CN103795473B - Method and system for eliminating power-frequency interference - Google Patents
Method and system for eliminating power-frequency interference Download PDFInfo
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- CN103795473B CN103795473B CN201210433266.6A CN201210433266A CN103795473B CN 103795473 B CN103795473 B CN 103795473B CN 201210433266 A CN201210433266 A CN 201210433266A CN 103795473 B CN103795473 B CN 103795473B
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Abstract
The invention provides a method and system for eliminating power-frequency interference. The method comprises that time of an input signal is delayed to obtain a time-delay signal, and a first power-frequency signal is obtained by calculation according to the time-delay signal; time-frequency transformation is implemented on the first power-frequency signal, and according to the stored amplitude of a power-frequency domain of a pure power-frequency-interference section, the amplitude of a second power-frequency signal after the time-frequency transformation is adjusted; time-frequency transformation is implemented on a third power-frequency signal after amplitude adjustment to obtain a corrected power-frequency signal; and the corrected power frequency signal is subtracted from the input signal to obtain an output signal. The method and system are used to eliminate both the power-frequency interference and echo caused by the time-delayed input signal.
Description
Technical field
The present invention relates to audio signal processing technique, more particularly to a kind of method and system for eliminating Hz noise.
Background technology
Various interference and noise are introduced during electronic device works often, most common of which is exactly Hz noise.
Hz noise is due to AC network power frequency electromagnet field distribution, thermally supply transformer earthing mode, the original such as employing of bottom technology
Thus introduce power frequency component produce interference, Hz noise will cause sound source signal introduce " too " ring current sound, seriously
Ear is affected to listen impression.Therefore, it is necessary to eliminate Hz noise, audio frequency effect could be improved.
In prior art, exist by the way of digital comb filter eliminates Hz noise, the comb filter is usual
Power frequency component can be calculated after input signal (input signal is audio signal) is carried out delay process, then in the base of input signal
The power frequency component is deducted on plinth, that is, the audio signal exported after the Hz noise that is eliminated.But, as comb filter is root
Power frequency component is calculated according to the input signal after time delay, thus the power frequency component for calculating be in fact with time delay after input
Signal, echo is carried in also causing the audio signal for exporting, affect audio frequency effect.
The content of the invention
The present invention provides a kind of method and system for eliminating Hz noise, so that while Hz noise is eliminated, disappearing
Except the echo that the input signal after time delay causes.
A first aspect of the present invention is to provide a kind of method for eliminating Hz noise, including：
Input signal time delay is obtained into time delayed signal, and the first power frequency component is calculated according to the time delayed signal；
First power frequency component is carried out into time-frequency convert, and the power frequency frequency domain width of the pure Hz noise section according to storage
Value, to time-frequency convert after the second power frequency component carry out range-adjusting；
The 3rd power frequency component after by range-adjusting is changed when entering line frequency, obtains correcting power frequency component；
The input signal is deducted into the amendment power frequency component, output signal is obtained.
With reference in a first aspect, in the first possible implementation, also including：It is described to time-frequency convert after second
After power frequency component carries out range-adjusting, the smoothing processing between neighbouring sample point is carried out, obtain the 3rd power frequency component；It is described
The 3rd power frequency component after by range-adjusting is changed when entering line frequency, specially：The 3rd power frequency after by the smoothing processing
Signal is changed when entering line frequency.
With reference in a first aspect, in second possible implementation, input signal time delay is obtained time delay letter described
Number afterwards, before being calculated the first power frequency component according to the time delayed signal, also include：Detect the time delayed signal whether only
Comprising the 4th power frequency component；When testing result is to be, it is determined that the time delayed signal is in the pure Hz noise section, according to
The time delayed signal is calculated the 4th power frequency component, and the 4th power frequency component is carried out time-frequency convert, obtains institute
State the power frequency frequency domain amplitude of pure Hz noise section；Store the power frequency frequency domain amplitude of the pure Hz noise section.
With reference to second possibility of the first possible implementation or first aspect of first aspect or first aspect
Implementation, in the third possible implementation, it is described input signal time delay is obtained into time delayed signal before, also wrap
Include：Detect that the input signal whether there is the 5th power frequency component；If existing, the fundamental frequency of the 5th power frequency component is obtained,
And frequency shift tracking is carried out to the fundamental frequency, obtain real-time fundamental frequency；Amount of delay is obtained according to the real-time fundamental frequency, to prolong according to described
When amount time delay described in input signal obtain the time delayed signal.
With reference to the third possible implementation of first aspect, in the 4th kind of possible implementation, the detection
The input signal whether there is the 5th power frequency component, including：By the input signal time delay power frequency period, the power frequency period
For the work frequency 50HZ or 60HZ corresponding cycle；According to the input signal after the input signal and time delay power frequency period,
Calculate the energy and cycle residual energy of the input signal；If the energy is more than cycle residual energy, calculate described defeated
Enter the energy difference log-domain average of signal；Return execution described by input signal time delay power frequency period, under the input signal is
One input signal, and obtain the energy difference log-domain average of the next input signal, until it reaches default detection time；
If in the default detection time, calculated multiple energy difference log-domain averages exceed given threshold, then sentence
There is the 5th power frequency component, and the fundamental frequency of the 5th power frequency component for power frequency period correspondence in the fixed input signal
Work frequency.
It is with reference to the third possible implementation of first aspect, in the 5th kind of possible implementation, described to institute
Stating fundamental frequency carries out frequency shift tracking, obtains real-time fundamental frequency, including：According to the fundamental frequency of the 5th power frequency component, from the input letter
Number extract the corresponding power frequency fundamental frequency signal of the fundamental frequency；Using method of correlation frequency shift tracking, phase is carried out to the power frequency fundamental frequency signal
Closing property is processed, and obtains the frequency shift value of the fundamental frequency；If the frequency shift value is in preset range, keep the fundamental frequency constant；It is no
Then, the real-time fundamental frequency is calculated according to the frequency shift value.
A second aspect of the present invention is to provide a kind of system for eliminating Hz noise, including：Power frequency filtration module, the work
Frequency filtration module includes：
Filtering delay-time unit, for input signal time delay is obtained time delayed signal；
Power frequency computing unit, for being calculated the first power frequency component according to the time delayed signal；
Power frequency amending unit, for first power frequency component is carried out time-frequency convert, and does according to the pure power frequency of storage
Disturb the power frequency frequency domain amplitude of section, to time-frequency convert after second described in power frequency component carry out range-adjusting；After range-adjusting
Power frequency component described in 3rd is changed when entering line frequency, obtains correcting power frequency component；
Filtering output unit, for the input signal is deducted amendment power frequency component, obtains output signal.
