CN103166887B - A kind of method of sideband modulated signal classification and device - Google Patents

Abstract

The invention discloses method and the device of the classification of a kind of sideband modulated signal, wherein the method comprises: according to the frequency spectrum correlation function of time-domain digital signal x [n] with conjugate spectrum correlation function obtain enhancement mode frequency spectrum correlation function according to described enhancement mode frequency spectrum correlation function calculate the cycle specificity collection of illustrative plates of described time-domain digital signal x [n], and obtain test statistics T by this cycle specificity collection of illustrative plates _p; By described test statistics T _pcompare with threshold value γ, if T _p≤ γ is then single sideband modulated signal, otherwise is double-sideband modulation signal.By the usage range adopting method disclosed by the invention and device to expand sideband signals classification and Detection.

Description

A kind of method of sideband modulated signal classification and device

Technical field

The present invention relates to cognitive radio technology field, particularly relate to method and the device of the classification of a kind of sideband modulated signal.

Background technology

The Classification and Identification of single sideband modulated signal and double-sideband modulation signal is a step important in modulated-analog signal classification, in detection of electrons and military communication, play the part of important function.

Existing sorting technique is all be based upon precognition signal carrier frequency or estimate on the basis of signal carrier frequency, but the carrier frequency information of signal is difficult to know in advance or accurately estimate in most cases, causes very large difficulty to the classification of sideband modulated signal.Therefore, how when unknown carrier frequency information, sideband modulated signal to be effectively categorized into as important subject.

Summary of the invention

The object of this invention is to provide method and the device of the classification of a kind of sideband modulated signal, solve the problem must knowing carrier frequency information in existing sideband modulated signal sorting technique in advance.

The object of the invention is to be achieved through the following technical solutions:

A method for sideband modulated signal classification, the method comprises:

According to the frequency spectrum correlation function of time-domain digital signal x [n] with conjugate spectrum correlation function obtain enhancement mode frequency spectrum correlation function

According to described enhancement mode frequency spectrum correlation function calculate the cycle specificity collection of illustrative plates of described time-domain digital signal x [n], and obtain test statistics T by this cycle specificity collection of illustrative plates _p;

By described test statistics T _pcompare with threshold value γ, if T _p≤ γ is then single sideband modulated signal, otherwise is double-sideband modulation signal.

A device for sideband modulated signal classification, comprise Anneta module, low noise amplifier, band pass filter, analog to digital converter and time-domain signal pretreatment module, this device also comprises Modulation recognition module, and this module comprises:

Enhancement mode frequency spectrum correlation function module, for the frequency spectrum correlation function according to time-domain digital signal x [n] with conjugate spectrum correlation function obtain enhancement mode frequency spectrum correlation function

Test statistics computing module, for according to described enhancement mode frequency spectrum correlation function calculate the cycle specificity collection of illustrative plates of described time-domain digital signal x [n], and obtain test statistics T by this cycle specificity collection of illustrative plates _p;

Comparison module, for by described test statistics T _pcompare with threshold value γ, if T _p≤ γ is then single sideband modulated signal, otherwise is double-sideband modulation signal.

As seen from the above technical solution provided by the invention, by forming enhancement mode frequency spectrum correlation function in conjunction with conjugate spectrum correlation function and frequency spectrum correlation function, cycle specificity collection of illustrative plates is obtained by enhancement mode frequency spectrum correlation function, thus realize the classification carrying out sideband modulated signal under unknown carrier frequency information condition, expand the usage range of sideband signals classification and Detection, and there is the advantage of low complex degree.

Accompanying drawing explanation

In order to be illustrated more clearly in the technical scheme of the embodiment of the present invention, below the accompanying drawing used required in describing embodiment is briefly described, 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 drawings can also be obtained according to these accompanying drawings.

The flow chart of the method for a kind of sideband modulated signal classification that Fig. 1 provides for the embodiment of the present invention one;

The enhancement mode frequency spectrum correlation function mould schematic three dimensional views of the single sideband modulated signal that Fig. 2 provides for the embodiment of the present invention one;

The enhancement mode frequency spectrum correlation function mould schematic three dimensional views of the double-sideband modulation signal that Fig. 3 provides for the embodiment of the present invention one;

The schematic diagram of the cycle specificity figure of the single sideband modulated signal that Fig. 4 provides for the embodiment of the present invention one;

The schematic diagram of the cycle specificity figure of the double-sideband modulation signal that Fig. 5 provides for the embodiment of the present invention one;

The schematic diagram of the device of a kind of sideband modulated signal classification that Fig. 6 provides for the embodiment of the present invention two;

The schematic diagram of the device of the another kind of sideband modulated signal classification that Fig. 7 provides for the embodiment of the present invention two;

The schematic diagram of the device of another sideband modulated signal classification that Fig. 8 provides for the embodiment of the present invention two.

