CN104581139A - Synchronous information extraction method and system for video leakage signal - Google Patents

Abstract

The invention provides a synchronous information extraction method for a video leakage signal. The method comprises the following steps: the power spectrum of the video leakage signal is acquired and divided into multiple sub-bands; the spectral centroid of each sub-band is acquired, and an interval between the spectral centroids of every two sub-bands is acquired; line frequency or field frequency of the signal is acquired according to the uniform degree of the spaced distribution of the spectral centroids. The invention further provides a synchronous information extraction system for the video leakage signal. The system comprises a segmentation module, a calculation module and an extraction module. The line frequency or field frequency of the video signal can be extracted accurately and automatically in the presence of noise and interference signals.

Description

The synch information extraction method and system of video leakage signal

Technical field

The present invention relates to communication technical field, be specifically related to the synch information extraction method and system of video leakage signal.

Background technology

Information equipment can produce electromagnetic leakage in various degree in the course of the work, the sensitive information of information equipment process may be contained in this electromagnetic leakage signal, intercepting and capturing to electromagnetic leakage signal can be realized and the sensitive information restored wherein, threat information safety by specific equipment and signal processing means.Therefore, as the key technology of this problem, electromagnetic leakage signal detects the focus and emphasis having become various countries' research, and the detection how effectively realizing electromagnetic leakage signal has become the problem in the urgent need to research.

Be used for extracting the technology mainly correlation detection technology of electromagnetic leakage signal synchronizing information at present.Correlation detection technology is the feature of the application periodicity of signal and the randomness of noise, is reached a kind of technology removing noise by related operation.When random function comprises cyclical component, auto-correlation function also comprises identical periodic component, and Autocorrelation Detection just applies this point.

The signal auto-correlation function being mixed with random noise is:

R(τ)＝R _ss(τ)+R _sn(τ)+R _ns(τ)+R _nn(τ)

R in formula _ss(τ) and R _nn(τ) auto-correlation function of signal and noise is respectively, and R _sn(τ) and R _ns(τ) be the cross-correlation function of signal and noise respectively.Because signal and noise are mutual incoherent random processes, if set the mean value of signal and noise as 0, so R _sn(τ) and R _ns(τ) also 0 is, along with the increase of τ, the auto-correlation function R of noise _nn(τ) will close to 0, and the auto-correlation function R of signal component _ss(τ) but remain periodically change, along with the increase of τ, consequently make the correlation function R of signal _ss(τ) show.

But according to the principle of coherent detection, utilize the method for coherent detection to extract synchronizing information, have following defect: require that long enough is wanted in delay, otherwise R _nn(τ) value is large, causes error; The time of integration, T should long enough, guarantee R _sn(τ)=R _ns(τ)=0, when T has in limited time, causes metrical error; When in signal except random noise, when being also superimposed with PERIODIC INTERFERENCE, R _sn(τ), R _ns(τ), R _nn(τ) value is not all 0, if PERIODIC INTERFERENCE is mixed into signal, cannot extract the synchronizing information of video leakage signal.

Summary of the invention

For the defect of prior art, the invention provides a kind of synch information extraction method and system of video leakage signal, when there is Noise and Interference signal, accurately automatically can extract line frequency frequency and the field frequency frequency of vision signal.

First aspect, the invention provides a kind of synch information extraction method of video leakage signal, described method comprises:

Obtain the power spectrum of video leakage signal, and according to the subband width preset, described power spectrum is divided into multiple subband;

Obtain the spectrum barycenter of each subband, and obtain the spectrum barycenter interval of each subband;

The uniformity coefficient spaced apart according to the spectrum barycenter that different sub-band width is corresponding, extracts line frequency frequency or the field frequency frequency of described signal.

Preferably, described power spectrum is divided into multiple subband by the subband width that described basis is preset, and comprising:

According to the span of line frequency frequency or field frequency frequency, choose line frequency frequency or field frequency frequency successively as subband width according to the step-length preset;

According to described subband width, described power spectrum is divided into multiple subband.

