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Power line carrier multi telephone extension system for full duplex conferencing and intercom between telephones

  • US 4,523,307 A
  • Filed: 11/30/1982
  • Issued: 06/11/1985
  • Est. Priority Date: 11/30/1982
  • Status: Expired due to Term
First Claim
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1. A power line RF carrier telephone extension system for signalling between (1) a telephone subscriber'"'"'s telephone line of a conventional telephone communication system wherein a separate telephone line is provided from a central switching system at one location to each subscriber at the subscriber'"'"'s location and each subscriber'"'"'s telephone line includes at least two wires, the ring line and the tip line and, (2) two or more of the subscriber'"'"'s extension telephones by RF carrier over the available power line at the subscriber'"'"'s location, including at the subscriber'"'"'s location or premises:

  • a subscriber main (M) station near said subscriber telephone line and having access to said power line and two or more (up to N) subscriber extension stations (E1, E2 --En--EN), each having access to said power line, comprising,(a) at the M station;

    (a1) detector means connected to the telephone line for detecting audio frequency signals on the telephone line, said detected signals referred to herein as TL signals,(a2) a transmitter for producing a main carrier frequency signal, Fm, and including modulating means in said transmitter modulating said Fm signal,(a3) N receivers, one for each of the En stations, each receiver for receiving a different one of the En stations transmitted RF carrier frequency signals, F1, F2 --Fn--FN, and said receiver including an Fn demodulator, for re-producing modulations of Fn at the output of the receivers,(a4) first combining means for combining the outputs of said N receivers to produce a combined receiver output signal referred to herein as MRXN,(a5) second combining means for combining the TL signals and MRXN signals and coupling the combined signals to the input of said transmitter, said transmitter input being referred to herein as MTX, and(a6) coupling means for coupling the transmitter output to the power line, and(a7) mode command means for producing an intercom mode command signal, herein referred to as the I signal, and wherein the second combining means comprises a multi-port hybrid network, referred to herein as the hydrid which is controlled by said I signal;

    (a8) whereby, said MRXN and TL signals are combined by said hybrid and the combination is coupled to the input MTX of the transmitter and MRXN is coupled to the telephone line or the MRXN and TL signals are not so combined and MRXN is not coupled to the telephone line, depending upon the occurrence of said I signals;

    whereby the power line carries the modulated Fm to the N E stations; and

    (b) at each E station, denoted generally as En;

    (b1) an En telephone,(b2) a source of power for the En telephone,(b3) said En telephone including means for producing audio and dial signals when it is used by the subscriber,(b4) an En receiver for receiving the modulated Fm from the power line, said En receiver including an Fm demodulator for re-producing the modulations of Fm in the output thereof, said output referred to herein as EnRX(b5) means for coupling the received modulated Fm from the power line to the input of the receiver, and(b6) means for coupling said EnRX from said En receiver to the En telephone,whereby the En telephone receives the TL and MRXN signals,(b7) an En transmitter including means for producing an En telephone carrier frequency signal, Fn, and modulating means in said En transmitter for modulating said Fn signal by the En telephone audio signals from the En telephone and signals representative of the En dial signals from the En telephone to produce a modulated Fn signal and(b8) means for coupling the modulated Fn signal to the power line,whereby the power line carries the modulated Fn to the main station and telephone calls from the telephone line can be answered by any of the E1, E2 --En--EN telephones and any or all of the E1, E2 --En--EN telephones can conference on a telephone line call.

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