CN103138854B - Method of detecting subaudio frequency signals and device using the same - Google Patents

Abstract

The invention relates to the technical field of communication, in particular to a method of detecting subaudio frequency signals and a device using the method of detecting the subaudio frequency signals and aims to solve the problem that a single point discrete fourier transform (DFT) algorithm in the prior art is prone to causing virtual detection of the subaudio frequency signals during detection of the subaudio frequency signals. The method includes the following steps: selecting more than one comparison frequency closest to the preset subaudio frequency from all the frequency; deciding normalization power value corresponding to each comparison frequency and normalization power value of the subaudio frequency; according to the normalization power value corresponding to each comparison frequency and normalization power value of the subaudio frequency, judging whether the received signals are the subaudio frequency signals. Due to the fact that the received signals are judged to be the subaudio frequency signals or not according to the normalization power value of at least one comparison frequency closest to the preset subaudio frequency, times of virtual detection of the subaudio frequency signals are reduced, and reliability and performance of the detection are improved.

Description

A kind of method and apparatus that detects infrasonic frequency signal

Technical field

The present invention relates to communication technical field, particularly a kind of method and apparatus that detects infrasonic frequency signal.

Background technology

Continuous speech control squelch system (CTCSS, Continuous Tone Controlled Squelch System), frequency lower than audio frequency (67Hz～250.3Hz, totally 39 subsonics points (or 50 points)) is attached to the technology of transmitting together in audio signal.Because its frequency range is below standard audio, therefore be called infrasonic frequency.

In intercom design, adopt infrasonic frequency technology its objective is to avoid the phase mutual interference of different user, avoid listening to irrelevant calling and interference signal.In the time that the transmitter of intercom sends voice signal, be accompanied by transmitter and constantly send infrasonic frequency continuous signal, after modulation, go out in same channels transmit.After receiving carrier signal and infrasonic frequency signal, receiver mediates, and compare identification to determine whether to open squelch circuit with the preset infrasonic frequency signal of the machine, while only having identical infrasonic frequency code, the output of squelch circuit audio frequency just can be opened by loud speaker and sound.Therefore it can prevent from other user's useless speech and other signaling and disturb in shared channel.So can say that it is to decode to improve communication network by infrasonic frequency signalling coding to resist external interference ability the solution signaling recognition system that the network user networks by no means.Infrasonic frequency signal has selective call function simultaneously, utilizes continuous tone frequently to encode and carry out selective call, and is also the most effective current selective call mode with transporting speech signal all the time simultaneously.Main calling is as long as press PTT (Push To Talk, PTT) just can send and group busy or generally call, when after intercom end of conversation also without button on-hook, than will be simply with interconnect call mode h coding selective call (DTMF), many easily and efficiently.

Current intercom is mainly to be modeled as master, thereby infrasonic frequency input is generally all realized by analog circuit.Along with the digitized propelling of intercom, for compatible analog-interphone, need to carry out digitized processing to analog-interphone.

Existing infrasonic frequency input scheme is to adopt single-point DFT (discrete Fourier transform) algorithm: based on receiving signal, utilize DFT to calculate target frequency upper frequency component, detect the amplitude of complex sequences, judge whether to exceed predefined threshold value.Because two adjacent frequency intervals in infrasonic frequency signal frequency used are less, while making single-point DFT algorithm detect infrasonic frequency signal, be easy to cause the void inspection (this does not send the subsonics of this frequency on channel) of infrasonic frequency signal, make detecting reliability not high.

In sum, the infrasonic frequency of single-point DFT algorithm detection at present signal is easy to cause the void inspection of infrasonic frequency signal, makes detecting reliability not high.

Summary of the invention

The embodiment of the present invention provides a kind of method and apparatus that detects infrasonic frequency signal, is easy to cause the void inspection of infrasonic frequency signal in order to solve the single-point DFT algorithm detection infrasonic frequency signal existing in prior art, makes the problem that detecting reliability is not high.

