A method and apparatus for identifying interference signals under periodic broadband suppression interference.

Abstract

This application relates to a method and apparatus for identifying interference signals under periodic broadband suppression interference, belonging to the field of satellite navigation and positioning technology. The method includes: in the false alarm verification stage, combining the current receiver positioning result with satellite ephemeris information, calculating the predicted pseudorange and predicted Doppler frequency shift of the acquired satellite, and performing a first-level interference signal detection by judging whether the deviation between the predicted value and the acquired value exceeds a preset range; in the tracking stage, designing a multi-channel correlator structure centered on the instantaneous code, symmetrically distributed with preset chip intervals and leading / lagging characteristics, and performing a second-level interference signal detection by monitoring whether the ratio between the autocorrelation amplitudes of the integrated outputs of each branch correlator is within the normal range constrained by the ideal autocorrelation function of the pseudo-random code. This method can reduce the probability of false acquisition and false tracking of interference signals, and improve the robustness and positioning success rate of the RNSS system under strong suppression interference environments.

Description

Technical Field

[0001] This application relates to the field of satellite navigation and positioning technology, and in particular to a method and apparatus for identifying interference signals under periodic broadband suppression interference. Background Technology

[0002] In the RNSS (Radio Navigation Satellite Service) civilian code positioning system, broadband suppression jamming is a typical hostile jamming tactic. Essentially, it involves transmitting high-power, wide-spectrum noise or noise-like signals to create a high signal-to-interference ratio (SIR) environment at the receiver, thereby "overwhelming" the real satellite signal and disrupting the receiver's normal positioning and communication functions. This type of jamming signal often employs the same pseudo-random code modulation method as the target satellite signal, specifically a periodic pseudo-random code generated by a linear feedback shift register. This code sequence exhibits statistical characteristics similar to white noise, while also possessing a periodic and reproducible structural feature.

[0003] When the power of a broadband jamming signal is strong enough to exceed the suppression capabilities of the anti-jamming antenna and front-end filter, the receiver, during the two-dimensional search process in signal acquisition, may mistakenly identify the jamming signal as a real satellite signal due to the high cross-correlation peak generated by the jamming signal and the local pseudo-random code. Conventional false alarm verification methods mainly rely on the peak power to average power ratio in the acquisition results. However, jamming signals often resemble real signals in this metric, making it easy to pass verification and enter the tracking phase. Once tracking begins, the jamming signal may appear normal in surface metrics such as carrier-to-noise ratio, typically within the range of 30-50 dB-Hz. However, this can lead to systematic deviations in pseudorange and Doppler measurements, causing the receiver to easily lock onto and track the jamming signal for extended periods under strong interference, ultimately resulting in abnormal positioning and velocity measurement results. Summary of the Invention

[0004] Based on this, it is necessary to provide a method and apparatus for identifying interference signals under periodic broadband suppression interference to address the above-mentioned technical problems, so as to improve the receiver's ability to distinguish the authenticity of signals obtained after re-acquisition after loss of lock in broadband suppression interference environment, thereby improving the robustness and positioning success rate of RNSS system in strong interference environment.

[0005] A method for identifying interference signals under periodic broadband suppression interference, the method comprising:

[0006] False Alarm Verification Phase: When the receiver loses signal lock due to periodic broadband suppression interference and reacquires the satellite signal, based on the satellite ephemeris data stored in the receiver's historical tracking and the receiver's current positioning, the predicted pseudorange and predicted Doppler shift of the currently acquired satellite relative to the receiver at the current moment are calculated. The predicted pseudorange and predicted Doppler shift are then compared with the current acquisition pseudorange and acquisition Doppler shift, respectively. The deviation between the acquired value and the predicted value is calculated, and it is determined whether the deviation exceeds a preset range. If it does, the currently acquired signal is determined to be an interference signal, the false alarm verification fails, and reacquisition is initiated; otherwise, the tracking phase begins.

[0007] Tracking Phase: In the baseband tracking channel of the receiver, a multi-correlator structure is designed with the instant code as the center and symmetrically distributed according to preset chip intervals and with lead / lag. Based on the correlation integration of the current acquired signal by each branch correlator and the output of the corresponding autocorrelation amplitude, the ratio of the autocorrelation amplitude output by the instant code branch correlator to the sum of the autocorrelation amplitudes output by the paired lead / lag branch correlators with different phase offsets is calculated. It is then determined whether the ratio is within the normal range of the ideal autocorrelation function constraint of the pseudo-random code. If so, the current acquired signal is determined to be a real satellite signal and tracking continues; otherwise, the current acquired signal is determined to be an interference signal and reacquisition is performed.

[0008] In one embodiment, based on satellite ephemeris data stored in the receiver's historical tracking and the receiver's current positioning, the predicted pseudorange and predicted Doppler shift of the currently captured satellite relative to the receiver at the current moment are calculated, including:

[0009] Based on the satellite ephemeris data that the receiver has historically tracked stably and successfully demodulated and stored, calculate the position and velocity of the currently captured satellite;

[0010] Based on the calculated satellite position and velocity, combined with the receiver's current position and velocity, the predicted pseudorange and predicted Doppler shift of the currently acquired satellite relative to the receiver at the current moment are calculated.

[0011] In one embodiment, based on the satellite ephemeris data that the receiver has historically stably tracked and successfully demodulated and stored, the position and velocity of the currently captured satellite are calculated, as follows:

[0012] ;

[0013] ;

[0014] in, and They represent The three-dimensional coordinates and velocity of the satellite in the geocentric rectangular coordinate system at the epoch are values ​​to be calculated and are referred to as satellite position and satellite velocity, respectively. , , , , and They represent At the epoch, the satellite's coordinates and velocity in the orbital plane, the longitude of the satellite's ascending node, the corrected orbital inclination, the rate of change of the ascending node's longitude, and the rate of change of the orbital inclination. , , and Obtained from satellite ephemeris data; and It is obtained by calculating satellite ephemeris parameters.

