CN105717518A - Code phase identification based deception signal detection method of satellite receiver - Google Patents

Abstract

The invention discloses a code phase identification based deception signal detection method of a satellite receiver. The method comprises the following steps that S1) when the satellite receiver recaptures and tracks signals, deception signal detection is carried out on the basis of code phase identification by utilizing peak value results related to pseudo code despreading in the baseband signal processing process of the satellite receiver; S2) if no deception signals are found via detection, a carrier movement state obtained by a track reckoning method and satellite movement state information obtained by ephemeris parameters are used to further carry out code phase identification on the recaptured and tracked signals, namely, the pseudo phase parameters despread by the satellite receiver are distinguished; and S3) if it is detected that the despreading demodulation signals of the satellite receiver include the deception signals, alarm is raised against the deception signals, the deception signals are isolated, and thus, capabilities of resisting cheating and interference of the satellite receiver are enhanced.

Description

A kind of DVB curve detection method based on code phase identification

Technical field

The invention belongs to satellite navigation and the technical field of receiver signal process, particularly to a kind of DVB curve detection method based on code phase identification.

Background technology

Satellite navigation, as the important technology approach in navigation field, can provide round-the-clock, continuous, high accuracy three-dimensional positional information to Global Subscriber in real time.Progressively development along with all kinds of satellite navigation interference, Cheating Technology, the precision of satellite navigation system, seriality and integrity are proposed stern challenge by interference and curve, and especially cheating interference is by effective application of serious threat satellite navigation system positioning performance.

Current satellite curve detection method is mostly employing multiple antenna method and is identified radiofrequency signal processing stage, hardware designs requires height, realize difficulty relatively big, and it is less to utilize code phase feature to carry out the method for curve detection in DVB base band signal process process.Curve is implemented the technological means of deception and is mainly the satellite-signal that analog-modulated carrier frequency is similar to actual signal, and due to its Location fraud demand, the code phase values of its code phase parameter and real satellite signal has larger difference, just can lure that DVB carries out location of mistake into, and general DVB to solution extend to tracking code phase value and do not distinguish, measuring and be directly used in the process of corresponding positioning calculation after obtaining, this just gives the chance that satellite cheating interference side is achieved its deception purpose.

Summary of the invention

Goal of the invention: the technical problem to be solved is the development for prior art Satellite Location fraud technology and the curve technological deficiency to the threat of DVB reliability application, it is provided that a kind of DVB curve detection method based on code phase identification.

In order to solve above-mentioned technical problem, the invention discloses a kind of DVB curve detection method based on code phase identification, after DVB experiences the cheating interference effect of satellite-signal interference unit, there is signal losing lock in DVB, comprises the following steps:

Step S1, when DVB recapture and tracking signal, the DVB curve based on code phase identification detects, and utilizes the correlation peak result of pseudo-code despreading in DVB base band signal process process, carries out curve detection；

Step S2, as do not detected curve, then utilize the carrier movement state that reckoning method obtains, and the satellite motion status information obtained by ephemeris parameter, further recapture and tracking signal are carried out code phase identification process, namely the pseudo-code phase parameter of DVB despreading is carried out true and false identification；

Step S3, after detecting that receiver despread-and-demodulation signal contains curve, carries out reporting to the police to curve and isolates, thus strengthening the anti-deceptive interference ability of DVB.

Step S1 Satellite receiver of the present invention utilize the actual signal received carry out baseband signal catch, tracking process and positioning calculation, and record tracking satellite asterisk；After the cheating interference effect of experience satellite-signal interference unit, there is signal losing lock in DVB, and the DVB curve detection starting based on code phase identification when DVB recapture and tracking signal processes.

Step S1 of the present invention includes:

Step S1-1, DVB is taked multi-channel parallel to catch and follows the tracks of tupe, after signal recapture, first differentiates that each passage follows the tracks of the satellite number of i-th passage after recapturingWith recapture before the satellite PRN of i-th passage that normally follows the tracks of of all passages_iWhether there is an identical star, i=1 ..., n, i represents channel number, and n represents total number of channels, is then made directly code phase identification such as difference and processes；If any identical, first carry out correlation peak detection, judge curve presence or absence further according to correlation peak result, as do not detected curve, further utilize code phase discrimination method to carry out curve detection.