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 embodiments of the invention, those of ordinary skill in the art, not making the every other embodiment obtained under creative work prerequisite, belong to protection scope of the present invention.

Embodiment one

The flow chart of the method for a kind of sideband modulated signal classification that Fig. 1 provides for the embodiment of the present invention one.As shown in Figure 1, mainly comprise the steps:

Step 11, obtain pretreated time-domain digital signal x [n].

Described pretreated time-domain digital signal x [n] can obtain by hardware device is auxiliary.Such as, first, Anneta module is utilized to receive aerial signal; Then, carry out low noise amplification to the received signal and bandpass filtering is carried out to the signal after amplifying; Again filtering signal is out sent in analog to digital converter and carries out analog-to-digital conversion, finally, digital signal after analog-to-digital conversion is sent into signal procesing in time domain module, the process such as the reception of complete pair signals and storage in this module, and then obtain pretreated time-domain digital signal x [n].

This time-domain digital signal x [n] can be single sideband modulated signal also can be double-sideband modulation signal.For example and without limitation, we are with x _m[n] represents intermediate frequency modulated-analog signal, then can set up following dualism hypothesis:

H ₁single sideband modulated signal:

H ₀double-sideband modulation signal:

Wherein, x _s[n] is by x _m[n] carries out Hilbert(Hilbert) conversion obtain, f _ccarrier frequency, T _sfor sample frequency, be [0,2 π) upper equally distributed phase place.

Step 12, frequency spectrum correlation function according to time-domain digital signal x [n] with conjugate spectrum correlation function obtain enhancement mode frequency spectrum correlation function

At acquisition enhancement mode frequency spectrum correlation function need the frequency spectrum correlation function precalculating x [n] before x [n] in the embodiment of the present invention (n=1,2 ..., N-1) frequency spectrum correlation function formulae discovery below can be adopted to obtain:

Wherein, M is positive odd number and M≤N, α are cycle frequencys, the discrete time Fourier transform (DTFT) that X (f) is x [] and $X\left(f\right)=\underset{n=0}{\overset{N-1}{\mathrm{\Σ}}}x\left[n\right]e^{-j2\mathrm{\πfn}}$ $(j=\sqrt{-1}),$ represent the conjugation of signal, namely for complex signal, obtain after the sign-flip of its imaginary part.

When f ± α/2 in above formula are integral multiples of 1/N, calculate X (f) by fast Fourier transform (FFT).But the frequency spectrum correlation function that the method calculates effectively can not show the difference between single sideband modulated signal and double-sideband modulation signal, therefore the embodiment of the present invention proposes conjugate spectrum correlation function and on this basis in conjunction with frequency spectrum correlation function structure enhancement mode frequency spectrum correlation function wherein, computing formula as follows:

Wherein, M is positive odd number and M≤N; The discrete time Fourier transform (DTFT) that X (f) is x [] and $X\left(f\right)=\underset{n=0}{\overset{N-1}{\mathrm{\Σ}}}x\left[n\right]e^{-j2\mathrm{\πfn}}$ $(j=\sqrt{-1}),$ represent the conjugation of signal, namely for complex signal, obtain after the sign-flip of its imaginary part.

Finally, by the frequency spectrum correlation function of x [n] with conjugate spectrum correlation function combine and obtain enhancement mode frequency spectrum correlation function

${\hat{S}}_x^{\mathrm{\α}}{\left(f\right)}_a={\mathrm{\κ}}_1{\hat{S}}_x^{\mathrm{\α}}\left(f\right)+{\mathrm{\κ}}_2{\hat{S}}_x^{\mathrm{\α}}{\left(f\right)}_c;$

Wherein, COEFFICIENT K ₁with K ₂for being greater than the real number of 0.

The enhancement mode frequency spectrum correlation function obtained by the way effectively can show the difference between single sideband modulated signal and double-sideband modulation signal, as Figure 2-3, respectively describe the graphics of the enhancement mode frequency spectrum correlation function of single sideband modulated signal and double-sideband modulation signal, wherein, signal to noise ratio snr in Fig. 2-Fig. 3=5dB, κ ₁=0.1, κ ₂=1.Visually can see both differences, the double-sideband modulation signal in Fig. 3 has an obvious spike in the middle of the continuum that amplitude is larger, and the single sideband modulated signal in Fig. 2 is without this feature.