[0015] In one embodiment, based on the calculated satellite position and velocity, and in conjunction with the receiver's current position and velocity, the predicted pseudorange and predicted Doppler shift of the currently acquired satellite relative to the receiver at the current moment are calculated, including:

[0016] Based on satellite location With satellite speed Combined with receiver location and receiver speed The predicted pseudorange and predicted Doppler shift of the satellite relative to the receiver at the current moment are calculated as follows:

[0017] ;

[0018] ;

[0019] ;

[0020] ;

[0021] in, The distance is calculated based on the satellite position and the receiver position. This represents the radial velocity component of the receiver relative to the satellite. To predict pseudorange, To predict Doppler frequency shift, For receiver clock bias, For receiver frequency difference, For signal lockout time, This is the atmospheric delay correction amount. The frequency point is the carrier frequency. At the speed of light, for Satellite clock bias at epochs For satellite signal transmission time, , , , and All The satellite clock bias parameters at the epoch are obtained from satellite ephemeris data.

[0022] In one embodiment, the predicted pseudorange and predicted Doppler shift are compared with the current acquisition pseudorange and acquisition Doppler shift, respectively. The deviation between the acquisition value and the predicted value is calculated, and it is determined whether the deviation exceeds a preset range, including:

[0023] Calculate the capture pseudorange With predicted pseudorange The deviation between them is ;

[0024] Calculate the capture Doppler frequency shift With prediction of Doppler frequency shift The deviation between them is ;

[0025] judge and If the value exceeds the reasonable range determined by receiver dynamics, clock error, and ephemeris error, the currently acquired signal is determined to be an interference signal, the false alarm verification fails, and a re-acquisition is performed; otherwise, the tracking phase begins.

[0026] In one embodiment, a multi-path correlator structure is designed with the instant code as the center and symmetrically distributed according to a preset chip interval and with lead / lag, including:

[0027] The design incorporates a 7-channel correlator structure centered on the instant code, spaced at 1 / 4 chip intervals, and symmetrically distributed with lead and lag. ;in, For real-time code branch correlators, and For paired lead branch correlators and lagging branch correlators, This represents the number of chips that are ahead or behind by 1 / 4 chip interval.

[0028] In one embodiment, after integrating the current captured signal based on each branch correlator and outputting the corresponding autocorrelation amplitude, the ratio of the autocorrelation amplitude output by the instantaneous code branch correlator to the sum of the autocorrelation amplitudes output by the paired lead / lag branch correlators with different phase offsets is calculated, including:

[0029] Based on the immediate code branch correlator, the leading branch correlator, and the lagging branch correlator, the current acquired signal is correlated and integrated, and the corresponding autocorrelation amplitude is output, expressed as:

[0030] ;

[0031] ;

[0032] ;

[0033] in, This represents the autocorrelation amplitude output by the instantaneous code branch correlator. This represents the autocorrelation amplitude of the output of the lag branch correlator. This represents the autocorrelation amplitude output by the lead branch correlator. and These are the real and imaginary parts of the integral of the instantaneous code branch correlator, respectively. and These are the real and imaginary parts of the integral of the lag branch correlator, respectively. and These are the real and imaginary parts of the integral of the lead branch correlator, respectively;

[0034] The ratio of the autocorrelation amplitude of the output of the instantaneous code branch correlator to the sum of the autocorrelation amplitudes of the outputs of the paired lead / lag branch correlators with different phase offsets is expressed as:

[0035] .

[0036] In one embodiment, determining whether the ratio is within the normal range constrained by the ideal autocorrelation function of the pseudo-random code includes:

[0037] The ideal autocorrelation function constraint for pseudo-random codes includes the following: when the received signal is perfectly aligned with the local pseudo-code, the autocorrelation amplitude output by the instantaneous code branch correlator is located at the peak point of the autocorrelation function. At this time, the ratio of the autocorrelation amplitude output by the instantaneous code branch correlator to the sum of the autocorrelation amplitudes output by the paired lead / lag branch correlators with different phase offsets has the following correspondence:

[0038] 1 / 4 chip offset ratio: The ratio of the autocorrelation amplitude of the output of the instantaneous code branch correlator to the sum of the autocorrelation amplitudes of the outputs of the 1 / 4 chip leading branch correlator and the 1 / 4 chip lagging branch correlator, which is stable around the theoretical value of 0.6 during precise tracking.

[0039] 1 / 2 chip offset ratio: The ratio of the autocorrelation amplitude of the output of the instantaneous code branch correlator to the sum of the autocorrelation amplitudes of the outputs of the 1 / 2 chip leading branch correlator and the 1 / 2 chip lagging branch correlator, which approaches the theoretical value of 1 under ideal alignment conditions;

[0040] 3 / 4 chip offset ratio: For 3 / 4 chip lead branch correlators and 3 / 4 chip lag branch correlators, since they are located on the slope or plateau region on both sides of the main peak of the autocorrelation function, the ratio of the sum of the autocorrelation amplitudes of their outputs to the autocorrelation amplitudes of the outputs of the instantaneous code branch correlators no longer has a stable theoretical value, and the response to phase error exhibits strong nonlinearity.

[0041] Based on the ideal autocorrelation function constraint of the pseudo-random code, first determine the ratio of the autocorrelation amplitude of the output of the instantaneous code branch correlator to the sum of the autocorrelation amplitudes of the outputs of the 1 / 4 chip leading branch correlator and the 1 / 4 chip lagging branch correlator. Whether the jitter exceeds 20% of the theoretical value of 0.6 is used to determine... If the signal is within the range of 0.4 to 0.8, and if not, determine that the currently acquired signal is an interference signal and perform a re-acquisition; if so, then determine the ratio of the autocorrelation amplitude output by the instantaneous code branch correlator to the sum of the autocorrelation amplitudes output by the 1 / 2 chip leading branch correlator and the 1 / 2 chip lagging branch correlator. Whether the jitter exceeds 20% of the theoretical value of 1, that is, to determine... If the signal is within the range of 0.8 to 1.2, and if not, determine that the currently acquired signal is an interference signal and perform a re-acquisition; if so, determine that the currently acquired signal is a real satellite signal and continue tracking.

