Clemar Manufacturing Corp.

Michael D Hollabaugh

Vinod Panday

A method and apparatus for the control of a number of valves in an irrigation system utilizing only two lines between a central encoder and a number of remotely located decoders. An alternating-current signal on the lines is used both to transmit power to the decoders and valves, and to convey control information in the form of decoder addresses and on/off signals represented in binary form by selectively clipping the alternating-current signal. The encoder includes timing and switching circuitry to effect temporary interruptions of the alternating-current signal, and to detect feedback signals transmitted from the decoders during the interruptions. At each decoder, the received control signals are recovered from the power lines, and each received decoder address is compared with one which identifies the decoder. When a match is found, the received on/off signal is employed to switch a valve and to initiate transmission of a confirmatory feedback signal. A portable operator, which may be connected to the power lines anywhere in the system, monitors the control signals transmitted from the encoder, and transmits special feedback signals which direct the encoder to perform functions selected at the portable operator.

Digital two-wire irrigation control system with feedback

Apparatus for the control of a number of remotely located irrigation or sprinkler valves from a central location by means of control signals encoded onto a single pair of power transmission lines linking a central encoder and a number of remote decoders. The encoder includes a multiplexer for selecting on/off signals supplied by a controller, an address generator to drive the multiplexer and to generate decoder addresses for transmission, and coupling circuitry to encode the generated decoder addresses and on/off signals onto an alternating-current power signal, by clipping half-portions of the signal to represent zero values. Each decoder includes a bridge rectifier, from which clock pulses and a serial data stream are derived. The data stream is continually shifted through a shift register, and a comparator compares a decoder address field in the register with the conditions of a set of manual switches indicative of the decoder address. When the comparator finds a match, the on/off signal is gated into a flip-flop and utilized to generate a valve control signal.

Growing community of inventors

San Jose, CA, United States of America

Michael D Hollabaugh