A kind of method that detects infrasonic frequency signal that the embodiment of the present invention provides, comprising:

From all frequencies, select and immediate at least one comparison frequency of infrasonic frequency setting in advance;

According to the DFT superposition value of each comparison frequency of the power estimated value of the signal of receiving and selection, determine the normalized power value that each comparison frequency is corresponding, and according to the DFT superposition value of the power estimated value of the signal of receiving and infrasonic frequency, determine the normalized power value that infrasonic frequency is corresponding;

According to normalized power value corresponding to each comparison frequency and normalized power value corresponding to infrasonic frequency, whether the signal that judgement is received is infrasonic frequency signal.

A kind of equipment that detects infrasonic frequency signal that the embodiment of the present invention provides, comprising:

Select module, for selecting and immediate at least one comparison frequency of infrasonic frequency setting in advance from all frequencies;

Determination module, the power estimated value of signal of receiving for basis and the DFT superposition value of each comparison frequency of selection, determine the normalized power value that each comparison frequency is corresponding, and according to the DFT superposition value of the power estimated value of the signal of receiving and infrasonic frequency, determine the normalized power value that infrasonic frequency is corresponding;

Judge module, for according to normalized power value corresponding to each comparison frequency and normalized power value corresponding to infrasonic frequency, judges whether the signal of receiving is infrasonic frequency signal.

Due to basis and the normalized power value of immediate at least one comparison frequency of infrasonic frequency setting in advance and the normalized power value of infrasonic frequency, whether the signal that judgement is received is infrasonic frequency signal, thereby reduce the number of times that occurs the empty inspection situation of infrasonic frequency signal, improved the performance of detecting reliability and detection.

Brief description of the drawings

Fig. 1 is the method flow schematic diagram that the embodiment of the present invention detects infrasonic frequency signal;

Fig. 2 is the method flow schematic diagram that the embodiment of the present invention is divided three frequency detecting infrasonic frequency signals;

Fig. 3 is the device structure schematic diagram that the embodiment of the present invention detects infrasonic frequency signal.

Embodiment

The embodiment of the present invention is selected and immediate at least one comparison frequency of infrasonic frequency setting in advance from all frequencies, according to normalized power value corresponding to each comparison frequency and normalized power value corresponding to infrasonic frequency, whether the signal that judgement is received is infrasonic frequency signal.Due to basis and the normalized power value of immediate at least one comparison frequency of infrasonic frequency setting in advance and the normalized power value of infrasonic frequency, whether the signal that judgement is received is infrasonic frequency signal, thereby reduce the number of times that occurs the empty inspection situation of infrasonic frequency signal, improved the performance of detecting reliability and detection.

Wherein, the embodiment of the present invention can be applied in the communication of analog-interphone special wireless network, also can be applied in the communication system of arbitrary tone signal detection.

Below in conjunction with Figure of description, the embodiment of the present invention is described in further detail.

As shown in Figure 1, the method for embodiment of the present invention detection infrasonic frequency signal comprises the following steps:

Step 101, immediate at least one comparison frequency of infrasonic frequency of selecting and set in advance from all frequencies;

The power estimated value of signal that step 102, basis are received and the DFT superposition value of each comparison frequency of selection, determine the normalized power value that each comparison frequency is corresponding, and according to the DFT superposition value of the power estimated value of the signal of receiving and infrasonic frequency, determine the normalized power value that infrasonic frequency is corresponding;

Step 103, according to normalized power value corresponding to each comparison frequency and normalized power value corresponding to infrasonic frequency, whether the signal received of judgement is infrasonic frequency signal.

In step 101, with immediate at least one comparison frequency of the infrasonic frequency setting in advance, immediate immediate at least one comparison frequency of corresponding frequency values that refers to here.

In force, the pre-stored all frequency values of meeting, then preset the frequency values that a frequency values is infrasonic frequency, at least one frequency values that finds the frequency values that approaches infrasonic frequency most from pre-stored all frequency values as with the frequency values of immediate at least one comparison frequency of infrasonic frequency setting in advance.

Such as needs are selected two comparison frequencies, in pre-stored frequency values, there is f ₁, f ₂, f ₃, f ₄and f ₅if, f ₁for the frequency values of infrasonic frequency, f ₂and f ₃it is exactly the frequency values of two comparison frequencies; If f ₂for the frequency values of infrasonic frequency, f ₁and f ₃it is exactly the frequency values of two comparison frequencies; If f ₅for the frequency values of infrasonic frequency, f ₃and f ₄it is exactly the frequency values of two comparison frequencies.