[0042] An interference signal identification device under periodic broadband suppression interference, the device comprising:

[0043] The first interference identification module is used to calculate the predicted pseudorange and predicted Doppler shift of the currently acquired satellite relative to the receiver at the current moment when the receiver loses signal lock due to periodic broadband suppression interference and reacquires the satellite signal. This is based on the satellite ephemeris data stored in the receiver's historical tracking and the receiver's current positioning. The module then compares the predicted pseudorange and predicted Doppler shift with the current acquisition pseudorange and acquisition Doppler shift, calculates the deviation between the acquisition value and the predicted value, and determines whether the deviation exceeds a preset range. If it does, the currently acquired signal is determined to be an interference signal, the false alarm verification fails, and a reacquisition is initiated. Otherwise, the tracking phase begins.

[0044] The second interference identification module is used in the baseband tracking channel of the receiver to design a multi-correlator structure centered on the instant code and symmetrically distributed with lead / lag at preset chip intervals. Based on the correlation integration of the current acquired signal by each branch correlator and the output of the corresponding autocorrelation amplitude, the module calculates the ratio of the autocorrelation amplitude output by the instant code branch correlator to the sum of the autocorrelation amplitudes output by the paired lead / lag branch correlators with different phase offsets, and determines whether the ratio is within the normal range of the pseudo-random code ideal autocorrelation function constraint. If so, the current acquired signal is determined to be a real satellite signal and tracking continues; otherwise, the current acquired signal is determined to be an interference signal and reacquisition is performed.

[0045] The above-mentioned method and apparatus for identifying interference signals under periodic broadband suppression interference have the following advantages compared with the prior art:

[0046] 1. During the false alarm verification phase, by comparing the acquisition pseudorange, acquisition Doppler shift, and the high-precision predicted pseudorange and predicted Doppler shift calculated using existing ephemeris and receiver status information, it is determined whether the currently acquired signal is an interference signal. This greatly improves the pertinence of the discrimination conditions, thereby enabling earlier and more accurate identification and elimination of broadband suppression interference disguised as satellite signals during the false alarm verification phase. This reduces the probability of erroneous tracking from the source and provides more reliable observational support for subsequent positioning calculations.

[0047] 2. During the tracking phase, a multi-correlator structure is designed with the instant code as the center and symmetrically distributed with lead / lag at preset chip intervals. The system determines whether the captured signal is interference by checking if the ratio of the autocorrelation amplitude output by the instant code branch correlator to the sum of the autocorrelation amplitudes output by the paired lead / lag branch correlators with different phase offsets is within the normal range constrained by the ideal autocorrelation function of the pseudo-random code. This effectively identifies whether the tracking loop has locked onto a real satellite signal with the correct signal structure or merely locked onto an interference signal with a similar autocorrelation function but an abnormal structure. Once interference is identified, the system will actively abandon that tracking channel to prevent its abnormal observations from contaminating the positioning calculation, thus ensuring that the positioning calculation is based solely on the real satellite signal and improving the system's robustness and positioning success rate in strong interference environments. Attached Figure Description

[0048] Figure 1 This is a flowchart illustrating an interference signal identification method under periodic broadband suppression interference in one embodiment.

[0049] Figure 2 This is a flowchart illustrating the false alarm verification phase in one embodiment;

[0050] Figure 3 This is a flowchart illustrating the tracking phase in one embodiment. Detailed Implementation

[0051] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0052] In one embodiment, such as Figure 1 As shown, a method for identifying interference signals under periodic broadband suppression interference is provided, applied to the RNSS system in GNSS (Global Navigation Satellite System), including the following steps:

[0053] Step 1, False Alarm Verification Phase: When the receiver loses signal lock due to periodic broadband suppression interference and reacquires the satellite signal, based on the satellite ephemeris data stored in the receiver's historical tracking and the receiver's current positioning, the predicted pseudorange and predicted Doppler shift of the currently acquired satellite relative to the receiver at the current moment are calculated. The predicted pseudorange and predicted Doppler shift are compared with the current acquisition pseudorange and acquisition Doppler shift, respectively. The deviation between the acquisition value and the predicted value is calculated, and it is determined whether the deviation value exceeds the preset range. If it exceeds the preset range, the currently acquired signal is determined to be an interference signal, the false alarm verification fails, and reacquisition is performed; otherwise, the tracking phase begins.

[0054] It should be understood that when a receiver loses signal lock due to periodic broadband suppression interference and reacquires it, if the acquisition unit claims successful satellite signal acquisition, it enters the false alarm verification stage. In conventional RNSS baseband design, the reasonableness check of the acquired pseudorange and Doppler values ​​usually relies on a very broad physical range criterion. For example, based on the orbital altitude range of the BeiDou satellite system (approximately 21,500~35,786 km), a corresponding theoretical range of pseudorange values ​​can be calculated. If the acquired pseudorange exceeds this range, it is judged as data anomaly, and therefore, it is considered that interference signals may have been acquired. Although this method is a widely used basic means of distinguishing between true and false signals, due to the continuous motion of the satellite, its true orbital altitude and corresponding pseudorange values ​​change in real time, resulting in an extremely broad reasonable range. In practical engineering applications, signals that can pass the front-end acquisition threshold and enter the false alarm verification stage are almost never eliminated by this coarse-grained criterion, thus its discrimination effectiveness in actual interference scenarios is limited.

