CN113315490A - Filtering reference affine projection symbol active control system based on post-filter - Google Patents
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Abstract
The invention discloses a post-filter-based filtering reference affine projection symbol active control system, which consists of a plurality of control subsystems, wherein each subsystem comprises a signal acquisition module, a primary path module, a control filter module and a post-filter module; the device comprises a secondary path module, a signal synthesis module and a weight coefficient updating module. The signal acquisition module is respectively connected with the primary path module, the control filter module and the secondary path estimation module; the control filter module is connected with the secondary path module through the post-filter module; the signal synthesis module is respectively connected with the primary path module and the secondary path module; and the weight coefficient updating module is respectively connected with the secondary path estimation module, the signal synthesis module and the control filter module. The invention has simple structure, convenient implementation, flexible adjustment of convergence speed and steady-state error and excellent noise reduction performance.
Description
Technical Field
The invention belongs to the field of noise active control, and particularly relates to a filtering reference affine projection symbol active control system based on a post filter.
Background
In a real environment, impulse noise subject to non-gaussian distribution widely exists. In an environment where impulse noise occurs, the performance of the conventional adaptive algorithm based on the second moment theory deteriorates or even deteriorates. With the application of the noise active control technology and the development of the noise active control algorithm, an affine projection symbolic algorithm based on 1-norm is generated, the algorithm combines the affine projection algorithm and the symbolic algorithm to effectively control impulse noise, and the algorithm performance under the impulse noise environment is improved. However, the algorithm does not consider the secondary path in the actual noise control, and in addition, the algorithm is also difficult to adjust the contradiction between the convergence rate and the steady-state error, and the convergence performance of the algorithm needs to be further improved.
Disclosure of Invention
The invention aims to solve the problem that the performance of the traditional algorithm is reduced due to the existence of impulse noise, and simultaneously adjust the contradiction between the convergence speed and the steady-state error of the algorithm when an actual secondary path exists, and provides a filtering reference affine projection sign active control system based on a post filter.
In order to achieve the purpose, the invention provides the following scheme: a post-filter based filtered reference affine projection symbol active control system, said system consisting of several control subsystems, wherein each subsystem comprises,
the signal acquisition module is used for acquiring pulse noise signals;
the primary path module is connected with the signal acquisition module;
the control filter module is connected with the signal acquisition module;
the rear filter module is connected with the control filter module;
a secondary path module connected with the post-filter module;
the signal synthesis module is respectively connected with the primary path module and the secondary path module;
the secondary path estimation module is connected with the signal acquisition module;
and the weight coefficient updating module is respectively connected with the secondary path estimation module, the signal synthesis module and the control filter module.
Preferably, the signal acquisition module is respectively connected with the primary path module, the control filter module and the secondary path estimation module;
the primary path module is used for obtaining a desired signal according to the impulse noise signal;
the control filter module is used for providing the pulse noise signal for the post filter;
the secondary path estimation module is used for obtaining a filtered impulse noise signal according to the impulse noise signal.
Preferably, the control filter module is respectively connected to the post-filter module and the weight coefficient update module;
the post-filter module is used for obtaining an output signal according to the pulse noise signal;
the weight coefficient updating module is used for updating the weight coefficient of the control filter.
Preferably, the post filter is connected with the control filter module and the secondary path module;
the secondary path module is used for obtaining an output signal according to the impulse noise signal.
Preferably, the signal synthesis module is respectively connected to the primary path module, the secondary path module, and the weight coefficient update module;
the signal synthesis module is used for obtaining a posterior error signal according to the expected signal and the output signal, and the posterior error signal is an error signal of the subsystem.
Preferably, the weight coefficient updating module controls the update of the weight coefficient of the control filter module according to the filtered impulse noise signal and the a posteriori error signal.
Preferably, the formula of the weight coefficient update module is:
wherein sgn (·) is a symbolic operation (·)TFor the transpose operation, n is the time coefficient, w (n +1) is the n +1 moment control filter weight coefficient vector, w (n) is the n moment control filter weight coefficient vector,
for a vector of filter weight coefficients after n instants, ep(n) is the a posteriori error vector at time n, xf(n) is a K-order filtered impulse noise signal vector at n moments, K is a projection order, xf(n) filtering the impulse noise signal vector at n time instants,
for the secondary path estimation model, xH(n) is an impulse noise signal vector at n moments, H is the length of a secondary path, d (n) is an expected signal vector at n moments, gamma is a weight factor of a post-filter, mu is an iteration step length of a control filter, and epsilon is a normalization parameter.
Preferably, the system further comprises a speaker, the speaker being connected to the subsystem.
Preferably, the subsystem further comprises a display module for displaying the impulse noise signal.