Infrasonic frequency can arbitrary disposition.

Preferably, before step 102, also comprise further and comprising:

According in the corresponding relation of predefined frequency range and band pass filter, determine band pass filter corresponding to frequency range that infrasonic frequency is affiliated;

By definite band pass filter, the signal of receiving is carried out to filtering.

Accordingly, can carry out power estimation to filtered signal, determine the power estimated value of the signal of receiving; And according to filtered signal, determine corresponding DFT value.

Owing to by band pass filter, the signal of receiving being carried out to filtering, thereby unnecessary out of band signal is filtered, further improve the detection performance of follow-up subsonics judgement.

Such as having three band pass filter A, B and C, the frequency range that A is corresponding is [f ₁～f ₂); The frequency range that B is corresponding is [f ₂～f ₃]; The frequency range that C is corresponding is (f ₃～f ₄].Suppose that infrasonic frequency is f:

If f ₁≤ f < f ₂, select tape bandpass filter A;

If f ₂≤ f≤f ₃, select tape bandpass filter B;

If f ₃< f≤f ₄, select tape bandpass filter C.

Due to the frequency separation according to different, signal is carried out to bandpass filtering, thereby the interference outside more accurate filtering expected frequency can improve the detection probability of infrasonic frequency signal;

Filtered signal is carried out to power estimation, determine the power estimated value of the signal of receiving, be normalized for the power to frequency-region signal.

Preferably, in step 102, in the time of definite DFT value of each comparison frequency and the DFT value of infrasonic frequency, a long L of DFT window can be set, long according to the DFT window of setting, the cycle is determined the DFT value of each comparison frequency and the DFT value of infrasonic frequency selected.

Concrete, in the time calculating, the length of each computation of Period DFT is counted L.Also just all right, every L length is slided once, and the DFT value of each comparison frequency and the DFT value of infrasonic frequency are once just calculated in every slip.

Wherein, the size of L can rule of thumb be determined.Because L is larger, accuracy of detection is higher, but corresponding detection time is just long; Contrary, L is less, and accuracy of detection is lower, but corresponding detection time is just few, so the size of L is also chosen according to the demand of accuracy of detection demand and detection time.Such as if desired higher accuracy of detection, just can L be set larger; If desired less detection time, just can L be set less.

Preferably, in step 102, according to the DFT value of each comparison frequency, determine respectively DFT superposition value corresponding to each comparison frequency.

In force, using a N continuous corresponding same comparison frequency DFT value sum as DFT superposition value corresponding to this comparison frequency; Wherein, N is positive integer, and N DFT value comprises DFT value that current period is definite and N-1 definite DFT value of cycle before.。

Preferably, in step 102, according to the DFT value of infrasonic frequency signal, determine the DFT superposition value that infrasonic frequency is corresponding.

In force, using N corresponding infrasonic frequency DFT value sum as DFT superposition value corresponding to infrasonic frequency; Wherein, N is positive integer, and N DFT value comprises DFT value that current period is definite and N-1 definite DFT value of cycle before.

If the DFT window of selecting is long less, infrasonic frequency signal undetected excessive when signal to noise ratio is low, thus affect the coverage distance of intercom.Preferably, if the N in the embodiment of the present invention is greater than 1,, in the DFT value that often calculates a L and order, all the N continuous calculating a recently DFT value is superposeed, be equivalent to and carried out the DFT that NL orders and calculate, thereby can propose the detection performance of infrasonic frequency signal.

In time, often complete a DFT and calculate, just by superimposed DFT value corresponding individual continuous N same frequency, thereby obtain DFT superposition value corresponding to this frequency.

Because DFT value is calculated in the accumulation of sliding by piece, on the basis that does not increase detection time, improve the detection probability of infrasonic frequency signal.

If the quantity of the DFT value calculating is altogether less than N, severally think zero by inadequate.Such as N is 3, the DFT value of period 1 is A, and the DFT superposition value obtaining after the period 1 is exactly A+0+0; The DFT value of second round is B, and the DFT superposition value obtaining after second round is exactly A+B+0; The DFT value of period 3 is C, and the DFT superposition value obtaining after second round is exactly A+B+C; The DFT value of period 4 is D, and the DFT superposition value obtaining after second round is exactly B+C+D, the like.