[0055] To address the aforementioned issues, this application incorporates a more precise and efficient signal authenticity verification step during the false alarm verification stage. The technical principle is as follows: For satellites requiring reacquisition due to brief loss of lock, the receiver should have successfully demodulated and stored the satellite's ephemeris data during the satellite's last stable tracking period. Utilizing this existing satellite ephemeris information, combined with the receiver's latest positioning results (including position, velocity, and time status), the predicted pseudorange and predicted Doppler shift of the satellite relative to the receiver at the current moment can be calculated in real time. This prediction is based on a precise satellite orbit and clock model, and its accuracy is far higher than a coarse estimate based solely on the orbital altitude range. Based on this, if... Figure 2 As shown, during the false alarm verification phase, the acquisition pseudorange and acquisition Doppler shift directly measured by the acquisition module are compared with the predicted pseudorange and predicted Doppler shift calculated above. By setting a reasonable deviation threshold, if the deviation between the acquired value and the predicted value exceeds the threshold, it is determined that the current acquired signal is highly likely to be an interference signal, and the false alarm verification fails; if the deviation is within the threshold, it is considered that the probability of acquiring a real signal is high, allowing entry into the subsequent tracking phase. Its core advantage lies in upgrading the judgment of signal authenticity from a broad physical range check to a consistency check based on a precise model and the current state. By utilizing existing satellite ephemeris data and receiver status information, the specificity of the discrimination conditions is greatly improved, thereby enabling earlier and more accurate identification and elimination of broadband suppression interference disguised as satellite signals during the false alarm phase, reducing the probability of erroneous tracking from the source, and providing more reliable observational support for subsequent positioning calculations.

[0056] Step 2, Tracking Phase: In the baseband tracking channel of the receiver, a multi-correlator structure is designed with the instant code as the center and symmetrically distributed according to a preset chip interval and with lead / lag. Based on the correlation integration of the current acquired signal by each branch correlator and the output of the corresponding autocorrelation amplitude, the ratio of the autocorrelation amplitude output by the instant code branch correlator to the sum of the autocorrelation amplitudes output by the paired lead / lag branch correlators with different phase offsets is calculated. It is then determined whether the ratio is within the normal range of the ideal autocorrelation function constraint of the pseudo-random code. If so, the current acquired signal is determined to be a real satellite signal and tracking continues; otherwise, the current acquired signal is determined to be an interference signal and reacquisition is performed.

[0057] It should be understood that during real-time tracking, the system continuously monitors and calculates the aforementioned multiple sets of autocorrelation amplitude ratios. For real satellite signals, due to the high degree of matching between the local pseudocode and the signal, these ratios will strictly follow the statistical laws determined by the ideal autocorrelation function of the pseudorandom code, fluctuating within a predictable and relatively narrow range. However, periodic broadband suppression interference signals, although potentially producing higher correlation outputs, exhibit a fundamentally different cross-correlation function shape between their cross-correlation function and the local pseudocode compared to the ideal autocorrelation function of the pseudorandom code. This leads to: abnormal distribution of autocorrelation amplitudes output by each branch correlator; chip offset ratios (especially the 1 / 2 chip and 1 / 4 chip offset ratios) significantly deviating from the theoretically expected range; and a lack of consistency in the changes between different offset ratios. Therefore, as... Figure 3 As shown, during the tracking phase, the measured ratio is compared with the theoretical expected model in real time using a multi-correlator structure, and a reasonable decision threshold is set. This effectively identifies whether the tracking loop has locked onto a real satellite signal with the correct signal structure, or merely locked onto an interference signal that is similar in autocorrelation function but has an abnormal structure. Once it is determined to be interference, the system will actively abandon the tracking channel to prevent its abnormal observations from contaminating the positioning solution, thereby ensuring the reliability of the navigation results.

[0058] In summary, the interference signal identification method proposed in this application under periodic broadband suppression interference proposes a two-stage signal discrimination mechanism that works synergistically in the false alarm verification and tracking stages. This mechanism enhances the receiver's ability to distinguish the authenticity of signals obtained after re-acquisition in a broadband suppression interference environment. In the false alarm verification stage, this mechanism introduces a threshold judgment based on motion consistency and the rationality of signal characteristics. In the tracking stage, it analyzes the distribution relationship between the autocorrelation amplitudes of the multi-correlator outputs to monitor signal structure anomalies in real time. The signal discrimination in the two stages complements each other, significantly improving interference signal identification performance while maintaining low computational complexity. This facilitates real-time processing on resource-constrained embedded receiver platforms, thereby effectively ensuring the positioning reliability and accuracy of the RNSS system in complex electromagnetic environments.

[0059] In one embodiment, based on satellite ephemeris data stored in the receiver's historical tracking and the receiver's current positioning, the predicted pseudorange and predicted Doppler shift of the currently captured satellite relative to the receiver at the current moment are calculated, including:

[0060] Based on the satellite ephemeris data that the receiver has historically tracked stably and successfully demodulated and stored, calculate the position and velocity of the currently captured satellite;

[0061] Based on the calculated satellite position and velocity, combined with the receiver's current position and velocity, the predicted pseudorange and predicted Doppler shift of the currently acquired satellite relative to the receiver at the current moment are calculated.

[0062] In one embodiment, based on the satellite ephemeris data that the receiver has historically stably tracked and successfully demodulated and stored, the position and velocity of the currently captured satellite are calculated, as follows:

[0063] ;

[0064] ;

[0065] in, and They represent The three-dimensional coordinates and velocity of the satellite in the geocentric rectangular coordinate system at the epoch are values ​​to be calculated and are referred to as satellite position and satellite velocity, respectively. , , , , and They represent At the epoch, the satellite's coordinates and velocity in the orbital plane, the longitude of the satellite's ascending node, the corrected orbital inclination, the rate of change of the ascending node's longitude, and the rate of change of the orbital inclination. , , and Obtained from satellite ephemeris data; and It is obtained by calculating satellite ephemeris parameters.