Preferably, the spectrum barycenter of each subband of described acquisition, comprising:

The spectrum barycenter f of each subband is calculated according to following formula _sC:

$\begin{array}{c}{f}_{\mathrm{SC}}={\mathrm{\Σ}}_{n=0}^{N-1}f\left(n\right)E\left(n\right)/{\mathrm{\Σ}}_{n=0}^{N-1}E\left(n\right)\\ =\underset{n=0}{\overset{N-1}{\mathrm{\Σ}}}f\left(n\right)E\left(n\right)/{\mathrm{\Σ}}_{n=0}^{N-1}E\left(n\right)\\ =\underset{n=0}{\overset{N-1}{\mathrm{\Σ}}}f\left(n\right)P\left(E\left(n\right)\right)\end{array}$

Wherein, n represents each point on subband width N, and f (n) is the frequency of often, the power spectrum that E (n) is signal, and N is subband width, and P (E (n)) is the probability of each point power spectrum in gross power spectrum.

Preferably, the spectrum barycenter interval of each subband of described acquisition, comprising:

The spectrum barycenter interval f of each subband is calculated according to following formula _sCD(m):

f _SCD(m)＝f _SC(m+1)-f _SC(m),m＝1,2,…,M

Wherein, m is the numbering of each subband, f _sCm () is the spectrum barycenter of m subband, f _sC(m+1) be the spectrum barycenter of m+1 subband, M represents the number of subband.

Preferably, the uniformity coefficient that the described spectrum barycenter corresponding according to different sub-band width is spaced apart, extracts line frequency frequency or the field frequency frequency of described signal, comprising:

Spectrum barycenter corresponding to different sub-band width uniformity coefficient spaced apart is obtained according to following formula:

SCDT＝SD(f _SCD)/MEAN(f _SCD)

Wherein, SCDT represents the uniformity coefficient that spectrum barycenter is spaced apart, SD (f _sCD) be spectrum barycenter interval f _sCDvariance, MEAN (f _sCD) be spectrum barycenter interval f _sCDaverage;

Choose the minimum value of SCDT, the line frequency frequency that minimum SCDT is corresponding or field frequency frequency are line frequency frequency or the field frequency frequency of final extraction.

Second aspect, the invention provides a kind of synch information extraction system of video leakage signal, described system comprises:

Segmentation module, for obtaining the power spectrum of video leakage signal, and is divided into multiple subband according to the subband width preset by described power spectrum;

Computing module, for obtaining the spectrum barycenter of each subband, and obtains the spectrum barycenter interval of each subband;

Extraction module, for the uniformity coefficient that the spectrum barycenter corresponding according to different sub-band width is spaced apart, extracts line frequency frequency or the field frequency frequency of described signal.

Preferably, described segmentation module, specifically for:

According to the span of line frequency frequency or field frequency frequency, choose line frequency frequency or field frequency frequency successively as subband width according to the step-length preset;

According to described subband width, described power spectrum is divided into multiple subband.

Preferably, described computing module, specifically for:

The spectrum barycenter f of each subband is calculated according to following formula _sC:

$\begin{array}{c}{f}_{\mathrm{SC}}={\mathrm{\Σ}}_{n=0}^{N-1}f\left(n\right)E\left(n\right)/{\mathrm{\Σ}}_{n=0}^{N-1}E\left(n\right)\\ =\underset{n=0}{\overset{N-1}{\mathrm{\Σ}}}f\left(n\right)E\left(n\right)/{\mathrm{\Σ}}_{n=0}^{N-1}E\left(n\right)\\ =\underset{n=0}{\overset{N-1}{\mathrm{\Σ}}}f\left(n\right)P\left(E\left(n\right)\right)\end{array}$

Wherein, n represents each point on subband width N, and f (n) is the frequency of often, the power spectrum that E (n) is signal, and N is subband width, and P (E (n)) is the probability of each point power spectrum in gross power spectrum;

The spectrum barycenter interval f of each subband is calculated according to following formula _sCD(m):

f _SCD(m)＝f _SC(m+1)-f _SC(m),m＝1,2,…,M

Wherein, m is the numbering of each subband, f _sCm () is the spectrum barycenter of m subband, f _sC(m+1) be the spectrum barycenter of m+1 subband, M represents the number of subband.

Preferably, described extraction module, specifically for:

Spectrum barycenter corresponding to different sub-band width uniformity coefficient spaced apart is obtained according to following formula:

SCDT＝SD(f _SCD)/MEAN(f _SCD)

Wherein, SCDT represents the uniformity coefficient that spectrum barycenter is spaced apart, SD (f _sCD) be spectrum barycenter interval f _sCDvariance, MEAN (f _sCD) be spectrum barycenter interval f _sCDaverage;

Choose the minimum value of SCDT, the line frequency frequency that minimum SCDT is corresponding or field frequency frequency are line frequency frequency or the field frequency frequency of final extraction.