Specifically can be referring to following expression formula:

D _x(n-N+1)＝D _x(n-N+2)；

D _x(n-1)＝D _x(n)；

D _x(n)＝V _x；

${\tilde{D}}_x\left(n\right)=D_x\left(n\right)+D_x(n-1)+......D_x(n-N+1).$

Wherein, V _xfor the corresponding DFT value of x frequency in current period; D _x(n) represent x frequency, n computation of Period DFT value out, D _x(N+1)=D _x(N+2)=...=D _x(1)=0; be illustrated in the superposition value of a n cycle x frequency N continuous DFT.。

Preferably, in step 102, by the mould value of DFT superposition value corresponding each comparison frequency square obtain normalized power value corresponding to each comparison frequency divided by the power estimated value of signal respectively, the mould value of DFT superposition value corresponding infrasonic frequency square obtained to the normalized power value that infrasonic frequency is corresponding divided by the power estimated value of signal.

Suppose to have selected two comparison frequencies. it is the DFT superposition value that infrasonic frequency is corresponding; it is a DFT superposition value that comparison frequency is corresponding; dFT superposition value corresponding to another comparison frequency.In force, can determine according to following formula the normalized power value of frequency:

${\tilde{P}}_{D0}\left(n\right)=\frac{{\left|{\tilde{D}}_0\left(n\right)\right|}^2}{P};$

${\tilde{P}}_{D1}\left(n\right)=\frac{{\left|{\tilde{D}}_1\left(n\right)\right|}^2}{P};$

${\tilde{P}}_{D2}\left(n\right)=\frac{{\left|{\tilde{D}}_2\left(n\right)\right|}^2}{P}.$

Wherein, P is the power estimated value of signal; it is the normalized power value that infrasonic frequency is corresponding; it is a normalized power value that comparison frequency is corresponding; normalized power value corresponding to another comparison frequency.

Preferably, in step 103, if normalized power value corresponding to infrasonic frequency is greater than threshold value, and normalized power value corresponding to infrasonic frequency be greater than normalized power value corresponding to any one comparison frequency, determines that the signal of receiving is infrasonic frequency signal; Otherwise, determine that the signal of receiving is not infrasonic frequency signal.

Whether the signal that each cycle needs judgement to receive is infrasonic frequency signal, as long as wherein a normalized power value corresponding to infrasonic frequency is greater than threshold value, and the normalized power value that infrasonic frequency is corresponding is greater than normalized power value corresponding to any one comparison frequency, just can determine that the signal of receiving is infrasonic frequency signal.

Wherein, threshold value can be as required or experience set.

Taking formula above as example:

If and and can determine that the signal of receiving is infrasonic frequency signal; Otherwise, determine that the signal of receiving is not infrasonic frequency signal.

After being infrasonic frequency signal, definite signal of receiving just can carry out subsequent treatment, such as opening loud speaker.

In force, the executive agent of embodiment of the present invention method can be that analog-interphone, simulating mobile terminal etc. can be applied in the equipment in the communication of analog-interphone special wireless network; Can also be can be applied in tone signal detect communication system in equipment.

With an example, the solution of the present invention is described below.

As shown in Figure 2, the method for three frequency detecting infrasonic frequency signals of embodiment of the present invention division comprises:

Step 201, reception signal.

Step 202, according in the corresponding relation of predefined frequency range and band pass filter, determine band pass filter corresponding to frequency range under infrasonic frequency.

Step 203, by definite band pass filter, the signal of receiving is carried out to filtering.

Step 204, filtered signal is carried out to power estimation, determine the power estimated value of the signal of receiving.

Step 205, the infrasonic frequency f that selects and set in advance from all frequencies ₁adjacent previous frequency frequency f as a comparison ₀and with the infrasonic frequency f setting in advance ₁adjacent rear frequency frequency f as a comparison ₂, and long according to the DFT window of setting, based on definite comparison frequency f of filtered signal period ₀dFT value, comparison frequency f ₂dFT value and infrasonic frequency f ₁dFT value.

