Patent US5511129A successfully refreshed from Google Patents.
US5511129A
Expired / Lapsed
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Compensating filters
Assignee: Individual
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Filing: 1991-12-11
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Granted: 1996-04-23
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Expires: 2011-12-11
Abstract
Abstract PCT No. PCT/GB91/02200 Sec. 371 Date Aug. 3, 1993 Sec. 102(e) Date Aug. 3, 1993 PCT Filed Dec. 11, 1991 PCT Pub. No. WO92/10876 PCT Pub. Date Jun. 25, 1992.A prefilter (5) for an audio system comprising a loudspeaker (1) in a room (2), which corrects both amplitude and phase errors due to the loudspeaker (1) by a linear phase correction filter response and corrects the amplitude response of the room (2) whilst introducing the minimum possible amount of extra phase distortion by employing a minimum phase correction filter stage. A test signal generator (8) generates a signal comprising a periodic frequency sweep with a greater phase repetition period than the frequency repetition period. A microphone (7) positioned at various points in the room (2) measures the audio signal processed by the room (2) and loudspeaker (1), and a coefficient calculator (6) (e.g. a digital signal processor device) derives the signal response of the room and thereby a requisite minimum phase correction to be cascaded with the linear phase correction already calculated for the loudspeaker (1). Filter (5) may comprise the same digital signal processor as the coefficient calculator (6). Applications in high fidelity audio reproduction, and in car stereo reproduction.
Inventors
- 👤 Peter G. Craven
- 👤 Michael A. Gerzon
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 15:24
CPC Classifications
H; H04; H04S; H04S7/00; H04S7/30; H04S7/307; H03; H03G; H03G5/00; H03G5/16; H03G5/165; H03H; H03H21/00; H03H21/0012; H04R; H04R3/00; H04R3/04; H04S7/305; H04R29/00; H04R29/001; H04S7/301; H04S7/40
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
151 words
A method of conditioning programmable filter apparatus (5) to filter a signal supplied to an acoustic transducer (1) located in an acoustic environment (2), comprising supplying, for storage in the apparatus, filter parameters derived by a method which comprises the steps of: (a) deriving first data relating to a transducer compensation signal response (F L -1 ) which, in combination with the signal response (F L ) of the transducer (1), substantially reduces the deviation of the transducer signal response (F L ) from uniformity; (b) deriving second data relating to an acoustic environment compensation signal response (F R -1 ) which, in combination with the signal response of the acoustic environment (2) over a path therethrough to a predetermined position therein, substantially reduces the deviation of the acoustic environment signal response (F R ) from uniformity; and (c) deriving subsequently said filter parameters from said first and said second data.
Claim 2
Independent Claim
151 words
A method of conditioning programmable filter apparatus (5) to filter a signal supplied to an acoustic transducer (1) located in an acoustic environment (2), comprising supplying, for storage in the apparatus, filter parameters derived by a method which comprises the steps of: (a) deriving first data relating to a transducer compensation signal response (F L -1 ) which, in combination with the signal response (F L ) of the transducer (1), substantially reduces the deviation of the transducer signal response (F L ) from uniformity; (b) deriving second data relating to an acoustic environment compensation signal response (F R -1 ) which, in combination with the signal response of the acoustic environment (2) over a path therethrough to a predetermined position therein, substantially reduces the deviation of the acoustic environment signal response (F R ) from uniformity; and (c) deriving subsequently said filter parameters from said first and said second data.
Claim 3
Dependent Claim
42 words
A method according to claim 1, in which the transducer compensation response (F L -1 ) is derived so that its effect, in combination with the transducer response (F L ) is such as to provide a substantially constant signal group delay.
Claim 4
Dependent Claim
68 words
A method according to claim 1, in which the transducer compensation response (F L -1 ) is derived so that its effect, when in combination with the transducer response (F L ), is such as to compensate phase distortions in the transducer response which are substantially independent of position or direction relative to the transducer (1), whilst leaving substantially uncompensated those phase distortions which are substantially dependent thereon.
Claim 5
Dependent Claim
77 words
A method according to claim 1, in which the acoustic environment compensation response (F R -1 ) is derived by the steps of: generating an acoustic signal within said environment (2) via a transducer (1) for which the transducer compensation response (F L -1 ) is derived to compensate; measuring the said signal at a place (3) in the environment (2); and processing the measured signal to derive the response (F R ) of the acoustic environment.
Claim 6
Dependent Claim
29 words
A method according to claim 4, in which the signal processing is responsive to, and is to take account of, data relating to the transducer response (F L ).
Claim 7
Dependent Claim
56 words
A method according to claim 1 including the step of generating spectral data relating to the signal response (F R ) of the acoustic environment, and processing said data to generate second data such that said acoustic environment compensation signal response includes substantially less long lasting resonance than the inverse of the acoustic environment signal response.
Claim 8
Dependent Claim
24 words
A method according to claim 6, in which the effect of said processing is greater at frequencies above a predetermined threshold (f LOW ).
Claim 9
Dependent Claim
33 words
A method according to claim 6 in which the effect of said processing is greater at frequencies below a predetermined threshold (f HIGH ) which is within a frequency range of said filter.
Claim 10
Dependent Claim
32 words
A method according to claim 6 in which said processing comprises a step of adjusting the amplitude of spectral coefficients of a magnitude which would give rise to a long lasting resonance.
Claim 11
Dependent Claim
27 words
A method according to claim 6 in which processing comprises a step of smoothing said data by processing each spectral datum in accordance with spectrally neighbouring data.
Claim 12
Dependent Claim
7 words
A filter conditioned according to claim 1.
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| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
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| 3.5 Years (Year 4) | 1999-04-23 | 1999-10-23 | 2000-04-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2003-04-23 | 2003-10-23 | 2004-04-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2007-04-23 | 2007-10-23 | 2008-04-23 | $7700.00 | Window Closed / Lapsed |