The invention has the beneficial effects that:
the invention realizes the low-frequency band-pass or high-frequency band-pass filtering of the weight coefficient of the control filter by reasonably selecting the parameters of the post filter, thereby adjusting the convergence speed and the steady-state error of the algorithm and improving the convergence performance of the control algorithm on the pulse noise. The parameters of the post-filter can also be flexibly selected according to the actual control requirement so as to obtain the convergence performance meeting the actual control requirement. The invention has simple structure, convenient implementation, flexible adjustment of convergence speed and steady-state error and excellent noise reduction performance.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings needed in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings without creative efforts.
FIG. 1 is a system block diagram of a post-filter based filtered reference affine projection sign active control system according to an embodiment of the present invention;
FIG. 2 is a flow diagram of a system implementation of a post-filter based filtered reference affine projection sign active control system in accordance with an embodiment of the present invention;
FIG. 3 is a graph comparing convergence curves of a filtered reference affine projection notation algorithm of a considered filter with a filtered reference normalized least mean square algorithm of the considered filter, a filtered reference affine projection algorithm and a filtered reference affine projection notation algorithm in accordance with an embodiment of the present invention;
FIG. 4 is a comparison graph of before and after noise reduction waveforms of a filtered reference affine projection notation algorithm of a considered post-filter and a filtered reference normalized least mean square algorithm of the considered post-filter, the filtered reference affine projection algorithm and the filtered reference affine projection notation algorithm, according to an embodiment of the present invention;
fig. 5 is a graph comparing tracking performance of a filtered reference affine projection notation algorithm of a considered filter with a filtered reference normalized least mean square algorithm, a filtered reference affine projection algorithm and a filtered reference affine projection notation algorithm of a considered filter according to an embodiment of the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in further detail below.
As shown in fig. 1, the present embodiment provides a post-filter based filtered reference affine projection sign active control system, which is composed of several control subsystems, wherein each subsystem comprises,
the signal acquisition module is used for acquiring pulse noise signals;
the primary path module is connected with the signal acquisition module;
the control filter module is connected with the signal acquisition module;
the rear filter module is connected with the control filter module;
the secondary path module is connected with the rear filter module;
the signal synthesis module is respectively connected with the primary path module and the secondary path module;
the secondary path estimation module is connected with the signal acquisition module;
and the weight coefficient updating module is respectively connected with the secondary path estimation module, the signal synthesis module and the control filter module.
The signal acquisition module is respectively connected with the primary path module, the control filter module and the secondary path estimation module;
the primary path module is used for obtaining a desired signal according to the impulse noise signal;
the control filter module is used for providing pulse noise signals for the post filter;
the secondary path estimation module is used for obtaining a filtered impulse noise signal according to the impulse noise signal.
The control filter module is respectively connected with the post-filter module and the weight coefficient updating module;
the post filter module is used for obtaining an output signal according to the pulse noise signal;
the weight coefficient updating module is used for controlling the weight coefficient updating of the filter.
The rear filter is connected with the control filter module and the secondary path module;
the secondary path module is used for obtaining an output signal according to the impulse noise signal.
The signal synthesis module is respectively connected with the primary path module, the secondary path module and the weight coefficient updating module;
and the signal synthesis module is used for obtaining a posterior error signal according to the expected signal and the output signal, wherein the posterior error signal is an error signal of the subsystem.
And the weight coefficient updating module controls and controls the weight coefficient of the filter module to update according to the filtering pulse noise signal and the posterior error signal.
The formula for updating the weight coefficient of the weight coefficient updating module is as follows:
wherein sgn (·) is a symbolic operation (·)TFor the transpose operation, n is the time coefficient, w (n +1) is the n +1 moment control filter weight coefficient vector, w (n) is the n moment control filter weight coefficient vector,
for a vector of filter weight coefficients after n instants, ep(n) is the a posteriori error vector at time n, xf(n) is a K-order filtered impulse noise signal vector at n moments, K is a projection order, xf(n) filtering the impulse noise signal vector at n time instants,
for the secondary path estimation model, xH(n) is an impulse noise signal vector at n moments, H is the length of a secondary path, d (n) is an expected signal vector at n moments, gamma is a weight factor of a post-filter, mu is an iteration step length of a control filter, and epsilon is a normalization parameter.
The system also comprises a plurality of loudspeakers which are respectively connected with the subsystems.
The subsystem further includes a display module for displaying the impulse noise signal.
The impulse noise signal in fig. 1 passes through the primary path to obtain the desired signal. The control filter takes the pulse noise signal as input, generates an output signal after passing through the post-filter and the secondary path model, and synthesizes the output signal and the expected signal into a posterior error signal. The posteriori error signal is used as an error signal of a control system and participates in the update of the weight coefficient of the control filter together with the impulse noise signal filtered by the secondary path estimation model.