As shown from the above technical solution, the invention provides a kind of synch information extraction method and system of video leakage signal, based on the uniformity coefficient that the spectrum barycenter of vision signal is spaced apart, when there is Noise and Interference signal, line frequency frequency and the field frequency frequency of vision signal accurately automatically can be extracted.

Accompanying drawing explanation

In order to be illustrated more clearly in the embodiment of the present invention or technical scheme of the prior art, be briefly described to the accompanying drawing used required in embodiment or description of the prior art below, apparently, accompanying drawing in the following describes is only some embodiments of the present invention, for those of ordinary skill in the art, under the prerequisite not paying creative work, other accompanying drawing can also be obtained according to these figure.

Fig. 1 is the schematic flow sheet of the synch information extraction method of the video leakage signal that one embodiment of the invention provides;

Fig. 2 is the stepwise schematic views of the signal that another embodiment of the present invention provides;

Fig. 3 is the structural representation of the synch information extraction system of the video leakage signal that one embodiment of the invention provides;

Fig. 4 is the comparison diagram of the spectrum centroid algorithm that provides of another embodiment of the present invention and related algorithm running time;

Fig. 5 is the comparison diagram of the spectrum centroid algorithm that provides of another embodiment of the present invention and related algorithm anti-interference.

Embodiment

Below in conjunction with the accompanying drawing in the embodiment of the present invention, be clearly and completely described the technical scheme in the embodiment of the present invention, obviously, described embodiment is only the present invention's part embodiment, instead of whole embodiments.Based on the embodiment in the present invention, those of ordinary skill in the art, not making the every other embodiment obtained under creative work prerequisite, belong to the scope of protection of the invention.

As shown in Figure 1, the schematic flow sheet of the synch information extraction method of the video leakage signal provided for one embodiment of the invention, the method comprises the steps:

101, obtain the power spectrum of video leakage signal, and according to the subband width preset, described power spectrum is divided into multiple subband.

102, obtain the spectrum barycenter of each subband, and obtain the spectrum barycenter interval of each subband.

103, uniformity coefficient spaced apart according to the spectrum barycenter that different sub-band width is corresponding, extracts line frequency frequency or the field frequency frequency of described signal.

In the present embodiment, in step 101, obtain the power spectrum of video leakage signal according to following formula:

$P\left(\mathrm{\ω}\right)=\underset{T\→\∞}{\lim }\frac{{\left|F_T\left(\mathrm{\ω}\right)\right|}^2}{T}$

Wherein, P (ω) represents the power spectrum of signal, and T represents the time, and f (t) is expressed as f on time period t ∈ [-T/2, T/2] _t(t), and f _tt the Fourier transform of () is: F _t(ω)=F [f _t(t)], wherein F [] represents Fourier transform.

In the present embodiment, in step 101, described power spectrum is divided into multiple subband, detailed process is as follows:

A01, span according to line frequency frequency or field frequency frequency, choose line frequency frequency or field frequency frequency as subband width successively according to the step-length preset.

Specifically, if the synchronizing information extracted is line frequency frequency, then the selection range of subband width equals the selection range of the frequent rate of video signal line, the span of line frequency frequency is 30-115KHz, take 1KHz as iteration step length, choose corresponding line frequency frequency successively as subband width, and N=f _h(i), i=30,31,32 ..., 115.

If the synchronizing information extracted is field frequency frequency, then the selection range of subband width equals the selection range of the frequent rate of video field signal, and the span of field frequency frequency is 40-86Hz, take 1Hz as iteration step length, choose corresponding line frequency frequency successively as subband width, and N=f _h(i), i=40,41,42 ..., 86.

A02, according to described subband width, described power spectrum is divided into multiple subband.As shown in Figure 2, wherein N represents subband width to stepwise schematic views, and M represents the number of subband.

In the present embodiment, obtain the spectrum barycenter of each subband in step 102, comprising:

The spectrum barycenter f of each subband is calculated according to following formula _sC:

$\begin{array}{c}{f}_{\mathrm{SC}}={\mathrm{\Σ}}_{n=0}^{N-1}f\left(n\right)E\left(n\right)/{\mathrm{\Σ}}_{n=0}^{N-1}E\left(n\right)\\ =\underset{n=0}{\overset{N-1}{\mathrm{\Σ}}}f\left(n\right)E\left(n\right)/{\mathrm{\Σ}}_{n=0}^{N-1}E\left(n\right)\\ =\underset{n=0}{\overset{N-1}{\mathrm{\Σ}}}f\left(n\right)P\left(E\left(n\right)\right)\end{array}$

Wherein, n represents each point on subband width N, and f (n) is the frequency of often, the power spectrum that E (n) is signal, and N is subband width, and P (E (n)) is the probability of each point power spectrum in gross power spectrum.