[0066] In one embodiment, based on the calculated satellite position and velocity, and in conjunction with the receiver's current position and velocity, the predicted pseudorange and predicted Doppler shift of the currently acquired satellite relative to the receiver at the current moment are calculated, including:

[0067] Based on satellite location With satellite speed Combined with receiver location and receiver speed The predicted pseudorange and predicted Doppler shift of the satellite relative to the receiver at the current moment are calculated as follows:

[0068] ;

[0069] ;

[0070] ;

[0071] ;

[0072] in, The distance is calculated based on the satellite position and the receiver position. This represents the radial velocity component of the receiver relative to the satellite. To predict pseudorange, To predict Doppler frequency shift, For receiver clock bias, For receiver frequency difference, For signal lockout time, This is a delay correction for atmospheric delays in the ionosphere, troposphere, etc. The frequency point is the carrier frequency. At the speed of light, for Satellite clock bias at epochs For satellite signal transmission time, , , , and All The satellite clock bias parameters at the epoch are obtained from satellite ephemeris data.

[0073] In one embodiment, the predicted pseudorange and predicted Doppler shift are compared with the current acquisition pseudorange and acquisition Doppler shift, respectively. The deviation between the acquisition value and the predicted value is calculated, and it is determined whether the deviation exceeds a preset range, including:

[0074] Calculate the capture pseudorange With predicted pseudorange The deviation between them is ;

[0075] Calculate the capture Doppler frequency shift With prediction of Doppler frequency shift The deviation between them is ;

[0076] judge and If the value exceeds the reasonable range determined by receiver dynamics, clock error, and ephemeris error, the currently acquired signal is determined to be an interference signal, the false alarm verification fails, and a re-acquisition is performed; otherwise, the tracking phase begins.

[0077] In one embodiment, a multi-path correlator structure is designed with the instant code as the center and symmetrically distributed according to a preset chip interval and with lead / lag, including:

[0078] The design incorporates a 7-channel correlator structure centered on the instant code, spaced at 1 / 4 chip intervals, and symmetrically distributed with lead and lag. ;in, For real-time code branch correlators, and For paired lead branch correlators and lagging branch correlators, This represents the number of chips that lead or lag by 1 / 4 chip interval. Each branch correlator is used to perform correlation integration on the input signal and output the corresponding autocorrelation amplitude.

[0079] The correlation integration process of each branch correlator is as follows: Figure 3 As shown. Figure 3 The intermediate carrier NCO (numerically controlled oscillator) is used to accurately generate two orthogonal digital signals based on the frequency control word sent from the carrier loop filter, with their frequency and phase dynamically adjusted. The C / A code generator is used for local pseudo-code reproduction, generating local C / A code lead, instant, and lag sequences in real time based on the code loop NCO. The code loop discriminator is used to calculate the code phase offset value. By analyzing the correlation results of the lead and lag branches, it uses a phase detection algorithm (such as the incoherent lead-lag amplitude method) to calculate the code phase offset value, expressed as:

[0080] ;

[0081] ;

[0082] ;

[0083] in, This represents the carrier frequency / phase offset value. The carrier loop discriminator is used to calculate the carrier frequency / phase offset value. By analyzing the correlation integral results of the instantaneous branch, it calculates the carrier frequency / phase offset value using frequency discrimination or phase discrimination formulas (such as the arctangent formula), expressed as:

[0084] ;

[0085] ;

[0086] in, This is the carrier frequency offset value. Carrier phase offset value, subscript Indicates time, and These represent the integral values ​​of the correlators in each branch at... The real and imaginary parts of time, For integration time. The carrier loop / code loop filter is used to receive the signal offset value from the corresponding discriminator, and through a low-pass filter and proportional-integral control, it filters out high-frequency noise and generates a stable control word.

[0087] In one embodiment, after integrating the current captured signal based on each branch correlator and outputting the corresponding autocorrelation amplitude, the ratio of the autocorrelation amplitude output by the instantaneous code branch correlator to the sum of the autocorrelation amplitudes output by the paired lead / lag branch correlators with different phase offsets is calculated, including:

[0088] Based on the immediate code branch correlator, the leading branch correlator, and the lagging branch correlator, the current acquired signal is correlated and integrated, and the corresponding autocorrelation amplitude is output, expressed as:

[0089] ;

[0090] ;

[0091] ;

[0092] in, This represents the autocorrelation amplitude output by the instantaneous code branch correlator. This represents the autocorrelation amplitude of the output of the lag branch correlator. This represents the autocorrelation amplitude output by the lead branch correlator. and These are the real and imaginary parts of the integral of the instantaneous code branch correlator, respectively. and These are the real and imaginary parts of the integral of the lag branch correlator, respectively. and These are the real and imaginary parts of the integral of the lead branch correlator, respectively;

[0093] The ratio of the autocorrelation amplitude of the output of the instantaneous code branch correlator to the sum of the autocorrelation amplitudes of the outputs of the paired lead / lag branch correlators with different phase offsets is expressed as:

[0094] .

[0095] In one embodiment, determining whether the ratio is within the normal range constrained by the ideal autocorrelation function of the pseudo-random code includes:

[0096] The ideal autocorrelation function constraint for pseudo-random codes includes the following: when the received signal is perfectly aligned with the local pseudo-code, the autocorrelation amplitude output by the instantaneous code branch correlator is located at the peak point of the autocorrelation function. At this time, the ratio of the autocorrelation amplitude output by the instantaneous code branch correlator to the sum of the autocorrelation amplitudes output by the paired lead / lag branch correlators with different phase offsets has the following correspondence:

[0097] 1. 1 / 4 chip offset ratio: The ratio of the autocorrelation amplitude of the output of the instantaneous code branch correlator to the sum of the autocorrelation amplitudes of the outputs of the 1 / 4 chip leading branch correlator and the 1 / 4 chip lagging branch correlator. During accurate tracking, this ratio should be stable around the theoretical value of 0.6. This ratio reflects whether the chip is offset.