Step 13, according to described enhancement mode frequency spectrum correlation function calculate the cycle specificity collection of illustrative plates of described time-domain digital signal x [n].

Cycle specificity collection of illustrative plates can have multiple design, for reducing the data volume of required process in the embodiment of the present invention, only gets enhancement mode frequency spectrum correlation function amplitude peak on each given cycle frequency point, corresponding cycle specificity collection of illustrative plates is defined as:

$p\left(\mathrm{\&alpha;}\right)\stackrel{\mathrm{\&Delta;}}{=}{\max }_{\left|f\right|<\mathrm{\&xi;}}\left[S_x^{\mathrm{\&alpha;}}\left(f\right)\right];$

Wherein, for define symbol; ξ is frequency threshold, namely only needs calculated rate absolute value to be less than the enhancement mode frequency spectrum correlation function of this value.

As illustrated in figures 4-5, be respectively the cycle specificity collection of illustrative plates of single sideband modulated signal and double-sideband modulation signal, wherein, the signal to noise ratio snr in Fig. 4-Fig. 5=5dB, κ ₁=0.1, κ ₂=1.It is equivalent to the three-dimensional enhancement mode frequency spectrum correlation function of Fig. 2-Fig. 3 to do a projection in cycle frequency territory.

Step 14, according to obtain cycle specificity collection of illustrative plates calculate test statistics.

For the ease of from the difference numerically embodying single sideband modulated signal and double-sideband modulation signal cycle characteristic spectrum, the embodiment of the present invention adopts following test statistics:

$T_p\stackrel{\mathrm{\&Delta;}}{=}{\mathrm{\&eta;e}}^{-\mathrm{\&tau;}};$

Wherein, η is the maximum of cycle specificity figure spectral amplitude, and e is the truth of a matter of natural logrithm, and τ is the symmetry coefficient of cycle specificity collection of illustrative plates.For ease of understanding the implication of τ in above-mentioned formula, a can be used _lrepresent that cycle specificity collection of illustrative plates is in the amplitude equalizing value on the Amplitude maxima point left side, uses a _rrepresent the right amplitude equalizing value, then:

τ＝|a _l-a _r|/(a _l+a _r)。

Step 15, by described test statistics T _pcompare with threshold value γ, if T _p≤ γ is then single sideband modulated signal, otherwise is double-sideband modulation signal.

Wherein, threshold value γ can also can according to monte carlo method analog computation according to actual numerical value analog computation; Describedly comprising according to monte carlo method analog computation: emulated the statistical distribution characteristic obtaining the test statistics of different signal to noise ratio lower-sideband modulation signal by monte carlo method, then under given false alarm rate (referring to that the probability of false-alarm appears in detection system when detecting), asking for threshold value γ.

The test statistics T after calculating threshold value γ, itself and step 14 calculated _pcompare.Under normal circumstances, the T of single sideband modulated signal _prelatively little, the T of double-sideband modulation signal _prelatively large; Therefore, T is worked as _pduring≤γ, judge that current demand signal is as single sideband modulated signal, otherwise be double-sideband modulation signal.

The embodiment of the present invention carries out sideband modulated signal sorting technique based on enhancement mode frequency spectrum correlation function, can carry out under different signal to noise ratio snr, in emulation experiment, as SNR=-10dB, still can keep high verification and measurement ratio.

The embodiment of the present invention is by forming enhancement mode frequency spectrum correlation function in conjunction with conjugate spectrum correlation function and frequency spectrum correlation function, cycle specificity collection of illustrative plates is obtained by enhancement mode frequency spectrum correlation function, thus realize the classification carrying out sideband modulated signal under unknown carrier frequency information condition, expand the usage range of sideband signals classification and Detection, and there is the advantage of low complex degree.

Through the above description of the embodiments, those skilled in the art can be well understood to above-described embodiment can by software simulating, and the mode that also can add necessary general hardware platform by software realizes.Based on such understanding, the technical scheme of above-described embodiment can embody with the form of software product, it (can be CD-ROM that this software product can be stored in a non-volatile memory medium, USB flash disk, portable hard drive etc.) in, comprise some instructions and perform method described in each embodiment of the present invention in order to make a computer equipment (can be personal computer, server, or the network equipment etc.).

