Deception signal detection method, receiver and related product

Abstract

The embodiment of the invention provides a deception signal detection method, a receiver and a related product. The method comprises the following steps: S1, performing positioning calculation based on intermediate frequency signals corresponding to N satellites acquired by the receiver; s3, for the intermediate frequency signal corresponding to each satellite, performing correlation processing on a plurality of phases to obtain a plurality of correlation values; s5, for any phase, performing superposition operation on the correlation values corresponding to the N satellites to obtain a superposition correlation value; based on the superposition correlation values corresponding to the plurality of phases, determining a correlation peak symmetric value of superposition of the N satellites; and S7, based on a comparison result of the correlation peak symmetry value and a set threshold value, determining whether a deception signal exists in the intermediate frequency signals corresponding to the N satellites. According to the embodiment of the invention, the distortion generated by the signal abnormity at the correlation peak can be weakened so as to distinguish the signal abnormity from the correlation peak distortion generated by the deception signal, and the detection accuracy of the deception signal is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of positioning and navigation, and in particular to a deception signal detection method, a receiver, an electronic device and a computer-readable storage medium. Background Art

[0002] Global Navigation Satellite System (GNSS) signals (hereinafter referred to as satellite signals) are mainly used for navigation and positioning of various devices such as aircraft, ships, vehicles and mobile phones. These devices are equipped with receivers to capture and process these satellite signals for positioning. Figure 1 As shown in the figure, in real positioning applications, for various illegal purposes, there are some fake base stations that send out a deceptive signal to mislead the target device, causing it to produce positioning deviation or false timing. Medium deception is a type of deception method for existing satellite signal receivers. This method first aligns the correlation peak of the deceptive signal with the real signal, then slowly increases the power of the deceptive signal to seize the tracking loop, and finally slowly pulls the correlation peak to mislead the receiver to produce incorrect positioning and timing results.

[0003] In the prior art, the Signal Quality Monitor method can be used to detect spoofing attacks. This method uses the symmetry of the correlation peak to make judgments during signal tracking. Specifically, when there is no spoofing signal, such as Figure 2 As shown in the figure, the curves on both sides of the correlation peak are roughly symmetrical (for example, at the position circled by the red circle in the figure, the two correlation values ​​under the symmetrical phase are basically equal); when there is a deceptive signal, such as Figure 3 As shown, since the power, code phase and carrier phase of the spoofed signal are not completely consistent with the real signal, this mixed signal will cause the shape of the correlation peak to be distorted like the one in the figure (for example, at the position circled by the red circle in the figure, there is a difference between the two correlation values ​​at the symmetric phase), resulting in obvious difference between the two correlation values ​​at the symmetric phase.

[0004] However, the above correlation peak distortion is not only caused by spoofing signals. In actual applications, there may be other non-ideal factors. For example, when the signal-to-noise ratio of the satellite signal is low, even if there is no influence of spoofing signals, please refer to Figure 2 The position circled by the middle green circle will also produce the above-mentioned correlation peak distortion (the symmetrical phases corresponding to the two green circles have differences in the two correlation values). Therefore, when the existing technology detects spoofing signals, the detection accuracy is poor and the false alarm rate is high. Summary of the invention

[0005] Based on the above situation, the main purpose of the present invention is to provide a deceptive signal detection method and related technical solutions, which can weaken the distortion caused by signal anomalies in the correlation peak to distinguish the correlation peak distortion caused by signal anomalies and deceptive signals, thereby improving the detection accuracy of deceptive signals.

[0006] To achieve the above purpose, the technical solution adopted by the present invention is as follows: A first aspect of an embodiment of the present invention provides a spoofing signal detection method, comprising: S1. Perform positioning calculation based on the intermediate frequency signals corresponding to N satellites acquired by the receiver to obtain the receiver position, the receiver clock error, and the satellite positions and satellite clock errors corresponding to the N satellites, respectively; wherein N is an integer greater than 3; S3. For the intermediate frequency signal corresponding to each satellite, the following correlation processing is performed on multiple phases respectively: based on the receiver position, the receiver clock error, and the satellite position and satellite clock error corresponding to the current satellite, the code phase of the receiver and the current satellite is determined; based on the code phase, the intermediate frequency signal is reproduced locally at the receiver to obtain a local signal; the local signal is correlated with the intermediate frequency signal to obtain a correlation value; the multiple phases include: an advanced phase, an instantaneous phase, and a lagging phase; the advanced phase and the lagging phase are symmetrical with the instantaneous phase as the center; S5. For any of the phases, superimpose the correlation values ​​corresponding to the N satellites to obtain a superimposed correlation value; determine the correlation peak symmetry value of the superimposed N satellites based on the superimposed correlation values ​​corresponding to the multiple phases; and S7. Based on the comparison result of the correlation peak symmetry value and the set threshold, determine whether there is a spoofing signal in the intermediate frequency signals corresponding to the N satellites.

[0007] Preferably, step S3 and step S5 are respectively performed on multiple monitoring dimensions to obtain the correlation peak symmetry values ​​corresponding to the multiple monitoring dimensions respectively, and the multiple monitoring dimensions include: X-axis dimension, Y-axis dimension, Z-axis dimension and time dimension.

[0008] Preferably, in step S7, determining whether there is a spoofing signal in the intermediate frequency signals corresponding to the N satellites based on the comparison result of the correlation peak symmetry value and a set threshold value includes: Acquire set thresholds corresponding to the multiple monitoring dimensions, respectively, where the set thresholds include: a first threshold corresponding to the X-axis dimension, a second threshold corresponding to the Y-axis dimension, a third threshold corresponding to the Z-axis dimension, and a fourth threshold corresponding to the time dimension; compare the correlation peak symmetry value of each monitoring dimension with the corresponding set threshold, and if the comparison result of any monitoring dimension does not meet the requirements, determine that there is a spoofing signal in the intermediate frequency signal corresponding to the N satellites; or, The average of the correlation peak symmetry values ​​of the multiple monitoring dimensions is obtained, and the average is compared with a set threshold. If the comparison result does not meet the requirements, it is determined that there are deception signals in the intermediate frequency signals corresponding to the N satellites.

[0009] Preferably, in step S3, the reproducing the intermediate frequency signal locally at the receiver based on the code phase includes: performing pseudo-code sampling based on the code phase and a pseudo-random sequence generation rule of the current satellite to obtain a pseudo-code sampling sequence; and reproducing the intermediate frequency signal corresponding to the current satellite based on the carrier frequency, sampling period, total number of sampling points and the pseudo-code sampling sequence of the current intermediate frequency signal to obtain a local signal.

[0010] Preferably, in step S5, the correlation values ​​corresponding to the N satellites are superimposed, including: determining the normalized weighting coefficient of each satellite by the following method: determining the weighting coefficient of the current satellite based on the signal-to-noise ratio of the current satellite and the cross-correlation peak values ​​of the current satellite and the other N-1 satellites; normalizing the weighting coefficient of the current satellite based on the ratio of the weighting coefficient of the current satellite to the sum of the weighting coefficients of the N satellites to obtain the normalized weighting coefficient; and accumulating the product of the normalized weighting coefficient of each satellite and its correlation value to obtain the superimposed correlation value.

[0011] Preferably, determining the weighting coefficient of the current satellite based on the signal-to-noise ratio of the current satellite and the cross-correlation peaks of the current satellite and the other N-1 satellites includes: The weighting coefficient of the current satellite is determined based on the following relationship:

[0012] In the formula, r i represents the weighting coefficient of the i-th satellite, CNR i Indicates i The carrier-to-noise ratio of the satellite, CNR j Indicates j The carrier-to-noise ratio of the satellite, U i,j Indicates i Satellites and j The ratio of the cross-correlation peaks between satellites to the autocorrelation peak of a certain satellite.

[0013] Preferably, in step S3 respectively performed in multiple monitoring dimensions, determining the code phase between the receiver and the current satellite based on the receiver position, the receiver clock error, the satellite position and the satellite clock error includes: The code phases corresponding to the X-axis dimension, the Y-axis dimension, the Z-axis dimension and the time dimension are calculated respectively based on the following relationship:

[0014] In the formula, the subscript i represents the serial number of the current satellite, τ x,i , τ y,i , τ z,i , τ t,i Respectively represent the code phases corresponding to the X-axis dimension, the Y-axis dimension, the Z-axis dimension, and the time dimension; x a , y a and z a Indicates the X-axis coordinate, Y-axis coordinate and Z-axis coordinate corresponding to the receiver position, δt u represents the receiver clock error, x i , y i and z i Indicates the X-axis coordinate, Y-axis coordinate and Z-axis coordinate corresponding to the satellite position of the i-th satellite, δt i represents the satellite clock error of the i-th satellite; f represents the phase value, f= -1 corresponds to the leading phase, f= 0 corresponds to the instantaneous phase, f= 1 corresponds to the lagging phase; d half represents the distance corresponding to half a chip signal, c represents the speed of light; cosu x , cosu y and cosu z Indicates the cosine value of the azimuth from the satellite to the receiver in the X-axis direction, Y-axis direction, and Z-axis direction respectively.