[0098] 2. Half-chip offset ratio: This is the ratio of the autocorrelation amplitude output by the code branch correlator to the sum of the autocorrelation amplitudes output by the half-chip leading branch correlator and the half-chip lagging branch correlator. Under ideal alignment, this ratio should approach the theoretical value of 1. This ratio is extremely sensitive to code phase deviation and is a core indicator for determining whether the code is accurately locked at the correlation peak.

[0099] 3. 3 / 4 chip offset ratio: For 3 / 4 chip lead branch correlators and 3 / 4 chip lag branch correlators, since they are located on the slope or plateau region on both sides of the main peak of the autocorrelation function, the ratio of the sum of the autocorrelation amplitudes of their outputs to the autocorrelation amplitudes of the outputs of the instantaneous code branch correlators no longer has a stable theoretical value, and the response to phase error exhibits strong nonlinearity.

[0100] Based on the ideal autocorrelation function constraint of the pseudo-random code, first determine the ratio of the autocorrelation amplitude of the output of the instantaneous code branch correlator to the sum of the autocorrelation amplitudes of the outputs of the 1 / 4 chip leading branch correlator and the 1 / 4 chip lagging branch correlator. Whether the jitter exceeds 20% of the theoretical value of 0.6 is used to determine... If the signal is within the range of 0.4 to 0.8, and if not, determine that the currently acquired signal is an interference signal and perform a re-acquisition; if so, then determine the ratio of the autocorrelation amplitude output by the instantaneous code branch correlator to the sum of the autocorrelation amplitudes output by the 1 / 2 chip leading branch correlator and the 1 / 2 chip lagging branch correlator. Whether the jitter exceeds 20% of the theoretical value of 1, that is, to determine... If the signal is within the range of 0.8 to 1.2, and if not, determine that the currently acquired signal is an interference signal and perform a re-acquisition; if so, determine that the currently acquired signal is a real satellite signal and continue tracking.

[0101] Furthermore, to verify the beneficial performance of the proposed method, a comparative experiment was conducted with traditional interference signal identification methods. The experiment was set under the same extreme broadband suppression interference environment, where the satellite signal repeatedly lost lock and reacquired, resulting in a total of 30 abnormal jumps in pseudorange and Doppler observations. This experiment used the significant deviation in the receiver positioning result after reacquisition as the criterion for determining whether the interference signal was effectively identified.

[0102] Experimental data show that traditional interference signal identification methods can only successfully identify 3 abnormal signals; however, by applying the method proposed in this application, the system successfully identified all 30 abnormal signals, achieving a 100% interference identification rate. This data demonstrates that, compared to traditional methods, the proposed method significantly improves the probability of interference detection, effectively avoiding positioning anomalies caused by false acquisition or tracking of interference signals. The robustness and usability of the system in strong interference environments are substantially enhanced.

[0103] In one embodiment, an interference signal identification device under periodic broadband suppression interference is provided, comprising:

[0104] The first interference identification module is used to calculate the predicted pseudorange and predicted Doppler shift of the currently acquired satellite relative to the receiver at the current moment when the receiver loses signal lock due to periodic broadband suppression interference and reacquires the satellite signal. This is based on the satellite ephemeris data stored in the receiver's historical tracking and the receiver's current positioning. The module then compares the predicted pseudorange and predicted Doppler shift with the current acquisition pseudorange and acquisition Doppler shift, calculates the deviation between the acquisition value and the predicted value, and determines whether the deviation exceeds a preset range. If it does, the currently acquired signal is determined to be an interference signal, the false alarm verification fails, and a reacquisition is initiated. Otherwise, the tracking phase begins.

[0105] The second interference identification module is used in the baseband tracking channel of the receiver to design a multi-correlator structure centered on the instant code and symmetrically distributed with lead / lag at preset chip intervals. Based on the correlation integration of the current acquired signal by each branch correlator and the output of the corresponding autocorrelation amplitude, the module calculates the ratio of the autocorrelation amplitude output by the instant code branch correlator to the sum of the autocorrelation amplitudes output by the paired lead / lag branch correlators with different phase offsets, and determines whether the ratio is within the normal range of the pseudo-random code ideal autocorrelation function constraint. If so, the current acquired signal is determined to be a real satellite signal and tracking continues; otherwise, the current acquired signal is determined to be an interference signal and reacquisition is performed.

[0106] Specific limitations regarding the interference signal identification device under periodic broadband suppression interference can be found in the limitations of the interference signal identification method under periodic broadband suppression interference mentioned above, and will not be repeated here. Each module in the aforementioned interference signal identification device under periodic broadband suppression interference can be implemented entirely or partially through software, hardware, or a combination thereof. These modules can be embedded in or independent of the processor in a computer device in hardware form, or stored in the memory of a computer device in software form, so that the processor can call and execute the corresponding operations of each module.

[0107] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0108] The above embodiments are merely illustrative of several implementation methods of this application, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of this application. It should be noted that those skilled in the art can make several modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application.