Embodiment two

The schematic diagram of the device of a kind of sideband modulated signal classification that Fig. 6 provides for the embodiment of the present invention.As shown in Figure 6, mainly comprise: Anneta module 71, low noise amplifier 72, band pass filter 73, analog to digital converter 74 and time-domain signal pretreatment module 75, it is characterized in that, this device also comprises Modulation recognition module 76, and this module comprises:

Enhancement mode frequency spectrum correlation function module 761, for the frequency spectrum correlation function according to time-domain digital signal x [n] with conjugate spectrum correlation function obtain enhancement mode frequency spectrum correlation function

Test statistics computing module 762, for according to described enhancement mode frequency spectrum correlation function calculate the cycle specificity collection of illustrative plates of described time-domain digital signal x [n], and obtain test statistics T by this cycle specificity collection of illustrative plates _p;

Comparison module 763, for by described test statistics T _pcompare with threshold value γ, if T _p≤ γ is then single sideband modulated signal, otherwise is double-sideband modulation signal.

Described Modulation recognition module 76 also comprises:

Threshold value computing module 764, for according to monte carlo method analog computation threshold value or according to actual numerical value analog computation threshold value.

In addition, the Modulation recognition module 76 in the present embodiment can be in PC(computer) in, see Fig. 7, namely Anneta module 71, low noise amplifier 72, band pass filter 73, analog to digital converter 74, time-domain signal pretreatment module 75 are connected successively with PC77.Also Modulation recognition module 76 can be placed in DSP78(digital signal processor), see Fig. 8, i.e. Anneta module 71, low noise amplifier 72, band pass filter 73, analog to digital converter 74, time-domain signal pretreatment module 75 is connected successively with DSP78, the data that time-domain signal pretreatment module 75 sends by this DSP78 are sent in data storage 781 by corresponding interface (as EMIF mouth), DSP78 reads data in real time and completes the classification of sideband modulated signal and Output rusults from memory 781, can deliver in the external equipment 782 be connected with DSP78 for the result exported, also can by some interfaces as USB port 783, network interface 784 etc. is transferred in other equipment.

It should be noted that, have a detailed description in the specific implementation of the function that each processing module comprised in said apparatus the realizes embodiment above, therefore here repeat no more.

Those skilled in the art can be well understood to, for convenience and simplicity of description, only be illustrated with the division of above-mentioned each functional module, in practical application, can distribute as required and by above-mentioned functions and be completed by different functional modules, internal structure by device is divided into different functional modules, to complete all or part of function described above.

The above; be only the present invention's preferably embodiment, but protection scope of the present invention is not limited thereto, is anyly familiar with those skilled in the art in the technical scope that the present invention discloses; the change that can expect easily or replacement, all should be encompassed within protection scope of the present invention.Therefore, protection scope of the present invention should be as the criterion with the protection range of claims.

Claims (4)

1. a method for sideband modulated signal classification, it is characterized in that, the method comprises:

According to the frequency spectrum correlation function of time-domain digital signal x [n] with conjugate spectrum correlation function obtain enhancement mode frequency spectrum correlation function n=1,2 ..., N-1;

According to described enhancement mode frequency spectrum correlation function calculate the cycle specificity collection of illustrative plates of described time-domain digital signal x [n], and obtain test statistics T by this cycle specificity collection of illustrative plates _p;

By described test statistics T _pcompare with threshold value γ, if T _p≤ γ is then single sideband modulated signal, otherwise is double-sideband modulation signal;

Wherein:

Calculate the frequency spectrum correlation function of described time-domain digital signal x [n] formula be:

Wherein, f is the frequency of signal, and M is positive odd number and M≤N, α are cycle frequency; The discrete time Fourier transform that X (f) is x [] and represent the conjugation of signal;

Calculate the conjugate spectrum correlation function of described time-domain digital signal x [n] formula be:

Wherein, M is positive odd number and M≤N, α are cycle frequency; The discrete time Fourier transform that X (f) is x [] and $X\left(f\right)=\underset{n=0}{\overset{N-1}{\&Sigma;}}x\&lsqb;n\&rsqb;e^{-j2\mathrm{\&pi;}fn};$ represent the conjugation of signal;

Calculate described enhancement mode frequency spectrum correlation function formula comprise:

${\hat{S}}_x^{\mathrm{\&alpha;}}{\left(f\right)}_a={\mathrm{\&kappa;}}_1{\hat{S}}_x^{\mathrm{\&alpha;}}\left(f\right)+{\mathrm{\&kappa;}}_2{\hat{S}}_x^{\mathrm{\&alpha;}}{\left(f\right)}_c;$