Step S1-2, utilize correlation peak result judge curve method as: after the two-way local replica carrier multiplication of input intermediate-freuqncy signal and phase 90 °, obtain signal I and signal Q two paths of signals, wherein I road signal is in-phase correlate, and Q road signal is quadrature related signals；Carry out coherent integration results calculating；Coherent integration results in each code phase values is carried out peak computational, when the peak number occurred under any one carrier Doppler frequency is be more than or equal to 2, namely judge that the satellite-signal of despreading exists satellite curve, this curve is the true satellite curve receiving asterisk that disguises oneself as, and the Doppler frequency parameter of camouflage is identical；When same satellite peak value sum under different carrier Doppler frequency occurring be more than or equal to 2, it is determined that the satellite-signal of despreading exists the true satellite curve receiving asterisk that disguises oneself as, and the Doppler frequency parameter of camouflage is different；As the peak number under searching carrier Doppler frequency is only 1, then carry out next step；Then it is considered as catching unsuccessfully as do not searched correlation peak, it is determined that this search of satellite is invisible star.

Signal after recapturing is carried out code phase identification process by step S2, including: signal after recapturing is tracked processing by each passage respectively；According to certain output cycle, (cycle can be set to 100ms to track loop, 500ms or 1000ms) obtain the required Pseudo-range Observations in DVB location (referring to Xie Gang .GPS principle and receiver design. Beijing: Electronic Industry Press, 2009), pseudolite receiver utilizes the location in last cycle obtained before meeting with the interference of satellite-signal interference unit, constant speed result carries out dead reckoning, reckoning method is the known location and speed state that utilize carrier to obtain before signal disturbing, run location and speed calculation according to a upper moment go out the carrier position at current time, then the positional information of subsequent time is calculated again from the position of current time, by utilizing the identification that the position result that dead reckoning obtains carries out code phase to process, determine in the signal followed the tracks of and whether contain curve.

Step S3 differentiates this curve type, this satellite is reported to the police and isolation processing simultaneously, including: first carry out curve type identification, shield the use of this deception satellite-signal pseudo range observed quantity simultaneously, the pseudo range observed quantity utilizing other any one actual signal is reorientated, if there is the satellite-signal of the process situation that quantity is curve more than 50% in tracking channel, then receiver is carried out cold start-up, namely scan for one by one whole satellites of whole constellation catching and curve detection, if still cannot be carried out normal location, dead-reckoning position result is adopted temporarily to position；If not detecting curve, then complete normal positioning function by receiver former positioning calculation mode.

The method of the correlation peak detection described in step S1 and differentiation curve is: first input intermediate-freuqncy signal is replicated after carrier signal is multiplied with the two-way of phase 90 ° respectively and obtains signal I and signal Q two paths of signals, wherein I road signal is in-phase correlate, and Q road signal is quadrature related signals；Then, again by signal I and signal Q with replicate pseudo-code signal (referring to: Xie Gang .GPS principle and receiver design. Beijing: Electronic Industry Press, 2009) time of carrying out is the related operation of 1ms, namely obtain input signal and the correlated results replicating pseudo-code, be then T by the correlated results elapsed time_cohCoherent integration after obtain coherent integration results I (n) of I, Q two-way and Q (n), shown in computational methods such as formula (1)；

I (n)=A_PD(n)R(τ)sinc(f_eT_coh)cosφ_e+n_I(1),

Q (n)=A_PD(n)R(τ)sinc(f_eT_coh)sinφ_e+n_Q

Wherein, A_pFor signal amplitude, D (n) is the navigation data bit level value that value is ± 1, the auto-correlation function that R (τ) is spreading code, and τ receives the difference between code phase and searching code phase place, f_eAnd φ_eFrequency-splitting and phase difference value, the n respectively receiving carrier signal and replicate carrier signal_IAnd n_QRespectively on I, Q two-way, average is the noise component(s) of 0 and orthogonal；

Coherent integration results in each code phase values carries out peak value V calculating, and result of calculation is as more than peak threshold, being then judged to detect peak value, and in the present invention, threshold value is set to 2.0～2.6, shown in computational methods such as formula (2)；

$V=\sqrt{I{\left(n\right)}^2+Q{\left(n\right)}^2}---\left(2\right);$

Carrier Doppler frequency scope and all code phase spaces of the described p-5KHz～5KHz of correlation peak detection process are searched for one by one, when the peak number occurred under any one carrier Doppler frequency is be more than or equal to 2, namely judge that the satellite-signal of despreading exists satellite curve, this curve is the true satellite curve receiving asterisk that disguises oneself as, and the Doppler frequency parameter of camouflage is identical；When same satellite peak value sum under different carrier Doppler frequency occurring be more than or equal to 2, it is determined that the satellite-signal of despreading exists the true satellite curve receiving asterisk that disguises oneself as, and the Doppler frequency parameter of camouflage is different.