FIG. 2 is a flow diagram of a system implementation of a filtered reference affine projection sign active control system in view of a post-filter. As shown in fig. 2, an embodiment provided by the present invention is a filtered reference affine projection sign active control system of a considered filter for impulse noise active control, comprising:
s201, acquiring an impulse noise signal by a reference sensor, and transmitting the impulse noise signal to a control filter;
s202, the control filter transmits the pulse noise signal to a post filter;
s203, the post filter generates a cancellation signal of the pulse noise signal according to the pulse noise signal and an internal active control algorithm, and transmits the cancellation signal to a loudspeaker;
s204, the loudspeaker sends out the cancellation signal, and the cancellation signal is superposed with the impulse noise signal to cancel the impulse noise signal.
In the invention, the weight coefficient of a control filter is updated by introducing a post filter in a filter reference affine projection symbolic algorithm, and the updating formula is
Wherein sgn (·) is a symbolic operation (·)TFor the transposition operation, n is the time coefficient, w (n +1) is the time instant control filter weight coefficient vector at time instant n +1, w (n) is the time instant control filter weight coefficient vector at time instant n, w (n) ═ w0(n)，w1(n)，…，wM-1(n)]T and M are the lengths of the control filters,
for the filter weight coefficient vector after time n,
ep(n) is the a posteriori error signal vector at time n, ep(n)＝[ep(n)，ep(n-1)，…，ep(n-K+1)]TK is the projection order, xf(n) is the filtered reference signal vector of K order at time n, Xf(n)＝[xf(n)，xf(n-1)，…，xf(n-K+1)]，xf(n) is the filtered reference signal vector at n time instances, xf(n)＝[xf(n)，xf(n-1)，…，xf(n-M+1)]T，
Is a secondary path estimation model, xH(n) is a reference signal vector at time n, xH(n)＝[x(n)，x(n-1)，…，x(n-H+1)]TH is the secondary path length, d (n) is the desired signal vector at time n, d (n) ═ d (n), d (n-1), …, d (n-K +1)]TGamma is the weight factor of the post-filter and mu is the controlAnd (4) making the iteration step length of the filter, wherein the epsilon is a normalized parameter.
The present embodiment sets the following simulation conditions: the order of the filter is 64, the projection order is 5, the normalized parameter is 0.0001, the primary path transfer function is [0.01670.48330.48330.0167], the secondary path transfer function is [00.20370.59260.2037], the secondary path estimation model is the same as the secondary path transfer function, the initial noise is impulse noise which is distributed stably according to standard symmetry, and the characteristic parameter alpha is 1.8. Setting the iteration step length of the filter to be 0.001, comparing the filtering reference affine projection sign active control algorithm of the filter after consideration with the filtering reference normalized least mean square algorithm of the filter after consideration when the weight factor gamma is-0.8 and gamma is 0.8, and the convergence performance of the filtering reference affine projection algorithm and the filtering reference affine projection sign algorithm, wherein the simulation result is shown in fig. 3. FxASPA represents a filtering reference affine projection symbol algorithm, PFFxASPA represents a filtering reference affine projection symbol active control algorithm of a considered post-filter, PFFxLMS represents a filtering reference normalization least mean square algorithm of the considered post-filter, and FxAPA represents a filtering reference affine projection algorithm. And when the weight factor gamma of the filtering reference affine projection sign active control algorithm of the rear filter is considered to be 0, the filtering reference affine projection sign active control algorithm of the rear filter is considered to be degenerated into a filtering reference affine projection sign algorithm. According to simulation results, by setting different weight factors, the convergence speed and the steady-state error of the filter reference affine projection symbol active control algorithm of the filter under consideration can be adjusted, and the convergence performance of the filter reference affine projection symbol active control algorithm of the filter under consideration is better than that of other algorithms when the weight factor gamma is-0.8 as found by comparison with other algorithms.
The simulation parameters are kept unchanged, when the weight factor γ is-0.8 and γ is 0.8, the filtering reference affine projection sign active control algorithm of the rear filter is considered and the filtering reference normalized least mean square algorithm of the rear filter is considered, and the noise reduction performance of the filtering reference affine projection algorithm and the filtering reference affine projection sign algorithm on the impulse noise is shown in fig. 4. According to simulation results, the filtering reference affine projection sign active control algorithm of the filter has better noise reduction performance under the impulse noise environment. In addition, when the primary path p (z) changes, the convergence performance of the filter-reference affine projection sign active control algorithm considering the post-filter and the filter-reference normalized least mean square algorithm considering the post-filter when the weight factor γ is-0.8 and γ is 0.8 are compared, and the filter-reference affine projection algorithm and the filter-reference affine projection sign algorithm are used. The primary path P (z) in the simulation is changed into-P (z) at the iteration of step 40000, and the simulation result is shown in FIG. 5. According to a simulation result, the filter reference affine projection sign active control algorithm of the considered filter still has better convergence performance than other algorithms when the weight factor gamma is-0.8.