Step 206, by comparison frequency f ₀corresponding N DFT value sum frequency f as a comparison ₀corresponding DFT superposition value, by comparison frequency f ₂corresponding N DFT value sum frequency f as a comparison ₂corresponding DFT superposition value and by infrasonic frequency f ₁n corresponding DFT value sum is as infrasonic frequency f ₁corresponding DFT superposition value.

Wherein, between step 205 and step 206, there is no inevitable sequential relationship.Can first perform step 205, then perform step 206; Also can first perform step 206, then perform step 207; Can also perform step 205 and step 206 simultaneously.

Step 207, by comparison frequency f ₀the mould value of corresponding DFT superposition value square obtain comparison frequency f divided by the power estimated value of signal respectively ₀corresponding normalized power value, by comparison frequency f ₂the mould value of corresponding DFT superposition value square obtain comparison frequency f divided by the power estimated value of signal respectively ₂corresponding normalized power value and by infrasonic frequency f ₁the mould value of corresponding DFT superposition value square obtain infrasonic frequency f divided by the power estimated value of signal ₁corresponding normalized power value.

If step 208 infrasonic frequency f ₁corresponding normalized power value is greater than threshold value, and infrasonic frequency f ₁corresponding normalized power value is greater than comparison frequency f ₀corresponding normalized power value, and infrasonic frequency f ₁corresponding normalized power value is greater than comparison frequency f ₂corresponding normalized power value, determines that the signal of receiving is infrasonic frequency signal; Otherwise, determine that the signal of receiving is not infrasonic frequency signal.

Based on same inventive concept, a kind of equipment that detects infrasonic frequency signal is also provided in the embodiment of the present invention, because the principle that this equipment is dealt with problems is similar to the method that detects infrasonic frequency signal, therefore the enforcement of this equipment can be referring to the enforcement of method, repeats part and repeat no more.

As shown in Figure 3, the equipment of embodiment of the present invention detection infrasonic frequency signal comprises: select module 30, determination module 31 and judge module 32.

Select module 30, for selecting and immediate at least one comparison frequency of infrasonic frequency setting in advance from all frequencies;

Determination module 31, the power estimated value of signal of receiving for basis and the DFT superposition value of each comparison frequency of selection, determine the normalized power value that each comparison frequency is corresponding, and according to the DFT superposition value of the power estimated value of the signal of receiving and infrasonic frequency, determine the normalized power value that infrasonic frequency is corresponding;

Judge module 32, for according to normalized power value corresponding to each comparison frequency and normalized power value corresponding to infrasonic frequency, judges whether the signal of receiving is infrasonic frequency signal.

Preferably, determination module 31, according in the corresponding relation of predefined frequency range and band pass filter, is determined band pass filter corresponding to frequency range that infrasonic frequency is affiliated; By definite band pass filter, the signal of receiving is carried out to filtering.

Preferably, determination module 31 is long according to the DFT window of setting, and the cycle is determined the DFT value of each comparison frequency and the DFT value of infrasonic frequency selected;

According to the DFT value of each comparison frequency, determine respectively DFT superposition value corresponding to each comparison frequency, and according to the DFT value of infrasonic frequency signal, determine the DFT superposition value that infrasonic frequency is corresponding.

Preferably, determination module 31 is using N corresponding same comparison frequency DFT value sum as DFT superposition value corresponding to this comparison frequency; Using N corresponding infrasonic frequency DFT value sum as DFT superposition value corresponding to infrasonic frequency;

Wherein, N is positive integer, and N DFT value comprises DFT value that current period is definite and N-1 definite DFT value of cycle before.

Preferably, determination module 31 is according to the DFT value of each comparison frequency, determine respectively DFT superposition value corresponding to each comparison frequency, the mould value of DFT superposition value corresponding each comparison frequency square obtained to normalized power value corresponding to each comparison frequency divided by the power estimated value of signal respectively; And according to the DFT value of infrasonic frequency signal, determine the DFT superposition value that infrasonic frequency is corresponding, the mould value of DFT superposition value corresponding infrasonic frequency square obtained to the normalized power value that infrasonic frequency is corresponding divided by the power estimated value of signal.

