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Expired Canadian patentCanada

Data compression method and apparatus

CA 1232357 A · Owner: Digital Recording Research Limited Partnership · Inventors: Leblanc, Robert A.; Weaver, Charles S.; Sweeney, Lawrence E. Jr.

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Abstract From the Canadian patent

A music data compression system is disclosed which includes an analog to digital converter for converting the analog music signal to digital sample signal form, a digital compression filter for compression filtering the digital sample signals, and an encoder for truncated Huffman encoding the compression filter output. An entropy setting unit is included in the system for step control of the signal supplied to the digital compression filter in accordance with one or more threshold levels of the envelope of the music signal, and for reducing the entropy of the signal with increases in the energy level of the music signal. Different codes may be implemented in accordance with 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 February 2, 1988. A Canadian patent filed before October 1, 1989 lasted 17 years from grant, so its term ended February 2, 2005.
  • We check Canadian rights only. A patent in its family in another country could still be in force: check its family on Google Patents.
FiledMay 30, 1984
GrantedFebruary 2, 1988
Term endedFebruary 2, 2005
Patent numberCA 1232357 A
Classification (IPC)H04B1/66 +2 more

Timeline

Timeline From CIPO dates

1985198819911994199720002003Application filedMay 30, 1984Patent grantedFeb 2, 1988Term endedFeb 2, 2005

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