With reference to second aspect, in the first possible implementation, the power frequency amending unit is additionally operable to described right
After the second power frequency component after time-frequency convert carries out range-adjusting, the smoothing processing between neighbouring sample point is carried out, obtain described
3rd power frequency component.
With reference to second aspect, in second possible implementation, the power frequency filtration module also includes：Amplitude is true
Order unit, for, after input signal time delay is obtained time delayed signal, being calculated the first power frequency according to the time delayed signal
Before signal, detect whether the time delayed signal only includes the 4th power frequency component；When testing result is to be, it is determined that described to prolong
When signal be in the pure Hz noise section, the 4th power frequency component is calculated according to the time delayed signal, and will be described
4th power frequency component carries out time-frequency convert, obtains the power frequency frequency domain amplitude of the pure Hz noise section；Store the pure power frequency to do
Disturb the power frequency frequency domain amplitude of section.
With reference to second possibility of the first possible implementation or second aspect of second aspect or second aspect
Implementation, in the third possible implementation, also include：Power frequency detection module, for by input signal time delay
Before obtaining time delayed signal, detect that the input signal whether there is the 5th power frequency component；And in testing result to there is power frequency
During signal, the fundamental frequency of the 5th power frequency component is obtained；Power frequency tracking module, for carrying out frequency shift tracking to the fundamental frequency, obtains
To real-time fundamental frequency；The filtering delay-time unit in the power frequency filtration module, specifically for being obtained according to the real-time fundamental frequency
Amount of delay, the input signal according to the amount of delay time delay obtain the time delayed signal.
With reference to the third possible implementation of second aspect, in the 4th kind of possible implementation, the power frequency
Detection module, including：Detection delay unit, for by the input signal time delay power frequency period, the power frequency period is power frequency
Frequency 50HZ or 60HZ corresponding cycles；Energy calculation unit, after according to the input signal and time delay power frequency period
Input signal, calculate the energy and cycle residual energy of the input signal, if the energy is more than the cycle residual error energy
Amount, then calculate the energy difference log-domain average of the input signal；Interference judging unit, for, in default detection time, counting
When the multiple described energy difference log-domain average for obtaining exceedes given threshold, then judge that the input signal has described the
Five power frequency components；Fundamental frequency determining unit, for when the input signal has five power frequency component, determining the described 5th
The fundamental frequency of power frequency component is the corresponding work frequency of the power frequency period.
With reference to the 4th kind of possible implementation of second aspect, in the 5th kind of possible implementation, the power frequency
Tracking module, including：Fundamental frequency signal extraction unit, for what is determined according to the fundamental frequency determining unit in the power frequency detection module
The fundamental frequency of the 5th power frequency component, extracts the corresponding power frequency fundamental frequency signal of the fundamental frequency from the input signal；Dependent frequency shift
Tracking cell, for using method of correlation frequency shift tracking, carrying out dependency process to the power frequency fundamental frequency signal, obtaining the fundamental frequency
Frequency shift value；Real-time fundamental frequency updating block, for when the frequency shift value is in preset range, keeping the fundamental frequency constant；It is no
Then, the real-time fundamental frequency is calculated according to the frequency shift value.
The method and system of the elimination Hz noise that the present invention is provided has the technical effect that：During by power frequency component being carried out
Frequency is changed, and according to the power frequency frequency domain amplitude of pure Hz noise section, is carried out range-adjusting to the power frequency component after time-frequency convert, disappeared
Except the voice signal in power frequency component, it is achieved thereby that while Hz noise is eliminated, eliminating the input signal after time delay
The echo for causing.
Description of the drawings
Fig. 1 is the schematic flow sheet of one embodiment of method that the present invention eliminates Hz noise；
Fig. 2 is the schematic flow sheet of another embodiment of method that the present invention eliminates Hz noise；
Fig. 3 is that the present invention eliminates the power frequency overhaul flow chart in another embodiment of method of Hz noise；
Fig. 4 is that the present invention eliminates the dependent frequency shift tracking schematic diagram in another embodiment of method of Hz noise；
Fig. 5 is that the present invention eliminates the comb filter process chart in another embodiment of method of Hz noise；
Fig. 6 is that the present invention eliminates the power frequency correcting process flow chart in another embodiment of method of Hz noise；
Fig. 7 is the structural representation of one embodiment of system that the present invention eliminates Hz noise；
Fig. 8 is the structural representation of another embodiment of system that the present invention eliminates Hz noise.
Specific embodiment
Embodiment one
The method of the elimination Hz noise of the embodiment of the present invention is the improvement that the handling process to comb filter is carried out, and is schemed
The schematic flow sheet of 1 one embodiment of method that Hz noise is eliminated for the present invention, as shown in figure 1, the method includes：
101st, input signal time delay is obtained into time delayed signal, and the first power frequency component is calculated according to time delayed signal；
Wherein, comb filter after receiving an input signal, can carry out delay process to the input signal；After time delay
Input signal is properly termed as time delayed signal.In the present embodiment, input signal is audio signal.
The first described power frequency component is the power frequency interference signals for existing in the input signal, the purpose of comb filter
Exactly first power frequency component is filtered out from input signal, to eliminate Hz noise.
It should be noted that the first described power frequency component and the second power frequency mentioned in follow-up each embodiment
Signal, the 3rd power frequency component, the 4th power frequency component etc., are essentially all power frequency component, and the embodiment of the present invention is intended merely to more preferably
Distinguish state of the power frequency component after the different process of correspondence, and be distinguish between using first, second, third, etc..For example,
Before and after time-frequency convert is carried out to certain power frequency component, it is two kinds of different power frequency components, one is the signal in time domain, another
Individual is the signal in frequency domain, can be made a distinction with first, second；Again for example, range-adjusting is carried out to certain power frequency component
In front and back, and two kinds of different power frequency components, the amplitude of both power frequency components is different, it is also possible to make a distinction.Follow-up
Occur no longer describing in detail during the different title of above-mentioned power frequency component in embodiment.
102nd, first power frequency component is carried out into time-frequency convert；
For example, it is possible to use discrete Fourier transform, time domain is carried out to the conversion of frequency domain to the first power frequency component.
103rd, according to storage pure Hz noise section power frequency frequency domain amplitude, to time-frequency convert after the second power frequency component enter
Row range-adjusting；
Wherein, described pure Hz noise section only has power frequency component in referring to input signal, and does not contain voice；Cause
For according to the characteristics of audio signal, voice is not generally continuous, has voice for some time, may separately for a period of time
Without voice, so, just appearing in does not have voice and the only state of power frequency component in certain time；The present embodiment is just by this
The state for kind there was only power frequency component is referred to as pure Hz noise section (actual to implement, pure Hz noise section also includes part background
Noise, but the background noise due to rear extended meeting carry out it is smooth wait post processing, so on going power frequency to affect less).
