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Expired Canadian patentCanada

Modem communication system having main and secondary channels

CA 1297599 C · Owner: Haagh, Johannes P.N. · Inventors: Kamerman, Adriaan; Haagh, Johannes P.N.

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Abstract From the Canadian patent

Abstract of the Disclosure, A data modem communication system includes a data modem transmitter adapted to transmit data on a main channel at a relatively high bit rate and to transmit data at a relatively low bit rate on a secondary channel. At the receiver, a single analogto-digital converter (54) supplies digital signals via a notch filter (58) to the main channel receiver (60) and to the secondary channel receiver (62) wherein a single IIR low-pass digital filter (110) is utilized for processing at three different sample rates to eliminate the main channel signal with frequency conversion taking place between processing at the first and second sample rates. The invention enables the …

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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 March 17, 1992. A Canadian patent filed before October 1, 1989 lasted 17 years from grant, so its term ended March 17, 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.
FiledSeptember 9, 1988
GrantedMarch 17, 1992
Term endedMarch 17, 2009
Patent numberCA 1297599 C
Classification (IPC)H04L27/00 +2 more

Timeline

Timeline From CIPO dates

1989199219951998200120042007Application filedSep 9, 1988Patent grantedMarch 17, 1992Term endedMarch 17, 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.