Preferably, if normalized power value corresponding to infrasonic frequency is greater than threshold value, and normalized power value corresponding to infrasonic frequency be greater than normalized power value corresponding to any one comparison frequency, and judge module 32 determines that the signal of receiving is infrasonic frequency signal; Otherwise, determine that the signal of receiving is not infrasonic frequency signal.

In force, the equipment of the embodiment of the present invention can be that analog-interphone, simulating mobile terminal etc. can be applied in the equipment in the communication of analog-interphone special wireless network; Can also be can be applied in tone signal detect communication system in equipment.

Those skilled in the art should understand, embodiments of the invention can be provided as method, system or computer program.Therefore, the present invention can adopt complete hardware implementation example, completely implement software example or the form in conjunction with the embodiment of software and hardware aspect.And the present invention can adopt the form at one or more upper computer programs of implementing of computer-usable storage medium (including but not limited to magnetic disc store, CD-ROM, optical memory etc.) that wherein include computer usable program code.

The present invention is with reference to describing according to flow chart and/or the block diagram of the method for the embodiment of the present invention, equipment (system) and computer program.Should understand can be by the flow process in each flow process in computer program instructions realization flow figure and/or block diagram and/or square frame and flow chart and/or block diagram and/or the combination of square frame.Can provide these computer program instructions to the processor of all-purpose computer, special-purpose computer, Embedded Processor or other programmable data processing device to produce a machine, the instruction that makes to carry out by the processor of computer or other programmable data processing device produces the device for realizing the function of specifying at flow process of flow chart or multiple flow process and/or square frame of block diagram or multiple square frame.

These computer program instructions also can be stored in energy vectoring computer or the computer-readable memory of other programmable data processing device with ad hoc fashion work, the instruction that makes to be stored in this computer-readable memory produces the manufacture that comprises command device, and this command device is realized the function of specifying in flow process of flow chart or multiple flow process and/or square frame of block diagram or multiple square frame.

These computer program instructions also can be loaded in computer or other programmable data processing device, make to carry out sequence of operations step to produce computer implemented processing on computer or other programmable devices, thereby the instruction of carrying out is provided for realizing the step of the function of specifying in flow process of flow chart or multiple flow process and/or square frame of block diagram or multiple square frame on computer or other programmable devices.

Although described the preferred embodiments of the present invention, once those skilled in the art obtain the basic creative concept of cicada, can make other change and amendment to these embodiment.So claims are intended to be interpreted as comprising preferred embodiment and fall into all changes and the amendment of the scope of the invention.

Obviously, those skilled in the art can carry out various changes and modification and not depart from the spirit and scope of the present invention the present invention.Like this, if these amendments of the present invention and within modification belongs to the scope of the claims in the present invention and equivalent technologies thereof, the present invention is also intended to comprise these changes and modification interior.

Claims (12)

1. a method that detects infrasonic frequency signal, is characterized in that, the method comprises:

From all frequencies, select and immediate at least one comparison frequency of infrasonic frequency setting in advance;

According to the discrete Fourier transform DFT superposition value of each comparison frequency of the power estimated value of the signal of receiving and selection, determine the normalized power value that each comparison frequency is corresponding, and according to the DFT superposition value of the power estimated value of the signal of receiving and infrasonic frequency, determine the normalized power value that infrasonic frequency is corresponding;

According to normalized power value corresponding to each comparison frequency and normalized power value corresponding to infrasonic frequency, whether the signal that judgement is received is infrasonic frequency signal.

2. the method for claim 1, is characterized in that, determines that DFT superposition value also comprises before:

According to the corresponding relation of predefined frequency range and band pass filter, determine band pass filter corresponding to frequency range that infrasonic frequency is affiliated;

By definite band pass filter, the signal of receiving is carried out to filtering.

3. the method for claim 1, is characterized in that, the DFT superposition value of each comparison frequency and the DFT superposition value of described infrasonic frequency are determined according to the following step:

Long according to the DFT window of setting, the cycle is determined the DFT value of each comparison frequency and the DFT value of infrasonic frequency selected;

According to the DFT value of each comparison frequency, determine respectively DFT superposition value corresponding to each comparison frequency, and according to the DFT value of infrasonic frequency signal, determine the DFT superposition value that infrasonic frequency is corresponding.