The power frequency frequency domain amplitude of described pure Hz noise section, and it is determined that input signal is in pure Hz noise section
When, the power frequency frequency domain amplitude that input signal is carried out, after time-frequency convert, obtaining.It should be noted that the pure power frequency for storing here
The power frequency frequency domain amplitude of interference section, a typically cycle power frequency frequency domain amplitude, for example, power frequency component is typically sine wave,
The frequency domain amplitude of one cycle power frequency frequency domain amplitude complete a cycle namely in the sine wave.
In the present embodiment, according to the power frequency frequency domain amplitude of pure Hz noise section, range-adjusting is carried out to the second power frequency component,
Described range-adjusting refers to the cycle power frequency frequency domain amplitude and pure power frequency that the current time of the second power frequency component is located
The proportional adjustment of power frequency frequency domain amplitude of interference section, from from waveform, is similar to the ripple of second power frequency component at current time
Shape is approximately the same with the power frequency waveform of pure Hz noise section, is only possible to amplitude different.
If including the input signal after the high-frequency signals such as voice signal, i.e. delay process in the first power frequency component, just
May cause that the waveform shape of the second power frequency component is irregular, amplitude is varied from, some projections or recessed etc. such as occur；
And after being adjusted according to the power frequency frequency domain amplitude of pure Hz noise section, obtain the 3rd power frequency component, it is possible to recover the second work
The due waveform shape of frequency signal, rejects voice signal therein so that the 3rd power frequency component is pure as far as possible, will not load
There is voice signal, so as to echo just can be eliminated in the output signal.
104th, by range-adjusting after the 3rd power frequency component change when entering line frequency, obtain correcting power frequency component；
Wherein, after the process of above-mentioned range-adjusting, obtain the 3rd power frequency information, it is possible to which the 3rd power frequency component is entered
Change during line frequency, obtain correcting power frequency component, the amendment power frequency component is exactly the pure power frequency component for eliminating voice signal.
105th, the input signal is deducted into the amendment power frequency component, obtains output signal.
Wherein, the amendment power frequency component is removed from input signal after obtaining correcting power frequency component by comb filter,
Eliminate the need for Hz noise.
The method of the elimination Hz noise of the present embodiment, by power frequency component is carried out time-frequency convert, and according to pure power frequency
The power frequency frequency domain amplitude of interference section, carries out range-adjusting to the power frequency component after time-frequency convert, eliminates the language in power frequency component
Message number, it is achieved thereby that while Hz noise is eliminated, eliminating the echo that the input signal after time delay causes.
Embodiment two
Method described in embodiment one, be to comb filter power frequency filtering stage changing of carrying out of handling process
Enter, the method for the elimination Hz noise of the present embodiment, on the basis of embodiment one, increased the work before power frequency filtering stage
Frequency detection, power frequency trace flow, further to improve the detection accuracy that whether there is Hz noise to input signal, to avoid
Process by mistake；Also, more accurate power frequency fundamental frequency is obtained, with the fundamental frequency drift for overcoming common frequency power network instability to cause, work is improved
The eradicating efficacy of frequency interference.
Fig. 2 is the schematic flow sheet of another embodiment of method that the present invention eliminates Hz noise, and the Fig. 2 shows this enforcement
The overall flow of example method, the method are performed by the system for eliminating Hz noise.Input signal be input into the system after,
System is performed the process that power frequency detection, power frequency tracking and power frequency filter three flow stages successively to the input signal, most
Output signal is obtained eventually.Wherein,
Power frequency is detected：Input signal is detected mainly in whether there is Hz noise with the presence or absence of power frequency component, can be with
The power frequency is detected whether into that the power frequency component for existing is referred to as the 5th power frequency component；If there is no Hz noise (" 0 " in Fig. 2
There is no Hz noise in expression), then input signal is left intact, and directly exports, that is, obtains output signal；Otherwise, if
There is Hz noise (" 1 " in Fig. 2 represents there is Hz noise), then the power frequency detection-phase can also obtain the 5th power frequency letter
Number fundamental frequency, and the fundamental frequency value is sent to power frequency tracking phase, power frequency tracking is carried out according to the fundamental frequency；
Power frequency is tracked：Real-time tracking is carried out to the fundamental frequency that power frequency detection-phase is obtained mainly, it is unstable to tackle electrical network
Property the fundamental frequency drift phenomenon that causes, when fundamental frequency skew is larger, the real-time fundamental frequency of acquisition is updated to fundamental frequency；
Power frequency is filtered：According to the real-time fundamental frequency that power frequency tracking phase determines, amount of delay is obtained；And according to the amount of delay to defeated
Enter signal and enter line delay to obtain time delayed signal, the first power frequency component is calculated according to time delay, by power frequency component from input signal
Remove, just complete the elimination to the Hz noise in input signal, obtain output signal.In the present embodiment, rank is filtered in power frequency
Section is filtered to Hz noise using comb filter.
Below by the order according to handling process, respectively to above-mentioned power frequency detection, power frequency tracking and power frequency filtering three
The process of individual flow stages elaborates：
Power frequency is detected：
Power frequency fundamental frequency is determined by electromotor, at present only two fundamental frequency standards：50HZ and 60HZ；The work of the present embodiment
The main purpose of frequency detection-phase is to whether there is power frequency component in detection input signal, if it is present the work is also predefined
The fundamental frequency of frequency signal is 50HZ or 60HZ.
The present embodiment, is by entering the calculating of line period residual energy to input signal, judging whether Hz noise
's；The given threshold of an energy difference log-domain average can be pre-set, and (detection time is preset within continuous a period of time
It is interior) multiple energy difference log-domain average is calculated, if in the default detection time, multiple calculated energy difference log-domain
Average has been above the given threshold, then be judged to that Hz noise is present；Otherwise Hz noise is not present；Because for example for certain
The music signals of some similar power frequency components, its frequency will not the frequency range that is located in power frequency component of long-time stable, so, it is logical
Cross the change of the stability of period of the energy difference log-domain average for tracking above-mentioned input signal, it is possible to reduce the generation of erroneous judgement.
Specifically, referring to Fig. 3, Fig. 3 is that the present invention eliminates the power frequency detection stream in another embodiment of method of Hz noise
Cheng Tu, the detection process include：
301st, receives input signal；For example, the input signal is audio signal；
Wherein, after receiving an input signal, 302 and 303 are performed respectively；
302nd, calculate the ENERGY E 0 of input signal；
Wherein it is possible to be the ENERGY E 0 of the input signal for calculating L length, the L length can for example be in the present embodiment
The input signal of one power frequency period T.
