EP0693747A2 - Anordnung zur Schwingungsunterdrückung - Google Patents

Anordnung zur Schwingungsunterdrückung Download PDF

Info

Publication number
EP0693747A2
EP0693747A2 EP95304332A EP95304332A EP0693747A2 EP 0693747 A2 EP0693747 A2 EP 0693747A2 EP 95304332 A EP95304332 A EP 95304332A EP 95304332 A EP95304332 A EP 95304332A EP 0693747 A2 EP0693747 A2 EP 0693747A2
Authority
EP
European Patent Office
Prior art keywords
updates
frequency components
vibrations
filter
reference signal
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
EP95304332A
Other languages
English (en)
French (fr)
Other versions
EP0693747A3 (de
Inventor
Malcolm Alexander Swinbanks
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
BAE Systems Electronics Ltd
Original Assignee
GEC Marconi Ltd
Marconi Co Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from GB9414484A external-priority patent/GB9414484D0/en
Application filed by GEC Marconi Ltd, Marconi Co Ltd filed Critical GEC Marconi Ltd
Publication of EP0693747A2 publication Critical patent/EP0693747A2/de
Publication of EP0693747A3 publication Critical patent/EP0693747A3/de
Ceased legal-status Critical Current

Links

Images

Classifications

    • G—PHYSICS
    • G10—MUSICAL INSTRUMENTS; ACOUSTICS
    • G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
    • G10K11/00—Methods or devices for transmitting, conducting or directing sound in general; Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
    • G10K11/16—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
    • G10K11/175—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general using interference effects; Masking sound
    • G10K11/178—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general using interference effects; Masking sound by electro-acoustically regenerating the original acoustic waves in anti-phase
    • G10K11/1781—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general using interference effects; Masking sound by electro-acoustically regenerating the original acoustic waves in anti-phase characterised by the analysis of input or output signals, e.g. frequency range, modes, transfer functions
    • G10K11/17813—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general using interference effects; Masking sound by electro-acoustically regenerating the original acoustic waves in anti-phase characterised by the analysis of input or output signals, e.g. frequency range, modes, transfer functions characterised by the analysis of the acoustic paths, e.g. estimating, calibrating or testing of transfer functions or cross-terms
    • G10K11/17817—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general using interference effects; Masking sound by electro-acoustically regenerating the original acoustic waves in anti-phase characterised by the analysis of input or output signals, e.g. frequency range, modes, transfer functions characterised by the analysis of the acoustic paths, e.g. estimating, calibrating or testing of transfer functions or cross-terms between the output signals and the error signals, i.e. secondary path
    • G—PHYSICS
    • G10—MUSICAL INSTRUMENTS; ACOUSTICS
    • G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
    • G10K11/00—Methods or devices for transmitting, conducting or directing sound in general; Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
    • G10K11/16—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
    • G10K11/175—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general using interference effects; Masking sound
    • G10K11/178—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general using interference effects; Masking sound by electro-acoustically regenerating the original acoustic waves in anti-phase
    • G10K11/1785—Methods, e.g. algorithms; Devices
    • G10K11/17853—Methods, e.g. algorithms; Devices of the filter
    • G10K11/17854—Methods, e.g. algorithms; Devices of the filter the filter being an adaptive filter
    • G—PHYSICS
    • G10—MUSICAL INSTRUMENTS; ACOUSTICS
    • G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
    • G10K11/00—Methods or devices for transmitting, conducting or directing sound in general; Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
    • G10K11/16—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
    • G10K11/175—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general using interference effects; Masking sound
    • G10K11/178—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general using interference effects; Masking sound by electro-acoustically regenerating the original acoustic waves in anti-phase
    • G10K11/1785—Methods, e.g. algorithms; Devices
    • G10K11/17857—Geometric disposition, e.g. placement of microphones
    • G—PHYSICS
    • G10—MUSICAL INSTRUMENTS; ACOUSTICS
    • G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
    • G10K11/00—Methods or devices for transmitting, conducting or directing sound in general; Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
    • G10K11/16—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
    • G10K11/175—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general using interference effects; Masking sound
    • G10K11/178—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general using interference effects; Masking sound by electro-acoustically regenerating the original acoustic waves in anti-phase
    • G10K11/1787—General system configurations
    • G10K11/17879—General system configurations using both a reference signal and an error signal
    • G10K11/17881—General system configurations using both a reference signal and an error signal the reference signal being an acoustic signal, e.g. recorded with a microphone
    • G—PHYSICS
    • G10—MUSICAL INSTRUMENTS; ACOUSTICS
    • G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
    • G10K11/00—Methods or devices for transmitting, conducting or directing sound in general; Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
    • G10K11/16—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
    • G10K11/175—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general using interference effects; Masking sound
    • G10K11/178—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general using interference effects; Masking sound by electro-acoustically regenerating the original acoustic waves in anti-phase
    • G10K11/1787—General system configurations
    • G10K11/17879—General system configurations using both a reference signal and an error signal
    • G10K11/17883—General system configurations using both a reference signal and an error signal the reference signal being derived from a machine operating condition, e.g. engine RPM or vehicle speed
    • G—PHYSICS
    • G10—MUSICAL INSTRUMENTS; ACOUSTICS
    • G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
    • G10K2210/00—Details of active noise control [ANC] covered by G10K11/178 but not provided for in any of its subgroups
    • G10K2210/10—Applications
    • G10K2210/128—Vehicles
    • G10K2210/1281—Aircraft, e.g. spacecraft, airplane or helicopter
    • G—PHYSICS
    • G10—MUSICAL INSTRUMENTS; ACOUSTICS
    • G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
    • G10K2210/00—Details of active noise control [ANC] covered by G10K11/178 but not provided for in any of its subgroups
    • G10K2210/30—Means
    • G10K2210/301—Computational
    • G10K2210/3018—Correlators, e.g. convolvers or coherence calculators
    • G—PHYSICS
    • G10—MUSICAL INSTRUMENTS; ACOUSTICS
    • G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
    • G10K2210/00—Details of active noise control [ANC] covered by G10K11/178 but not provided for in any of its subgroups
    • G10K2210/30—Means
    • G10K2210/301—Computational
    • G10K2210/3025—Determination of spectrum characteristics, e.g. FFT
    • G—PHYSICS
    • G10—MUSICAL INSTRUMENTS; ACOUSTICS
    • G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
    • G10K2210/00—Details of active noise control [ANC] covered by G10K11/178 but not provided for in any of its subgroups
    • G10K2210/30—Means
    • G10K2210/301—Computational
    • G10K2210/3042—Parallel processing
    • G—PHYSICS
    • G10—MUSICAL INSTRUMENTS; ACOUSTICS
    • G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
    • G10K2210/00—Details of active noise control [ANC] covered by G10K11/178 but not provided for in any of its subgroups
    • G10K2210/30—Means
    • G10K2210/301—Computational
    • G10K2210/3045—Multiple acoustic inputs, single acoustic output
    • G—PHYSICS
    • G10—MUSICAL INSTRUMENTS; ACOUSTICS
    • G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
    • G10K2210/00—Details of active noise control [ANC] covered by G10K11/178 but not provided for in any of its subgroups
    • G10K2210/30—Means
    • G10K2210/301—Computational
    • G10K2210/3051—Sampling, e.g. variable rate, synchronous, decimated or interpolated