Code phase identification described in step S1 of the present invention and step S2 processes, including: signal after recapturing is tracked processing by each passage respectively, then according to certain output cycle, (cycle can be set to 100ms to track loop, 500ms or 1000ms) obtain the Pseudo-range Observations that DVB location is required, concrete grammar is received signal time t by the DVB kth cycle in each cycle (following k all represents periodicity)_u,kWith satellite kth periodic emission signal time t_s,kBetween difference be multiplied by light velocity c and calculate Pseudo-range Observations, and satellite kth periodic emission signal time t_s,kThe code phase values τ obtained by kth period tracking_code,kReckoning obtains, and computational methods are shown in formula (3)；

$t_{s,k}=SOW+(30w+b)\×0.020+(cy+\frac{{\mathrm{\τ}}_{code,k}}{f_{code}\×{10}^{-3}})\×0.001---\left(3\right),$

Wherein, w is the whole navigation message numeric data code having been received by k moment number of words in present sub-frame, and when SOW is in week in seconds, b is the bit number having been received by text in current word, and cy is the pseudo-code complete cycle number having been received by current bit, f_codeFor bit rate；

Rise in compacting interference and the cheating interference moment of DVB experience satellite-signal interference unit, before utilizing DVB to meet with the interference of satellite-signal interference unit, the location in last cycle of acquisition, constant speed result carry out dead reckoning, and the position result obtained by dead reckoning carries out the code phase valuation of kth cycleCalculate, the code phase values τ that tracking is obtained_codeWith code phase valuationDo difference, it is thus achieved that code phase difference Δ τ_code；The code phase difference in 10 cycles of Continuous plus, if be wherein all higher than setting code phase threshold value more than the difference in 5 cycles, it is determined that containing curve in followed the tracks of signal, code phase threshold value elects number of chips, i.e. f contained by the complete cycle as herein_code×10^-3, otherwise it is judged to without curve；

In step S2, code phase identification utilizes the three-dimensional position X that boat position calculates in processing_r=(x_r,y_r,z_r) calculate code phase valuationMethod such as formula (4) shown in:

${\mathrm{\τ}}_{code,k}^e=(t_{u,k}-\frac{{\left|X_r-X_S\right|}_k}{c}-SOW-(30w+b)\×0.020-cy\×0.001)\×f_{code}---\left(4\right)$

Wherein, X_S=(x_s,y_s,z_s) for the three-dimensional position at signal x time satellite place, the ephemeris parameter preserved in DVB calculate and obtain, | X_r-X_S| for the Euclidean distance between DVB DR position and satellite position, formula (5) calculate and obtain:

$\left|X_r-X_S\right|=\sqrt{{(x_r-x_s)}^2+{(y_r-y_s)}^2+{(z_r-z_s)}^2}---\left(5\right)$

Reckoning method utilized DVB carrier at the known kinestate residing for the upper moment, goes out the carrier position at current time according to current operation course and dead reckoning, then calculates the positional information of subsequent time again from the position of current time.

Curve type identification method of the present invention is as follows: detect and whether compare the satellite asterisk of all channels track before satellite number used by this curve and recapture signal identical, as identical, then this curve is the true satellite curve receiving asterisk that disguises oneself as；Such as difference, then this curve has satellite curve for non-existent void originally.

Curve partition method described in step S3 of the present invention is: shield the use of this deception satellite-signal pseudo range observed quantity, the pseudo range observed quantity utilizing other actual signal is reorientated, if there is the satellite-signal of the process situation that quantity is curve more than 50% in tracking channel, then receiver is carried out cold start-up, namely scanning for one by one whole satellites of whole constellation catching and curve detection, then adopting dead-reckoning position result temporarily to position as still cannot be carried out normal location.

Follow the tracks of the relative position between pseudo-code phase and satellite and receiver due to DVB and have the internal relation of essence, therefore utilize code phase parameter identification DVB curve to provide technical foundation in the present invention, improve the unfailing performance of the DVB discrimination capabilities to curve and receiver self application.

