CN107563300A - Noise reduction preconditioning technique based on prewhitening method - Google Patents
Noise reduction preconditioning technique based on prewhitening method Download PDFInfo
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Abstract
The invention discloses a kind of noise reduction preconditioning technique based on prewhitening method, pass through the pre -whitening processing to three dimensional signal image, the noise profile of a certain frequency range be will be distributed in each frequency range, it is especially smaller and in the case that frequency domain upward peak is more in noise, the frequency range of the frequency range of desired signal and noise signal is distinguished, so as to provide more convenient, polynary thinking for follow-up noise reduction process.So as to effectively separate vibration signal with noise signal, the original characteristic of desired signal after noise reduction is at utmost restored, improves the reliability of signal monitoring and fault analysis and diagnosis.
Description
Technical field
The invention belongs to field of signal processing, more particularly to it is a kind of smaller in noise, so that can not divide on frequency domain
Discern the processing method in the case of desired signal and noise signal.
Background technology
By signal means come detection blower fan signal so as to judge fan operation situation be instantly fan trouble monitor weight
Means are wanted, so the reliability of blower fan original vibration signal directly affects the detection to fan operation situation.
The purpose of the pretreatment of signal is the reliability of information and the precision of data analysis included in raising signal,
The reliability and sensitivity for making signal monitoring and fault diagnosis improve.Existing preconditioning technique is mostly the method by filtering
Improve signal to noise ratio, but when signal to noise ratio is sufficiently small, or when desired signal and noise signal can not be told on frequency domain, filtering
Loss of the method to primary signal will be bigger, so as to influence the effect of noise reduction.Therefore it is proposed that prewhitening technology with
The method that noise reduction blends, for the method for filtering, prewhitening method coordinates noise reduction can be effectively by vibration signal
Separated with noise signal, at utmost restore the original characteristic of desired signal after noise reduction, improve signal monitoring and failure point
Analyse the reliability of diagnosis.
The content of the invention
In order to solve the defects of classical signal noise reduction technology, the dependable with function of fan trouble detection technique is improved,
We have proposed the noise reduction preconditioning technique based on prewhitening method, by the pre -whitening processing to gathering signal, removes some
The mutation of signal energy and the correlation of signal, make noise signal be evenly distributed on each frequency range on frequency band, follow-up so as to optimize
To the result of signal extraction and separation, the reliability of raising signal detection and fault diagnosis desired signal.
The technical scheme is that：A kind of noise reduction preconditioning technique based on prewhitening method, comprises the following steps：
Step 1：Collect the fan vibration signal of high s/n ratio and the blower fan of low signal-to-noise ratio respectively using acceleration transducer
The blower fan signal of vibration signal, wherein high s/n ratio is reference signal；
Step 2：Short Time Fourier Transform is carried out to the vibration signal of low signal-to-noise ratio, obtains the three of T/F-amplitude
Tie up stereo-picture；
Step 3：Pre-whitening operation is carried out to above-mentioned three-dimensional image, obtains the T/F after prewhitening-shake
Width 3-D view；
Step 4：Inverse Short Time Fourier Transform is carried out to the image after prewhitening, image institute is right after obtaining prewhitening
The time domain vibrational image answered；
Step 5：Noise reduction process is carried out to the vibrational image after prewhitening, the image after noise reduction is obtained, by prewhitening
And the reference signal of the image crossed of noise reduction process and high s/n ratio is contrasted, the noise reduction after prewhitening is analyzed, so as to
Further carry out signal detection and fault diagnosis.
Further, the noise reduction preconditioning technique of the present invention based on prewhitening method, the specific step of its step 3
Suddenly can be divided into：
Step 3-1 obtains the covariance matrix of the three-dimensional image homography of T/F-amplitude, calculates sample
Covariance；
- 2 pairs of covariance matrixes of step 3 carry out albefaction computing, obtain whitening matrix；
The T/F that step 3-3 is obtained by whitening matrix to short time discrete Fourier transform-amplitude 3-D view is carried out
Albefaction, obtain the image after prewhitening.
