CN104391305A - Satellite navigation deception interference suppression method based on deception interference DOA estimation - Google Patents

Abstract

Provided is a satellite navigation deception interference suppression method based on deception interference DOA estimation. The method comprises the following sequentially performed steps that firstly radio frequency signals received by array antennas are down-converted into digital intermediate-frequency signals; influence of noise on estimation of coming direction of deception interference is reduced by utilizing the periodic repetition characteristic of C/A codes, and then a CLEAN method is adopted to estimate coming direction of multiple deception interference sources and the number of the deception interference sources is judged; and finally a linearly constrained minimum variance (LCMV) algorithm is utilized to obtain antenna beams when deception interference coming direction constrains are null, and antenna null is broadened by adopting a first-order differential constraint algorithm. Multiple forwarding sources can be effectively suppressed so that the method is easy to realize and small in computation amount and can act as an independent anti-deception interference module to be embedded in a common receiver.

Description

Based on the satellite navigation Deceiving interference suppressing method that Deceiving interference DOA estimates

Technical field

The invention belongs to satellite navigation Anti-Jamming Technique field, particularly relate to a kind of satellite navigation Deceiving interference suppressing method estimated based on Deceiving interference DOA.

Background technology

Due to GPS (Global Position System) (Global Navigation Satellite System, guide number SS) can provide time/space reference and all real-time dynamic informations relevant to position, thus be widely applied in navigation, time service, precision measurement etc., therefore guarantee that the security of GPS (Global Position System) is particularly important.But, because when GNSS signal arrives ground, signal power is very faint, the therefore impact that is very easily interfered of GNSS receiver.

At present, the research about GNSS disturbance restraining method mainly concentrates on suppression jamming suppressing method, relatively less to the research of Deceiving interference suppressing method.Different from suppression jamming, Deceiving interference refers to that the undesired signal identical or similar with real satellite navigation signal launched by jammer, satellite navigation receiver is guided to occur Wrong localization, required jamming power is little, disguised strong, interference effect is good, and the method suppressed for suppression jamming cannot suppress Deceiving interference effectively, and Deceiving interference becomes the important threat of satellite navigation system gradually.

In recent years, Chinese scholars is all finding the effective way suppressed for Deceiving interference always.Existing method be from interference to, catch link, aspect such as tracking link, positioning result and navigation message etc. starts with and to suppress cheating interference.Wherein, Deceiving interference is to being a kind of main Deceiving interference suppressing method to utilize array antenna to estimate.S.Daneshmand proposes a kind of Deceiving interference suppression technology based on multiple antennas, the Received signal strength of every root antenna and reference antenna are carried out computing cross-correlation to obtain the next to angle of Deceiving interference, but this suppression technology can not be applicable to the scene in multiple deception source.Rockwell Collins company of the U.S. proposes a kind of array antenna that utilizes to suppress the method for Deceiving interference, this method according to receiver to the information after every Satellite Tracking estimate satellite-signal to, and therefrom identify Deceiving interference come to, finally carry out antenna zeroing at Deceiving interference to direction, to suppress Deceiving interference, but this method needs the feedback information of receiver, complex structure, and operand is large.Therefore, the invention provides one utilize array antenna estimate multiple Deceiving interference source come to, identify Deceiving interference source number, and effectively suppress the method for Deceiving interference, realize simple, operand is little, does not need receiver feedback information, can as independently anti-Deceiving interference Module-embedding common receiver.

Summary of the invention

In order to solve the problem, the object of the present invention is to provide a kind of satellite navigation Deceiving interference suppressing method estimated based on Deceiving interference DOA.

In order to achieve the above object, the satellite navigation Deceiving interference suppressing method estimated based on Deceiving interference DOA provided by the invention comprises the following step carried out in order:

(1) by array antenna received to radiofrequency signal down coversion change into digital medium-frequency signal;

(2) utilize the characteristic of cycle repetition of C/A code, adopt CLEAN method estimate from above-mentioned digital medium-frequency signal multiple Deceiving interference source come to, to judge Deceiving interference source number;

(3) utilize the Deceiving interference source in step (2) to come to array of designs adaptive weight vector, to suppress Deceiving interference, finally the satellite navigation signals after Wave beam forming be converted to analog radio-frequency signal and send into conventional satellite receiver.

