EP1800400A1 - Method for stabilizing an adaptive algorithm and device for carrying out said method - Google Patents
Method for stabilizing an adaptive algorithm and device for carrying out said methodInfo
- Publication number
- EP1800400A1 EP1800400A1 EP05788936A EP05788936A EP1800400A1 EP 1800400 A1 EP1800400 A1 EP 1800400A1 EP 05788936 A EP05788936 A EP 05788936A EP 05788936 A EP05788936 A EP 05788936A EP 1800400 A1 EP1800400 A1 EP 1800400A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- signal
- output signal
- input
- error
- estimated output
- 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.)
- Withdrawn
Links
Classifications
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
- H03H21/00—Adaptive networks
- H03H21/0012—Digital adaptive filters
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
- H03H21/00—Adaptive networks
- H03H21/0012—Digital adaptive filters
- H03H2021/0085—Applications
- H03H2021/0089—System identification, i.e. modeling
Definitions
- the present invention relates to a method for stabilizing an adaptive algorithm according to the preamble of claim 1, an application of the method, a device for carrying out the method and a use of the device.
- Noise sources are increasingly perceived as an environmental impact and are considered to reduce the quality of life.
- noise reduction methods based on the principle of wave cancellation have already been proposed.
- ANC Active Noise Canceling
- the principle of Active Noise Canceling is based on the cancellation of sound waves due to interference. These interferences are generated by one or more electro-acoustic transducers, such as loudspeakers.
- the signal radiated by the electro-acoustic transducers is calculated by means of a suitable algorithm and continuously corrected.
- the basis for the calculation of the signal to be radiated by the electro-acoustic transducers is the information supplied by one or more sensors. These are on the one hand information about the nature of the signal to be minimized. For example, a microphone can be used for this purpose which detects the noise to be minimized. On the other hand, information about the remaining residual signal is needed. Again, microphones can be used.
- LMS Least Mean Square
- FxLMS FxLMS
- NLMS NLMS
- An algorithm for active noise reduction requires information from at least one sensor (for example a microphone), which determines the residual error - also referred to below as an error signal.
- another sensor is provided that provides information about the nature of the signal to be minimized.
- an adaptive noise reduction system requires one or more actuators (for example in the form of loudspeakers) to output the correction signal.
- the information from the sensors must be converted by an analog / digital converter into a suitable format. After being processed by the algorithm, the signal is reconverted from a digital to analogue converter and sent to the Actuators transmitted.
- the present invention is therefore based on the object of specifying a method for stabilizing an adaptive algorithm which does not have the above disadvantages.
- a method of stabilizing an adaptive algorithm by which an unknown transfer function having an input signal and an actual output signal is estimated the method being that a is generated using the input signal by means of an adaptive process such that an error signal is generated from the actual output signal and the estimated output signal and that the adaptive process due to the
- Error signal is improved.
- at least one of the following signal paths is interrupted or opened as a function of at least one condition:
- a method which is particularly suitable for stabilizing adaptive algorithms, since signals which can not be processed by the method according to the invention can be kept away from the adaptive process from the outset, making the system more stable and robust overall.
- Another embodiment of the present invention is that a predetermined signal level or a predetermined average signal power of one of the following signals is exceeded or exceeded: - input signal;
- Methods according to the invention are particularly suitable for improving the stability and robustness of all adaptive systems.
- the subject of the present invention is a device which comprises the following features:
- An adaptive processor unit for determining an estimated output signal, wherein the processor unit an input signal is applied, - means for determining an error signal from an actual output signal and the estimated output signal, wherein the error signal is supplied to the adaptive processor unit, and
- a switching unit in at least one of the following signal paths: a signal path carrying the error signal;
- a further embodiment variant comprises means for determining a level or an average power of a signal, wherein these means are operatively connected to at least one switching unit.
- the means for determining a level or an average power of a signal is operatively connected to the switching unit in the same signal path.
- a plurality of switching units can be activated simultaneously.
- the switching unit has an adjustable switching characteristic.
- the switching units are operatively connected to each other.
