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Expired Canadian patentCanada

Frequency-domain block-adaptive digital filter

CA 1266893 C · Owner: Claasen, Theodoor A.C.M. · Inventors: Sommen, Petrus C.W.; Van Gerwen, Petrus J.; Claasen, Theodoor A.C.M.

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Abstract From the Canadian patent

Frequency-domain block-adaptive digital filter". A frequency-domain block-adaptive digital filter (FDAF) having a finite impulse response of length N for filtering a time-domain input signal in accordance with the overlap-save method includes window means (11) for obtaining modifications (B(p;m)) of the 2N frequencydomain weighting factors (W(p;m)) from correlation products (A(p;m)). A known FDAF of this type contains five 2N-point FFT's, two of which are used in the window means (11). By utilizing a special time-domain window function which can be implemented very efficiently in the window means (11) with the aid of a frequency-domain convolution, a FDAF of this type containing only three …

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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 20, 1990. A Canadian patent filed before October 1, 1989 lasted 17 years from grant, so its term ended March 20, 2007.
  • We check Canadian rights only. A patent in its family in another country could still be in force: check its family on Google Patents.
FiledJune 18, 1987
GrantedMarch 20, 1990
Term endedMarch 20, 2007
Patent numberCA 1266893 C
Classification (IPC)H03H21/00

Timeline

Timeline From CIPO dates

1988199019921994199619982000200220042006Application filedJune 18, 1987Patent grantedMarch 20, 1990Term endedMarch 20, 2007

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