303rd, by input signal time delay power frequency period T；
Wherein, if input signal is x (n), it is x (n-T) after time delay power frequency period T.Described x (n) represents wherein one
The input signal of individual sampling, for example, has extracted 100 input signals, that is, carried out 100 sampling, then x (1), x (2)
... x (100) represents this 100 input signals respectively.
Described power frequency period is the work frequency 50HZ or 60HZ corresponding cycle；As described in front, current power frequency
Fundamental frequency is that work frequency only has 50HZ or 60HZ, if there is Hz noise, the present embodiment to determine be on earth 50HZ or
60HZ, so, the present embodiment really calculates the corresponding cycle residual energy of power frequency component of 50HZ, 60HZ simultaneously, also
It is input signal, in this step 303, to be distinguished the power frequency period of the power frequency period and 60HZ of time delay 50HZ, is obtained two and is prolonged
When after input signal.After assuming the power frequency period T1 of input signal x (n) time delay 50HZ, time delayed signal x (n-T1) is obtained,
After the power frequency period T2 of input signal x (n) time delay 60HZ, the time delayed signal for obtaining is x (n-T2).
304th, calculate cycle residual energy E1 of input signal；
Wherein, the calculating of cycle residual energy, actually by the input signal after time delay in input signal and 303
The amplitude of corresponding sample point subtracted each other, such as subtracted each other by the subtractor G1 shown in Fig. 3, then calculated after correspondence subtracts each other
Square, the above-mentioned square of quadratic sum afterwards that carry out for finally calculating each sample point obtains cycle residual energy E1.
Ibid, it is also required to calculate the cycle residual energy of correspondence 50HZ, 60HZ respectively in this step；For example, by input letter
Number subtract each other with time delayed signal x (n-T1) obtain be corresponding 50HZ cycle residual energy E150, by input signal and time delayed signal
X (n-T2) subtract each other obtain be correspondence 60HZ cycle residual energy E160。
305th, judge the ENERGY E 0 of input signal whether more than cycle residual energy E1；
If E0 is not more than E1 (" 0 " in Fig. 3 represents that judged result is no), the energy difference logarithm of input signal is obtained
Domain average (Par Energy, referred to as：PE it is) 0, does not do subsequent treatment；
If E0 continues executing with 306 more than E1 (" 1 " in Fig. 3 represents that judged result is yes).
In the same manner, it is also required to be respectively compared 50HZ, 60HZ corresponding E0 and E1 in this step, for example, compares E0 and E150, and
Relatively E0 and E160。
306th, calculate energy difference log-domain average PE=10*lg of input signal10((E0-E1)/L。
Wherein, energy difference log-domain average PE for obtaining includes the PE for corresponding to 50HZ, 60HZ respectively.
Additionally, the method for the elimination Hz noise of the present embodiment, when the elimination of Hz noise is carried out to audio signal, is
The mode of sample process is taken, for example, single sample is carried out at interval of time t, obtain an input signal, carry out the present embodiment
The signal processing of methods described；So, in above-mentioned step, it is the process to wherein single sample, is such as to certain week
The process of phase signal, as mentioned in 302, is the input signal to L length (can be a power frequency period T).If examined
The audio signal is surveyed with the presence or absence of Hz noise, according to the stability of period principle of foregoing Hz noise, the present embodiment
By the energy difference log-domain average of tracking a period of time, for example, whether the input signal can be judged with 4 cycles of Continuous plus
It is stable.So, as shown in figure 3, return performing 301, the process of next input signal is performed, and finally gives next input
Energy difference log-domain average PE of signal.Then, return again to execution 301, until it reaches default detection time, during the default detection
Between be to can interpolate that whether signal meets a period of time of stability of period, example can be 4 power frequencies of Continuous plus as mentioned
Cycle.
307th, when default detection time is reached, judge whether calculated multiple energy difference log-domain averages PE surpass
Cross given threshold；
If it is judged that to be (branch 1 in Fig. 3), then showing that the input signal has stability of period, because example
As if for the music signal of some similar power frequencies, its frequency will not the scope that is located in Hz noise of long-time stable,
Calculated energy difference log-domain average also will not be in exceed all the time given threshold in a period of time, so determining the input
There is Hz noise, i.e. input signal in signal and there is the 5th power frequency component, continue executing with 308.Otherwise, if it is determined that knot
Fruit is no (branch 0 in Fig. 3), then show that the input signal does not have Hz noise.Described given threshold is being embodied as
In rule of thumb can set.
When input signal does not have Hz noise, Fig. 2 is may refer to, the branch " 0 " in Fig. 2 represents that there is no power frequency does
Disturb, input signal will not continue to perform the flow process of power frequency tracking phase, because there is no Hz noise, institute in the input signal
So that follow-up power frequency tracking, power frequency filtering need not be performed, directly export；When there is Hz noise in input signal, Fig. 2
In branch " 1 " represent there is Hz noise, input signal just continues executing with the process of power frequency tracking phase.
308th, determine the fundamental frequency of the 5th power frequency component present in input signal；
Wherein, the fundamental frequency of the 5th described power frequency component is exactly the corresponding work frequency of the power frequency period.
For example, if correspondence is by the situation of the power frequency period T1 of input signal time delay 50HZ, the 50HZ correspondences are finally given
PE exceed given threshold in default detection time, then just can determine the fundamental frequency of power frequency component present in input signal
It is 50HZ；In the same manner, if the corresponding PE of 60HZ exceed given threshold in default detection time, can determine input signal
Present in the fundamental frequency of power frequency component be exactly 60HZ.Generally testing result only has a kind of fundamental frequency, will not two kinds of fundamental frequencies be satisfied by bar
Part.
By above-mentioned power frequency detection-phase, it has been determined that whether there is the 5th power frequency component in input signal, also,
If it does, having had also determined that the fundamental frequency of the 5th power frequency component；Afterwards, input signal will be power frequency into the next stage
Tracking phase.
It should be noted that assuming, in the system for eliminating Hz noise, to perform at power frequency detection-phase input signal
Reason is power frequency detection module, and perform the process of power frequency tracking phase is power frequency tracking module, performs power frequency filtering stage and processes
Be power frequency filtration module (the power filter module can be comb filter), then input signal performing power frequency detection
After phase process, the power frequency tracking module (delay process described in 303 steps performed in power frequency detection-phase is will be directed into
The process simply taken in the detection-phase, remains input signal x (n) into power frequency tracking module).