- the present invention is based on
- FIG. 2 is a simplified block diagram of the embodiment variant shown in FIG. 1, also in a schematic representation,
- Fig. 3 is a simplified block diagram of a switching unit used in Figs. 1 and 2 and
- FIG. 4 shows a signal curve for illustrating a possible mode of operation of a switching unit according to FIG. 3.
- Fig. 1 shows an embodiment of an inventive device for the reduction of noise. It is a so-called Adaptive Noise Canceller (ANC) system that eliminates or at least reduces a noise in a room R using the principle of signal cancellation.
- ANC Adaptive Noise Canceller
- Central unit of such an adaptive noise reduction system is an adaptive
- Processor unit 3 which is operatively connected to an external microphone unit 1, wherein the addition "externally” indicates a arranged outside the space R microphone unit.
- an external microphone unit 1 wherein the addition "externally” indicates a arranged outside the space R microphone unit.
- two internal microphone units 5 and two loudspeaker units 7 are provided in the space R, all of which are operatively connected to the adaptive processor unit 3.
- a switching unit 2, 4, 6 is provided in each case between one of the microphone units 1, 5 and the adaptive processor unit 3 or respectively between one of the loudspeaker units 7 and the adaptive processor unit 3, which makes it possible to control the respective one Signal path to interrupt.
- a reduction signal is fed via the loudspeakers 7 into the room R, so that an interference signal passing through the walls or windows into the room R is deleted by signal cancellation or reduction in the room R. or reduced. So that this can be achieved successfully under changing conditions, an error signal is picked up with the aid of the microphone units 5 and fed back to the adaptive processor unit 3, so that in the adaptive processor unit 3 the calculations of the reduction signal can be improved and, as a consequence, optimum signal cancellation or signal reduction can be achieved.
- FIG. 1 shows a block diagram in a simplified equivalent circuit diagram of the embodiment variant of the invention according to FIG. 1.
- the signal paths can be interrupted, which is accomplished with the aid of switching units 2, 4, 6.
- a switching unit 2, 4, 6 in this case denotes a switch which is controlled by the size of a parameter.
- the size of the parameter corresponds, for example, to the average input power or the input level.
- the switching unit 2, which is connected between the microphone unit 1 and the adaptive processor unit 3, is used to interrupt the signal path to the adaptive processor unit 3 as soon as, for example, the noise recorded with the microphone unit 1 is below a predetermined one
- the adaptive processor unit 3 no longer receives any noise as a consequence of the signal path interruption, as a result of which the adaptive processor unit 3 no longer outputs a reduction signal to the loudspeaker unit 7.
- This configuration makes sense, for example, when a noise below a certain volume need not be actively minimized because the walls or windows already sufficiently attenuate the noise.
- Configurations make sense, for example, if the adaptive processor unit 3 should only work if a specific limit value in the space R is exceeded.
- a switching unit 2, 4, 6 functions like a switch whose state is determined by the input quantity. It is not important for the function of a switching unit 2, 4, 6 whether the input signal detects the level, the average power or another magnitude.
- Fig. 3 shows one of the switching units 2, 4, 6, the one
- Input signal 9 is acted upon.
- an output signal 10 is generated, resulting for example from the input / output waveform according to FIG. 4.
- an arbitrary characteristic curve can be provided, in particular based on the function of a so-called AGC (Automatic Gain Control) unit conceivable that the signal can also experience a gain or a weakening.
- AGC Automatic Gain Control
- Output signal 10 applied. From the course shown, the following can be derived: As soon as the input signal 9 of the switching unit 2, 4, 6 falls below a predetermined threshold value, the output signal 10 of the switching unit 2, 4, 6 is switched to zero, i. the signal path through the switching unit 2, 4, 6 is interrupted. The output signal 10 thus has no value when the input signal 9 is below the predetermined threshold. On the other hand, the output signal 10 corresponds to the input signal 9 when the input signal 9 exceeds the predetermined threshold.
- a further embodiment - as can also be seen from Fig. 4 - is that the
- Switching unit 2, 4, 6 has a control input 12. Via this control input 12, the switching unit 2, 4, 6 can be controlled, wherein a control signal is generated for example in the adaptive processor unit 3 or in another switching unit 2, 4, 6.