Definitions

  • This invention relates to an apparatus for cancelling vibrations, be they vibrations in a gas, liquid or solid.
  • GB-2054999-A, EP-43565-A1, and GB-2107960-A disclose examples of apparatus for cancelling vibrations which employ frequency domain filtering.
  • the vibrations to be cancelled must be periodic and the resolving into the frequency components synchronised to this periodicity, or, in the case where the vibrations are random (aperiodic), the resolving into the frequency components must be a continuously updated process.
  • an apparatus for cancelling vibrations comprising: means for providing a reference signal representative of the vibrations to be cancelled; filter means comprising means for resolving the reference signal into its frequency components, means for applying weights to these frequency components, and means for combining the weighted frequency components to provide an output signal of said filter means; and actuator means responsive to said output signal to produce vibrations which destructively interfere with the vibrations to be cancelled, said means for resolving utilising N updates of said reference signal to resolve it into its frequency components, said means for resolving being updated by n times between successive resolutions of the reference signal into its frequency components where 1 ⁇ n ⁇ N, there being a correlation between the weights applied by said means for applying so as to reduce discontinuity in the operation of said filter means.
  • the invention arose in the making of an apparatus for cancelling vibrations employing frequency domain filtering. It was decided that block processing be used by the frequency domain filter to improve the processing efficiency of the apparatus, i.e. the filter would take a block of data, rather than just one sample, and process it all in one go to provide a number of sequential outputs. First trials of the apparatus were not successful, since it was found that in two cases the filter outputs were discontinuous, the first case being where the vibrations to be cancelled are periodic and the resolving into the frequency components not synchronised to this periodicity, the second case being where the vibrations are random. Even when attempting to cancel a pure tone not synchronised, in addition to the production of the cancelling tone, unwanted side bands were produced.
  • the apparatus is for cancelling engine noise in an aircraft cabin.
  • the apparatus includes a loudspeaker 1 located in the region of the aircraft cabin where it is desired that the noise produced by an engine 3 be cancelled.
  • the loudspeaker 1 produces the aforementioned interfering anti-phase vibrations.
  • the apparatus further includes an adaptive control filter 5, a model filter 7, a controller 9, updates modifying circuitry 10, an arithmetic circuit 12, and an error microphone 11, which microphone 11 is located in the aforementioned region of the aircraft cabin.
  • Control filter 5 comprises a fast Fourier transform (FFT) circuit 13, a processor 15, and an inverse FFT circuit 17.
  • Controller 9 comprises an FFT circuit 19 and a processor 21.
  • Updates modifying circuitry 10 comprises an inverse FFT circuit 23, an arithmetic circuit 25, and an FFT circuit 27.
  • a reference signal x(t) representative of the noise to be cancelled at time t is supplied to control filter 5.
  • This signal may be obtained from a microphone located in the aforementioned region of the aircraft cabin, or by means of a tachometer from the aircraft engine 3 itself.
  • FFT circuit 13 Fourier transforms x(t) from the time domain to the frequency domain and provides to processor 15 a plurality of frequency components x t (f) of x(t). Processor 15 multiplies each x t (f) by an appropriate weight (see below). Let the resulting frequency components be y t (f). Processor 15 provides the y t (f) to inverse FFT circuit 17. Circuit 17 inverse Fourier transforms the y t (f) from the frequency domain to the time domain to provide to loudspeaker 1 an appropriate driving signal y(t) to cancel the noise.
  • the weights utilised by processor 15 perform amongst other things, a phase inversion of x(t) to provide the interfering anti-phase signal.
  • An explanation of the derivation of the weights utilised by processor 15 will now be given.
  • Error microphone 11 detects any residual noise remaining after interference between the primary noise produced by noise source 3 and the interfering sound produced by loudspeaker 1.
  • a signal e(t) representative of this residual noise passes from microphone 11 to FFT circuit 19 of controller 9 where it is Fourier transformed from the time domain to the frequency domain.
  • FFT circuit 19 provides to processor 21 a plurality of frequency components e t (f) of e(t).