[0015] A second aspect of an embodiment of the present invention provides a receiver, including: The acquisition unit is used to perform down-conversion and analog-to-digital conversion (ADC) sampling processing on the satellite signal received by the antenna to obtain an intermediate frequency signal; A positioning solution unit, used to perform positioning solution based on the intermediate frequency signals corresponding to N satellites, to obtain the receiver position, the receiver clock error, and the satellite positions and satellite clock errors corresponding to the N satellites, respectively; N is an integer greater than 3; and A deception detection unit includes processing channels, a superposition module and a determination module corresponding to N satellites respectively, and each processing channel includes a signal generator and a related module; The signal generator is used to determine the code phase between the receiver and the current satellite based on the receiver position, the receiver clock error, and the satellite position and satellite clock error corresponding to the current satellite at multiple phases, and reproduce the intermediate frequency signal locally based on the code phase to obtain a local signal; the correlation module is used to perform correlation operations on the local signal and the intermediate frequency signal at multiple phases to obtain correlation values; the multiple phases include: an advanced phase, an instantaneous phase and a lagging phase; the advanced phase and the lagging phase are symmetrical with the instantaneous phase as the center; the superposition module is used to perform superposition operations on the correlation values ​​corresponding to N satellites for any of the phases to obtain a superimposed correlation value; the correlation peak symmetry value of the superimposed N satellites is determined based on the superimposed correlation values ​​corresponding to the multiple phases; the determination module is used to determine whether there is a spoofing signal in the intermediate frequency signals corresponding to the N satellites based on the comparison result of the correlation peak symmetry value and a set threshold.

[0016] Preferably, in one of the processing channels, the signal generator includes: an X signal generator, a Y signal generator, a Z signal generator and a T signal generator; the correlation module includes: an X correlation module, a Y correlation module, a Z correlation module and a T correlation module; the X signal generator and the X correlation module perform correlation processing on the intermediate frequency signal in an X-axis dimension; the Y signal generator and the Y correlation module perform correlation processing on the intermediate frequency signal in a Y-axis dimension; the Z signal generator and the Z correlation module perform correlation processing on the intermediate frequency signal in a Z-axis dimension; the T signal generator and the T correlation module perform correlation processing on the intermediate frequency signal in a time dimension.

[0017] Preferably, the determination module is specifically used for: Acquire set thresholds corresponding to the multiple monitoring dimensions, respectively, where the set thresholds include: a first threshold corresponding to the X-axis dimension, a second threshold corresponding to the Y-axis dimension, a third threshold corresponding to the Z-axis dimension, and a fourth threshold corresponding to the time dimension; compare the correlation peak symmetry value of each monitoring dimension with the corresponding set threshold, and if the comparison result of any monitoring dimension does not meet the requirements, determine that there is a spoofing signal in the intermediate frequency signal corresponding to the N satellites; Alternatively, the average of the correlation peak symmetry values ​​of the multiple monitoring dimensions is obtained, and the average is compared with a set threshold. If the comparison result does not meet the requirements, it is determined that there are deception signals in the intermediate frequency signals corresponding to the N satellites.

[0018] Preferably, the signal generator is specifically used to: perform pseudo-code sampling based on the code phase and the pseudo-code generation rule of the current satellite to obtain a pseudo-code sampling sequence; and locally reproduce the intermediate frequency signal corresponding to the current satellite based on the carrier frequency, sampling period, total number of sampling points and the pseudo-code sampling sequence of the current intermediate frequency signal to obtain a local signal.

[0019] Preferably, the superposition module is specifically used to: determine the normalized weighting coefficient of each satellite by the following method: determine the weighting coefficient of the current satellite based on the signal-to-noise ratio of the current satellite and the cross-correlation peaks of the current satellite and the other N-1 satellites; normalize the weighting coefficient of the current satellite based on the ratio of the weighting coefficient of the current satellite to the sum of the weighting coefficients of N satellites to obtain the normalized weighting coefficient; and accumulate the product of the normalized weighting coefficient of each satellite and its correlation value to obtain the superposition correlation value.

[0020] Preferably, determining the weighting coefficient of the current satellite based on the signal-to-noise ratio of the current satellite and the cross-correlation peaks of the current satellite and the other N-1 satellites includes: The weighting coefficient of the current satellite is determined based on the following relationship:

[0021] In the formula, r i represents the weighting coefficient of the i-th satellite, CNR i Indicates i The carrier-to-noise ratio of the satellite, CNR j Indicates j The carrier-to-noise ratio of the satellite, U i,j Indicates i Satellites and j The ratio of the cross-correlation peaks between satellites to the autocorrelation peak of a certain satellite.

[0022] Preferably, the X signal generator, the Y signal generator, the Z signal generator and the T signal generator calculate the code phases corresponding to the X-axis dimension, the Y-axis dimension, the Z-axis dimension and the time dimension respectively based on the following relationship;

[0023] In the formula, the subscript i represents the serial number of the current satellite, τ x,i , τ y,i , τ z,i , τ t,i Respectively represent the code phases corresponding to the X-axis dimension, the Y-axis dimension, the Z-axis dimension, and the time dimension; x a ,y a and z a Indicates the X-axis coordinate, Y-axis coordinate and Z-axis coordinate corresponding to the receiver position, δt u represents the receiver clock error, x i , y i and z i Indicates the X-axis coordinate, Y-axis coordinate and Z-axis coordinate corresponding to the satellite position of the i-th satellite, δt i represents the satellite clock error of the i-th satellite; f represents the phase value, f= -1 corresponds to the leading phase, f= 0 corresponds to the instantaneous phase, f= 1 corresponds to the lagging phase; d half represents the distance corresponding to half a chip signal, c represents the speed of light; cosu x , cosu y and cosu z Indicates the cosine value of the azimuth from the satellite to the receiver in the X-axis direction, Y-axis direction, and Z-axis direction respectively.

[0024] The third aspect of the embodiment of the present invention provides a computer program stored thereon, and when the computer program is executed by a processor, the spoofing signal detection method described in any one of the first aspects above is implemented.

[0025] An electronic device provided in a fourth aspect of an embodiment of the present invention includes a storage medium storing a computer program, and when the computer program is executed by a processor, the spoofing signal detection method described in any one of the first aspects above is implemented.

[0026] In an embodiment of the present invention, correlation values ​​are calculated respectively using multiple satellite signals, and superimposed correlation values ​​are obtained according to the correlation values ​​corresponding to the multiple satellites. The correlation peak formed by the superimposed correlation values ​​can weaken the distortion formed on the correlation peak due to low signal-to-noise ratio or signal abnormality of any satellite. As long as there is a spoofing signal in the multiple satellite signals, the correlation peak formed by the superimposed correlation values ​​of the multiple satellite signals will still have obvious distortion. Therefore, the embodiment of the present invention can effectively distinguish the correlation peak distortion formed by the two situations by setting a threshold, thereby improving the accuracy of spoofing signal detection and reducing the false alarm rate.