4. method as claimed in claim 3, is characterized in that, determines that DFT superposition value and DFT superposition value corresponding to definite infrasonic frequency that each comparison frequency is corresponding comprise:

Using N corresponding same comparison frequency DFT value sum as DFT superposition value corresponding to this comparison frequency;

Using N corresponding infrasonic frequency DFT value sum as DFT superposition value corresponding to infrasonic frequency;

Wherein, N is positive integer, and N DFT value comprises DFT value that current period is definite and N-1 definite DFT value of cycle before.

5. the method for claim 1, is characterized in that, the normalized power value that the normalized power value that each comparison frequency is corresponding and described infrasonic frequency are corresponding is determined according to the following step:

The mould value of DFT superposition value corresponding each comparison frequency square obtained to normalized power value corresponding to each comparison frequency divided by the power estimated value of signal respectively; And

The mould value of DFT superposition value corresponding infrasonic frequency square obtained to the normalized power value that infrasonic frequency is corresponding divided by the power estimated value of signal.

6. the method as described in as arbitrary in claim 1～5, is characterized in that, whether the signal that judgement is received is that infrasonic frequency signal comprises:

If the normalized power value that infrasonic frequency is corresponding is greater than threshold value, and normalized power value corresponding to infrasonic frequency be greater than normalized power value corresponding to any one comparison frequency, determines that the signal of receiving is infrasonic frequency signal; Otherwise, determine that the signal of receiving is not infrasonic frequency signal.

7. an equipment that detects infrasonic frequency signal, is characterized in that, this equipment comprises:

Select module, for selecting and immediate at least one comparison frequency of infrasonic frequency setting in advance from all frequencies;

Determination module, the power estimated value of signal of receiving for basis and the DFT superposition value of each comparison frequency of selection, determine the normalized power value that each comparison frequency is corresponding, and according to the DFT superposition value of the power estimated value of the signal of receiving and infrasonic frequency, determine the normalized power value that infrasonic frequency is corresponding;

Judge module, for according to normalized power value corresponding to each comparison frequency and normalized power value corresponding to infrasonic frequency, judges whether the signal of receiving is infrasonic frequency signal.

8. equipment as claimed in claim 7, is characterized in that, described determination module also for:

According to the corresponding relation of predefined frequency range and band pass filter, determine band pass filter corresponding to frequency range that infrasonic frequency is affiliated; By definite band pass filter, the signal of receiving is carried out to filtering.

9. equipment as claimed in claim 7, is characterized in that, described determination module specifically for:

Long according to the DFT window of setting, the cycle is determined the DFT value of each comparison frequency and the DFT value of infrasonic frequency selected;

According to the DFT value of each comparison frequency, determine respectively DFT superposition value corresponding to each comparison frequency, and according to the DFT value of infrasonic frequency signal, determine the DFT superposition value that infrasonic frequency is corresponding.

10. equipment as claimed in claim 9, is characterized in that, described determination module specifically for:

Using N corresponding same comparison frequency DFT value sum as DFT superposition value corresponding to this comparison frequency; Using N corresponding infrasonic frequency DFT value sum as DFT superposition value corresponding to infrasonic frequency;

Wherein, N is positive integer, and N DFT value comprises DFT value that current period is definite and N-1 definite DFT value of cycle before.

11. equipment as claimed in claim 7, is characterized in that, described determination module specifically for:

The mould value of DFT superposition value corresponding each comparison frequency square obtained to normalized power value corresponding to each comparison frequency divided by the power estimated value of signal respectively; And the mould value of DFT superposition value corresponding infrasonic frequency square obtained to the normalized power value that infrasonic frequency is corresponding divided by the power estimated value of signal.

12. equipment as described in as arbitrary in claim 7～11, is characterized in that, described judge module specifically for:

If the normalized power value that infrasonic frequency is corresponding is greater than threshold value, and normalized power value corresponding to infrasonic frequency be greater than normalized power value corresponding to any one comparison frequency, determines that the signal of receiving is infrasonic frequency signal; Otherwise, determine that the signal of receiving is not infrasonic frequency signal.