The present invention compared with prior art overcomes, when existing satellite curve detection method is identified radiofrequency signal processing stage, hardware designs is required higher difficulty, construct a kind of DVB curve detection method based on code phase identification, by the autocorrelation peak of pseudo-code despreading in DVB base band signal process process is detected, then the carrier movement state that reckoning obtains and the pseudo-code phase that DVB is de-spread by the satellite motion status information obtained by ephemeris parameter is utilized to carry out true and false identification, realize DVB to whether despread-and-demodulation signal containing curve and differentiating the discrimination function of curve type, thus strengthening anti-deceptive interference ability and the application reliability of DVB.The DVB curve detection method based on code phase identification proposed has the advantage that (1) provides and utilizes the autocorrelation peak result of pseudo-code despreading in base band signal process process to carry out the function of curve detection；(2) provide and utilize the satellitosis that reckoning carrier state and ephemeris parameter obtain that curve is carried out discriminating function；(3) discrimination function of satellite curve type is provided.

Accompanying drawing explanation

Below in conjunction with the drawings and specific embodiments the present invention being done and further illustrate, the above-mentioned and/or otherwise advantage of the present invention will become apparent.

Fig. 1 is the DVB curve detection method flow chart based on code phase identification of the present invention.

Fig. 2 be the present invention utilize code phase identification curve method flow diagram.

Fig. 3 is that the correlation peak detection method that utilizes corresponding to the present invention differentiates actual signal and curve result figure.

Fig. 4 is the DVB curve test experience result figure based on code phase identification that the present invention is corresponding.

Detailed description of the invention

As shown in Figure 1, principles of the invention is: by the autocorrelation peak of pseudo-code despreading in DVB base band signal process process is detected, the pseudo-code phase that DVB is de-spread by the carrier movement state recycling the acquisition of reckoning method and the satellite motion status information obtained by ephemeris parameter carries out true and false identification, last after detecting that receiver despread-and-demodulation signal contains curve, carry out reporting to the police to curve and isolate, realize DVB to the detection of curve and discriminating function, realize a kind of DVB curve detection method based on code phase identification.Specific implementation method is as follows:

(1) DVB first with the actual signal received carry out normal baseband signal catch, tracking process and positioning calculation, and record tracking satellite asterisk, then after the compacting interference of experience satellite-signal interference unit and cheating interference effect, recapture signal being tracked after satellite receiver signal losing lock, the detection of DVB curve and the differentiation that now start based on code phase identification process.

(2) DVB is taked multi-channel parallel to catch and follows the tracks of tupe, after signal recapture, first differentiate each passage recapture after tracking satellite numberWith recapture before the satellite PRN that normally follows the tracks of of all passages_iWhether there is an identical asterisk, i=1 ..., n, i represent channel number, and n represents total number of channels, if any identical, first carry out correlation peak detection, judge further after then directly judging curve testing result further according to correlation peak detection result or process then through code phase identification；Then it is made directly code phase identification to process such as difference.

(3) the correlation peak detection method of discrimination of curve need to utilize the correlation properties of spread spectrum code in satellite navigation system, method particularly includes: after the two-way local replica carrier multiplication of input intermediate-freuqncy signal and phase 90 °, obtain I, Q two paths of signals, wherein I road signal is in-phase correlate, Q road signal is quadrature related signals, it is then passed through Fourier transformation to be multiplied with the local replica pseudo-code signal under frequency domain again, after being multiplied, result is again converted to time-domain signal through inverse Fourier transform, namely the correlated results of input signal and local pseudo-code is obtained after amplitude calculates, then it is T by the correlated results elapsed time_cohCoherent integration after obtain coherent integration results I (n) of I, Q two-way and Q (n), concrete form is shown in shown in formula (1), coherent integration results in each code phase values is carried out peak value V calculating, shown in computational methods such as formula (2), result of calculation is as more than peak threshold, then being judged to detect peak value, peak threshold rule of thumb sets, and is set to 2.6 in the method.

Correlation peak detection process needs the carrier Doppler frequency scope of p-5KHz～5KHz and all code phase spaces to search for one by one, when the peak number occurred under certain carrier Doppler frequency is more than or equal to 2, namely judge that the satellite-signal of despreading exists satellite curve, this curve is the true satellite curve receiving asterisk that disguises oneself as, and the Doppler frequency parameter of camouflage is identical；When same satellite peak value sum under different carrier Doppler frequency occurring more than or equal to 2, the same satellite-signal judging despreading exists the true satellite curve receiving asterisk that disguises oneself as, and the Doppler frequency parameter of camouflage is different.