In step (2), described is the characteristic of cycle repetition utilizing C/A code, adopt CLEAN method estimate from above-mentioned digital medium-frequency signal multiple Deceiving interference source come to, to judge that the method for Deceiving interference source number is: first all after dates of a receiving signal delayed C/A code of first array element in array antenna are carried out relevant to array antenna received signals, thus make the noise correlation in Received signal strength greatly reduce; Then utilize CLEAN algorithm estimate multiple Deceiving interference source come to, and judged the number in Deceiving interference source by the power calculating estimated signal.

In step (3), the described Deceiving interference source in step (2) that utilizes is come to designing antenna adaptive weight vector, to suppress Deceiving interference, finally the satellite navigation signals after Wave beam forming is converted to analog radio-frequency signal and the method sending into conventional satellite navigation neceiver is: calculate antenna self-adaptive weights be Deceiving interference source estimated by step (2) come to, consider to arrive and there is error to estimation, in conjunction with linearly constrained minimum variance algorithm and first differential bounding algorithm, calculate antenna self-adaptive weights, finally the digital medium-frequency signal after weighting is sent into conventional satellite navigation navigation neceiver.

The satellite navigation Deceiving interference suppressing method estimated based on Deceiving interference DOA provided by the invention utilizes Deceiving interference space and power features, adopt CLEAN method of estimation estimate Deceiving interference to, in conjunction with linear constraint minimal variance (LCMV) algorithm, Deceiving interference direction is formed zero fall into, and adopt first differential bounding algorithm to carry out broadening to antenna zero is sunken, to suppress Deceiving interference, the inventive method realizes simple, operand is little, do not need receiver feedback information, and can as an independently anti-Deceiving interference Module-embedding common receiver.

Accompanying drawing explanation

Fig. 1 is the antenna radiation pattern that in the inventive method, adaptive weight is corresponding.

Fig. 2 is the peak results of the PRN1 that when not taking the inventive method suppression Deceiving interference, receiver acquisition arrives.

Fig. 3 is the peak results of the PRN1 that when taking the inventive method suppression Deceiving interference, receiver acquisition arrives.

Fig. 4 is the satellite navigation Deceiving interference suppressing method process flow diagram estimated based on Deceiving interference DOA provided by the invention.

Embodiment

With specific embodiment, the satellite navigation Deceiving interference suppressing method estimated based on Deceiving interference DOA provided by the invention is described in detail with reference to the accompanying drawings.For convenience's sake, be illustrated for the uniform line-array of GPS (Global PositioningSystem) system and N number of array element composition below.

As shown in Figure 4, the satellite navigation Deceiving interference suppressing method estimated based on Deceiving interference DOA provided by the invention comprises the following step carried out in order:

(1) by array antenna received to radiofrequency signal down coversion change into digital medium-frequency signal:

Relay type Deceiving interference is made up of the forward signal (Pseudolite signal) of many real satellite signals and launches in the same direction, in order to can jamming target receiver effectively, the power of the forward signal of every real satellite signal be slightly stronger than the power of real satellite signal.Therefore the be superimposed power of the single real satellite signal of power ratio of the single relay type Deceiving interference formed of the forward signal of many real satellite signals wants high.When multiple relay type Deceiving interference incides on array antenna, the intermediate-freuqncy signal that GPS antenna array receives is:

$y\left(n{T}_s\right)=\underset{m=1}{\overset{M}{\mathrm{\Σ}}}{a}_m{s}_m^a\left({\mathrm{nT}}_s\right)+\underset{k=1}{\overset{K}{\mathrm{\Σ}}}{b}_k{j}_k^s\left({\mathrm{nT}}_s\right)+n\left({\mathrm{nT}}_s\right)---\left(1\right)$

Wherein, M and K represents the number of actual signal and the number in Deceiving interference source respectively.A _ma (θ _m) write a Chinese character in simplified form, represent the steering vector of m real satellite signal, θ _mrepresent coming to angle of m real satellite signal,

$a_m=a\left({\mathrm{\θ}}_m\right)={\left[\begin{array}{cccc}1& e^{-j\frac{2\mathrm{\π}}{\mathrm{\λ}}d\sin {\mathrm{\θ}}_m}& ...& e^{-j(N-1)\frac{2\mathrm{\π}}{\mathrm{\λ}}d\sin {\mathrm{\θ}}_m}\end{array}\right]}^T---\left(2\right)$