[0027] Other beneficial effects of the present invention will be explained in the specific implementation manner through the introduction of specific technical features and technical solutions. Through the introduction of these technical features and technical solutions, those skilled in the art should be able to understand the beneficial technical effects brought about by the technical features and technical solutions. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The preferred embodiments of the present invention will be described below with reference to the accompanying drawings. Figure 1 A schematic diagram showing spoofing signals in a GNSS scenario; Figure 2 A schematic diagram showing correlation peaks for a single satellite in a scenario without deceptive signals; Figure 3 A schematic diagram showing correlation peaks of a single satellite in a scenario with a spoofed signal; Figure 4 A flow chart showing a method for detecting a fraudulent signal according to an embodiment of the present invention is shown; Figure 5 A schematic diagram showing the variation of the superposition correlation value with the phase in a scenario without a spoofing signal in an embodiment of the present invention; Figure 6 A schematic diagram showing the variation of the superposition correlation value with the phase in a scenario with a spoofing signal in an embodiment of the present invention; Figure 7 A flow chart showing a method for determining a correlation value in an embodiment of the present invention is shown; Figure 8 A flow chart showing a method for determining a correlation peak symmetry value in an embodiment of the present invention; Fig. 9 A schematic diagram showing statistics of correlation peak symmetry values ​​in the X-axis dimension in an embodiment of the present invention; Fig.10 A schematic diagram showing statistics of correlation peak symmetry values ​​in the Y-axis dimension in an embodiment of the present invention; Fig.11 A schematic diagram showing statistics of correlation peak symmetry values ​​in the Z-axis dimension in an embodiment of the present invention; Fig.12 A schematic diagram showing statistics of correlation peak symmetry values ​​in the time dimension in an embodiment of the present invention; Fig.13 A schematic diagram showing the statistics of the correlation peak symmetry value of satellite No. 2 under the traditional SQM method; Fig.14 A schematic diagram showing the statistics of the correlation peak symmetry value of satellite No. 8 under the traditional SQM method; Fig.15 A schematic diagram showing the structure of a receiver in an embodiment of the present invention is shown; Fig.16A schematic diagram of an electronic device for implementing a spoof signal detection method according to an embodiment of the present invention is shown. DETAILED DESCRIPTION

[0029] The present invention is described below based on embodiments, but the present invention is not limited to these embodiments. In the following detailed description of the present invention, some specific details are described in detail. In order to avoid confusing the essence of the present invention, known methods, processes, procedures, and components are not described in detail.

[0030] In addition, persons of ordinary skill in the art will appreciate that the drawings provided herein are for illustration purposes and are not necessarily drawn to scale.

[0031] Unless the context clearly requires otherwise, throughout the specification and claims, the words "include", "comprising" and similar words should be interpreted in an inclusive sense rather than an exclusive or exhaustive sense; that is, in the sense of "including but not limited to".

[0032] In the description of the present invention, it should be understood that the terms "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance. In addition, in the description of the present invention, unless otherwise specified, "plurality" means two or more.

[0033] Pseudorange refers to the measured distance obtained by multiplying the propagation time of the signal transmitted by the satellite to the receiver by the speed of light. By measuring the pseudorange between the receiver and multiple satellites, the receiver can be positioned.

[0034] Regarding pseudo-random noise codes, in the measurement of pseudo-range, satellite signals need to be identified and tracked. Pseudo-random noise (PRN) codes are a special pseudo-random code sequence used to identify and distinguish different satellites, that is, the identification (ID) of each satellite. Each satellite sends its own unique PRN code, which has good high autocorrelation in time and space (autocorrelation indicates the degree of correlation between the same satellite signal and itself at different time delays, and high autocorrelation is conducive to signal identification and tracking) and low cross-correlation (cross-correlation indicates the degree of correlation between two satellite signals at different time delays, and low cross-correlation indicates that the degree of mutual interference between different satellite signals is low), so that the receiver can accurately identify and track the signal of a specific satellite. Based on the needs of signal tracking, the receiver will also generate the same PRN code as the satellite locally. Only when the local PRN code completely matches the received PRN code can the satellite signal be correctly demodulated.

[0035] Regarding the code phase, since there is a time difference from the satellite transmitting the satellite signal to the receiver receiving the satellite signal, there is an offset between the starting points of the PRN code at the satellite and the receiver. The code phase is used to represent the time offset between the starting point of the PRN code in the satellite signal received by the receiver and the starting point of the locally generated PRN code.

[0036] The correlation peak refers to a peak signal generated when the receiver captures and tracks satellite signals after correlating the locally generated PRN code with the received satellite signal through a correlator.

[0037] Specifically, the code phase can be calculated through correlation operation. Please refer to the following relationship:

[0038] In the formula, s(t) refers to the received satellite signal, c(t) refers to the locally generated PRN code, τ refers to the time offset, and R(τ) refers to the correlation value, which specifically indicates the degree of matching under different time offsets τ. The correlation value in the R(τ) function has a peak value (i.e., correlation peak), and the time offset τ corresponding to the correlation peak is the best matching position of the PRN code (i.e., code phase). When the receiver tracks the real satellite signal, the curves on both sides of the correlation peak are roughly symmetrical.

[0039] Spoofing signals refer to false satellite signals that contain erroneous signals. Spoofing signals usually imitate the PRN code of any satellite. When the receiver receives the real signal and the spoofing signal of the satellite, it will mistakenly think that they are all real signals and superimpose the real signal and the spoofing signal. Since the receiver usually locks on the signal source with stronger signal power during the code tracking stage, the power of the spoofing signal will be slightly higher than that of the real signal, making the spoofing signal dominate the signal superposition process, thereby pulling the correlation peak.

[0040] As described in the background technology, the medium-level deception signal mainly misleads the receiver to produce erroneous positioning and timing results by pulling the correlation peak off. Since the signal parameters of the deception signal are not completely consistent with the real signal, the mixing of the deception signal and the real signal will destroy the symmetry of the correlation peak. The traditional SQM method identifies the deception signal based on this. However, when the signal-to-noise ratio of the satellite signal is low, the strong noise will interfere with the shape of the correlation peak and also destroy the symmetry of the correlation peak, resulting in a high false alarm rate for the traditional SQM method to detect deception signals. In view of this, an embodiment of the present invention proposes a deception signal detection method, which can weaken the distortion caused by the signal anomaly in the correlation peak to distinguish the correlation peak distortion caused by the signal anomaly and the deception signal, thereby improving the accuracy of detecting deception signals.

[0041] The specific embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0042] See also Figure 4 , Figure 4 A flow chart of a spoofing signal detection method in an embodiment of the present invention is shown. The embodiment of the present invention provides a spoofing signal detection method, which includes steps S1, S3, S5 and S7.

[0043] S1. Perform positioning calculation based on the intermediate frequency signals corresponding to N satellites acquired by the receiver to obtain the receiver position, receiver clock error, and the satellite positions and satellite clock errors corresponding to the N satellites respectively; N is an integer greater than 3.

[0044] In actual applications, the receiver obtains satellite signals through a local antenna, and performs down-conversion and ADC sampling on the satellite signals, converting the high-frequency satellite signals in analog signal format into intermediate frequency signals in digital signal format. Over a period of time, the receiver can obtain the intermediate frequency signals corresponding to N satellites, and then perform positioning based on the intermediate frequency signals of N satellites. Specifically, different satellites have different identity identifiers (such as the PRN code number of the satellite), and the receiver can distinguish satellite signals sent by different satellites by identifying the PRN code number in the satellite signal.

[0045] Regarding satellite signals, the satellite signals acquired by the receiver include carrier, PRN code and navigation message. The carrier has a stable frequency and phase. It is the high-frequency part of the satellite signal and carries the PRN code and navigation message. The PRN code is a pseudo-random sequence. Different satellites have different PRN code codes. Different PRN code codes correspond to different pseudo-random sequence generation rules. The navigation message is binary data sent by the satellite to the receiver. It contains the satellite's satellite ephemeris (the precise orbital parameters of the satellite, used to calculate the position of the satellite at any time), satellite clock error (the deviation of the satellite clock from the standard time, used to correct the time error), ionospheric delay correction parameters (used to correct the impact of the ionosphere on the signal propagation time) and other information.

[0046] Regarding positioning solution, it refers to calculating the satellite position and corresponding pseudorange of each satellite based on the intermediate frequency signals of multiple satellites, and further solving the receiver position and receiver clock error through these parameters. Specifically, before the receiver performs positioning solution, it is also necessary to perform code capture, code tracking, and observation extraction based on the intermediate frequency signal. Among them, code capture specifically includes: multiplying the received PRN code with the locally generated PRN code point by point, integrating the multiplication result, and the maximum point of the integration result is the code phase. Code tracking specifically includes: generating PRN codes of leading phase, instantaneous phase and lagging phase, and adjusting the phase by calculating the correlation value of the PRN code of the leading phase and the lagging phase, so that the PRN code corresponding to the instantaneous phase is optimally aligned with the received PRN code. Observation extraction specifically includes: extracting key measurement data for positioning calculation from the received intermediate frequency signal, and the key measurement data mainly includes pseudorange, carrier phase, carrier frequency, navigation message, and signal strength. Specifically, there are many methods for positioning solution in the prior art, which are not limited here.

[0047] It should be noted that in step S1 of the embodiment of the present invention, it is temporarily impossible to identify whether there are deception signals in the multiple satellite signals used for positioning solution. Therefore, the receiver position and receiver clock error calculated here are both provisional values, and are not the final positioning output results of the receiver.