I (n)=A_PD(n)R(τ)sinc(f_eT_coh)cosφ_e+n_I(1)

Q (n)=A_PD(n)R(τ)sinc(f_eT_coh)sinφ_e+n_Q

$V=\sqrt{I{\left(n\right)}^2+Q{\left(n\right)}^2}---\left(2\right)$

Wherein, A_pFor signal amplitude, D (n) is the navigation data bit level value that value is ± 1, the auto-correlation function that R (τ) is spreading code, and τ receives the difference between code phase and searching code phase place, f_eAnd φ_eFrequency-splitting and phase difference value, the n respectively receiving carrier signal and replicate carrier signal_IAnd n_QRespectively on I, Q two-way, average is the noise component(s) of 0 and orthogonal.

(4) as in step (3) correlation peak detection method of discrimination unidentified go out curve, or processed operation by step (2) is made directly code phase identification, then start the signal after recapturing is carried out code phase identification process, method particularly includes:

Signal after recapturing is tracked processing by each passage first respectively, and then track loop obtains, according to certain output cycle, the Pseudo-range Observations that DVB location is required, and Pseudo-range Observations is then by signal reception time t_uWith signal transmission time t_sendBetween difference be multiplied by light velocity c and obtain, signal transmission time is then followed the tracks of, by each cycle, the code phase values τ that obtains_codeReckoning obtains, computational methods are shown in formula (3), rise in compacting interference and the cheating interference moment of DVB experience satellite-signal interference unit, the positioning result in last cycle obtained before starting with interference carries out dead reckoning, then passes through the position result that dead reckoning obtains and carries out code phase valuationCalculate, the code phase values τ that tracking is obtained_codeWith code phase valuationDo difference, it is thus achieved that code phase difference Δ τ_code, calculate the code phase difference in continuous 10 cycles, when being wherein all higher than setting code phase threshold value more than the difference in 5 cycles, it is determined that containing curve in followed the tracks of signal, code phase threshold value elects number of chips, i.e. f contained by the complete cycle as herein_code×10^-3；Otherwise it is judged to without curve.

$t_{s,k}=SOW+(30w+b)\×0.020+(cy+\frac{{\mathrm{\τ}}_{code,k}}{f_{code}\×{10}^{-3}})\×0.001---\left(3\right)$

Wherein, w is the whole navigation message numeric data code having been received by k moment number of words in present sub-frame, and when SOW is in week in seconds, b is the bit number having been received by text in current word, and cy is the pseudo-code complete cycle number having been received by current bit, f_codeFor bit rate.Except τ_codeOutside, in formula (3), on the right of equal sign, parameter is known.

Herein, code phase identification utilizes the three-dimensional position result X that boat position calculates in processing_r=(x_r,y_r,z_r) calculateMethod is shown in shown in formula (4).

${\mathrm{\τ}}_{code,k}^e=(t_{u,k}-\frac{{\left|X_r-X_S\right|}_k}{c}-SOW-(30w+b)\×0.020-cy\×0.001)\×f_{code}---\left(4\right)$

Wherein, X_S=(x_s,y_s,z_s) for the three-dimensional position at signal x time satellite place, the ephemeris parameter preserved in DVB calculate and obtain, | X_r-X_S| for the Euclidean distance between receiver DR position and satellite position, formula (5) calculate and obtain.

$\left|X_r-X_S\right|=\sqrt{{(x_r-x_s)}^2+{(y_r-y_s)}^2+{(z_r-z_s)}^2}---\left(5\right)$

Additionally, reckoning method utilized DVB carrier at the known kinestate residing for the upper moment, go out the carrier position at current time according to current operation course and dead reckoning, then calculate the positional information of subsequent time again from the position of current time, reciprocal with this.

(5) learn that such as certain satellite-signal is curve through step (4) detection, differentiate this curve type further, curve type identification method is as follows: detect and whether compare the satellite asterisk of all channels track before satellite number used by this curve and recapture signal identical, as identical, then this curve is the true satellite curve receiving asterisk that disguises oneself as；Such as difference, then this curve has satellite curve for non-existent void originally.Simultaneously, this satellite is reported to the police and isolation processing, the method of being specifically isolated is shield the use of this deception satellite-signal pseudo range observed quantity, the pseudo range observed quantity utilizing other actual signal is reorientated, as occurred, the satellite-signal processed in tracking channel exceedes the situation that half is curve, then receiver is carried out cold start-up, namely scanning for one by one whole satellites of whole constellation catching and curve detection, then adopting dead-reckoning position result temporarily to position as still cannot be carried out normal location；As do not detected curve, then complete normal positioning function by receiver former positioning calculation mode.