Further, the noise reduction preconditioning technique of the present invention based on prewhitening method, suitable for all types of
Common noise, other kinds of noise can be converted into the signal with white noise character by prewhitening method, be distributed in
Each frequency range, it is easy to follow-up noise reduction process.
Wavelet de-noising processing is carried out after prewhitening time-domain image is obtained, by the signal after processing and high s/n ratio
Reference signal compares, and selects preferable noise reduction image, applied in malfunction monitoring and fault diagnosis, improves signal monitoring
The reliability of means.
The present invention improves the accuracy and practicality of signal after processing in traditional pretreatment and noise reduction technology,
And method is simple for beginner, readily appreciates, there is good development in the signal detection field of the machinery such as blower fan
Prospect.
Brief description of the drawings
Fig. 1 is the flow chart of pre -whitening processing application；
Fig. 2 is the frequency domain distribution schematic diagram of pending signal；
Fig. 3 is reference signal frequency domain distribution schematic diagram；
Fig. 4 is the frequency domain distribution schematic diagram of pending signal after pre -whitening processing.
Embodiment
In order to more specifically describe the present invention, below in conjunction with the accompanying drawings and embodiment is to technical scheme
It is described in detail.
Referring to Fig. 1 to Fig. 4, the noise reduction preconditioning technique based on prewhitening method in the present embodiment, comprise the following steps：
The blower fan of fan vibration signal and low signal-to-noise ratio that S01 collects high s/n ratio using acceleration transducer respectively shakes
Dynamic signal, the wherein blower fan signal of high s/n ratio is reference signal.
SO2 sets appropriate window length and Duplication, the vibration signal of low signal-to-noise ratio is carried out in short-term in processing routine
Fourier transformation, obtain the three-dimensional image of T/F-amplitude.
S03 carries out pre-whitening operation to above-mentioned three-dimensional image, in MATLAB, first obtains the association side of above-mentioned matrix
Poor matrix：
Wherein Z is the three-dimensional image homography of T/F-amplitude in S02
The inverse root mean square T of covariance matrix is obtained by function afterwards, as whitening matrix, the Z_W finally obtained is
Matrix after prewhitening, so as to realize albefaction.
S04, according to the parameters of S02 settings, inverse Fu in short-term is carried out to the image after prewhitening in processing routine
In leaf transformation, obtain the time domain vibrational image corresponding to image after prewhitening.
S05 carries out noise reduction process to the vibrational image after prewhitening, obtains the image after noise reduction, by prewhitening simultaneously
Signal after noise reduction is contrasted with reference signal by coefficient correlation, so as to optimize pre -whitening processing step by step to noise reduction mistake
The influence of journey, obtain true and reliable collection signal.
To highlight the superiority of the inventive method, the present embodiment is imitated the sinusoidal signal with coloured noise of collection
True experiment (signal to noise ratio is about -9db during emulation experiment), process and result are as described below.
Primary signal is sinusoidal signal, and its expression formula is：Sig0=sin (2 π ft), wherein f is signal frequency, in emulation
F=50Hz is taken, i.e., amplitude is 1 in 50Hz on frequency domain, in addition without other frequency ranges.
Noise signal is coloured noise, in order to consider the needs of signal to noise ratio, to former expression formula divided by particular factor:
Above-mentioned noise signal frequency-domain waveform integrated distribution, to 200Hz, wherein in 100Hz or so amplitudes maximum, approaches original in 0
The amplitude of beginning sinusoidal signal.
Above two signal is discrete signal, and wherein t is time quantum, and 1000 are taken in 1 second in time domain in emulation adopts
Sampling point, i.e. sampling interval are 1ms, and signal length is sampled for 1000.