  • each of these components also passes to model filter 7, where it is multiplied by a frequency dependent function C(f).
  • C(f) is the transfer function from loudspeaker 1 to microphone 11, and it is necessary that this function be involved in the derivation of the weights utilised by processor 15 to take account of the physical path from loudspeaker 1 to microphone 11 within the aircraft cabin.
  • microphone 11 is detecting the residual noise at a different physical location within the aforementioned cabin region to the physical location where loudspeaker 1 is attempting to eliminate this residual noise.
  • any attempt to eliminate the residual noise at one location by the generation of interfering sound at another different location must take into account the physical path travelled by the sound between the locations.
  • C(f) is a previously determined transfer function which describes the change which the physical path within the cabin from loudspeaker 1 to microphone 11 will have on the passage of sound therealong.
  • the frequency components x t (f).C(f) resulting after multiplication by C(f) pass to processor 21 of controller 9, where each is multiplied by a respective frequency component e t (f) from FFT circuit 19.
  • the resulting frequency components or provisional filter updates x t (f).C(f).e t (f) are supplied by processor 21 to updates modifying circuitry 10.
  • the actual filter updates (x t (f). C(f). e t (f))' are supplied to arithmetic circuit 12.
  • the weights utilised by filter 5 phase invert the reference representative of the noise, attempt to eliminate detected residual noise, and take into account the physical path from the actuator which produces the cancelling sound to the detector which detects residual noise.
  • filter 5 For correct operation of the apparatus, the operation of filter 5 must take account of filter settling time, otherwise discontinuous filter outputs result.
  • each FFT performed by circuit 13 of filter 5 is performed on 128 samples of reference signal x(t).
  • 64 complex frequency components x t (f) of x(t) are presented to processor 15 where each is multiplied by its respective weight w t (f).
  • the resulting 64 complex frequency components y t (f) are passed to inverse FFT circuit 17 where they are inverse transformed to 128 'samples' of y(t).
  • the number of samples of x(t) by which FFT circuit 13 is updated between the performance of successive FFTs be 32.
  • samples of x(t) are taken by filter 5 and 32 samples of y(t) are provided by filter 5.
  • the aforementioned provisional updates x t (f). C(f). e t (f) are passed by processor 21 to inverse FFT circuit 23 of updates modifying circuitry 10, where they are inverse Fourier transformed from the frequency domain to the time domain to provide to arithmetic circuit 25 the equivalent 128 time domain updates.
  • Arithmetic circuit 25 sets to zero the last 31 (128 - 97) of these 128 updates so as to effectively leave 97 updates for a 97 weight filter. Note, it is the last 31 updates that are set to zero since it is the 97th (mth) data output that is the first accurate data output, see above.
  • N-m or N-(N-n+1) (taking the limit where the least updates are set to zero giving the greatest flexibility for filter 5) or n-1 updates are set to zero.
  • the resulting updates are passed to FFT circuit 27 where they are Fourier transformed from the time domain to the frequency domain to provide to arithmetic circuit 12 the actual constrained frequency domain updates (x t (f). C(f). e t (f))'.
  • Circuit 12 calculates the new constrained weights according to equation (1).
  • the FFT process effectively assumes periodic behaviour, i.e. it fits a set of periodic functions to the data samples on the assumption that the data is periodic outside the N sample block.
  • the FFT process will always be accurate without the need to observe the m ⁇ N-n+1 constraint. Therefore, when the vibrations to be cancelled are periodic, and the resolving of the reference signal representative of these vibrations into its frequency components is synchronised to this periodicity, then constraint for successful operation is not required. In all other circumstances, i.e.
  • n is greater than 1 and constraint for correct operation is required (unless the data is periodic and synchronised).
  • n may be chosen from the upper end of the range, i.e. the end approaching N, with a consequent benefit in processing efficiency.
  • the disadvantage is that the corresponding convolution window involves complex, asymmetric coefficients.
  • the advantage would be that the corresponding convolution window is symmetric, and a simple 5-point convolution would suffice.
  • the resolving of the reference signal into its frequency components need not be by means of Fourier transformation, for example frequency sampling filtering could be used.