Power frequency is tracked：
The main purpose of this power frequency tracking phase process is as follows：In the power filter stage of back, the present embodiment is to adopt
What comb filter was processed, comb filter generally needs to enter input signal after line delay, further according to time delayed signal meter
Calculation obtains power frequency component, and is to be determined according to power frequency fundamental frequency to the amount of delay of input signal, and such as power frequency detection module determines
Power frequency fundamental frequency (50HZ or 60HZ).But, in being embodied as, may especially will not be managed due to generator operation stability
Think, network load change etc. cause frequency drift, so, the power frequency component of non-standard fundamental frequency is likely to be encountered in practical application, such as
Fruit is filtered still according to the power frequency fundamental frequency (50HZ or 60HZ) of standard, the eradicating efficacy possible deviation of Hz noise.It is based on
This, the present embodiment by the power frequency tracking phase, detects frequency drift amount, and obtains to improve the eradicating efficacy of Hz noise
Fundamental frequency during treating excess syndrome, so that fundamental frequency is more accurate, so sends real-time fundamental frequency to comb filter (i.e. power frequency filtration module),
Comb filter just can determine amount of delay according to the real-time fundamental frequency, also so that the elimination of Hz noise is more accurate.
Wherein, input signal, through power frequency detection module, is directly sent out for the first time into after the system of the elimination Hz noise
Deliver to power frequency tracking module；Also, when there is Hz noise in the input signal is determined for the first time in power frequency detection module, can be by really
Fixed power frequency fundamental frequency is sent to power frequency tracking module, and there is Hz noise in informing the power frequency tracking module input signal；Work
Frequency tracking module can carry out the fundamental frequency tracking of the present embodiment and process.The input signal sampled below enters the elimination Hz noise
System after, due to being same input signal (simply corresponding sample time different), power frequency detection module no longer will be informed
Power frequency tracking module power frequency fundamental frequency, that is to say, that the input signal must be always this fundamental frequency, it is not necessary to which detection every time is all led to
Know power frequency tracking module.
Specifically, the present embodiment carries out two-part process in power frequency tracking phase：The extraction of power frequency fundamental frequency signal and
The process of method of correlation frequency shift tracking；It is respectively described below：
The extraction of power frequency fundamental frequency signal：The power frequency tracking module of the present embodiment, has used wave trap, and the wave trap can be with root
According to the power frequency fundamental frequency that power frequency detection module sends, power frequency fundamental frequency signal is extracted from the input signal for receiving, with phase below
Dependency process is done processing stage the method frequency shift tracking of pass to the power frequency fundamental frequency signal of the extraction, fundamental frequency side-play amount is calculated and (also may be used
To be referred to as frequency shift value).
The transmission function of wave trap is as follows：
Wherein, in order to obtain power frequency fundamental frequency signal as stable as possible, make wave trap precipitous enough, in above-mentioned formula (1)
Coefficient a press following value：
α=- 2*cos (2*pi*f/Fs) ... (2)
In formula (2), it is, for example, that power frequency detection module sends that f is the target fundamental frequency for needing wave trap to carry out trap process
Power frequency fundamental frequency, Fs for input signal sampling frequency.
According to wave trap transmission function above, the formula that implements that can obtain wave trap is：
Y (n)=x (n)+α * x (n-1)+* x (n-2)-α * p*y (n-1)-p2*x(n-2)
.........(3)
According to above-mentioned formula (3), power frequency fundamental frequency signal can be obtained as follows：
Z (n)=- (α * x (n-1)+* x (n-2)-α * p*y (n-1)-p2*x(n-2))............(4)
N in above-mentioned formula (3) and (4) represents each sampled signal；According to above-mentioned each formula, wave trap just can be from
Power frequency fundamental frequency signal is extracted in input signal.
The process of method of correlation frequency shift tracking：What the method for correlation frequency shift tracking was processed realizes that process is mainly, and referring to Fig. 4, Fig. 4 is
The present invention eliminates the dependent frequency shift tracking schematic diagram in another embodiment of method of Hz noise.The present embodiment setting correlation away from
From for L=10T, T is power frequency period；Take the power frequency base in former and later two cycles of the position Z1 that currently processed input signal is located
Frequency signal (S1 i.e. shown in Fig. 4), and the past is apart from power frequency fundamental frequency signal (the i.e. Fig. 4 in former and later two cycles of L positions Z2
Shown in S2)；Power frequency fundamental frequency signal S2 is carried out into 5 sampling points skew correlation computations.Here 5 sampling points skew correlation computations can be with
Calculation according to conventional method of correlation frequency shift tracking is processed, and specific calculation is no longer described in detail.
Mainly by power frequency fundamental frequency signal S2, both direction is calculated one by one with a sampling dot spacing to the left and right respectively, is often moved
Dynamic sampling dot spacing, the power frequency fundamental frequency signal after movement and power frequency fundamental frequency signal S1 are just carried out the amplitude of corresponding sample point
It is multiplied, obtains the correlation of the two signals.Power frequency fundamental frequency signal S2 maximums are moved to the left into 5 sample points, it is also maximum to the right
Mobile 5 sample points, obtain the position that the corresponding power frequency fundamental frequency signal of correlation of maximum is located, that is to say the correlation of maximum
The deviant of corresponding power frequency fundamental frequency signal and Z2, for example, power frequency fundamental frequency signal offset by 5 sample points to the left relative to Z2,
The power frequency fundamental frequency signal of the S3 indications i.e. shown in Fig. 4.
5 sample points of skew obtained above are the side-play amounts of L length i.e. 10 power frequency period, then are calculated accordingly flat
The skew sampling point of equal a cycle；If a cycle mean deviation is less than a sampling point, show that power frequency fundamental frequency is relatively stable,
Former base frequency is kept to be worth constant, former base frequency here is the fundamental frequency referred to by the f in formula (2), equivalent to target fundamental frequency；Such as
Fruit power frequency fundamental frequency is unstable, and a cycle mean deviation is larger, then need to be updated former base frequency, and the method for renewal is, than
Such as, it is assumed that a cycle averagely offset by 2 sample points to the left, and an original cycle power frequency fundamental frequency signal is sampled comprising 4
Point, then be changed to a cycle comprising 6 sample points (equivalent to 2 sample points are increased, if to right avertence by power frequency fundamental frequency signal
Move, then remove two sample points), so as sampling frequency is certain, so the power frequency fundamental frequency signal in a cycle is corresponding
Time will increase, and the fundamental frequency of power frequency fundamental frequency signal will reduce, and can be calculated new power frequency fundamental frequency, i.e., real-time fundamental frequency.
According to principles described above, 2 for offseting to the left sample point is properly termed as the frequency shift value of power frequency fundamental frequency, if described
Frequency shift value (such as frequency displacement is less than sample point) in preset range, then keep the fundamental frequency constant；Otherwise, according to the frequency
Shifting value is calculated the real-time fundamental frequency.The method of correlation frequency shift tracking of the present embodiment, unstable in power frequency fundamental frequency, frequency deviation is larger
When, can be with self-adaptative adjustment tracking velocity, you can accordingly to turn correlation distance L down.