B _kbe write a Chinese character in simplified form, represent the steering vector in a kth Deceiving interference source, represent coming to angle of a kth Deceiving interference source,

$b_k=b\left({\mathrm{\θ}}_k^s\right)={\left[\begin{array}{cccc}1& e^{-j\frac{2\mathrm{\π}}{\mathrm{\λ}}d\sin {\mathrm{\θ}}_k^s}& ...& e^{-j(N-1)\frac{2\mathrm{\π}}{\mathrm{\λ}}d\sin {\mathrm{\θ}}_k^s}\end{array}\right]}^T---\left(3\right)$

In formula (2) and formula (3), d represents array element distance, and λ is satellite signal wave lengths.N (nT _s) be additive white Gaussian noise, T _sfor sampling interval. represent m real satellite navigation signals, represent a kth relay type Deceiving interference, wherein include multiple Pseudolite signal, subscript a and s indicates real satellite signal and Deceiving interference respectively.Wherein:

$s_m^a\left({\mathrm{nT}}_s\right)=\sqrt{p_m^a}{D}_m^a({\mathrm{nT}}_s-{\mathrm{\τ}}_m^a)c_m^a({\mathrm{nT}}_s-{\mathrm{\τ}}_m^a)e^{j{\mathrm{\φ}}_m^a+j2\mathrm{\π}{f}_m^{\′a}{\mathrm{nT}}_s}---\left(4\right)$

$j_k^s\left({\mathrm{nT}}_s\right)=\underset{l=1}{\overset{L_k}{\mathrm{\Σ}}}\sqrt{p_l^s}{D}_l^s({\mathrm{nT}}_s-{\mathrm{\τ}}_l^s)c_l^s({\mathrm{nT}}_s-{\mathrm{\τ}}_l^s)e^{j{\mathrm{\φ}}_l^s+j2\mathrm{\π}{f}_l^{\′s}{\mathrm{nT}}_s}---\left(5\right)$

φ, f ', p and τ represent the phase place of Received signal strength, Doppler frequency and code time delay respectively.D (nT _s) and c (nT _s) represent navigation message and C/A code respectively.Because relay type Deceiving interference source includes many Pseudolite signals, the L in formula (5) _krepresent the number of a kth Pseudolite signal that relay type Deceiving interference source comprises.

(2) utilize the characteristic of cycle repetition of C/A code, adopt CLEAN method estimate from above-mentioned digital medium-frequency signal multiple Deceiving interference source come to, to judge Deceiving interference source number:

The Gold code of C/A code to be a kind of code check be 1.023Mchips/s, the code cycle is 1023 chips, and every 1 millisecond is repeated once.D code code check is 50Hz, at the C/A code of a D code cycle memory 20 repetition periods, because D code does not change in one-period, so 20 of correspondence C/A codes have identical structure, and the characteristic that the cycle that namely shows repeats.The Received signal strength of antenna array first array element can be expressed as:

$y_1\left({\mathrm{nT}}_s\right)=\underset{m=1}{\overset{M}{\mathrm{\Σ}}}{a}_{m,1}{s}_m^a\left({\mathrm{nT}}_s\right)+\underset{k=1}{\overset{K}{\mathrm{\Σ}}}{b}_{k,1}{j}_k^s\left({\mathrm{nT}}_s\right)+e\left({\mathrm{nT}}_s\right)---\left(6\right)$

Wherein, a _{m, 1}, b _{k, 1}steering vector a respectively _m, b _kfirst element.To Received signal strength time delay C/A code cycle T of first array element, then have:

$y_1({\mathrm{nT}}_s-T)=\underset{m=1}{\overset{M}{\mathrm{\Σ}}}{a}_{m,1}{s}_m^a({\mathrm{nT}}_s-T)+\underset{k=1}{\overset{K}{\mathrm{\Σ}}}{b}_{k,1}{j}_k^s({\mathrm{nT}}_s-T)+e({\mathrm{nT}}_s-T)---\left(7\right)$

Within a D code cycle, $s_m^a({\mathrm{nT}}_s-T)=s_m^a\left({\mathrm{nT}}_s\right),j_k^s({\mathrm{nT}}_s-T)=j_k^s\left({\mathrm{nT}}_s\right).$ Formula (7) can be expressed as:

$y_1({\mathrm{nT}}_s-T)=\underset{m=1}{\overset{M}{\mathrm{\Σ}}}{a}_{m,1}{s}_m^a\left({\mathrm{nT}}_s\right)+\underset{k=1}{\overset{K}{\mathrm{\Σ}}}{b}_{k,1}{j}_k^s\left({\mathrm{nT}}_s\right)+e({\mathrm{nT}}_s-T)---\left(8\right)$

Because institute's plus noise is white Gaussian noise, therefore y ₁(nT _s-T) and y (nT _s) dependent vector be:

$\begin{array}{c}r=E\left\{y_1^{*}({\mathrm{nT}}_s-T)y\left({\mathrm{nT}}_s\right)\right\}=\underset{m=1}{\overset{M}{\mathrm{\Σ}}}{p}_m^a{R}_{\mathrm{\τ}}{a}_{m,1}{a}_m+\underset{k=1}{\overset{K}{\mathrm{\Σ}}}\underset{l=1}{\overset{L_k}{\mathrm{\Σ}}}{p}_l^s{R}_{\mathrm{\τ}}{b}_{k,1}{b}_k\\ =\underset{m=1}{\overset{M}{\mathrm{\Σ}}}{\mathrm{\β}}_m^a{a}_m+\underset{k=1}{\overset{K}{\mathrm{\Σ}}}{\mathrm{\β}}_k^s{b}_k\end{array}---\left(9\right)$

Wherein, R _τrepresent the related gain of spreading code, for the complex amplitude of satellite-signal, for the complex amplitude of Deceiving interference.Formula (9) can be expressed as further:

$r=E\left\{y_1^{*}({\mathrm{nT}}_s-T)y\left({\mathrm{nT}}_s\right)\right\}=\underset{q=1}{\overset{Q}{\mathrm{\Σ}}}{\mathrm{\β}}_q{\stackrel{\‾}{a}}_q---\left(10\right)$

Wherein, Q=M+K represents the number of Deceiving interference source and satellite-signal, and β _qrepresent corresponding steering vector and complex amplitude.According to formula (10), by making, following formula is minimum calculates direction of signal, that is:

$\underset{{\mathrm{\θ}}_q,{\mathrm{\β}}_q}{\min }{\left|\right|\hat{r}-\underset{q=1}{\overset{Q}{\mathrm{\Σ}}}{\mathrm{\β}}_q{\stackrel{\‾}{a}}_q\left|\right|}_2^2---\left(11\right)$

Wherein, $\hat{r}=\frac{1}{G}\underset{g=1}{\overset{G}{\mathrm{\Σ}}}{y}_1^{*}\left(g\right)y\left(g\right)$ For the valuation of r.

Solved the estimation problem of formula (11) by CLEAN algorithm, its step is as follows:

Step 1: suppose Q=1, estimates from r according to formula (12) and formula (13) with

${\widehat{\mathrm{\θ}}}_1=\arg \underset{\mathrm{\θ}}{\max }\left|{\stackrel{\‾}{a}}^H\left(\mathrm{\θ}\right)r\right|---\left(12\right)$

${\widehat{\mathrm{\β}}}_1=\frac{{\stackrel{\‾}{a}}^H\left({\widehat{\mathrm{\θ}}}_1\right)r}{{\left|\right|\stackrel{\‾}{a}\left({\widehat{\mathrm{\θ}}}_1\right)\left|\right|}^2}---\left(13\right)$

Step 2: suppose Q=2, according to with obtain r ₂:

$r_2=r-{\widehat{\mathrm{\β}}}_1{\widehat{\stackrel{\‾}{a}}}_1---\left(14\right)$

According to formula (15) and formula (16) from r ₂middle estimation with

${\widehat{\mathrm{\θ}}}_2=\arg \underset{\mathrm{\θ}}{\max }\left|{\stackrel{\‾}{a}}^H\left(\mathrm{\θ}\right)r_2\right|---\left(15\right)$

${\widehat{\mathrm{\β}}}_2=\frac{{\stackrel{\‾}{a}}^H\left({\widehat{\mathrm{\θ}}}_2\right)r_2}{{\left|\right|\stackrel{\‾}{a}\left({\widehat{\mathrm{\θ}}}_2\right)\left|\right|}^2}---\left(16\right)$