Landscapes

  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Acoustics & Sound (AREA)
  • Multimedia (AREA)
  • Soundproofing, Sound Blocking, And Sound Damping (AREA)
  • Vibration Prevention Devices (AREA)
EP95304332A 1994-07-18 1995-06-21 Anordnung zur Schwingungsunterdrückung Ceased EP0693747A3 (de)

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
GB9414484A GB9414484D0 (en) 1994-07-18 1994-07-18 An apparatus for cancelling vibrations
GB9414484 1994-07-18
GB9415763A GB2291559B (en) 1994-07-18 1994-08-04 An apparatus for cancelling vibrations
GB9415763 1994-08-04

Publications (2)

Publication Number Publication Date
EP0693747A2 true EP0693747A2 (de) 1996-01-24
EP0693747A3 EP0693747A3 (de) 1997-12-29

Family

ID=26305292

Family Applications (1)

Application Number Title Priority Date Filing Date
EP95304332A Ceased EP0693747A3 (de) 1994-07-18 1995-06-21 Anordnung zur Schwingungsunterdrückung

Country Status (3)

Country Link
EP (1) EP0693747A3 (de)
JP (1) JPH0883086A (de)
CA (1) CA2154027A1 (de)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN112066909A (zh) * 2020-08-24 2020-12-11 南京理工大学 一种基于倾斜平面高精度提取的抗振动干涉测量方法

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2054999A (en) 1979-06-28 1981-02-18 Nat Res Dev Signal Processing Systems
EP0043565A1 (de) 1980-07-03 1982-01-13 Hitachi, Ltd. Vorrichtung zur Vibrations- und/oder Lärmreduktion für elektrische Geräte
GB2107960A (en) 1981-10-21 1983-05-05 George Brian Barrie Chaplin Method and apparatus for cancelling vibrations

