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Multiplexing system line fault isolation and identification

  • US 4,209,666 A
  • Filed: 10/03/1978
  • Issued: 06/24/1980
  • Est. Priority Date: 10/03/1978
  • Status: Expired due to Term
First Claim
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1. A multiplexing system for two-way data transmission over a single transmission line between a control station and a plurality of remote transponder units, the control station including transmitter-receiver means for selectively addressing the transponder units and receiving response signals therefrom, wherein the transmission line is configured as a loop terminating at each end at the control station, the transmitter-receiving means being coupled to respective ends of the transmission line for transmitting address signals to the transponder units and receiving response signals therefrom, the transmission line thereby furnishing two communication paths between the control station and each transponder unit, said transmitter-receiver means including means for differentiating between response signals received via the two ends of the line, and the transponder units being distributed along the transmission line and connected thereto by respective line connection circuits each comprising:

  • a two-state impedance device having high and low impedance states, the devices of the respective units being serially interconnected in said line,respective output means connected to the line on opposite sides of the impedance device for transmitting said response signals via the two communication paths,respective input means connected to the line on opposite sides of the impedance device for receiving address signals transmitted via the two communication paths, andlogic circuit means coupled to said input means and operable in response to address signals received by both input means to switch said impedance device from a high to a low impedance state.

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