The invention realizes the low-frequency band-pass or high-frequency band-pass filtering of the weight coefficient of the control filter by reasonably selecting the parameters of the post filter, thereby adjusting the convergence speed and the steady-state error of the algorithm and improving the convergence performance of the control algorithm on the pulse noise. The parameters of the post-filter can also be flexibly selected according to the actual control requirement so as to obtain the convergence performance meeting the actual control requirement. The invention has simple structure, convenient implementation, flexible adjustment of convergence speed and steady-state error and excellent noise reduction performance.
The above-described embodiments are merely illustrative of the preferred embodiments of the present invention, and do not limit the scope of the present invention, and various modifications and improvements of the technical solutions of the present invention can be made by those skilled in the art without departing from the spirit of the present invention, and the technical solutions of the present invention are within the scope of the present invention defined by the claims.
Claims (9)
1. A post-filter based filtered reference affine projection symbol active control system, characterized in that said system is composed of several subsystems, wherein said subsystems comprise,
the signal acquisition module is used for acquiring pulse noise signals;
the primary path module is connected with the signal acquisition module;
the control filter module is connected with the signal acquisition module;
the rear filter module is connected with the control filter module;
a secondary path module connected with the post-filter module;
the signal synthesis module is respectively connected with the primary path module and the secondary path module;
the secondary path estimation module is connected with the signal acquisition module;
and the weight coefficient updating module is respectively connected with the secondary path estimation module, the signal synthesis module and the control filter module.
2. The post-filter based filtered reference affine projection sign active control system of claim 1,
the signal acquisition module is respectively connected with the primary path module, the control filter module and the secondary path estimation module;
the primary path module is used for obtaining a desired signal according to the impulse noise signal;
the control filter module is used for providing the pulse noise signal for the post filter;
the secondary path estimation module is used for obtaining a filtered impulse noise signal according to the impulse noise signal.
3. The post-filter based filtered reference affine projection sign active control system of claim 2,
the control filter module is respectively connected with the post-filter module and the weight coefficient updating module;
the post-filter module is used for obtaining an output signal according to the pulse noise signal;
the weight coefficient updating module is used for updating the weight coefficient of the control filter.
4. The post-filter based filtered reference affine projection sign active control system of claim 1,
the rear filter is connected with the control filter module and the secondary path module;
the secondary path module is used for obtaining an output signal according to the impulse noise signal.
5. The post-filter based filtered reference affine projection sign active control system of claim 4,
the signal synthesis module is respectively connected with the primary path module, the secondary path module and the weight coefficient updating module;
the signal synthesis module is used for obtaining a posterior error signal according to the expected signal and the output signal, and the posterior error signal is an error signal of the subsystem.
6. The post-filter based filtered reference affine projection sign active control system of claim 5,
and the weight coefficient updating module controls the weight coefficient of the control filter module to update according to the filtering pulse noise signal and the posterior error signal.
7. The post-filter based filtered reference affine projection sign active control system of claim 4,
the formula for updating the weight coefficient of the weight coefficient updating module is as follows:
wherein sgn (·) is a symbolic operation (·)TFor the transpose operation, n is the time coefficient, w (n +1) is the n +1 moment control filter weight coefficient vector, w (n) is the n moment control filter weight coefficient vector,
for a vector of filter weight coefficients after n instants, ep(n) is the a posteriori error vector at time n, xf(n) is a K-order filtered impulse noise signal vector at n moments, K is a projection order, xf(n) filtering the impulse noise signal vector at n time instants,
for the secondary path estimation model, xH(n) is an impulse noise signal vector at n moments, H is the length of a secondary path, d (n) is an expected signal vector at n moments, gamma is a weight factor of a post-filter, mu is an iteration step length of a control filter, and epsilon is a normalization parameter.
8. The post-filter based filtered reference affine projection sign active control system of claim 1,
the system also includes a speaker coupled to the subsystem.
9. The post-filter based filtered reference affine projection sign active control system of claim 1,
the subsystem further comprises a display module for displaying the impulse noise signal.
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| CN106788337A (en) * | 2016-10-11 | 2017-05-31 | 沈阳工业大学 | Sane affine projection symbol adaptive filter algorithm |
| CN109714023A (en) * | 2018-12-28 | 2019-05-03 | 歌尔股份有限公司 | Adaptive filter method, sef-adapting filter and noise control system |
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