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1988003341A1 (en) * 1986-10-30 1988-05-05 Fujitsu Limited Echo canceller with short processing delay and decreased multiplication number
GB8801014D0 (en) * 1988-01-18 1988-02-17 British Telecomm Noise reduction
US5233540A (en) * 1990-08-30 1993-08-03 The Boeing Company Method and apparatus for actively reducing repetitive vibrations
US5309378A (en) * 1991-11-18 1994-05-03 Hughes Aircraft Company Multi-channel adaptive canceler
GB9222103D0 (en) * 1992-10-21 1992-12-02 Lotus Car Adaptive control system

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2054999A (en) 1979-06-28 1981-02-18 Nat Res Dev Signal Processing Systems
EP0043565A1 (de) 1980-07-03 1982-01-13 Hitachi, Ltd. Vorrichtung zur Vibrations- und/oder Lärmreduktion für elektrische Geräte
GB2107960A (en) 1981-10-21 1983-05-05 George Brian Barrie Chaplin Method and apparatus for cancelling vibrations

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN112066909A (zh) * 2020-08-24 2020-12-11 南京理工大学 一种基于倾斜平面高精度提取的抗振动干涉测量方法

Also Published As

Publication number Publication date
CA2154027A1 (en) 1996-01-19
JPH0883086A (ja) 1996-03-26
EP0693747A3 (de) 1997-12-29

Similar Documents

Publication Publication Date Title
US5838802A (en) Apparatus for cancelling vibrations
JP2889114B2 (ja) 能動雑音消去装置
KR950005181B1 (ko) 적응형 능동소음장치
US4490841A (en) Method and apparatus for cancelling vibrations
EP0724415B1 (de) Ein- und mehrkanalige blockadaptive verfahren zur schall- und schwingungsregelung und vorrichtungen dafür
US5365594A (en) Active sound and/or vibration control
Kuo et al. Frequency-domain delayless active sound quality control algorithm
KR0164236B1 (ko) 비정수 표본 지연 활성 잡음 소거기
WO1994024970A9 (en) Single and multiple channel block adaptive methods and apparatus for active sound and vibration control
CN105679304B (zh) 用于宽带主动噪声控制系统的可变带宽无延迟子带算法
GB2149614A (en) Active noise reduction apparatus
CN110718205B (zh) 一种无次级路径有源噪声控制系统及实现方法
Kuo et al. Frequency-domain periodic active noise control and equalization
JPH05501488A (ja) 配線内選択消去システム
DE69513849T2 (de) Reduzierung der berechnungslast bei der adaptiven aktualisierung von steuerungsfiltern in aktiven systemen
Pauline et al. Variable-stage cascaded adaptive filter technique for signal de-noising application
GB2107960A (en) Method and apparatus for cancelling vibrations
EP0693747A2 (de) Anordnung zur Schwingungsunterdrückung
JP3646809B2 (ja) 時間領域適応制御システム
EP0805432A2 (de) Rückkopplungsverfahren zur Kontrolle des Rauschens mit mehreren Eingängen und Ausgängen
JPH0651787A (ja) 能動型消音装置
EP0694234B1 (de) System zur reduktion von periodischen störungen
JPH05313672A (ja) 騒音制御装置
JPH0973295A (ja) 能動制御装置
DE69231855T2 (de) Preisgünstiger regler

Legal Events

Date Code Title Description
PUAI Public reference made under article 153(3) epc to a published international application that has entered the european phase

Free format text: ORIGINAL CODE: 0009012

AK Designated contracting states

Kind code of ref document: A2

Designated state(s): DE ES FR GB IT NL SE

PUAL Search report despatched

Free format text: ORIGINAL CODE: 0009013

AK Designated contracting states

Kind code of ref document: A3

Designated state(s): DE ES FR GB IT NL SE

17P Request for examination filed

Effective date: 19980625

RAP1 Party data changed (applicant data changed or rights of an application transferred)

Owner name: BAE SYSTEMS ELECTRONICS LTD.

GRAG Despatch of communication of intention to grant

Free format text: ORIGINAL CODE: EPIDOS AGRA

17Q First examination report despatched

Effective date: 20020128

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: THE APPLICATION HAS BEEN REFUSED

18R Application refused

Effective date: 20020725