Embodiment

The present embodiment utilizes the actual signal that curve that satellite signal simulator generates and open antenna receive to carry out verifying based on the DVB curve detection method of code phase identification, first, the DVB development board utilizing FPGA and DSP individually gather actual signal that open antenna receives with complete baseband signal in DVB normally catch and tracking processes, next utilizes indoor signal interference unit that DVB carries out compacting interference, cause former tracking signal losing lock, then the curve that the L1 frequency gps satellite signal received by antenna further and satellite signal simulator generate becomes digital medium-frequency signal after development board radio-frequency front-end processes, and this satellite intermediate frequency signal is acquired and storage, finally, utilize DVB that the intermediate-freuqncy signal of storage is carried out processed offline and experimental verification.DVB curve detection method based on code phase identification is tested, draws useful conclusion, it is provided that the dependence diagram of detection method is such as shown in Fig. 1～2, and the experimental result of actual signal and curve detection and differentiation is as shown in figs. 34.

Fig. 1 is the DVB curve detection method flow chart based on code phase identification of the present invention, includes the initial alignment of DVB, signal disturbing and deception, asterisk of recapturing compare, correlation peak detection, code phase identification, curve differentiate and isolation etc. processes；

Fig. 2 be the present invention utilize code phase identification curve method flow diagram, describe the method utilizing reckoning method estimated code phase parameter and the method utilizing code phase parameter identification curve；

The correlation peak detection method that utilizes that Fig. 3 is the present invention differentiates actual signal and curve result figure, as can be seen from Figure, when curve similar carrier Doppler frequency modulated is caught with actual signal simultaneously, there are occurring in the same Doppler frequency interval with a satellite two correlation peaks, show the satellite-signal of despreading exists satellite curve, and the Doppler frequency parameter of curve is identical with the Doppler frequency of true reception satellite.

Fig. 4 is the DVB curve test experience result figure based on code phase identification that the present invention is corresponding, successfully the curve that satellite signal simulator is launched can be detected by correlation peak detection method and code phase parameter identification method, differentiate simultaneously and distinguish actual signal and curve, and curve is isolated, demonstrate the DVB curve detection method based on code phase identification.

The invention provides a kind of DVB curve detection method based on code phase identification; the method and the approach that implement this technical scheme are a lot; the above is only the preferred embodiment of the present invention; should be understood that; for those skilled in the art; under the premise without departing from the principles of the invention, it is also possible to make some improvements and modifications, these improvements and modifications also should be regarded as protection scope of the present invention.The all available prior art of each ingredient not clear and definite in the present embodiment is realized.

Claims (9)

1. the DVB curve detection method based on code phase identification, after DVB experiences the cheating interference effect of satellite-signal interference unit, there is signal losing lock in DVB, it is characterized in that, comprising the following steps: step S1, when DVB recapture and tracking signal, the DVB curve based on code phase identification detects, utilize the correlation peak result of pseudo-code despreading in DVB base band signal process process, carry out curve detection；

Step S2, as do not detected curve, then utilize the carrier movement state that reckoning method obtains, and the satellite motion status information obtained by ephemeris parameter, further recapture and tracking signal are carried out code phase identification process, namely the pseudo-code phase parameter of DVB despreading is carried out true and false identification；

Step S3, after detecting that receiver despread-and-demodulation signal contains curve, reports to the police to curve and isolation processing, thus strengthening the anti-deceptive interference ability of DVB.

2. a kind of DVB curve detection method based on code phase identification according to claim 1, it is characterized in that, step S1 Satellite receiver utilize the actual signal received carry out baseband signal catch, tracking process and positioning calculation, and record tracking satellite asterisk；After the cheating interference effect of experience satellite-signal interference unit, there is signal losing lock in DVB, and the DVB curve detection starting based on code phase identification when DVB recapture and tracking signal processes.

