external circuitry and functional portions of the device. The device includes a pulse generator for providing digital signals at its output according to a preselected code. The output of the generator is coupled to an output port for supplying the digital signals to a transmitter when used in the encoding mode, and provides the internally generated comparison code in the decoder mode. Improved circuitry is provided for selectively adjusting the level of security for a system utilizing the device in a transmitter-receiver system for activating a load such as a garage door opener, as well as for accommodating noise levels which may be encountered in authorized use.

Abstract: A data communication system for selectively activating a plurality of remote loads. The system includes a transmitter having an encoder with first and second sets of inputs. The encoder provides a multi-bit pulse train for transmission to a receiver. Selected bits of the pulse train are associated with the first set of inputs to the encoder and define an address code. Other bits of the transmitted pulse train are associated with the second set of encoder inputs and define data. A receiver incorporates a decoder coupled for receipt of the pulse train from the transmitter. A set of code select inputs for the decoder defines a local address code for the receiver. A pulse generator provides a local pulse train which is a function of the code select inputs. A comparator normally operates to compare all of the bits in the local pulse train with those in the received pulse train from the transmitter, with the comparator output preventing load actuation unless all of the bits match.

Abstract: A decoder circuit for selectively activating external loads which finds particular utility in automatic garage door operators. The coincidence of a repeatedly received digital word code with an internally generated local code results in a matched signal, each of the matched signals being stored in an accumulator device. A free running oscillator is used to reset the accumulator if a predetermined number of successive clock pulses are generated without an intervening matched signal. If a given plurality of matched signals are received and stored in the accumulator before it is reset, the accumulator will provide an output signal to a latch which activates the load. Once set, the output latch will not be reset unless a subsequent given number of successive clock pulses are generated without an intervening matched signal. In such manner, the decoder circuitry accommodates a limited number of mismatches possibly due to interference while still maintaining significant security aspects of the decoder circuitry.

Abstract: A digital radio control system comprising a transmitter for producing a repeating series of width modulated pulses, and a receiver responsive only to a series of predetermined pulse characters to actuate a load device such as a garage door operator. Both the transmitter and the receiver circuits comprise simple counter circuits and switches to define the pulse codes. The receiver counter is clocked by the transmitted pulse series and actuates the output circuit only if it reaches the final counter stage at least once.