When the input signal on once carries out power frequency tracking process, for example, the audio signal of next frame is processed
When, fundamental frequency of the real-time fundamental frequency that frame under process can be obtained by power frequency tracking module as next secondary tracking, that is, as public
F in formula (2), wave trap power frequency fundamental frequency signal pair to be extracted when the real-time fundamental frequency of frame under process will become next process frame
The fundamental frequency answered.Using the method for the present embodiment, 0.04HZ is reached to the acquisition high precision of power frequency fundamental frequency, follow-up work will be greatly improved
The effect of Hz noise is eliminated in frequency filtering stage according to the power frequency fundamental frequency.
Power frequency is filtered：
The real-time fundamental frequency that power frequency filtering stage will be obtained according to power frequency tracking phase, carries out the Processing for removing of power frequency component.
The power frequency filtration module of the present embodiment uses comb filter, and Fig. 5 is another reality of method that the present invention eliminates Hz noise
The comb filter process chart in example is applied, as shown in figure 5, original work of the comb filter before the present embodiment improvement
Frequency filtering principle is mainly, and after input signal x (n) is received, the x (n) is entered line delay first, obtains time delayed signal x (n-
T), power frequency component z (n) is calculated further according to time delayed signal x (n-T), finally deduct from input signal x (n) and calculate
To power frequency component z (n) just obtain filtered output signals y (n).
In the present embodiment, mainly power frequency component is calculated in view of by thus according to time delayed signal x (n-T), so obtaining
Power frequency component z (n) be in fact with time delay after input signal information, that is, there is echo；The improvement of the present embodiment is main
It is to eliminate the echo in power frequency component z (n) so that the power frequency component of calculating is pure as far as possible.Referring to Fig. 5, according to time delay
After signal x (n-T) is calculated power frequency component z (n), increased power frequency amendment processing stage, the main mesh of the power frequency amendment
Be exactly to eliminate the echo information in power frequency component z (n), obtain correcting power frequency component z ' (n), deduct from input signal x (n)
Amendment power frequency component z ' (n), obtains filtered output signals y ' (n), the y ' (n) in do not contain echo.
Below the handling process of the comb filter is elaborated：
The transmission function of the comb filter is：
Wherein, T is amount of delay, is power frequency fundamental frequency cycles (i.e. power frequency period), is calculated according to T=Fs/f, round numbers；System
Number α1、α2、b1、b2Set according to the remainder of T=Fs/f；Fs is sampling frequency, and f is power frequency fundamental frequency；Coefficient p：0 ＜ p ＜ 1.
According to above-mentioned transmission function, the process that can obtain comb filter realizes that equation is as follows：
Y (n)=x (n)-b1*x(n-T)-b2*x(n-T+1)+α1*p*y(n-T)+α2*p*x(n-T+1)
.........(6)
According to the equation that above-mentioned formula (6) can obtain comb filter calculating power frequency component it is：
Z (n)=b1*x(n-T)+b2*x(n-T+1)-α1*p*y(n-T)-α2*p*x(n-T+1)...(7)
According to formula (7), comb filter just can be calculated power frequency component z (n) according to time delayed signal.Then, it is right
Power frequency component z (n) is modified process and obtains correcting power frequency component z ' (n), and the detailed process of the correcting process may refer to figure
6, Fig. 6 is that the present invention eliminates the power frequency correcting process flow chart in another embodiment of method of Hz noise.
It is shown in Figure 6, after by input signal time delay T, power frequency component z (n) is being calculated according to time delayed signal x (n-T)
Before, detect whether x (n-T) only includes power frequency component, you can to carry out voice activity detection (Voice Activation
Detection, referred to as：VAD), whether may determine that in time delayed signal x (n-T) comprising voice by the detection.Assume VAD
In the Liang Ge branches of detection, 0 represents containing voice,
1 represents that pure interference only includes power frequency component without voice, the power frequency component can be referred to as the 4th power frequency component.
When testing result is 1, pure disturbance state i.e. time delayed signal is shown to be in pure Hz noise section；Now, continue to be prolonged according to this
When signal x (n-T) be calculated the 4th power frequency component z (n), and the 4th power frequency component z (n) carried out into time-frequency convert obtain Z
N (), can now obtain the power frequency frequency domain amplitude of pure Hz noise section, preserve the frequency domain amplitude.The frequency domain of the preservation
Amplitude is a cycle power frequency frequency domain amplitude of current time i.e. frame under process, is the complete a cycle of the power frequency component for preserving
Amplitude.
Afterwards, as long as receiving input signal, after by input signal time delay, all time delayed signal x (n-T) can be carried out
The VAD detections stated；In each pure Hz noise section, if power frequency frequency domain changes, will be to the frequency domain that preserves before
Amplitude is updated.And if the testing result of VAD is 0, shows containing voice, be not pure Hz noise section, then do not process,
Continue to keep the frequency domain amplitude of storage constant.
If the part for detecting above-mentioned VAD is referred to as branch F1, another branch F2 is then the primary process of power frequency amendment,
In fact, the VAD done by branch F1 detects and stores power frequency frequency domain amplitude, and it is to service for branch F2, will in branch F2
According to the frequency domain amplitude stored in branch F1, range-adjusting is carried out to power frequency component.Furthermore, it is necessary to explanation, will be defeated
Enter after signal lag obtains time delayed signal x (n-T), branch F1 and branch F2 will be performed.
For branch F2, according to time delayed signal x (n-T), and formula recited above (7) be calculated the first power frequency
After signal z (n), time-frequency convert is carried out to the first power frequency component z (n) and obtains the second power frequency component Z (n), for example, can be to utilize
Discrete Fourier transform technology carries out time-frequency convert.Then, to time-frequency convert after the second power frequency component Z (n) carry out amplitude tune
It is whole, range-adjusting is carried out according to the power frequency frequency domain amplitude of the pure Hz noise section for storing before specifically, the principle of adjustment is to incite somebody to action
A cycle power frequency frequency domain amplitude in the second current power frequency component Z (n) enters according to the power frequency frequency domain amplitude of pure Hz noise section
Row equal proportion is adjusted so that the waveform in current second power frequency component Z (n) is consistent with the power frequency waveform of pure Hz noise section, this
Sample can will not be loaded with the impact of voice signal so that the second power frequency component is pure as far as possible；Work after range-adjusting
Frequency signal be Z ' (n), be properly termed as the 3rd power frequency component.Wherein, after range-adjusting is carried out, can also to adjustment after
Two power frequency components carry out the smoothing processing between neighbouring sample point, obtain the 3rd power frequency component, so that voice signal disappears
Except effect it is more preferable.