[0048] S3. For the intermediate frequency signal corresponding to each satellite, the following correlation processing is performed on multiple phases: based on the receiver position, the receiver clock error, and the satellite position and satellite clock error corresponding to the current satellite, the code phase between the receiver and the current satellite is determined; based on the code phase, the intermediate frequency signal is reproduced locally at the receiver to obtain a local signal; the local signal is correlated with the intermediate frequency signal to obtain a correlation value.

[0049] The above-mentioned multiple phases include: an advanced phase, an instantaneous phase and a lagging phase. Specifically, the advanced phase and the lagging phase are symmetrical with the instantaneous phase as the center. Figure 5 As shown in the figure, the leading phase, instantaneous phase and lagging phase are separated by half a chip in sequence (taking GPS L1 C / A code as an example, the value of one chip is about 300 meters), the leading phase is about -150 meters, and the corresponding lagging phase is about 150 meters. In practical applications, based on different requirements for measurement accuracy, multiple groups of symmetrical leading phases and lagging phases can be included. The calculation results of the correlation values ​​of multiple groups of symmetrical phases can weaken the impact of the low signal-to-noise ratio of the satellite signal in a certain local period on the correlation peak.

[0050] For example, the pseudorange is determined based on the receiver position and the satellite position, and the pseudorange is divided by the speed of light to determine the propagation time of the current satellite signal, and then the code phase can be determined based on the following relationship. The satellite clock error of the current satellite can be extracted from the satellite ephemeris corresponding to the current intermediate frequency signal.

[0051] Code phase = propagation time + receiver clock error - satellite clock error.

[0052] Specifically, before reproducing the intermediate frequency signal of the current satellite, the PRN code number in the intermediate frequency signal can be extracted first, and the pseudo-random sequence generation rule corresponding to the current satellite can be determined based on the number. Then, according to the rule, a pseudo-code sampling sequence matching the current satellite is generated according to the set sampling period and total number of sampling points.

[0053] In the embodiment of the present invention, the correlation operation between the intermediate frequency signal and the local signal has many implementations in the prior art, which are not specifically limited here.

[0054] S5. For any phase, the correlation values ​​corresponding to the N satellites are superimposed to obtain a superimposed correlation value; based on the superimposed correlation values ​​corresponding to the multiple phases, a correlation peak symmetry value of the superimposed N satellites is determined.

[0055] In one implementation, the correlation values ​​corresponding to the N satellites may be accumulated, and the accumulated results may be averaged, and the average may be used as the superposition correlation value. This calculation method is simple and direct, and can efficiently calculate the superposition correlation value.

[0056] In another embodiment, the normalized weighting coefficient of each satellite can be determined by the following method: based on the signal-to-noise ratio of the current satellite and the cross-correlation peaks of the current satellite and the other N-1 satellites, the weighting coefficient of the current satellite is determined; based on the ratio of the weighting coefficient of the current satellite to the sum of the weighting coefficients of N satellites, the weighting coefficient of the current satellite is normalized to obtain the normalized weighting coefficient; and the product of the normalized weighting coefficient of each satellite and its correlation value is accumulated to obtain the superposition correlation value. This calculation method takes into account the influence of the signal strength of different satellites and can more accurately calculate the superposition correlation value.

[0057] In practical applications, a single satellite may have a low signal-to-noise ratio or other signal anomalies, which may affect the calculation result of the correlation value. The embodiment of the present invention calculates the correlation values ​​by using multiple satellite signals respectively, and performs superposition operation on the correlation values ​​corresponding to the multiple satellites respectively, thereby weakening the impact of the low signal-to-noise ratio or other signal anomalies of any satellite.

[0058] Specifically, the superposition correlation values ​​corresponding to the leading phase, the instantaneous phase and the lagging phase are respectively the first correlation values , the second correlation value and the third correlation value , take the absolute value of the difference between the first correlation value and the third correlation value, and divide the absolute value by the second correlation value to obtain the correlation peak symmetry value of N satellite superposition. For example, the following relationship can be referred to:

[0059] The above relationship between the correlation peak symmetry value S represents the degree of symmetry of the correlation peak. Under ideal conditions, the correlation peak is perfectly symmetrical ( ), the correlation peak symmetry value S is equal to zero; the larger the correlation peak symmetry value S is, the greater the distortion of the correlation peak is.

[0060] S7. Based on the comparison result of the correlation peak symmetry value and the set threshold, determine whether there is a spoofing signal in the intermediate frequency signals corresponding to the N satellites.

[0061] In an ideal state, the correlation peak symmetry value S approaches or is equal to zero. Considering the existence of noise and measurement errors, the embodiment of the present application sets a set threshold value S0 of the correlation peak symmetry value to assist in determining whether the correlation peak has obvious distortion.

[0062] Below Figure 5 and Figure 6 Take this as an example to illustrate: Figure 5 A schematic diagram showing the variation of the superposition correlation value with the phase in a scenario without a spoofing signal in an embodiment of the present invention; Figure 6 FIG. 1 is a schematic diagram showing the variation of the superposition correlation value with the phase in a spoofing signal scenario in an embodiment of the present invention. Assuming that the threshold S0 is set to 0.1, Figure 5 As shown in the figure, the superposition correlation values ​​corresponding to the leading phase, instantaneous phase and lagging phase are approximately 1400, 5400 and 1100 respectively, and the correlation peak symmetry value at this time is approximately 0.056. The correlation peak symmetry value S is less than the set threshold S0, and the two sides of the correlation peak are roughly symmetrical. It can be considered that there is no deception signal in the intermediate frequency signals corresponding to the above N satellites. Figure 6 As shown in the figure, the superposition correlation values ​​corresponding to the leading phase, instantaneous phase and lagging phase are approximately 2400, 4400 and 900 respectively, and the correlation peak symmetry value at this time is approximately 0.34. The correlation peak symmetry value S is greater than the set threshold S0, and the correlation peak is obviously distorted. It can be considered that there are deception signals in the intermediate frequency signals corresponding to the above N satellites.

[0063] Exemplarily, regarding setting the threshold S0, statistics of the receiver in a state without a spoofing signal over a period of time may be collected, the mean u and standard deviation σ of the statistics may be determined, and the threshold S0=u+3σ may be set.

[0064] Since the satellite signal of a single satellite may have a low signal-to-noise ratio, the embodiment of the present invention uses the satellite signals of multiple satellites to calculate the superimposed correlation values. The correlation peak formed by the superimposed correlation values ​​can weaken the distortion on the correlation peak caused by the low signal-to-noise ratio or signal abnormality of any satellite. As long as there is a spoofing signal in the multiple satellite signals, the correlation peak formed by the superimposed correlation values ​​of the multiple satellite signals will still have obvious distortion. Therefore, the embodiment of the present invention can effectively distinguish the correlation peak distortion formed by the two situations by setting a threshold, thereby improving the accuracy of spoofing signal detection and reducing the false alarm rate.

[0065] In practical applications, since spoofing signals may pull correlation peaks in multiple dimensions such as the X-axis, Y-axis, Z-axis and time, and the correlation peak distortions formed in different dimensions may have different distortion characteristics (i.e., present different correlation peak symmetry values), in order to detect spoofing signals more accurately, In the embodiment of the present application, the above steps S3 and S5 are respectively executed in multiple monitoring dimensions to obtain the correlation peak symmetry values ​​corresponding to the multiple monitoring dimensions, and the multiple monitoring dimensions include: X-axis dimension, Y-axis dimension, Z-axis dimension and time dimension.

[0066] In one embodiment, see Figure 7 , Figure 7 A flow chart of a method for determining a correlation value in an embodiment of the present invention is shown. The above step S3 may include: steps S31, S33, S35 and S37.

[0067] S31. Determine the code phase between the receiver and the current satellite based on the receiver position, the receiver clock error, and the satellite position and satellite clock error corresponding to the current satellite.

[0068] Exemplarily, the code phases corresponding to the X-axis dimension, the Y-axis dimension, the Z-axis dimension, and the time dimension may be calculated based on the following relationship:

[0069] In the formula, the subscript i represents the serial number of the current satellite, τ x,i , τ y,i , τ z,i , τ t,i Respectively represent the code phases corresponding to the X-axis dimension, the Y-axis dimension, the Z-axis dimension, and the time dimension; x a , y a and z a Indicates the X-axis coordinate, Y-axis coordinate and Z-axis coordinate corresponding to the receiver position. δt u represents the receiver clock error, xi , y i and z i Indicates the X-axis coordinate, Y-axis coordinate and Z-axis coordinate corresponding to the satellite position of the i-th satellite, δt i represents the satellite clock error of the i-th satellite; f represents the phase value, f= -1 corresponds to the leading phase, f= 0 corresponds to the instantaneous phase, f= 1 corresponds to the lagging phase; d half represents the distance corresponding to half a chip signal, c represents the speed of light; cosu x , cosu y and cosu z Indicates the cosine value of the azimuth from the satellite to the receiver in the X-axis direction, Y-axis direction, and Z-axis direction respectively.