For the validity of the qualitative analysis technology, by signal to noise ratio qualitative analysis, prewhitening pre-processes in noise reduction for we
When advantage where, the results showed that, for above-mentioned coloured noise, when signal to noise ratio is more than -10, the present invention can will focus on certain
Noise uniformly dispersing in the range of one band frequency is in each frequency range, and so as to clearly distinguish the frequency range of desired signal, Fig. 2 is represented
The frequency domain distribution schematic diagram of pending signal and reference signal, Fig. 3 represent that the frequency domain distribution after pending signal prewhitening is shown
It is intended to.
It is not difficult to find out, the inventive method can be more in peak value and in the case of being distributed in different frequency range, by main signal
The frequency range of frequency range and noise signal is distinguished, and this technology is by noise reduction of the noise in the case of smaller and traditional filtering side
Method has extremely strong directive significance.
Technical scheme and beneficial effect are described in detail above-described embodiment, Ying Li
Solution is to the foregoing is only presently most preferred embodiment of the invention, is not intended to limit the invention, all principle models in the present invention
Interior done any modification, supplement and equivalent substitution etc. are enclosed, should be included in the scope of the protection.
Claims (3)
1. a kind of noise reduction preconditioning technique based on prewhitening method, comprises the following steps：
Step 1：Collect the fan vibration signal of high s/n ratio and the fan vibration of low signal-to-noise ratio respectively using acceleration transducer
The blower fan signal of signal, wherein high s/n ratio is reference signal；
Step 2：Short Time Fourier Transform is carried out to the vibration signal of low signal-to-noise ratio, the three-dimensional for obtaining T/F-amplitude is stood
Body image；
Step 3：Pre-whitening operation is carried out to above-mentioned three-dimensional image, obtains T/F-amplitude three after prewhitening
Tie up image；
Step 4：Inverse Short Time Fourier Transform is carried out to the image after prewhitening, obtained after prewhitening corresponding to image
Time domain vibrational image；
Step 5：Noise reduction process is carried out to the vibrational image after prewhitening, the image after noise reduction is obtained, by prewhitening and drops
The reference signal of treated image and high s/n ratio of making an uproar is contrasted, and the noise reduction after prewhitening is analyzed, so as to enter one
Step carries out signal detection and fault diagnosis.
2. the noise reduction preconditioning technique based on prewhitening method as claimed in claim 1, it is characterised in that step 3 it is specific
Step is：
Step 3-1 obtains the covariance matrix of the three-dimensional image homography of T/F-amplitude, calculates the association of sample
Variance；
- 2 pairs of covariance matrixes of step 3 carry out albefaction computing, obtain whitening matrix；
The T/F that step 3-3 is obtained by whitening matrix to short time discrete Fourier transform-amplitude 3-D view carries out albefaction,
Obtain the image after prewhitening.
3. the noise reduction preconditioning technique based on prewhitening method as claimed in claim 1, it is characterised in that this method is applied to
All types of common noises, other kinds of noise can be converted into the letter with white noise character by prewhitening method
Number, each frequency range is distributed in, is easy to follow-up noise reduction process.
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Cited By (1)
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| CN114687955A (en) * | 2020-12-31 | 2022-07-01 | 北京金风科创风电设备有限公司 | Blade fault diagnosis method and device for wind generating set and electronic equipment |
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Effective date of registration: 20180608 Address after: 312300 No. 1818 West Renmin Road, Shangyu District, Shaoxing, Zhejiang Applicant after: ZHEJIANG SHANGFENG GAOKE SPECIAL FAN INDUSTRY CO., LTD. Applicant after: GUANGZHOU METRO GROUP CO., LTD. Address before: 312300 No. 1818 West Renmin Road, Shangyu District, Shaoxing, Zhejiang Applicant before: ZHEJIANG SHANGFENG GAOKE SPECIAL FAN INDUSTRY CO., LTD. |
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Application publication date: 20180109 |