Finally, by range-adjusting after the 3rd power frequency component Z ' change when (n) entering line frequency, obtain correcting power frequency component z '
(n).In conjunction with Fig. 5, amendment power frequency component z ' is deducted from input signal x (n) and (n), just obtains output signal y ' (n).
By power frequency component is carried out time-frequency convert, and according to the power frequency frequency domain amplitude of pure Hz noise section, time-frequency is turned
Power frequency component after changing carries out range-adjusting, eliminates the voice signal in power frequency component, it is achieved thereby that doing power frequency is eliminated
While disturbing, the echo that the input signal after time delay causes is eliminated.
Embodiment three
Fig. 7 is the structural representation of one embodiment of system that the present invention eliminates Hz noise, as shown in fig. 7, in the system
Including：Power frequency filtration module 11；The power frequency filtration module 11 includes：Filtering delay-time unit 111, power frequency computing unit 112, power frequency
Amending unit 113 and filtering output unit 114；Wherein,
Filtering delay-time unit 111, for input signal time delay is obtained time delayed signal；
Power frequency computing unit 112, for being calculated the first power frequency component according to the time delayed signal；
Power frequency amending unit 113, for first power frequency component is carried out time-frequency convert, and according to the pure power frequency of storage
Interference section power frequency frequency domain amplitude, to time-frequency convert after the second power frequency component carry out range-adjusting；After by range-adjusting
Three power frequency components are changed when entering line frequency, obtain correcting power frequency component；
Filtering output unit 114, for input signal is deducted amendment power frequency component, obtains output signal.
Further, power frequency amending unit 113, be additionally operable to it is described to time-frequency convert after the second power frequency component carry out width
After value adjustment, the smoothing processing between neighbouring sample point is carried out, the 3rd power frequency component is obtained.
Fig. 8 is the structural representation of another embodiment of system that the present invention eliminates Hz noise, as shown in figure 8, in Fig. 7 institutes
On the basis of showing structure, power frequency filtration module 11 also includes：Amplitude determining unit 115；
The amplitude determining unit 115, for, after input signal time delay is obtained time delayed signal, being believed according to the time delay
Before number being calculated the first power frequency component, detect whether the time delayed signal only includes the 4th power frequency component；In testing result
During to be, it is determined that the time delayed signal is in the pure Hz noise section, described the is calculated according to the time delayed signal
Four power frequency components, and the 4th power frequency component is carried out into time-frequency convert, obtain the power frequency frequency domain width of the pure Hz noise section
Value；Store the power frequency frequency domain amplitude of pure Hz noise section.
Further, the system also includes：Power frequency detection module 12 and power frequency tracking module 13；Wherein,
Power frequency detection module 12, for, before input signal time delay is obtained time delayed signal, detecting the input signal
With the presence or absence of the 5th power frequency component；And when testing result is to have power frequency component, obtain the fundamental frequency of the 5th power frequency component；
Power frequency tracking module 13, for carrying out frequency shift tracking to the fundamental frequency, obtains real-time fundamental frequency；
The filtering delay-time unit 111 in the power frequency filtration module, specifically for being obtained according to the real-time fundamental frequency
Amount of delay, the input signal according to the amount of delay time delay obtain the time delayed signal.
Further, power frequency detection module 12, including：Detection delay unit 121, energy calculation unit 122, interference judge
Unit 123 and fundamental frequency determining unit 124；Wherein,
Detection delay unit 121, for by the input signal time delay power frequency period, the power frequency period is work frequency
The 50HZ or 60HZ corresponding cycles；
Energy calculation unit 122, for according to the input signal after the input signal and time delay power frequency period, calculating
The energy and cycle residual energy of the input signal, if the energy is more than the cycle residual energy, calculates described defeated
Enter the energy difference log-domain average of signal；
Interference judging unit 123, for, in default detection time, calculated multiple energy difference log-domains are equal
When value exceedes given threshold, then judge that the input signal has the 5th power frequency component；
Fundamental frequency determining unit 124, for when the input signal has five power frequency component, determining the described 5th
The fundamental frequency of power frequency component is the corresponding work frequency of the power frequency period.
Further, power frequency tracking module 13, can include：Fundamental frequency signal extraction unit 131, dependent frequency shift tracking cell
132 and real-time fundamental frequency updating block 133；Wherein,
Fundamental frequency signal extraction unit 131, for the institute determined according to the fundamental frequency determining unit in the power frequency detection module
The fundamental frequency of the 5th power frequency component is stated, and the corresponding power frequency fundamental frequency signal of the fundamental frequency is extracted from the input signal；
Dependent frequency shift tracking cell 132, for using method of correlation frequency shift tracking, carrying out correlation to the power frequency fundamental frequency signal
Property process, obtain the frequency shift value of the fundamental frequency；
Real-time fundamental frequency updating block 133, for when the frequency shift value is in preset range, keeping the fundamental frequency constant；
Otherwise, the real-time fundamental frequency is calculated according to the frequency shift value.
One of ordinary skill in the art will appreciate that：Realize that all or part of step of above-mentioned each method embodiment can be led to
Cross the related hardware of programmed instruction to complete.Aforesaid program can be stored in a computer read/write memory medium.The journey
Sequence upon execution, performs the step of including above-mentioned each method embodiment；And aforesaid storage medium includes：ROM, RAM, magnetic disc or
Person's CD etc. is various can be with the medium of store program codes.
Finally it should be noted that：Various embodiments above only to illustrate technical scheme, rather than a limitation；To the greatest extent
Pipe has been described in detail to the present invention with reference to foregoing embodiments, it will be understood by those within the art that：Its according to
So the technical scheme described in foregoing embodiments can be modified, or which part or all technical characteristic are entered
Row equivalent；And these modifications or replacement, do not make the essence of appropriate technical solution depart from various embodiments of the present invention technology
The scope of scheme.
Claims (10)
1. it is a kind of eliminate Hz noise method, it is characterised in that include：
Input signal time delay is obtained into time delayed signal, and the first power frequency component is calculated according to the time delayed signal；
First power frequency component is carried out into time-frequency convert, and the power frequency frequency domain amplitude of the pure Hz noise section according to storage, it is right
The second power frequency component after time-frequency convert carries out range-adjusting, wherein, the range-adjusting refers to second power frequency component
The cycle power frequency frequency domain amplitude adjustment proportional to the power frequency frequency domain amplitude of pure Hz noise section that current time is located；
The 3rd power frequency component after by range-adjusting is changed when entering line frequency, obtains correcting power frequency component；
The input signal is deducted into the amendment power frequency component, output signal is obtained；
Wherein, it is described input signal time delay is obtained into time delayed signal after, and be calculated first according to the time delayed signal
Before power frequency component, also include：
Detect whether the time delayed signal only includes power frequency component；
When testing result is to be, it is determined that the time delayed signal is in the pure Hz noise section, according to the time delayed signal
The 4th power frequency component is calculated, and the 4th power frequency component is carried out into time-frequency convert, obtain the pure Hz noise section
Power frequency frequency domain amplitude；Store the power frequency frequency domain amplitude of the pure Hz noise section.