- the switching unit 2, 4, 6 has a control output 13, via which also other switching units 2, 4, 6 can be controlled. It is also conceivable the state of the switching unit 2, 4, 6 is transmitted via the control output 13 to the adaptive processor unit 3 or another arithmetic unit for further processing.
- the control output 13 and the control input 12 can also be used inverted.
- a switching unit 2, 4, 6 is then opened (i.e., the signal path through the switching unit 2, 4, ⁇ is not interrupted) when the signal path is interrupted by another switching unit 2, 4, 6. It is provided, for example, that the time it takes for the switching unit 2, 4, ⁇ after exceeding the predetermined threshold value interrupts the signal path, can be set. Likewise, the time required by the switching unit 2, 4, 6 to reopen the signal path after falling below the predetermined threshold value can be set. This has the advantage that thus the signal path through the switching unit 2, 4, 6 is not interrupted or opened before and after each zero crossing, whereby further instabilities of the overall system are prevented by the invention.
Landscapes
- Soundproofing, Sound Blocking, And Sound Damping (AREA)
Abstract
Description
Claims
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
CH16912004 | 2004-10-12 | ||
PCT/CH2005/000589 WO2006039826A1 (en) | 2004-10-12 | 2005-10-07 | Method for stabilizing an adaptive algorithm and device for carrying out said method |
Publications (1)
Publication Number | Publication Date |
---|---|
EP1800400A1 true EP1800400A1 (en) | 2007-06-27 |
Family
ID=35523455
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP05788936A Withdrawn EP1800400A1 (en) | 2004-10-12 | 2005-10-07 | Method for stabilizing an adaptive algorithm and device for carrying out said method |
Country Status (4)
Country | Link |
---|---|
US (1) | US20090052690A1 (en) |
EP (1) | EP1800400A1 (en) |
JP (1) | JP2008516540A (en) |
WO (1) | WO2006039826A1 (en) |
Families Citing this family (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20090225998A1 (en) * | 2005-10-25 | 2009-09-10 | Harry Bachmann | Method for determining a transmission function and a device for carrying out said method |
JP7304576B2 (en) * | 2019-11-15 | 2023-07-07 | パナソニックIpマネジメント株式会社 | NOISE REDUCTION DEVICE, MOBILE DEVICE, AND NOISE REDUCTION METHOD |
Family Cites Families (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4584441A (en) * | 1984-09-07 | 1986-04-22 | At&T Bell Laboratories | Bidirectional adaptive voice frequency repeater |
JP2748626B2 (en) * | 1989-12-29 | 1998-05-13 | 日産自動車株式会社 | Active noise control device |
US5809152A (en) * | 1991-07-11 | 1998-09-15 | Hitachi, Ltd. | Apparatus for reducing noise in a closed space having divergence detector |
US5140283A (en) * | 1991-08-02 | 1992-08-18 | Reed Lockwood W | Time variant analog signal switching apparatus including switching transient avoidance |
US5404397A (en) * | 1992-04-16 | 1995-04-04 | U.S. Phillips Corporation | Conference system with automatic speaker detection and speaker unit |
US7103188B1 (en) * | 1993-06-23 | 2006-09-05 | Owen Jones | Variable gain active noise cancelling system with improved residual noise sensing |
-
2005
- 2005-10-07 JP JP2007535978A patent/JP2008516540A/en active Pending
- 2005-10-07 US US11/577,121 patent/US20090052690A1/en not_active Abandoned
- 2005-10-07 WO PCT/CH2005/000589 patent/WO2006039826A1/en active Application Filing
- 2005-10-07 EP EP05788936A patent/EP1800400A1/en not_active Withdrawn
Non-Patent Citations (1)
Title |
---|
See references of WO2006039826A1 * |
Also Published As
Publication number | Publication date |
---|---|
US20090052690A1 (en) | 2009-02-26 |
JP2008516540A (en) | 2008-05-15 |
WO2006039826A1 (en) | 2006-04-20 |
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