Step 3: suppose Q=3, according to obtain r ₃:

$r_3=r-\underset{q=1}{\overset{2}{\mathrm{\Σ}}}{\widehat{\mathrm{\β}}}_q{\widehat{\stackrel{\‾}{a}}}_q---\left(17\right)$

From r ₃middle estimation obtains with

Repeat above-mentioned step, often estimate a signal to complex amplitude after calculate the power of this signal, deceiving jamming comprises many Pseudolite signals, so the power of deceiving jamming is higher than the power of real satellite signal.Therefore, Deceiving interference to being estimated at first, according to estimating that the power that the complex amplitude that obtains can obtain Deceiving interference is after treating that Deceiving interference all estimates, CLEAN algorithm start to estimate satellite-signal come to and complex amplitude, the power of estimated satellite-signal is can obviously find out, the power of the power ratio satellite-signal of Deceiving interference is high a lot, therefore can identify the number in Deceiving interference source.

(3) utilize the Deceiving interference source in step (2) to come to array of designs adaptive weight vector, to suppress Deceiving interference, the satellite navigation signals after Wave beam forming be converted to analog radio-frequency signal and send into conventional satellite navigation neceiver:

The Deceiving interference source estimated according to CLEAN algorithm come to, in conjunction with linear constraint minimal variance (LCMV) algorithm, calculate antenna self-adaptive weights.Responding in constraint first array element is 1, and the Deceiving interference source directional response of estimation is under the condition of 0, and adaptive weight has minimum modulus value, and can obtain upwards having zero in Deceiving interference source side and fall into, all the other directions have the antenna radiation pattern of flat gain.Consider that the estimated accuracy of CLEAN algorithm is not high, adopt first differential bounding algorithm, antenna zero is fallen into and carries out broadening.The antenna self-adaptive weights meeting above-mentioned requirements are w, then w is the solution of restricted problem below:

$\left\{\begin{array}{c}\begin{array}{cc}\min & w^{H}w\end{array}\\ \begin{array}{cc}s.t.& w^{H}g=1\end{array}\\ w^{H}A=\left[\begin{array}{ccc}0& ...& 0\end{array}\right]\\ {\frac{\∂\left(w^{H}A\right)}{\∂\mathrm{\ξ}}|}_{\mathrm{\θ}={\mathrm{\θ}}_K}=0\end{array}\right.---\left(18\right)$

Wherein, ξ=-π sin θ, g=[1 0 ... 0] ^t, $A=\left[\begin{array}{cccc}b\left({\widehat{\mathrm{\θ}}}_1\right)& b\left({\widehat{\mathrm{\θ}}}_2\right)& ...& b\left({\widehat{\mathrm{\θ}}}_K\right)\end{array}\right].$ Formula (18) can be expressed as further:

$\left\{\begin{array}{c}\begin{array}{cc}\min & w^{H}w\end{array}\\ \begin{array}{cc}s.t.& w^{H}g=1\end{array}\\ w^{H}A=\left[\begin{array}{ccc}0& ...& 0\end{array}\right]\\ w^H\mathrm{BA}=\left[\begin{array}{ccc}0& ...& 0\end{array}\right]\end{array}\right.---\left(19\right)$

Wherein, B=diag{0,1 ..., N-1} is that N × N ties up diagonal matrix.Make C=[A BA g], s=[0 ... 0 1] ^t, the optimum solution of formula (19) is:

w _opt＝C(C ^HC) ^-1s (20)

Finally, with antenna self-adaptive weights, antenna zeroing is carried out to Deceiving interference.The data without Deceiving interference after antenna zeroing are:

$z\left({\mathrm{nT}}_s\right)=w_{\mathrm{opt}}^{H}y\left({\mathrm{nT}}_s\right)=\underset{m=1}{\overset{M}{\mathrm{\Σ}}}{P}_m{s}_m^a\left({\mathrm{nT}}_s\right)+e\left({\mathrm{nT}}_s\right)---\left(21\right)$

Wherein, represent the array response of m satellite, e (nT _s) represent noise.

Finally, the digital medium-frequency signal after weighting is sent into conventional satellite navigation neceiver.

