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Expired Canadian patentCanada

Methods and apparatus for providing reciprocal impedance conversion

CA 1295381 C · Owner: Chambers, Charles W. · Inventors: Chambers, Charles W.

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Abstract From the Canadian patent

A reciprocal impedance conversion network is disclosed. Such conversion network preferably is used in a reciprocal negative impedance repeater for the nonloaded cable facilities of a telephone system. Two independent voltage sources for generating reciprocal negative impedance are connected between a first port and a second port. The first port is operably connected to the first voltage source such that a series negative impedance appears at that port. This port is specifically connected to the switching equipment of the telephone system. The second port is operably connected to the second voltage source such that a shunt negative impedance appears at that port. The second port is …

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Listed from its CIPO record in Patent Yard's archive of Canadian patents past their term. Its claims, description and drawings are in the CIPO record and on Google Patents, and the Claude kit works from them.

Why it's free to use

  • Granted February 4, 1992. A Canadian patent filed before October 1, 1989 lasted 17 years from grant, so its term ended February 4, 2009.
  • We check Canadian rights only. A patent in its family in another country could still be in force: check its family on Google Patents.
FiledNovember 1, 1988
GrantedFebruary 4, 1992
Term endedFebruary 4, 2009
Patent numberCA 1295381 C
Classification (IPC)H04B3/04 +2 more

Timeline

Timeline From CIPO dates

1989199219951998200120042007Application filedNov 1, 1988Patent grantedFeb 4, 1992Term endedFeb 4, 2009

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Everything on this page comes from the CIPO record linked above. Contains information licensed under the Open Government Licence – Canada.