[0070] Specifically, cosu x represents the projection length of the vector from the satellite to the receiver in the X-axis direction, cosu y represents the projection length of the vector from the satellite to the receiver in the Y-axis direction, cosu z represents the projection length of the vector from the satellite to the receiver in the Z-axis direction, cosu x , cosu y and cosu z The calculation method of the three can refer to the following relationship.

[0071]

[0072] The above relationship calculates the vector u a −u b and x, y, z Unit vector of the axis e x ，e y ，e z The dot product of u a −u b The modulus length is u a −u b The cosine of the angle between and each coordinate axis. u a ，u b，e x ，e y and e z They are: .

[0073] S33, performing pseudo-code sampling based on the code phase and the pseudo-random sequence generation rule of the current satellite to obtain a pseudo-code sampling sequence.

[0074] In practical applications, different satellites have different pseudo-random sequence generation rules. The embodiment of the present invention can confirm the pseudo-random sequence generation rule of the current satellite by extracting the PRN code number in the intermediate frequency signal, and generate pseudo-code sampling sequences corresponding to multiple phases in the above-mentioned multiple monitoring dimensions.

[0075] Exemplarily, the generation result of the pseudo code sampling sequence is as follows:

[0076] Among them, the subscripts "E", "C" and "L" represent the leading phase, the immediate phase and the lagging phase respectively; the subscripts "x", "y", "z" and "t" represent the four dimensions of X-axis, Y-axis, Z-axis and time respectively.

[0077] S35. Reproduce the intermediate frequency signal corresponding to the current satellite based on the carrier frequency, sampling period, total number of sampling points and pseudo code sampling sequence of the current intermediate frequency signal to obtain a local signal.

[0078] Specifically, the receiver can calculate the carrier frequency of the current intermediate frequency signal based on the intermediate frequency signal, and reproduce the intermediate frequency signal corresponding to the current satellite according to the above pseudo code sampling sequence, the sampling period of the intermediate frequency signal and the total number of sampling points. Exemplarily, the local signal can be calculated by referring to the following relationship:

[0079] In the formula, ” is the complex exponential term of the Doppler frequency shift corresponding to the K sampling points, indicating the phase change of the signal at different sampling points; represents the pseudo code sampling sequence of the i-th satellite signal, represents the carrier frequency of the ith satellite, represents the sampling period, K represents the total number of sampling points, and j represents the jth satellite among N satellites.

[0080] Exemplarily, the reproduced local signal is as follows:

[0081] S37, performing correlation operation on the local signal and the intermediate frequency signal to obtain a correlation value.

[0082] Exemplarily, the correlation value may be calculated with reference to the following relationship:

[0084] In the formula, the superscript "H" represents the conjugate transpose operation. represents the intermediate frequency signal of the i-th satellite, represents the local signal of the i-th satellite, represents the correlation value of the i-th satellite.

[0085] Exemplarily, the corresponding correlation values ​​in multiple monitoring dimensions and multiple phases are as follows:

[0087] Furthermore, for the correlation value of the i-th satellite , the M correlation values ​​collected within a period of time can also be non-coherently accumulated to improve the signal-to-noise ratio. For example, the following relationship can be used:

[0088] In the formula, Indicates the corresponding i The mth correlation value of a satellite in a certain period of time, Indicates M consecutive Incoherent accumulation results.

[0089] In one embodiment, see Figure 8 , Figure 8 A flow chart of a method for determining a correlation peak symmetry value in an embodiment of the present invention is shown. The above step S5 may include: steps S51, S53, S55 and S57.

[0090] S51, determining a weighting coefficient of the current satellite based on the signal-to-noise ratio of the current satellite and the cross-correlation peaks between the current satellite and the other N-1 satellites.

[0091] For example, the weighting coefficient may be determined by referring to the following relationship:

[0092] In the formula, r i represents the weighting coefficient of the i-th satellite, CNR i Indicates i The carrier-to-noise ratio of the satellite, CNR j Indicates j The carrier-to-noise ratio of the satellite, Ui,j Indicates i Satellites and j The ratio between the cross-correlation peaks of satellites and the autocorrelation peak of a certain satellite. U i,j It is related to the characteristics of the PRN codes corresponding to the two satellites. In practical applications, since each satellite has its own unique PRN code, the PRN codes of any two satellites are U i,j The value is fixed, such as GPS L1 C / A code signal, any two satellites U i,j The value is about 0.063. In addition, the carrier-to-noise ratio of different satellites can be calculated based on the intermediate frequency signals corresponding to different satellites.

[0093] The derivation logic of the above weighted coefficient relationship is as follows: For the kth element of the intermediate frequency signal x, it can be expressed by the following relationship:

[0094] In the formula, represents the signal power, Indicates the navigation message. represents the code phase, represents the PRN code of the i-th satellite signal received by the receiver, represents the carrier frequency of the i-th satellite, is the sampling period, j represents the jth satellite among N satellites, The complex exponential term representing the Doppler frequency shift of the kth sampling point.

[0095] Since the navigation message flip rate is much lower than the PRN code, the navigation message in a short period of time can be considered unchanged, so the above formula can be simplified to:

[0096] Combined Relationship , you can The relationship is simplified to:

[0097] In the formula, represents the pseudo code sampling sequence of the j-th satellite signal, represents the autocorrelation peak of the PRN code of the i-th satellite, represents the cross-correlation peak value between the PRN codes of the i-th satellite and the j-th satellite.

[0098] It can be seen from the above relationship that the correlation value P i Including autocorrelation components and the cross-correlation components In the correlation operation of satellite signals, the higher the autocorrelation component, the better (which is conducive to signal identification and tracking), and the lower the cross-correlation component, the better (which indicates that the degree of mutual interference between different satellite signals is low). Assuming is 1, then in the GPS L1 C / A code signal, U i,j The value is about 0.063, which shows that the autocorrelation peak is much larger than the cross-correlation peak. When the power of different satellite signals is close (i.e., ), the cross-correlation component can be ignored. However, when the signal power of a satellite is much higher than that of other satellites (i.e., ), then its autocorrelation component may not be much higher than the cross-correlation component between it and other satellite signals (i.e., The value of cannot be ignored). At this time, if the P between different signals i (or Q after incoherent accumulation i ) are accumulated, the correlation peak will be closer to the signal with strong power, and the cross-correlation brought by the strong signal to the weak signal will further reduce the proportion of the weak signal autocorrelation peak in the total accumulation result. In order to better utilize the components of all signals, P can be adjusted before accumulation. i Perform weighted operation, according to the above formula, assuming is 1, the weighting coefficient can be set as:

[0099] In actual signal processing, Hard to get, but and During the tracking process, the signal-to-noise ratio can be approximately proportional to the following:

[0100] So we can get the weighting coefficient The relationship is:

[0101] This step uses the correlation coefficient of the mutual correlation between different satellites and the correlation between signal power and signal-to-noise ratio to set the weighting coefficient of each satellite signal in the superposition of correlation values, thereby reducing the proportion of the mutual correlation component of the strong signal in the superposition correlation value, thereby reducing the signal interference between different satellites, so that the superposition correlation value can more accurately reflect the correlation degree of the same satellite signal at different time delays.

[0102] S53. Based on the ratio of the weighting coefficient of the current satellite to the sum of the weighting coefficients of N satellites, normalize the weighting coefficient of the current satellite to obtain a normalized weighting coefficient.

[0103] For example, the normalization process may refer to the following relationship:

[0104] In the formula, represents the normalized weighting coefficient, represents the weighting coefficient of the i-th satellite, represents the weighting coefficient of the jth satellite, where i and j both belong to N.

[0105] S55. Accumulate the product of the normalized weighted coefficient of each satellite and its correlation value to obtain a superimposed correlation value.

[0106] Exemplarily, the calculation of the superposition correlation value may refer to the following relationship:

[0107] If non-coherent accumulation is used in the above step S37, then If the non-coherent accumulation is not used in the above step S37, then the use of Perform cumulative calculations.