3. a kind of DVB curve detection method based on code phase identification according to claim 2, it is characterised in that step S1 includes:

Step S1-1, DVB is taked multi-channel parallel to catch and follows the tracks of tupe, after signal recapture and tracking, follows the tracks of the satellite number of i-th passage after first differentiating each passage recapture signalThe satellite PRN of the normal i-th passage followed the tracks of with before recapture signal_iWhether identical, i=1 ..., n, i represents channel number, and n represents total number of channels, is then made directly code phase identification such as difference and processes；If any identical, first carry out correlation peak detection, judge curve presence or absence further according to correlation peak result, as do not detected curve, further utilize code phase discrimination method to carry out curve detection；

Step S1-2, utilize correlation peak result judge curve method as: after the two-way local replica carrier multiplication of input intermediate-freuqncy signal and phase 90 °, obtain signal I and signal Q two paths of signals, wherein I road signal is in-phase correlate, and Q road signal is quadrature related signals；Carry out coherent integration results calculating；Coherent integration results in each code phase values is carried out peak computational, when the peak number occurred under any one carrier Doppler frequency is be more than or equal to 2, namely judge that the satellite-signal of despreading exists satellite curve, this curve is the true satellite curve receiving asterisk that disguises oneself as, and the Doppler frequency parameter of camouflage is identical；When same satellite peak value sum under different carrier Doppler frequency occurring be more than or equal to 2, it is determined that the satellite-signal of despreading exists the true satellite curve receiving asterisk that disguises oneself as, and the Doppler frequency parameter of camouflage is different；As the peak number under searching carrier Doppler frequency is only 1, then carry out next step；Then it is considered as catching unsuccessfully as do not searched correlation peak, it is determined that this search of satellite is invisible star.

4. a kind of DVB curve detection method based on code phase identification according to claim 3, it is characterized in that, the signal of recapture and tracking is carried out code phase identification process by step S2, including: signal after recapture signal is tracked processing by each passage respectively, track loop obtains, according to certain output cycle, the Pseudo-range Observations that DVB location is required, DVB utilizes the location in last cycle obtained before meeting with the interference of satellite-signal interference unit, constant speed result carries out dead reckoning, by utilizing the identification that the position result that dead reckoning obtains carries out code phase to process, determine in the signal followed the tracks of and whether contain curve.

5. a kind of DVB curve detection method based on code phase identification according to claim 4, it is characterized in that, this satellite is reported to the police and isolation processing by step S3, including: shield the use of this deception satellite-signal pseudo range observed quantity, the pseudo range observed quantity utilizing other any one actual signal is reorientated, if there is the satellite-signal of the process situation that quantity is curve more than 50% in tracking channel, then receiver is carried out cold start-up, namely scan for one by one whole satellites of whole constellation catching and curve detection, if still cannot be carried out normal location, dead-reckoning position result is adopted temporarily to position；If not detecting curve, then complete normal positioning function by receiver former positioning calculation mode.

6. a kind of DVB curve detection method based on code phase identification according to claim 5, it is characterized in that, the method utilizing correlation peak detection curve described in step S1 is: first input intermediate-freuqncy signal is replicated after carrier signal is multiplied with the two-way of phase 90 ° respectively and obtains signal I and signal Q two paths of signals, wherein I road signal is in-phase correlate, and Q road signal is quadrature related signals；Then by signal I and signal Q with to replicate the pseudo-code signal time of carrying out be the related operation of 1ms, namely obtain input signal and the correlated results replicating pseudo-code, be then T by the correlated results elapsed time then,_cohCoherent integration after obtain coherent integration results I (n) of I, Q two-way and Q (n), shown in computational methods such as formula (1)；

$\begin{array}{c}I\left(n\right)=A_{P}D\left(n\right)R\left(\mathrm{\δ}\mathrm{\τ}\right)\sin c\left(f_e{T}_{coh}\right){\mathrm{cos\φ}}_e+n_I\\ Q\left(n\right)=A_{P}D\left(n\right)R\left(\mathrm{\δ}\mathrm{\τ}\right)\sin c\left(f_e{T}_{coh}\right){\mathrm{sin\φ}}_e+n_Q\end{array}---\left(1\right),$

Wherein, A_pFor signal amplitude, D (n) is the navigation data bit level value that value is ± 1, the auto-correlation function that R (δ τ) is spreading code, and δ τ receives the difference between code phase and searching code phase place, f_eAnd φ_eFrequency-splitting and phase difference value, the n respectively receiving carrier signal and replicate carrier signal_IAnd n_QRespectively on I, Q two-way, average is the noise component(s) of 0 and orthogonal；

Coherent integration results in each code phase values carries out peak value V calculating, and result of calculation is as more than peak threshold, being then judged to detect peak value, shown in computational methods such as formula (2)；

