US5014232A
Expired / Lapsed
US
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Adaptive digital filter having non-recursive and recursive filter elements
Assignee: Telefonaktiebolaget LM Ericsson AB
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Filing: 1989-04-07
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Granted: 1991-05-07
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Expires: 2009-04-07
Abstract
Abstract An adaptive digital filter including a non-recursive part and a recursive part, and which can be updated in a simple and reliable manner. The recursive part of the filter has a plurality of separate, permanently set recursive filters (13-16) with different impulse responses, and a linear combination is formed with adaptive weighting factors (W0-W3) from the output signals of the recursive filters (13-16). The filter is updated by a single (e(n)) being utilized for updating the non-recursive part (11) of the filter and the adaptive weighting factors (W0-W3) in the recursive part of the filter.
Inventors
- 👤 Tore M. Andre
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 13:57
CPC Classifications
H; H03; H03H; H03H21/00; H03H21/0012; H04; H04B; H04B3/00; H04B3/02; H04B3/20; H04B3/23; H04B3/237
Claims Analysis
Total Claims: 15
Claim 1
Independent Claim
136 words
An adaptive digital filter for filtering digital input signals, comprising: non-recursive filtering means for non-recursively filtering said input signals; recursive filtering means for recursively filtering said input signals, said recursive filtering means including: a plurality of preset recursive filters each recursive filter having a different impulse response characteristic; a plurality of multiplication means, associated with said plurality of recursive filters, for multiplying an output signal of each recursive filter by a corresponding adaptive multiplication factor; and summing means for forming a linear combination of output signals from said multiplication means; means for generating an update signal on the basis of an output signal from said summing means and an output from said non-recursive filtering means; and updating means for updating both said non-recursive filtering means and said adaptive multiplication factors in accordance with said update signal.
Claim 2
Dependent Claim
136 words
An adaptive digital filter for filtering digital input signals, comprising: non-recursive filtering means for non-recursively filtering said input signals; recursive filtering means for recursively filtering said input signals, said recursive filtering means including: a plurality of preset recursive filters each recursive filter having a different impulse response characteristic; a plurality of multiplication means, associated with said plurality of recursive filters, for multiplying an output signal of each recursive filter by a corresponding adaptive multiplication factor; and summing means for forming a linear combination of output signals from said multiplication means; means for generating an update signal on the basis of an output signal from said summing means and an output from said non-recursive filtering means; and updating means for updating both said non-recursive filtering means and said adaptive multiplication factors in accordance with said update signal.
Claim 3
Dependent Claim
16 words
The adaptive filter according to claim 1, wherein said recursive filters are of the first degree.
Claim 4
Dependent Claim
31 words
The adaptive filter according to claim 2, further comprising: delay means connected to said input signal, for delaying said input signal to said recursive filtering means for a predetermined delay period.
Claim 5
Dependent Claim
36 words
The adaptive filter according to claim 1, further comprising: combining means for linearly combining output signals from said recursive filters and transmitting linear combinations of said recursive filter output signals to said plurality of multiplication means.
Claim 6
Dependent Claim
81 words
An adaptive digital filter for filtering a digital input signal, comprising: non-recursive filtering means for non-recursively filtering said input signal; recursive filtering means for recursively filtering said input signal; summing means for summing output signals from said non-recursive filtering means and said recursive filtering means; error generating means for calculating a difference between an output signal from said summing means and a reference signal; adjusting means for adjusting said non-recursive filtering means and said recursive filtering means based on said difference.
Claim 7
Dependent Claim
81 words
An adaptive digital filter for filtering a digital input signal, comprising: non-recursive filtering means for non-recursively filtering said input signal; recursive filtering means for recursively filtering said input signal; summing means for summing output signals from said non-recursive filtering means and said recursive filtering means; error generating means for calculating a difference between an output signal from said summing means and a reference signal; adjusting means for adjusting said non-recursive filtering means and said recursive filtering means based on said difference.
Claim 8
Dependent Claim
50 words
The adaptive filter according to claim 5, wherein said non-recursive filtering means includes: a plurality of first delay means for generating a series of first delayed input signals; a plurality of weighting means for weighting said first delay inputs, wherein said adjusting means adjusts the value of each weighting means.
Claim 9
Dependent Claim
26 words
The adaptive digital filter according to claim 5, wherein said recursive filtering means includes plural recursive filters, each recursive filter having a preset impulse response characteristic.
Claim 10
Dependent Claim
84 words
The adaptive filter according to claim 7, wherein each recursive filter includes: summing means for summing said input signal and a feedback signal; second delay means for delaying an output signal of said summing means; multiplication means for multiplying an output signal of said second delay means by a preset constant and generating said feedback signal; and weighting means for weighting an output signal of said second delay means, said adjusting means adjusting the value of said weighting means in accordance with said difference.
Claim 11
Dependent Claim
38 words
The adaptive digital filter according to claim 8, further comprising: combining means for linearly combining the output signals of each of said weighting means to generate a linear combination of the infinite impulse responses of said recursive filters.
Claim 12
Dependent Claim
38 words
The adaptive digital filter according to claim 8, further comprising: combining means for linearly combining recursive output signals of said second delay means and transmitting linear combinations of said recursive output signal to said plurality of weighting means.
Claim 13
Dependent Claim
88 words
An adaptive digital filter for filtering a digital input signal, comprising: non-recursive filtering means having a finite impulse response for filtering said input signal; recursive filtering means having an infinite impulse response for filtering said input signal; summing means for summing output signals from said non-recursive filtering means and said recursive filtering means; differencing means for calculating a difference between an output signal from said summing means and a desired signal; adjusting means for adjusting said non-recursive filtering means and said recursive filtering means relative to said difference.
Claim 14
Dependent Claim
88 words
An adaptive digital filter for filtering a digital input signal, comprising: non-recursive filtering means having a finite impulse response for filtering said input signal; recursive filtering means having an infinite impulse response for filtering said input signal; summing means for summing output signals from said non-recursive filtering means and said recursive filtering means; differencing means for calculating a difference between an output signal from said summing means and a desired signal; adjusting means for adjusting said non-recursive filtering means and said recursive filtering means relative to said difference.
Claim 15
Dependent Claim
23 words
The adaptive digital filter according to claim 11, wherein said recursive filtering means includes a plurality of recursive filters of the first degree.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1994-05-06 | 1994-11-05 | 1995-05-07 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1998-05-06 | 1998-11-05 | 1999-05-07 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2002-05-06 | 2002-11-05 | 2003-05-07 | $7700.00 | Window Closed / Lapsed |