Claims

1. A method for identifying interference signals under periodic broadband suppression interference, characterized in that, The method includes: False Alarm Verification Phase: When the receiver loses signal lock due to periodic broadband suppression interference and reacquires the satellite signal, based on the satellite ephemeris data stored in the receiver's historical tracking and the receiver's current positioning, the predicted pseudorange and predicted Doppler shift of the currently acquired satellite relative to the receiver at the current moment are calculated. The predicted pseudorange and predicted Doppler shift are compared with the acquisition pseudorange and acquisition Doppler shift at the current moment, respectively. The deviation between the acquisition value and the predicted value is calculated, and it is determined whether the deviation value exceeds a preset range. If it exceeds the preset range, the currently acquired signal is determined to be an interference signal, the false alarm verification fails, and reacquisition is performed; otherwise, the tracking phase begins. Tracking Phase: In the baseband tracking channel of the receiver, a multi-correlator structure is designed with the instant code as the center and symmetrically distributed according to a preset chip interval and with lead / lag. Based on the correlation integration of the current acquired signal by each branch correlator and the output of the corresponding autocorrelation amplitude, the ratio of the autocorrelation amplitude output by the instant code branch correlator to the sum of the autocorrelation amplitudes output by the paired lead / lag branch correlators with different phase offsets is calculated. It is then determined whether the ratio is within the normal range of the pseudo-random code ideal autocorrelation function constraint. If so, the current acquired signal is determined to be a real satellite signal and tracking continues; otherwise, the current acquired signal is determined to be an interference signal and re-acquisition is performed. The determination of whether the ratio is within the normal range constrained by the ideal autocorrelation function of the pseudo-random code includes: The ideal autocorrelation function constraint of the pseudo-random code includes: when the received signal is perfectly aligned with the local pseudo-code, the autocorrelation amplitude output by the instantaneous code branch correlator is located at the peak point of the autocorrelation function. At this time, the ratio of the autocorrelation amplitude output by the instantaneous code branch correlator to the sum of the autocorrelation amplitudes output by the paired lead / lag branch correlators with different phase offsets has the following correspondence: 1 / 4 chip offset ratio: The ratio of the autocorrelation amplitude of the output of the instantaneous code branch correlator to the sum of the autocorrelation amplitudes of the outputs of the 1 / 4 chip leading branch correlator and the 1 / 4 chip lagging branch correlator, which is stable around the theoretical value of 0.6 during precise tracking. 1 / 2 chip offset ratio: The ratio of the autocorrelation amplitude of the output of the instantaneous code branch correlator to the sum of the autocorrelation amplitudes of the outputs of the 1 / 2 chip leading branch correlator and the 1 / 2 chip lagging branch correlator, which approaches the theoretical value of 1 under ideal alignment conditions; Based on the ideal autocorrelation function constraint of the pseudo-random code, first determine the ratio of the autocorrelation amplitude of the output of the instantaneous code branch correlator to the sum of the autocorrelation amplitudes of the outputs of the 1 / 4 chip leading branch correlator and the 1 / 4 chip lagging branch correlator. Whether the jitter exceeds 20% of the theoretical value of 0.6 is used to determine... If the signal is within the range of 0.4 to 0.8, and if not, determine that the currently acquired signal is an interference signal and perform a re-acquisition; if so, then determine the ratio of the autocorrelation amplitude output by the instantaneous code branch correlator to the sum of the autocorrelation amplitudes output by the 1 / 2 chip leading branch correlator and the 1 / 2 chip lagging branch correlator. Whether the jitter exceeds 20% of the theoretical value of 1, that is, to determine... If the signal is within the range of 0.8 to 1.2, and if not, determine that the currently acquired signal is an interference signal and perform a re-acquisition; if so, determine that the currently acquired signal is a real satellite signal and continue tracking.

2. The method for identifying interference signals under periodic broadband suppression interference according to claim 1, characterized in that, Based on the satellite ephemeris data stored in the receiver's historical tracking data and the receiver's current positioning, the predicted pseudorange and predicted Doppler shift of the currently acquired satellite relative to the receiver at the current moment are calculated, including: Based on the satellite ephemeris data that the receiver has historically tracked stably and successfully demodulated and stored, calculate the position and velocity of the currently captured satellite; Based on the calculated satellite position and velocity, combined with the receiver's current position and velocity, the predicted pseudorange and predicted Doppler shift of the currently acquired satellite relative to the receiver at the current moment are calculated.

3. The method for identifying interference signals under periodic broadband suppression interference according to claim 2, characterized in that, Based on the satellite ephemeris data that the receiver has historically stably tracked and successfully demodulated and stored, the position and velocity of the currently captured satellite are calculated and expressed as follows: ； ； in, and They represent The three-dimensional coordinates and velocity of the satellite in the geocentric rectangular coordinate system at the epoch are values ​​to be calculated and are referred to as satellite position and satellite velocity, respectively. , , , , and They represent At the epoch, the satellite's coordinates and velocity in the orbital plane, the longitude of the satellite's ascending node, the corrected orbital inclination, the rate of change of the ascending node's longitude, and the rate of change of the orbital inclination. , , and Obtained from satellite ephemeris data; and It is obtained by calculating satellite ephemeris parameters.

4. The method for identifying interference signals under periodic broadband suppression interference according to claim 3, characterized in that, Based on the calculated satellite position and velocity, combined with the receiver's current position and velocity, the predicted pseudorange and predicted Doppler shift of the currently acquired satellite relative to the receiver at the current moment are calculated, including: Based on satellite location With satellite speed Combined with receiver location and receiver speed The predicted pseudorange and predicted Doppler shift of the satellite relative to the receiver at the current moment are calculated as follows: ； ； ； ； in, The distance is calculated based on the satellite position and the receiver position. This represents the radial velocity component of the receiver relative to the satellite. To predict pseudorange, To predict Doppler frequency shift, For receiver clock bias, For receiver frequency difference, For signal lockout time, This is the atmospheric delay correction amount. The frequency point is the carrier frequency. At the speed of light, for Satellite clock bias at epochs For satellite signal transmission time, , , , and All The satellite clock bias parameters at the epoch are obtained from satellite ephemeris data.

5. The method for identifying interference signals under periodic broadband suppression interference according to claim 4, characterized in that, The predicted pseudorange and predicted Doppler frequency shift are compared with the current acquisition pseudorange and acquisition Doppler frequency shift, respectively. The deviation between the acquisition value and the predicted value is calculated, and it is determined whether the deviation value exceeds a preset range, including: Calculate the capture pseudorange With predicted pseudorange The deviation between them is ; Calculate the capture Doppler frequency shift With prediction of Doppler frequency shift The deviation between them is ; judge and If the value exceeds the reasonable range determined by receiver dynamics, clock error, and ephemeris error, the currently acquired signal is determined to be an interference signal, the false alarm verification fails, and a re-acquisition is performed; otherwise, the tracking phase begins.