[0108] Exemplarily, the corresponding superposition correlation values ​​in multiple monitoring dimensions and multiple phases are as follows:

[0109] S57. In multiple monitoring dimensions, determine the correlation peak symmetry value of the superposition of N satellites based on the superposition correlation values ​​corresponding to multiple phases.

[0110] Exemplarily, the correlation peak symmetry values ​​of multiple monitoring dimensions can refer to the following relationship:

[0111] Accordingly, in an implementation of step S7, the first threshold T corresponding to the X-axis dimension can be obtained. x , the second threshold T corresponding to the Y-axis dimension y , the third threshold T corresponding to the Z-axis dimension z The fourth threshold T corresponding to the time dimension t ; The correlation peak symmetry value of each monitoring dimension is compared with its corresponding set threshold value. If the comparison result of any monitoring dimension does not meet the requirements, it is determined that there is a deception signal in the intermediate frequency signal corresponding to the N satellites.

[0112] The embodiments of the present invention have the following beneficial effects: On the one hand, the embodiment of the present invention constructs four corresponding monitoring dimensions, performs correlation value superposition processing of multiple satellite signals in these four monitoring dimensions, and sets four set thresholds for judgment accordingly. As long as any monitoring dimension is deviated by a spoofing signal, it will be reflected in the symmetric value of the correlation peak of the corresponding monitoring dimension (that is, distortion is formed on the correlation peak), thereby improving the recognition rate of the spoofing signal.

[0113] On the other hand, the embodiment of the present invention sets a weighted coefficient for each satellite signal when superimposing correlation values, thereby reducing the proportion of the cross-correlation component of the strong signal in the superimposed correlation value, thereby reducing the signal interference between different satellites, so that the superimposed correlation value can more accurately reflect the correlation degree of the same satellite signal at different time delays, further improving the accuracy of detecting deceptive signals.

[0114] In order to illustrate the technical effect of the embodiment of the present invention, the present invention also provides a simulation embodiment, which specifically simulates a scene with a total of 8 satellites. In the scene where deception exists, each real signal has a corresponding deception signal, and the power of the deception signal is 1dB higher than the power of the real signal. The deception signal is pulling the user's position away, and the position deviation is (x, y, z) = (150, 0, 0) meters.

[0115] This simulation embodiment provides Figures 9 to 14 , Fig. 9 A schematic diagram showing statistics of the correlation peak symmetry value in the X-axis dimension in an embodiment of the present invention is shown, Fig.10 A schematic diagram showing statistics of the correlation peak symmetry value in the Y-axis dimension in an embodiment of the present invention is shown, Fig.11 A schematic diagram showing statistics of the correlation peak symmetry value in the Z-axis dimension in an embodiment of the present invention is shown, Fig.12 A schematic diagram showing statistics of correlation peak symmetry values ​​in the time dimension in an embodiment of the present invention is shown, Fig.13 The figure shows the statistics of the correlation peak symmetry value of satellite No. 2 under the traditional SQM method. Fig.14 The figure shows the statistics of the correlation peak symmetry value of satellite No. 8 under the traditional SQM method. In the figure, an "*" represents a simulation result with a spoofing signal, and a "." represents a simulation result without a spoofing signal. The ordinate in the figure represents the correlation peak symmetry value, and the abscissa in the figure represents the number of simulations.

[0116] like Figures 9 to 12As shown in the figure, in the X-axis dimension, when there is a deception signal, the statistics of the correlation peak symmetry value are significantly different from those when there is no deception signal, and the statistics are relatively stable, with a low false alarm probability. In the other three dimensions, when there is a deception signal, the statistical variance of the correlation peak symmetry value increases, but its mean does not change much from that when there is no deception signal. This shows that distinguishing multiple monitoring dimensions for deception signal detection can more effectively identify the correlation peak distortion when there is a deception signal.

[0117] like Figure 13 to Figure 14 As shown, satellite No. 2 and satellite No. 8 are two satellites with low signal-to-noise ratio. The traditional SQM method is used to perform statistics on the correlation peak symmetry values ​​of a single satellite. It can be seen from the figure that in the same deception scenario, the correlation peak symmetry values ​​of different satellites show different performances. The statistics of satellite No. 2 have obvious changes when the deception signal exists, but they are not stable, and the false alarm rate is high. In addition, in some simulation results, the correlation peak symmetry values ​​with and without deception signals are mixed together, and it is difficult to effectively distinguish the two with a fixed set threshold. When there is a deception signal on satellite No. 8, there is no obvious change in the correlation peak symmetry value relative to the absence of a deception signal, and effective deception signal detection cannot be performed. It can be seen that if the deception signal only deviates from the dimension of a certain position direction, some single satellites cannot be effectively identified. The method for determining the superimposed correlation value based on N satellites in the embodiment of the present invention can effectively overcome this problem.

[0118] The receiver in the embodiment of the present invention is described below. Fig.15 , Fig.15 The structure diagram of the receiver in the embodiment of the present invention is shown. Specifically, the receiver in the embodiment of the present invention includes: The acquisition unit is used to perform down-conversion and analog-to-digital conversion (ADC) sampling processing on the satellite signal received by the antenna to obtain an intermediate frequency signal; A positioning solution unit, used to perform positioning solution based on the intermediate frequency signals corresponding to N satellites, to obtain the receiver position, the receiver clock error, and the satellite positions and satellite clock errors corresponding to the N satellites respectively; N is an integer greater than 3; and A deception detection unit includes processing channels, a superposition module and a determination module corresponding to N satellites respectively, and each processing channel includes a signal generator and a related module; Among them, the signal generator is used to determine the code phase between the receiver and the current satellite based on the receiver position, the receiver clock error, and the satellite position and satellite clock error corresponding to the current satellite at multiple phases, and reproduce the intermediate frequency signal locally based on the code phase to obtain a local signal; the correlation module is used to perform correlation operations on the local signal and the intermediate frequency signal at multiple phases to obtain correlation values; the multiple phases include: an advanced phase, an instantaneous phase and a lagging phase; the advanced phase and the lagging phase are symmetrical with the instantaneous phase as the center; the superposition module is used to perform superposition operations on the correlation values ​​corresponding to N satellites for any phase to obtain a superimposed correlation value; the correlation peak symmetry value of the superimposed N satellites is determined based on the superimposed correlation values ​​corresponding to the multiple phases; the judgment module is used to determine whether there is a deceptive signal in the intermediate frequency signal corresponding to the N satellites based on the comparison result of the correlation peak symmetry value and the set threshold.

[0119] Further, a signal generator of a processing channel includes: an X signal generator, a Y signal generator, a Z signal generator and a T signal generator; the correlation modules include: an X correlation module, a Y correlation module, a Z correlation module and a T correlation module; the X signal generator and the X correlation module perform correlation processing on the intermediate frequency signal in the X-axis dimension; the Y signal generator and the Y correlation module perform correlation processing on the intermediate frequency signal in the Y-axis dimension; the Z signal generator and the Z correlation module perform correlation processing on the intermediate frequency signal in the Z-axis dimension; the T signal generator and the T correlation module perform correlation processing on the intermediate frequency signal in the time dimension.

[0120] Further, the determination module is specifically used to: obtain set thresholds corresponding to multiple monitoring dimensions, the set thresholds include: a first threshold corresponding to the X-axis dimension, a second threshold corresponding to the Y-axis dimension, a third threshold corresponding to the Z-axis dimension, and a fourth threshold corresponding to the time dimension; compare the correlation peak symmetry value of each monitoring dimension with the corresponding set threshold, if the comparison result of any monitoring dimension does not meet the requirements, it is determined that there is a deception signal in the intermediate frequency signal corresponding to the N satellites; Alternatively, the determination module is specifically used to: obtain the average of the correlation peak symmetry values ​​of multiple monitoring dimensions, compare the average with a set threshold, and if the comparison result does not meet the requirements, determine that there are deception signals in the intermediate frequency signals corresponding to the N satellites.

[0121] Furthermore, the signal generator is specifically used to: perform pseudo code sampling based on the code phase and the pseudo code generation rule of the current satellite to obtain a pseudo code sampling sequence; and locally reproduce the intermediate frequency signal corresponding to the current satellite based on the carrier frequency, sampling period, total number of sampling points and pseudo code sampling sequence of the current intermediate frequency signal to obtain a local signal.

[0122] Furthermore, the superposition module is specifically used to: determine the normalized weighting coefficient of each satellite by the following method: determine the weighting coefficient of the current satellite based on the signal-to-noise ratio of the current satellite and the cross-correlation peak values ​​of the current satellite and the other N-1 satellites; normalize the weighting coefficient of the current satellite based on the ratio of the weighting coefficient of the current satellite to the sum of the weighting coefficients of N satellites to obtain the normalized weighting coefficient; and accumulate the product of the normalized weighting coefficient of each satellite and its correlation value to obtain the superposition correlation value.

