Digital two-wire irrigation control system
First Claim
1. Decoding apparatus for use in an irrigation control system in which both power and control signals are transmitted from a central location along a single pair of conductors, said apparatus comprising:
- rectifier means for generating a direct-current signal from a basically sinusoidal received power signal, and for dividing the power signal into a first signal reflecting power signal excursions only in one direction with respect to a zero reference, and a second signal reflecting power signal excursions only in the other direction, the presence of excursions of said first signal being indicative of encoded ones;
electronic switch means for connecting the direct-current signal from said rectifier means to at least one valve solenoid;
means for indentifying said decoding apparatus; and
digital logic means utilizing complementary metal-oxide-semiconductor logic for deriving sets of control signals and decoder addresses from said first signal, and for operating said electronic switch means in accordance with those of said control signals accompanied by a decoder address equivalent to said means for identifying said decoding apparatus.
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Abstract
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.
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Citations
12 Claims
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1. Decoding apparatus for use in an irrigation control system in which both power and control signals are transmitted from a central location along a single pair of conductors, said apparatus comprising:
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rectifier means for generating a direct-current signal from a basically sinusoidal received power signal, and for dividing the power signal into a first signal reflecting power signal excursions only in one direction with respect to a zero reference, and a second signal reflecting power signal excursions only in the other direction, the presence of excursions of said first signal being indicative of encoded ones; electronic switch means for connecting the direct-current signal from said rectifier means to at least one valve solenoid; means for indentifying said decoding apparatus; and digital logic means utilizing complementary metal-oxide-semiconductor logic for deriving sets of control signals and decoder addresses from said first signal, and for operating said electronic switch means in accordance with those of said control signals accompanied by a decoder address equivalent to said means for identifying said decoding apparatus. - View Dependent Claims (2, 3, 4)
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5. Encoding apparatus for use in an irrigation control system having a plurality of encoders connected to said encoding apparatus by a single pair of conductors, said apparatus comprising:
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digital logic means utilizing complementary metal-oxide-semiconductor logic, including multiplexer means for selecting for output one of a plurality of on/off signals supplied by a controller, clock pulse generation means for deriving clock signals from an alternating-current supply, digital counting means for generating decoder addresses to drive said multiplexer means, register means coupled with said counting means and with the output of said multiplexer means, for holding successive blocks of control information, each block comprising a decoder address, an on/off signal, and leading and trailing delimiting zeros, and gating means actuated by said counting means and said clock pulse generation means, for serially gating successive blocks of control information from said register means; and coupling circuit means connected with said gating means, for selectively suppressing current flow in one direction through one of the conductors from said encoding apparatus, in accordance with the contents of the successive blocks of control information from said gating means. - View Dependent Claims (6, 7)
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8. A digital two-wire irrigation control system, comprising:
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an encoder, including decoder address generation means, means for selecting on/off signals for transmission with decoder addresses, and means for encoding decoder addresses and on/off control signals onto an alternating-current power signal by selectively suppressing excursions of the power signal in one direction; a pair of conductors for transmission of the power signal, encoded with decoder addresses and on/off control signals, from said encoder; and at least one decoder connected to said pair of conductors and including rectifier means for generating a direct-current signal from the power signal, and for generating a data stream derived from excursions of the power signal in the one direction, electronic switch means for connecting the direct-current signal from said rectifier means to at least one valve solenoid, means for identifying said decoder, and digital logic means utilizing complementary metal-oxide-semiconductor logic for deriving the encoded decoder addresses and control signals from said data stream, and for operating said electronic switch means in accordance with those of said control signals accompanied by a decoder address equivalent to said means for identifying said decoder. - View Dependent Claims (9, 10, 11, 12)
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Specification