Fig. 1 is the antenna radiation pattern that in the inventive method, adaptive weight is corresponding.In the present embodiment, array antenna is 10 yuan of even linear arrays, four gps satellite signal PRN1, PRN3, PRN22, PRN25 is respectively from 0 °, and 20 ° ,-15 ° ,-30 ° of directions are incided on array antenna, and code time delay is respectively 407,830,623,306 chips, signal to noise ratio (S/N ratio) is-20dB.Deceiving interference source 1 (comprises four Pseudolite signal PRN1, PRN3, the forward signal of PRN22, PRN25, time delay 580 chips) incide array antenna from 40 ° of directions, Deceiving interference source 2 (comprises four Pseudolite signal PRN1, the forward signal of PRN3, PRN22, PRN25, time delay 280 chips) incide array antenna from-20 ° of directions, the signal to noise ratio (S/N ratio) of each pseudo satellite, pseudolite is-18dB.In Fig. 1 black dotted lines represent Deceiving interference source come to, the antenna radiation pattern that obtains of the inventive method only upwards forms darker zero in Deceiving interference source side and falls into as can be seen from Figure 1, thus can Deceiving interference be suppressed, and gain is more smooth in the other direction, to ensure passing through of real satellite signal.

Fig. 2 is the peak results of the PRN1 that when not taking the inventive method suppression Deceiving interference, receiver acquisition arrives.In the present embodiment, the code time delay of real satellite signal PRN1 is 407 chips, and the PRN1 code time delay in Deceiving interference source 1 is 990 chips, and the PRN1 code time delay in Deceiving interference source 2 is 686 chips.From Fig. 2 can obviously observe receiver acquisition to the peak value of PRN1 be the correlation peak of Deceiving interference PRN1.

Fig. 3 is the peak results of the PRN1 that when taking the inventive method suppression Deceiving interference, receiver acquisition arrives.In the present embodiment, the code time delay of real satellite signal PRN1 is 407 chips, and the code time delay of Deceiving interference PRN1 is 990 chips, and the PRN1 code time delay in Deceiving interference source 2 is 686 chips.From Fig. 3 can obviously observe receiver acquisition to the peak value of PRN1 be the correlation peak of real satellite signal PRN1.

Claims (3)

1., based on the satellite navigation Deceiving interference suppressing method that Deceiving interference DOA estimates, it is characterized in that: it comprises the following step carried out in order:

(1) by array antenna received to radiofrequency signal down coversion change into digital medium-frequency signal;

(2) utilize the characteristic of cycle repetition of C/A code, adopt CLEAN method estimate from above-mentioned digital medium-frequency signal multiple Deceiving interference source come to, to judge Deceiving interference source number;

(3) the Deceiving interference source in step (2) is utilized to come to array of designs adaptive weight vector, to suppress Deceiving interference, finally the satellite navigation signals after Wave beam forming be converted to analog radio-frequency signal and send into conventional satellite navigation neceiver.

2. the satellite navigation Deceiving interference suppressing method estimated based on Deceiving interference DOA according to claim 1, it is characterized in that, in step (2), described is the characteristic of cycle repetition utilizing C/A code, adopt CLEAN method estimate from above-mentioned digital medium-frequency signal multiple Deceiving interference source come to, to judge that the method for Deceiving interference source number is: first all after dates of a receiving signal delayed C/A code of first array element in array antenna are carried out relevant to array antenna received signals, thus the noise correlation in Received signal strength is reduced greatly, then utilize CLEAN algorithm estimate multiple Deceiving interference source come to, and judged the number in Deceiving interference source by the power calculating estimated signal.

3. the satellite navigation Deceiving interference suppressing method estimated based on Deceiving interference DOA according to claim 1, it is characterized in that: in step (3), the described Deceiving interference source in step (2) that utilizes is come to designing antenna adaptive weight vector, to suppress Deceiving interference, finally the satellite navigation signals after Wave beam forming is converted to analog radio-frequency signal and the method sending into conventional satellite navigation neceiver is: calculate antenna self-adaptive weights be Deceiving interference source estimated by step (2) come to, consider to arrive and there is error to estimation, in conjunction with linearly constrained minimum variance algorithm and first differential bounding algorithm, calculate antenna self-adaptive weights, finally the digital medium-frequency signal after weighting is sent into conventional satellite navigation neceiver.