Further, the spectrum barycenter interval f of each subband is calculated according to following formula _sCD(m):

f _SCD(m)＝f _SC(m+1)-f _SC(m),m＝1,2,…,M

Wherein, m is the numbering of each subband, f _sCm () is the spectrum barycenter of m subband, f _sC(m+1) be the spectrum barycenter of m+1 subband, M represents the number of subband.

Due to power spectrum signal, to present with line frequency frequency be interval is spacedly distributed, then, when group strip length equals correct line frequency frequency, the spectrum barycenter interval of vision signal should be roughly equal, that is:

f _SCD(m)≈f _SCD(m+1)

When subband width is not equal to line frequency frequency, the spectrum barycenter interval of vision signal should present non-uniform Distribution.Therefore the foundation uniformity coefficient at spectrum barycenter interval can extracted as video synchronizing information.

In the present embodiment, the detailed process of step 103 is as follows:

B01, definition spectrum barycenter distribution character (Spectral Centroid Distribution Trait, be called for short SCDT) spectrum barycenter uniformity coefficient spaced apart is described, then obtain spectrum barycenter corresponding to different subband width uniformity coefficient spaced apart according to following formula:

SCDT＝SD(f _SCD)/MEAN(f _SCD)

Wherein, SCDT represents the uniformity coefficient that spectrum barycenter is spaced apart, SD (f _sCD) be spectrum barycenter interval f _sCDvariance, MEAN (f _sCD) be spectrum barycenter interval f _sCDaverage.

Known, the SCDT that different subband width is corresponding is different, and when group strip length just equals correct line frequency frequency, when namely needing the line frequency frequency extracted, spectrum barycenter is the most evenly spaced apart, i.e. SD (f _sCD) obtain minimum value, namely SCDT obtains minimum value.

B02, then choose the minimum value of SCDT, the line frequency frequency that minimum SCDT is corresponding or field frequency frequency are the final line frequency frequency extracted or field frequency frequency.

In this step, because subband width equals line frequency frequency or field frequency frequency, then the subband width that minimum SCDT is corresponding is line frequency frequency or the field frequency frequency of final extraction.

It should be noted that, after extracting correct line frequency frequency or field frequency frequency according to said method, subband iterative compensation can be reduced to improve the precision of frequency values centered by this frequency.

Present embodiments provide a kind of synch information extraction method of video leakage signal, based on the uniformity coefficient that the spectrum barycenter of vision signal is spaced apart, when there is Noise and Interference signal, line frequency frequency and the field frequency frequency of vision signal accurately automatically can be extracted.

As shown in Figure 3, be the synch information extraction system of the video leakage signal that another embodiment of the present invention provides, this system comprises segmentation module 301, computing module 302 and extraction module 303.

Wherein, segmentation module 301, for obtaining the power spectrum of video leakage signal, and is divided into multiple subband by described power spectrum.

Computing module 302, for obtaining the spectrum barycenter of each subband, and obtains the spectrum barycenter interval of each subband.

Extraction module 303, for the uniformity coefficient that the described spectrum barycenter according to each frequency range is spaced apart, extracts line frequency frequency or the field frequency frequency of described signal.

In the present embodiment, segmentation module 301, specifically for:

According to the span of line frequency frequency or field frequency frequency, choose line frequency frequency or field frequency frequency successively as subband width; According to described subband width, described power spectrum is divided into multiple subband.

In the present embodiment, computing module 302, specifically for:

(1) the spectrum barycenter f of each subband is calculated according to following formula _sC:

$\begin{array}{c}{f}_{\mathrm{SC}}={\mathrm{\Σ}}_{n=0}^{N-1}f\left(n\right)E\left(n\right)/{\mathrm{\Σ}}_{n=0}^{N-1}E\left(n\right)\\ =\underset{n=0}{\overset{N-1}{\mathrm{\Σ}}}f\left(n\right)E\left(n\right)/{\mathrm{\Σ}}_{n=0}^{N-1}E\left(n\right)\\ =\underset{n=0}{\overset{N-1}{\mathrm{\Σ}}}f\left(n\right)P\left(E\left(n\right)\right)\end{array}$

Wherein, n represents each point on subband width N, and f (n) is the frequency of often, the power spectrum that E (n) is signal, and N is subband width, and P (E (n)) is the probability of each point power spectrum in gross power spectrum.