[0123] It should be noted that the method steps executed by each unit or module of the receiver in the embodiment of the present invention are consistent with the contents of the above method embodiment and will not be repeated here.

[0124] Fig.16 A schematic diagram of an electronic device for implementing a spoofing signal detection method in an embodiment of the present invention is shown. The electronic device includes: a memory 1100 and a processor 1200 .

[0125] The processor 1200 may be a central processing unit (CPU), or other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field-programmable gate arrays (FPGA), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. A general-purpose processor may be a microprocessor or the processor may be any conventional processor, etc.

[0126] The memory 1100 may include various types of storage units, such as system memory, read-only memory (ROM), and permanent storage devices. Among them, ROM can store static data or instructions required by the processor 1200 or other modules of the computer. The permanent storage device may be a readable and writable storage device. The permanent storage device may be a non-volatile storage device that does not lose the stored instructions and data even after the computer is powered off. In some embodiments, the permanent storage device uses a large-capacity storage device (such as a magnetic or optical disk, flash memory) as a permanent storage device. In some other embodiments, the permanent storage device may be a removable storage device (such as a floppy disk, optical drive). The system memory may be a readable and writable storage device or a volatile readable and writable storage device, such as a dynamic random access memory. The system memory may store some or all instructions and data required by the processor at run time. In addition, the memory 1100 may include any combination of computer-readable storage media, including various types of semiconductor memory chips (DRAM, SRAM, SDRAM, flash memory, programmable read-only memory), and disks and / or optical disks may also be used. In some embodiments, the memory 1100 may include a readable and / or writable removable storage device, such as a laser disc (CD), a read-only digital versatile disc (e.g., DVD-ROM, double-layer DVD-ROM), a read-only Blu-ray disc, an ultra-density optical disc, a flash memory card (e.g., SD card, mini SD card, Micro-SD card, etc.), a magnetic floppy disk, etc. The computer-readable storage medium does not include carrier waves and transient electronic signals transmitted wirelessly or wired.

[0127] The memory 1100 stores executable codes for executing the spoofing signal detection method in the above method embodiment. When the executable codes are processed by the processor 1200, the processor 1200 can execute part or all of the above method.

[0128] In addition, the present invention also provides a computer-readable storage medium, such as a chip, a CD, etc., on which an execution program is stored. When the execution program is executed, the above-mentioned deception signal detection method is implemented.

[0129] It should be noted that the computer-readable storage medium described in the embodiments of the present disclosure is not limited to the above-mentioned embodiments, and may also be, for example, an electrical, magnetic, optical, electromagnetic, infrared, or semiconductor system, device or device, or any combination thereof. More specific examples of computer-readable storage media may include, but are not limited to: an electrical connection with one or more wires, a portable computer disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disk read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination thereof. In the embodiments of the present disclosure, a computer-readable storage medium may be any tangible medium containing or storing a program, which may be used by or in combination with an instruction execution system, device, or device.

[0130] It will be appreciated by those skilled in the art that, under the premise of no conflict, the above-mentioned preferred solutions can be freely combined and superimposed. Among them, the flowcharts and block diagrams in the accompanying drawings illustrate the possible architecture, functions and operations of the systems, methods and computer program products according to various embodiments of the present disclosure. In this regard, each box in the flowchart or block diagram can represent a module, a program segment, or a part of a code, and the module, program segment, or a part of a code contains one or more executable instructions for implementing the specified logical function. It should also be noted that in some alternative implementations, the functions marked in the box can also occur in an order different from that marked in the accompanying drawings, for example, two boxes represented in succession can actually be executed substantially in parallel, and they can sometimes be executed in the opposite order, depending on the functions involved. It should also be noted that each box in the block diagram and / or flowchart, and the combination of boxes in the block diagram and / or flowchart can be implemented with a dedicated hardware-based system that performs a specified function or operation, or can be implemented with a combination of dedicated hardware and computer instructions. The numbering of each step in this article is only for the convenience of description and reference, and is not used to limit the order of execution. The specific execution order is determined by the technology itself, and those skilled in the art can determine various allowable and reasonable orders based on the technology itself.

[0131] It should be noted that the use of step numbers (letters or numbers) to refer to certain specific method steps in the present invention is only for the purpose of convenience and simplicity of description, and is by no means intended to limit the order of these method steps. Those skilled in the art will understand that the order of the relevant method steps should be determined by the technology itself and should not be inappropriately limited by the existence of step numbers. Those skilled in the art can determine various permissible and reasonable step orders based on the technology itself.

[0132] Those skilled in the art will appreciate that, without conflict, the above-mentioned preferred solutions can be freely combined and superimposed.

[0133] It should be understood that the above-mentioned embodiments are merely illustrative and not restrictive. Without departing from the basic principles of the present invention, various obvious or equivalent modifications or substitutions that can be made by those skilled in the art to the above-mentioned details will all be included in the scope of the claims of the present invention.

Claims

1. A method for detecting a spoofing signal, characterized in that: include: S1. Perform positioning calculation based on the intermediate frequency signals corresponding to N satellites acquired by the receiver to obtain the receiver position, the receiver clock error, and the satellite positions and satellite clock errors corresponding to the N satellites, respectively; wherein N is an integer greater than 3; S3, for the intermediate frequency signal corresponding to each satellite, performing the following correlation processing at multiple phases respectively: determining the code phase between the receiver and the current satellite based on the receiver position, the receiver clock error, and the satellite position and satellite clock error corresponding to the current satellite; Reproducing the intermediate frequency signal locally at the receiver based on the code phase to obtain a local signal; The local signal is correlated with the intermediate frequency signal to obtain a correlation value; the multiple phases include: an advanced phase, an instantaneous phase and a lagging phase; the advanced phase and the lagging phase are symmetrical with the instantaneous phase as the center; S5. For any of the phases, superimpose the correlation values ​​corresponding to the N satellites to obtain a superimposed correlation value; determine the correlation peak symmetry value of the superimposed N satellites based on the superimposed correlation values ​​corresponding to the multiple phases; and S7. Based on the comparison result of the correlation peak symmetry value and the set threshold, determine whether there is a spoofing signal in the intermediate frequency signals corresponding to the N satellites.

2. The method for detecting spoofing signals according to claim 1, characterized in that: Step S3 and step S5 are respectively performed on multiple monitoring dimensions to obtain correlation peak symmetry values ​​corresponding to the multiple monitoring dimensions, wherein the multiple monitoring dimensions include: an X-axis dimension, a Y-axis dimension, a Z-axis dimension and a time dimension.

3. The method for detecting spoofing signals according to claim 2, characterized in that: In step S7, determining whether there is a spoofing signal in the intermediate frequency signals corresponding to the N satellites based on the comparison result of the correlation peak symmetry value and the set threshold value includes: Acquire set thresholds corresponding to the multiple monitoring dimensions, respectively, where the set thresholds include: a first threshold corresponding to the X-axis dimension, a second threshold corresponding to the Y-axis dimension, a third threshold corresponding to the Z-axis dimension, and a fourth threshold corresponding to the time dimension; compare the correlation peak symmetry value of each monitoring dimension with the corresponding set threshold, and if the comparison result of any monitoring dimension does not meet the requirements, determine that there is a spoofing signal in the intermediate frequency signal corresponding to the N satellites; or, The average of the correlation peak symmetry values ​​of the multiple monitoring dimensions is obtained, and the average is compared with a set threshold. If the comparison result does not meet the requirements, it is determined that there are deception signals in the intermediate frequency signals corresponding to the N satellites.

4. The method for detecting spoofing signals according to claim 1, characterized in that: In step S3, the reproducing the intermediate frequency signal locally at the receiver based on the code phase includes: Perform pseudo-code sampling based on the code phase and the pseudo-random sequence generation rule of the current satellite to obtain a pseudo-code sampling sequence; and The intermediate frequency signal corresponding to the current satellite is reproduced based on the carrier frequency of the current intermediate frequency signal, the sampling period, the total number of sampling points and the pseudo code sampling sequence to obtain a local signal.