$V=\sqrt{I{\left(n\right)}^2+Q{\left(n\right)}^2}---\left(2\right);$

Carrier Doppler frequency scope and all code phase spaces of the described p-5KHz～5KHz of correlation peak detection process are searched for one by one, when the peak number occurred under any one carrier Doppler frequency is be more than or equal to 2, namely judge that the satellite-signal of despreading exists satellite curve, this curve is the true satellite curve receiving asterisk that disguises oneself as, and the Doppler frequency parameter of camouflage is identical；When same satellite peak value sum under different carrier Doppler frequency occurring be more than or equal to 2, it is determined that the satellite-signal of despreading exists the true satellite curve receiving asterisk that disguises oneself as, and the Doppler frequency parameter of camouflage is different.

7. a kind of DVB curve detection method based on code phase identification according to claim 6, it is characterized in that, code phase identification described in step S1 and step S2 processes, including: signal after recapture signal is tracked processing by each passage respectively, then track loop obtains, according to certain output cycle, the Pseudo-range Observations that DVB location is required, the DVB in each cycle receive signal time t_u,kWith satellite emission signal time t_s,kBetween difference be multiplied by light velocity c and calculate Pseudo-range Observations, k all represents periodicity, and satellite emission signal time t_s,kThe code phase values τ obtained is followed the tracks of by each cycle_code,kReckoning obtains, and computational methods are shown in formula (3)；

$t_{s,k}=SOW+(30w+b)\×0.020+(cy+\frac{{\mathrm{\τ}}_{code,k}}{f_{code}\×{10}^{-3}})\×0.001---\left(3\right),$

Wherein, w is the whole navigation message numeric data code having been received by k moment number of words in present sub-frame, and when SOW is in week in seconds, b is the bit number having been received by text in current word, and cy is the pseudo-code complete cycle number having been received by current bit, f_codeFor bit rate；

Before utilizing DVB to meet with the interference of satellite-signal interference unit, the location in last cycle of acquisition, constant speed result carry out dead reckoning, and the position result obtained by dead reckoning carries out the code phase valuation of kth cycleCalculate, the code phase values τ that tracking is obtained_code,kWith code phase valuationDo difference, it is thus achieved that code phase difference Δ τ_code,k；The code phase difference in 10 cycles of Continuous plus, if be wherein all higher than setting code phase threshold value more than the difference in 5 cycles, it is determined that containing curve in followed the tracks of signal, code phase threshold value elects number of chips, i.e. f contained by the complete cycle as herein_code×10^-3, otherwise it is judged to without curve；

In step S2, code phase identification utilizes the three-dimensional position X that boat position calculates in processing_r=(x_r,y_r,z_r) calculate code phase valuationMethod such as formula (4) shown in:

${\mathrm{\τ}}_{code,k}^e=(t_{u,k}-\frac{{\left|X_r-X_S\right|}_k}{c}-SOW-(30w+b)\×0.020-cy\×0.001)\×f_{code}---\left(4\right)$

Wherein, X_S=(x_s,y_s,z_s) for the three-dimensional position at signal x time satellite place, the ephemeris parameter preserved in DVB calculate and obtain, | X_r-X_S| for the Euclidean distance between DVB DR position and satellite position, formula (5) calculate and obtain:

$\left|X_r-X_S\right|=\sqrt{{(x_r-x_s)}^2+{(y_r-y_s)}^2+{(z_r-z_s)}^2}---\left(5\right)$

As utilized code phase discrimination method to detect that curve exists, then carry out curve type identification.

8. a kind of DVB curve detection method based on code phase identification according to claim 7, it is characterized in that, described curve type identification method is as follows: detect and whether compare the satellite asterisk of all channels track before satellite number used by this curve and recapture signal identical, as identical, then this curve is the true satellite curve receiving asterisk that disguises oneself as；Such as difference, then this curve has satellite curve for non-existent void originally.

9. a kind of DVB curve detection method based on code phase identification according to claim 8, it is characterized in that, curve partition method described in step S3 is: shield the use of this deception satellite-signal pseudo range observed quantity, the pseudo range observed quantity utilizing other actual signal is reorientated, if there is the satellite-signal of the process situation that quantity is curve more than 50% in tracking channel, then receiver is carried out cold start-up, namely scan for one by one whole satellites of whole constellation catching and curve detection, dead-reckoning position result is then adopted temporarily to position as still cannot be carried out normal location.