Wherein, COEFFICIENT K ₁with K ₂for being greater than the real number of 0;

Described according to described enhancement mode frequency spectrum correlation function the formula calculating the cycle specificity collection of illustrative plates of described time-domain digital signal x [n] is:

$p\left(\mathrm{\&alpha;}\right)\stackrel{\mathrm{\&Delta;}}{=}{\max }_{\left|f\right|<\mathrm{\&xi;}}\&lsqb;S_x^{\mathrm{\&alpha;}}\left(f\right)\&rsqb;;$

Wherein, ξ is frequency threshold;

Described by this cycle specificity collection of illustrative plates acquisition test statistics T _pformula be:

$T_p\stackrel{\mathrm{\&Delta;}}{=}{\mathrm{\&eta;e}}^{-\mathrm{\&tau;}};$

Wherein, η is the maximum of cycle specificity figure spectral amplitude, and τ is the symmetry coefficient of cycle specificity collection of illustrative plates, and e is the truth of a matter of natural logrithm.

2. method according to claim 1, is characterized in that, the method calculating described threshold value γ comprises:

Emulated by monte carlo method and obtain the statistical distribution characteristic of the test statistics of different signal to noise ratio lower-sideband modulation signal, under predetermined false alarm rate, then ask for threshold value or according to actual numerical value analog computation threshold value.

3. a device for sideband modulated signal classification, comprise Anneta module, low noise amplifier, band pass filter, analog to digital converter and time-domain signal pretreatment module, it is characterized in that, this device also comprises Modulation recognition module, and this module comprises:

Enhancement mode frequency spectrum correlation function module, for the frequency spectrum correlation function according to time-domain digital signal x [n] with conjugate spectrum correlation function obtain enhancement mode frequency spectrum correlation function n=1,2 ..., N-1; Wherein:

Calculate the frequency spectrum correlation function of described time-domain digital signal x [n] formula be:

Wherein, f is the frequency of signal, and M is positive odd number and M≤N, α are cycle frequency; The discrete time Fourier transform that X (f) is x [] and represent the conjugation of signal;

Calculate the conjugate spectrum correlation function of described time-domain digital signal x [n] formula be:

Wherein, M is positive odd number and M≤N, α are cycle frequency; The discrete time Fourier transform that X (f) is x [] and $X\left(f\right)=\underset{n=0}{\overset{N-1}{\&Sigma;}}x\&lsqb;n\&rsqb;e^{-j2\mathrm{\&pi;}fn};$ represent the conjugation of signal;

Calculate described enhancement mode frequency spectrum correlation function formula comprise:

${\hat{S}}_x^{\mathrm{\&alpha;}}{\left(f\right)}_a={\mathrm{\&kappa;}}_1{\hat{S}}_x^{\mathrm{\&alpha;}}\left(f\right)+{\mathrm{\&kappa;}}_2{\hat{S}}_x^{\mathrm{\&alpha;}}{\left(f\right)}_c;$

Wherein, COEFFICIENT K ₁with K ₂for being greater than the real number of 0;

Test statistics computing module, for according to described enhancement mode frequency spectrum correlation function calculate the cycle specificity collection of illustrative plates of described time-domain digital signal x [n], and obtain test statistics T by this cycle specificity collection of illustrative plates _p; Wherein:

Described according to described enhancement mode frequency spectrum correlation function the formula calculating the cycle specificity collection of illustrative plates of described time-domain digital signal x [n] is:

$p\left(\mathrm{\&alpha;}\right)\stackrel{\mathrm{\&Delta;}}{=}{\max }_{\left|f\right|<\mathrm{\&xi;}}\&lsqb;S_x^{\mathrm{\&alpha;}}\left(f\right)\&rsqb;;$

Wherein, ξ is frequency threshold;

Described by this cycle specificity collection of illustrative plates acquisition test statistics T _pformula be:

$T_p\stackrel{\mathrm{\&Delta;}}{=}{\mathrm{\&eta;e}}^{-\mathrm{\&tau;}};$

Wherein, η is the maximum of cycle specificity figure spectral amplitude, and τ is the symmetry coefficient of cycle specificity collection of illustrative plates, and e is the truth of a matter of natural logrithm;

Comparison module, for by described test statistics T _pcompare with threshold value γ, if T _p≤ γ is then single sideband modulated signal, otherwise is double-sideband modulation signal.

4. device according to claim 3, is characterized in that, described Modulation recognition module also comprises:

Threshold value computing module, for according to monte carlo method analog computation threshold value or according to actual numerical value analog computation threshold value.