6. The method for identifying interference signals under periodic broadband suppression interference according to claim 1, characterized in that, The design incorporates a multichannel correlator structure centered on the instant code and symmetrically distributed with lead / lag at preset chip intervals, including: The design incorporates a 7-channel correlator structure centered on the instant code, spaced at 1 / 4 chip intervals, and symmetrically distributed with lead and lag. ;in, For real-time code branch correlators, and For paired lead branch correlators and lagging branch correlators, This represents the number of chips that are ahead or behind by 1 / 4 chip interval.

7. The method for identifying interference signals under periodic broadband suppression interference according to claim 6, characterized in that, After each branch correlator performs correlation integration on the currently acquired signal and outputs the corresponding autocorrelation amplitude, the ratio of the autocorrelation amplitude output by the instantaneous code branch correlator to the sum of the autocorrelation amplitudes output by the paired lead / lag branch correlators with different phase offsets is calculated, including: Based on the immediate code branch correlator, the leading branch correlator, and the lagging branch correlator, the current acquired signal is correlated and integrated, and the corresponding autocorrelation amplitude is output, expressed as: ； ； ； in, This represents the autocorrelation amplitude output by the instantaneous code branch correlator. This represents the autocorrelation amplitude of the output of the lag branch correlator. This represents the autocorrelation amplitude output by the lead branch correlator. and These are the real and imaginary parts of the integral of the instantaneous code branch correlator, respectively. and These are the real and imaginary parts of the integral of the lagging branch correlator, respectively. and These are the real and imaginary parts of the integral of the lead branch correlator, respectively; The ratio of the autocorrelation amplitude of the output of the instantaneous code branch correlator to the sum of the autocorrelation amplitudes of the outputs of the paired lead / lag branch correlators with different phase offsets is expressed as: 。 8. A device for identifying interference signals under periodic broadband suppression interference, characterized in that, The device includes: The first interference identification module is used to calculate the predicted pseudorange and predicted Doppler shift of the currently captured satellite relative to the receiver at the current moment, based on the satellite ephemeris data stored in the receiver's historical tracking and the receiver's current positioning, when the receiver loses signal lock due to periodic broadband suppression interference and reacquires the satellite signal. The module then compares the predicted pseudorange and predicted Doppler shift with the current acquisition pseudorange and acquisition Doppler shift, calculates the deviation between the acquisition value and the predicted value, and determines whether the deviation exceeds a preset range. If it does, the currently captured signal is determined to be an interference signal, the false alarm verification fails, and a reacquisition is performed; otherwise, the tracking phase begins. The second interference identification module is used to design a multi-correlator structure in the baseband tracking channel of the receiver, centered on the instant code and symmetrically distributed with lead / lag at preset chip intervals. Based on the correlation integration of the current acquired signal by each branch correlator and the output of the corresponding autocorrelation amplitude, the module calculates the ratio of the autocorrelation amplitude output by the instant code branch correlator to the sum of the autocorrelation amplitudes output by the paired lead / lag branch correlators with different phase offsets, and determines whether the ratio is within the normal range of the pseudo-random code ideal autocorrelation function constraint. If so, the current acquired signal is determined to be a real satellite signal and tracking continues; otherwise, the current acquired signal is determined to be an interference signal and reacquisition is performed. The determination of whether the ratio is within the normal range constrained by the ideal autocorrelation function of the pseudo-random code includes: The ideal autocorrelation function constraint of the pseudo-random code includes: when the received signal is perfectly aligned with the local pseudo-code, the autocorrelation amplitude output by the instantaneous code branch correlator is located at the peak point of the autocorrelation function. At this time, the ratio of the autocorrelation amplitude output by the instantaneous code branch correlator to the sum of the autocorrelation amplitudes output by the paired lead / lag branch correlators with different phase offsets has the following correspondence: 1 / 4 chip offset ratio: The ratio of the autocorrelation amplitude of the output of the instantaneous code branch correlator to the sum of the autocorrelation amplitudes of the outputs of the 1 / 4 chip leading branch correlator and the 1 / 4 chip lagging branch correlator, which is stable around the theoretical value of 0.6 during precise tracking. 1 / 2 chip offset ratio: The ratio of the autocorrelation amplitude of the output of the instantaneous code branch correlator to the sum of the autocorrelation amplitudes of the outputs of the 1 / 2 chip leading branch correlator and the 1 / 2 chip lagging branch correlator, which approaches the theoretical value of 1 under ideal alignment conditions; Based on the ideal autocorrelation function constraint of the pseudo-random code, first determine the ratio of the autocorrelation amplitude of the output of the instantaneous code branch correlator to the sum of the autocorrelation amplitudes of the outputs of the 1 / 4 chip leading branch correlator and the 1 / 4 chip lagging branch correlator. Whether the jitter exceeds 20% of the theoretical value of 0.6 is used to determine... If the signal is within the range of 0.4 to 0.8, and if not, determine that the currently acquired signal is an interference signal and perform a re-acquisition; if so, then determine the ratio of the autocorrelation amplitude output by the instantaneous code branch correlator to the sum of the autocorrelation amplitudes output by the 1 / 2 chip leading branch correlator and the 1 / 2 chip lagging branch correlator. Whether the jitter exceeds 20% of the theoretical value of 1, that is, to determine... If the signal is within the range of 0.8 to 1.2, and if not, determine that the currently acquired signal is an interference signal and perform a re-acquisition; if so, determine that the currently acquired signal is a real satellite signal and continue tracking.

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