5. The method for detecting spoofing signals according to claim 1, characterized in that: In step S5, the correlation values ​​corresponding to the N satellites are superimposed, including: Determine the normalized weighting coefficient of each satellite by: determining the weighting coefficient of the current satellite based on the signal-to-noise ratio of the current satellite and the cross-correlation peaks of the current satellite and the other N-1 satellites; normalize the weighting coefficient of the current satellite based on the ratio of the weighting coefficient of the current satellite to the sum of the weighting coefficients of the N satellites to obtain the normalized weighting coefficient; and The product of the normalized weighted coefficient of each satellite and its correlation value is accumulated to obtain the superimposed correlation value.

6. The method for detecting spoofing signals according to claim 5, characterized in that: The step of determining the weighting coefficient of the current satellite based on the signal carrier-to-noise ratio of the current satellite and the cross-correlation peaks between the current satellite and the other N-1 satellites comprises: The weighting coefficient of the current satellite is determined based on the following relationship: ； In the formula, r i represents the weighting coefficient of the i-th satellite, CNR i Indicates i The carrier-to-noise ratio of the satellite, CNR j Indicates j The carrier-to-noise ratio of the satellite, U i,j Indicates i Satellites and j The ratio of the cross-correlation peaks between satellites to the autocorrelation peak of a certain satellite.

7. The method for detecting spoofing signals according to claim 2, characterized in that: In step S3 respectively performed in multiple monitoring dimensions, determining the code phase between the receiver and the current satellite based on the receiver position, the receiver clock error, the satellite position and the satellite clock error includes: The code phases corresponding to the X-axis dimension, the Y-axis dimension, the Z-axis dimension and the time dimension are calculated respectively based on the following relationship: In the formula, the subscript i represents the serial number of the current satellite, τ x,i , τ y,i , τ z,i , τ t,i Respectively represent the code phases corresponding to the X-axis dimension, the Y-axis dimension, the Z-axis dimension, and the time dimension; x a , y a and z a Indicates the X-axis coordinate, Y-axis coordinate and Z-axis coordinate corresponding to the receiver position, δt u represents the receiver clock error, x i , y i and z i Indicates the X-axis coordinate, Y-axis coordinate and Z-axis coordinate corresponding to the satellite position of the i-th satellite, δt i represents the satellite clock error of the i-th satellite; f represents the phase value, f= -1 corresponds to the leading phase, f= 0 corresponds to the instantaneous phase, f= 1 corresponds to the lagging phase; d half represents the distance corresponding to half a chip signal, c represents the speed of light; cosu x , cosu y and cosu z Indicates the cosine value of the azimuth from the satellite to the receiver in the X-axis direction, Y-axis direction, and Z-axis direction respectively.

8. A receiver, characterized in that: include: The acquisition unit is used to perform down-conversion and analog-to-digital conversion (ADC) sampling processing on the satellite signal received by the antenna to obtain an intermediate frequency signal; A positioning solution unit, used to perform positioning solution based on the intermediate frequency signals corresponding to N satellites, to obtain the receiver position, the receiver clock error, and the satellite positions and satellite clock errors corresponding to the N satellites, respectively; N is an integer greater than 3; as well as A deception detection unit includes processing channels, a superposition module and a determination module corresponding to N satellites respectively, and each processing channel includes a signal generator and a related module; The signal generator is used to determine the code phase between the receiver and the current satellite based on the receiver position, the receiver clock error, and the satellite position and satellite clock error corresponding to the current satellite at multiple phases, and reproduce the intermediate frequency signal locally based on the code phase to obtain a local signal; the correlation module is used to perform correlation operations on the local signal and the intermediate frequency signal at multiple phases to obtain correlation values; the multiple phases include: an advanced phase, an instantaneous phase and a lagging phase; the advanced phase and the lagging phase are symmetrical with the instantaneous phase as the center; the superposition module is used to perform superposition operations on the correlation values ​​corresponding to N satellites for any of the phases to obtain a superimposed correlation value; the correlation peak symmetry value of the superimposed N satellites is determined based on the superimposed correlation values ​​corresponding to the multiple phases; the determination module is used to determine whether there is a spoofing signal in the intermediate frequency signals corresponding to the N satellites based on the comparison result of the correlation peak symmetry value and a set threshold.

9. The receiver according to claim 8, characterized in that In one of the processing channels, the signal generator includes: an X signal generator, a Y signal generator, a Z signal generator and a T signal generator; the correlation module includes: an X correlation module, a Y correlation module, a Z correlation module and a T correlation module; the X signal generator and the X correlation module perform correlation processing on the intermediate frequency signal in the X-axis dimension; the Y signal generator and the Y correlation module perform correlation processing on the intermediate frequency signal in the Y-axis dimension; the Z signal generator and the Z correlation module perform correlation processing on the intermediate frequency signal in the Z-axis dimension; the T signal generator and the T correlation module perform correlation processing on the intermediate frequency signal in the time dimension.

10. The receiver according to claim 9, characterized in that The determination module is specifically used for: Acquire set thresholds corresponding to multiple monitoring dimensions, respectively, where the set thresholds include: a first threshold corresponding to the X-axis dimension, a second threshold corresponding to the Y-axis dimension, a third threshold corresponding to the Z-axis dimension, and a fourth threshold corresponding to the time dimension; compare the correlation peak symmetry value of each monitoring dimension with the corresponding set threshold, and if the comparison result of any monitoring dimension does not meet the requirements, determine that there is a spoofing signal in the intermediate frequency signal corresponding to the N satellites; or, The average of the correlation peak symmetry values ​​of multiple monitoring dimensions is obtained, and the average is compared with a set threshold. If the comparison result does not meet the requirements, it is determined that there are deception signals in the intermediate frequency signals corresponding to the N satellites.

11. The receiver according to claim 8, characterized in that The signal generator is specifically used for: Perform pseudo code sampling based on the code phase and the pseudo code generation rule of the current satellite to obtain a pseudo code sampling sequence; and Based on the carrier frequency, sampling period, total number of sampling points and pseudo code sampling sequence of the current intermediate frequency signal, the intermediate frequency signal corresponding to the current satellite is reproduced locally to obtain a local signal.

12. The receiver according to claim 8, characterized in that The superposition module is specifically used for: The normalized weighting coefficient of each satellite is determined by the following method: the weighting coefficient of the current satellite is determined based on the signal carrier-to-noise ratio of the current satellite and the cross-correlation peaks of the current satellite and the other N-1 satellites; Based on the ratio of the weighting coefficient of the current satellite to the sum of the weighting coefficients of N satellites, the weighting coefficient of the current satellite is normalized to obtain a normalized weighting coefficient; as well as The product of the normalized weighted coefficient of each satellite and its correlation value is accumulated to obtain the superimposed correlation value.

13. The receiver according to claim 12, characterized in that The step of determining the weighting coefficient of the current satellite based on the signal carrier-to-noise ratio of the current satellite and the cross-correlation peaks between the current satellite and the other N-1 satellites comprises: The weighting coefficient of the current satellite is determined based on the following relationship: ； In the formula, r i represents the weighting coefficient of the i-th satellite, CNR i Indicates i The carrier-to-noise ratio of the satellite, CNR j Indicates j The carrier-to-noise ratio of the satellite, U i,j Indicates i Satellites and j The ratio of the cross-correlation peaks between satellites to the autocorrelation peak of a certain satellite.

14. The receiver according to claim 10, characterized in that The X signal generator, the Y signal generator, the Z signal generator and the T signal generator respectively calculate the code phases corresponding to the X-axis dimension, the Y-axis dimension, the Z-axis dimension and the time dimension based on the following relationship; In the formula, the subscript i represents the serial number of the current satellite, τ x,i , τ y,i , τ z,i , τ t,i Respectively represent the code phases corresponding to the X-axis dimension, the Y-axis dimension, the Z-axis dimension, and the time dimension; x a , y a and z a Indicates the X-axis coordinate, Y-axis coordinate and Z-axis coordinate corresponding to the receiver position, δt u represents the receiver clock error, x i , y i and z i Indicates the X-axis coordinate, Y-axis coordinate and Z-axis coordinate corresponding to the satellite position of the i-th satellite, δt i represents the satellite clock error of the i-th satellite; f represents the phase value, f= -1 corresponds to the leading phase, f= 0 corresponds to the instantaneous phase, f= 1 corresponds to the lagging phase; d half represents the distance corresponding to half a chip signal, c represents the speed of light; cosu x , cosu y and cosu z Indicates the cosine value of the azimuth from the satellite to the receiver in the X-axis direction, Y-axis direction, and Z-axis direction respectively.

15. An electronic device comprising a processor storing a computer program, characterized in that: When the computer program is executed by a processor, the spoof signal detection method according to any one of claims 1 to 7 is implemented.

16. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the spoof signal detection method according to any one of claims 1 to 7 is implemented.

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