(2) the spectrum barycenter interval f of each subband is calculated according to following formula _sCD(m):

f _SCD(m)＝f _SC(m+1)-f _SC(m),m＝1,2,…,M

Wherein, m is the numbering of each subband, f _sCm () is the spectrum barycenter of m subband, f _sC(m+1) be the spectrum barycenter of m+1 subband, M represents the number of subband.

In the present embodiment, extraction module 303, specifically for:

(1) uniformity coefficient that spectrum barycenter when obtaining different sub-band width according to following formula is spaced apart:

SCDT＝SD(f _SCD)/MEAN(f _SCD)

Wherein, SCDT represents the uniformity coefficient that spectrum barycenter is spaced apart, SD (f _sCD) be spectrum barycenter interval f _sCDvariance, MEAN (f _sCD) be spectrum barycenter interval f _sCDaverage.

(2) choose the minimum value of SCDT, the line frequency frequency that minimum SCDT is corresponding or field frequency frequency are line frequency frequency or the field frequency frequency of final extraction.

Below, the effect of said method and system is described by a specific embodiment.

1, running time

As shown in Figure 4, transverse axis is the length of data, represents here with the field duration of vision signal.The longitudinal axis is the running time of algorithm, and running time is obtained by the profiler instrument in MATLAB software.As shown in Figure 4, the present embodiment propose based on spectrum barycenter algorithm operationally between on be significantly less than existing related algorithm.

2, anti-interference

Performance comparision is as shown in Figure 5 easily in anti-interference for the spectrum centroid algorithm that the present embodiment proposes and related algorithm.In Fig. 5, transverse axis is the ratio of electromagnetic leakage signal and interference signal, i.e. signal interference ratio, and the longitudinal axis is accuracy rate accurary, and computing formula is as follows:

accurary＝1-(|f _h-f _h(right)|/f _h)×(|f _v-f _v(right)|/f _v)

As seen from Figure 5, compose centroid algorithm in jamproof performance comparatively related algorithm have obvious lifting.

Above embodiment only in order to technical scheme of the present invention to be described, is not intended to limit; Although with reference to previous embodiment to invention has been detailed description, those of ordinary skill in the art is to be understood that; It still can be modified to the technical scheme described in foregoing embodiments, or carries out equivalent replacement to wherein portion of techniques feature; And these amendments or replacement, do not make the essence of appropriate technical solution depart from the spirit and scope of various embodiments of the present invention technical scheme.

Claims (10)

1. a synch information extraction method for video leakage signal, is characterized in that, described method comprises:

Obtain the power spectrum of video leakage signal, and according to the subband width preset, described power spectrum is divided into multiple subband;

Obtain the spectrum barycenter of each subband, and obtain the spectrum barycenter interval of each subband;

The uniformity coefficient spaced apart according to the spectrum barycenter that different sub-band width is corresponding, extracts line frequency frequency or the field frequency frequency of described signal.

2. method according to claim 1, is characterized in that, described power spectrum is divided into multiple subband by the subband width that described basis is preset, and comprising:

According to the span of line frequency frequency or field frequency frequency, choose line frequency frequency or field frequency frequency successively as subband width according to the step-length preset;

According to described subband width, described power spectrum is divided into multiple subband.

3. method according to claim 1, is characterized in that, the spectrum barycenter of each subband of described acquisition, comprising:

The spectrum barycenter f of each subband is calculated according to following formula _sC:

$\begin{array}{c}{f}_{\mathrm{SC}}={\mathrm{\Σ}}_{n=0}^{N-1}f\left(n\right)E\left(n\right)/{\mathrm{\Σ}}_{n=0}^{N-1}E\left(n\right)\\ =\underset{n=0}{\overset{N-1}{\mathrm{\Σ}}}f\left(n\right)E\left(n\right)/{\mathrm{\Σ}}_{n=0}^{N-1}E\left(n\right)\\ =\underset{n=0}{\overset{N-1}{\mathrm{\Σ}}}f\left(n\right)P\left(E\left(n\right)\right)\end{array}$

Wherein, n represents each point on subband width N, and f (n) is the frequency of often, the power spectrum that E (n) is signal, and N is subband width, and P (E (n)) is the probability of each point power spectrum in gross power spectrum.