2. it is according to claim 1 eliminate Hz noise method, it is characterised in that also include：Time-frequency is turned described
After the second power frequency component after changing carries out range-adjusting,
The smoothing processing between neighbouring sample point is carried out, the 3rd power frequency component is obtained；
It is described by range-adjusting after the 3rd power frequency component change when entering line frequency, specially：Described in after the smoothing processing
3rd power frequency component is changed when entering line frequency.
3. it is according to claim 1 and 2 eliminate Hz noise method, it is characterised in that it is described by input signal time delay
Before obtaining time delayed signal, also include：
The input signal is detected with the presence or absence of the 5th power frequency component, wherein, the 5th power frequency component is Hz noise；
If existing, the fundamental frequency of the 5th power frequency component is obtained, and frequency shift tracking is carried out to the fundamental frequency, obtain real-time base
Frequently；
Amount of delay is obtained according to the real-time fundamental frequency, the time delay letter is obtained with the input signal according to the amount of delay time delay
Number.
4. the method for eliminating Hz noise according to claim 3, it is characterised in that the detection input signal is
The 5th power frequency component of no presence, including：
By the input signal time delay power frequency period, the power frequency period is the work frequency 50HZ or 60HZ corresponding cycle；
According to the input signal after the input signal and time delay power frequency period, energy and the cycle of the input signal are calculated
Residual energy；
If the energy is more than cycle residual energy, the energy difference log-domain average of the input signal is calculated；
Return execution described by input signal time delay power frequency period, the input signal is next input signal, and obtains institute
State the energy difference log-domain average of next input signal, until it reaches default detection time；
If in the default detection time, calculated multiple energy difference log-domain averages exceed given threshold,
Then judge that the input signal has the 5th power frequency component, and the fundamental frequency of the 5th power frequency component is the power frequency period
Corresponding work frequency.
5. it is according to claim 3 eliminate Hz noise method, it is characterised in that it is described that frequency displacement is carried out to the fundamental frequency
Tracking, obtains real-time fundamental frequency, including：
According to the fundamental frequency of the 5th power frequency component, the corresponding power frequency fundamental frequency signal of the fundamental frequency is extracted from the input signal；
Using method of correlation frequency shift tracking, dependency process is carried out to the power frequency fundamental frequency signal, the frequency shift value of the fundamental frequency is obtained；
If the frequency shift value is in preset range, keep the fundamental frequency constant；Otherwise, institute is calculated according to the frequency shift value
State real-time fundamental frequency.
6. it is a kind of eliminate Hz noise system, it is characterised in that include：Power frequency filtration module, the power frequency filtration module bag
Include：
Filtering delay-time unit, for input signal time delay is obtained time delayed signal；
Power frequency computing unit, for being calculated the first power frequency component according to the time delayed signal；
Power frequency amending unit, for first power frequency component is carried out time-frequency convert, and according to the pure Hz noise section of storage
Power frequency frequency domain amplitude, to time-frequency convert after the second power frequency component carry out range-adjusting；The 3rd power frequency after by range-adjusting
Signal is changed when entering line frequency, obtains correcting power frequency component, wherein, the range-adjusting refers to the current of second power frequency component
The cycle power frequency frequency domain amplitude adjustment proportional to the power frequency frequency domain amplitude of pure Hz noise section that moment is located；
Filtering output unit, for the input signal is deducted amendment power frequency component, obtains output signal；
Wherein, the power frequency filtration module, also includes：
Amplitude determining unit, for after input signal time delay is obtained time delayed signal, and calculates according to the time delayed signal
Before obtaining the first power frequency component, detect whether the time delayed signal only includes power frequency component；When testing result is to be, then really
The fixed time delayed signal is in the pure Hz noise section, is calculated the 4th power frequency component according to the time delayed signal, and will
4th power frequency component carries out time-frequency convert, obtains the power frequency frequency domain amplitude of the pure Hz noise section；Store the pure work
Frequency disturbs the power frequency frequency domain amplitude of section.
7. it is according to claim 6 eliminate Hz noise system, it is characterised in that the power frequency amending unit, also use
In it is described to time-frequency convert after the second power frequency component carry out range-adjusting after, carry out the smooth place between neighbouring sample point
Reason, obtains the 3rd power frequency component.
8. according to claim 6 or 7 elimination Hz noise system, it is characterised in that also include：
Power frequency detection module, for, before input signal time delay is obtained time delayed signal, detecting whether the input signal deposits
In the 5th power frequency component, wherein, the 5th power frequency component is Hz noise；And when testing result is to have power frequency component,
Obtain the fundamental frequency of the 5th power frequency component；
Power frequency tracking module, for carrying out frequency shift tracking to the fundamental frequency, obtains real-time fundamental frequency；
The filtering delay-time unit in the power frequency filtration module, specifically for obtaining amount of delay according to the real-time fundamental frequency,
The input signal according to the amount of delay time delay obtains the time delayed signal.
9. it is according to claim 8 eliminate Hz noise system, it is characterised in that the power frequency detection module, including：
Detection delay unit, for by the input signal time delay power frequency period, the power frequency period be work frequency 50HZ or
The 60HZ corresponding cycles；
Energy calculation unit, for according to the input signal after the input signal and time delay power frequency period, calculating described defeated
Enter the energy and cycle residual energy of signal, if the energy is more than the cycle residual energy, calculate the input signal
Energy difference log-domain average；
Interference judging unit, for, in default detection time, calculated multiple energy difference log-domain averages surpass
When crossing given threshold, then judge that the input signal has the 5th power frequency component；
Fundamental frequency determining unit, for when the input signal has five power frequency component, determining the 5th power frequency letter
Number fundamental frequency be the corresponding work frequency of the power frequency period.
10. it is according to claim 9 eliminate Hz noise system, it is characterised in that the power frequency tracking module, bag
Include：
Fundamental frequency signal extraction unit, for the 5th work determined according to the fundamental frequency determining unit in the power frequency detection module
The fundamental frequency of frequency signal, extracts the corresponding power frequency fundamental frequency signal of the fundamental frequency from the input signal；
Dependent frequency shift tracking cell, for using method of correlation frequency shift tracking, carrying out dependency process to the power frequency fundamental frequency signal,
Obtain the frequency shift value of the fundamental frequency；
Real-time fundamental frequency updating block, for when the frequency shift value is in preset range, keeping the fundamental frequency constant；Otherwise, root
The real-time fundamental frequency is calculated according to the frequency shift value.
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