4. method according to claim 3, is characterized in that, the spectrum barycenter interval of each subband of described acquisition, comprising:

The spectrum barycenter interval f of each subband is calculated according to following formula _sCD(m):

f _SCD(m)＝f _SC(m+1)-f _SC(m),m＝1,2,…,M

Wherein, m is the numbering of each subband, f _sCm () is the spectrum barycenter of m subband, f _sC(m+1) be the spectrum barycenter of m+1 subband, M represents the number of subband.

5. method according to claim 1, is characterized in that, the uniformity coefficient that the described spectrum barycenter corresponding according to different sub-band width is spaced apart, extracts line frequency frequency or the field frequency frequency of described signal, comprising:

Spectrum barycenter corresponding to different sub-band width uniformity coefficient spaced apart is obtained according to following formula:

SCDT＝SD(f _SCD)/MEAN(f _SCD)

Wherein, SCDT represents the uniformity coefficient that spectrum barycenter is spaced apart, SD (f _sCD) be spectrum barycenter interval f _sCDvariance, MEAN (f _sCD) be spectrum barycenter interval f _sCDaverage;

Choose the minimum value of SCDT, the line frequency frequency that minimum SCDT is corresponding or field frequency frequency are line frequency frequency or the field frequency frequency of final extraction.

6. a synch information extraction system for video leakage signal, is characterized in that, described system comprises:

Segmentation module, for obtaining the power spectrum of video leakage signal, and is divided into multiple subband according to the subband width preset by described power spectrum;

Computing module, for obtaining the spectrum barycenter of each subband, and obtains the spectrum barycenter interval of each subband;

Extraction module, for the uniformity coefficient that the spectrum barycenter corresponding according to different sub-band width is spaced apart, extracts line frequency frequency or the field frequency frequency of described signal.

7. system according to claim 6, is characterized in that, described segmentation module, specifically for:

According to the span of line frequency frequency or field frequency frequency, choose line frequency frequency or field frequency frequency successively as subband width according to the step-length preset;

According to described subband width, described power spectrum is divided into multiple subband.

8. system according to claim 6, is characterized in that, described computing module, specifically for:

The spectrum barycenter f of each subband is calculated according to following formula _sC:

$\begin{array}{c}{f}_{\mathrm{SC}}={\mathrm{\Σ}}_{n=0}^{N-1}f\left(n\right)E\left(n\right)/{\mathrm{\Σ}}_{n=0}^{N-1}E\left(n\right)\\ =\underset{n=0}{\overset{N-1}{\mathrm{\Σ}}}f\left(n\right)E\left(n\right)/{\mathrm{\Σ}}_{n=0}^{N-1}E\left(n\right)\\ =\underset{n=0}{\overset{N-1}{\mathrm{\Σ}}}f\left(n\right)P\left(E\left(n\right)\right)\end{array}$

Wherein, n represents each point on subband width N, and f (n) is the frequency of often, the power spectrum that E (n) is signal, and N is subband width, and P (E (n)) is the probability of each point power spectrum in gross power spectrum.

9. system according to claim 6, is characterized in that, described computing module, also for:

The spectrum barycenter interval f of each subband is calculated according to following formula _sCD(m):

f _SCD(m)＝f _SC(m+1)-f _SC(m),m＝1,2,…,M

Wherein, m is the numbering of each subband, f _sC( _m) be the spectrum barycenter of m subband, f _sC(m+1) be the spectrum barycenter of m+1 subband, M represents the number of subband.

10. system according to claim 6, is characterized in that, described extraction module, specifically for:

Spectrum barycenter corresponding to different sub-band width uniformity coefficient spaced apart is obtained according to following formula:

SCDT＝SD(f _SCD)/MEAN(f _SCD)

Wherein, SCDT represents the uniformity coefficient that spectrum barycenter is spaced apart, SD (f _sCD) be spectrum barycenter interval f _sCDvariance, MEAN (f _sCD) be spectrum barycenter interval f _sCDaverage;

Choose the minimum value of SCDT, the line frequency frequency that minimum SCDT is corresponding or field frequency frequency are line frequency frequency or the field frequency frequency of final extraction.