Method for preventing forwarding type satellite navigation deception

Abstract

The invention discloses a method for preventing forwarding type satellite navigation deception, which comprises the following steps: firstly, carrying out multi-correlation peak preliminary detection to identify abnormal signal features; then, a power estimation module is used for carrying out power analysis on the signals, a power threshold value is set, and deception signals are recognized through comparison; in order to further improve the recognition accuracy, a constellation model is established in the scheme, and two methods of arrival time monitoring and autonomous integrity detection are adopted to comprehensively recognize the forwarding deception jamming; if the two methods both indicate that cheating exists, judging that a cheating behavior exists; once deception interference is confirmed to exist, anti-interference measures such as receiver parameter adjustment and antenna switching are immediately started, and normal operation of the system is ensured; meanwhile, abnormal signals are removed through autonomous integrity detection, and the accuracy of positioning information is guaranteed; in addition, the deception jamming condition is comprehensively monitored, jamming event information is recorded in detail, and powerful support is provided for follow-up analysis and processing.

Description

Technical Field

[0001] The present invention relates to the field of satellite navigation technology, and in particular to a method for preventing forwarding satellite navigation deception. Background Art

[0002] Deception jamming on target receivers is generally divided into forwarding deception jamming and generative deception jamming. Forwarding deception jamming changes the time delay of the signal reaching the target receiver, causing it to generate erroneous pseudo-range information, resulting in errors in the calculation of position and clock difference. Generative deception jamming tampers with the satellite position information in the received navigation message, causing the receiver to misposition. Summary of the Invention

[0003] This application provides a method for preventing forwarding satellite navigation deception. This technical solution comprehensively improves the accuracy of deception interference identification and enhances the system's anti-interference capability through methods such as multi-correlation peak detection, power estimation, arrival time monitoring and autonomous integrity detection. At the same time, it eliminates abnormal satellite signals, improves the reliability of positioning information, and comprehensively monitors and records deception interference situations, providing strong support for subsequent analysis.

[0004] This application provides a method for preventing forwarding satellite navigation deception, including:

[0005] S1, performing preliminary multi-correlation peak detection on the signal layer of the navigation satellite signal received by the satellite navigation to identify possible abnormal signal characteristics;

[0006] S2 uses the power estimation module in the receiver to estimate the power of the received navigation satellite signal and set a reasonable power threshold. It then identifies spoofing signals by comparing the signal power with the threshold.

[0007] S3 uses the known constellation layout and satellite orbit parameters to build a constellation model. Based on this model, it uses arrival time monitoring and autonomous integrity monitoring to comprehensively identify and respond to forwarding deceptive interference.

[0008] S4, combining the results of arrival time monitoring and autonomous integrity testing, if both methods indicate the presence of deception interference, then deception is determined to have occurred;

[0009] S5. If deceptive interference is confirmed through the above steps, anti-interference measures should be initiated immediately and key information of the interference event should be recorded in detail.

[0010] Preferably, the preliminary detection of multiple correlation peaks specifically includes:

[0011] S11, performing the first capture process on the intermediate frequency signal and narrowing the range of the capture window; wherein, the search window time is set to 2 seconds to start the first capture attempt; determining whether the peak value of the first capture exceeds the preset threshold; if not, re-capture the first time; if so, executing S12;

[0012] S12, based on the code phase obtained in the first capture, the search window time is set to 40 milliseconds and a second capture is performed; based on the result of the first capture, whether the peak value of the second capture exceeds the threshold is determined; if not, the second capture is repeated; if so, S13 is executed;

[0013] S13, based on the code phase obtained in the second capture, the search starting point is offset by 2046 chips to perform a third capture;

[0014] S14, analyzing the second and third capture results;

[0015] Preferably, the step S14 of analyzing the second and third capture results includes:

[0016] S141, if the second capture is successful and the third capture is unsuccessful, and if the third capture conditions are confirmed to be reasonable, the second capture is considered to be a real signal, and the result is transferred to tracking processing;

[0017] S142, if both the second and third captures are successful, after comparing the consistency of the two capture results, it is considered that the third capture is a real signal, and the tracking process is performed;

[0018] S143, in each capture attempt, recording all peak values ​​exceeding a preset threshold;

[0019] S144, counting the number of peaks exceeding the threshold. If multiple independent correlation peaks greater than the threshold are detected, it is preliminarily determined that deceptive interference exists.

[0020] Preferably, the step S2 of identifying a spoofing signal by detecting signal power includes:

[0021] S21, the power estimation module integrates the signal over a period of time, calculates and outputs its signal power;

[0022] S22 , setting the normal operating range to -110 dBm to -133 dBm, comparing the calculated signal power with the normal operating range, and performing spoof signal identification if the signal power exceeds the normal operating range.

[0023] Preferably, the step S22, identifying a fraudulent signal, includes:

[0024] S221, comparing the current branch power in the three-way product branch with the noise power;

[0025] S222, if the current branch power is higher than the noise power threshold and the signal power is greater than the normal operating range, it is determined that deceptive interference exists;

[0026] S223, when it is detected that the absolute power of the signal exceeds the preset enhanced signal power threshold, it is considered that suppressive deception interference is currently present;

[0027] S224: A corresponding interference identifier is given according to the detection result, and the anti-interference antenna can start space-time anti-interference processing according to the interference identifier to deal with the detected deceptive signal.

[0028] Preferably, the step S3, monitoring arrival time, includes:

[0029] S3A1, through simulation calculation, obtain the theoretical normal range of the relative time difference between different satellite signals reaching the target receiver antenna;

[0030] S3A2 monitors the arrival time of received satellite signals in real time and calculates the difference between the arrival time of each satellite signal and the arrival time of other satellite signals;

[0031] S3A3, if the difference between the arrival time of a certain satellite signal and the arrival time of other satellite signals exceeds the normal range obtained by simulation, it is preliminarily determined that the signal has deceptive interference.

[0032] Preferably, in S3, autonomous integrity detection includes:

[0033] S3B1, randomly select 4 satellites from the 5 received satellites to calculate the position, velocity, and time, and obtain the current position estimate of the target receiver through the calculation;

[0034] S3B2: Repeat the above process and perform five different combined calculations on the five satellites to obtain five position results. Compare the consistency of these five calculation results. If there is a difference, it indicates the presence of deception interference.

[0035] S3B3, based on abnormal information, identifies and eliminates interfering satellites.

[0036] One or more technical solutions provided in this application have at least the following technical effects or advantages:

[0037] Through a variety of methods, including preliminary detection of multiple correlation peaks, power estimation and threshold comparison, arrival time monitoring, and autonomous integrity testing, the system comprehensively identifies spoofing signals, significantly improving identification accuracy and reliability. Once spoofing interference is detected, anti-interference measures are immediately initiated, such as adjusting receiver parameters and switching antennas, effectively countering various spoofing attacks and ensuring normal system operation. Autonomous integrity testing eliminates anomalous satellite signals, ensuring the accuracy of the remaining satellite signal solutions and providing users with reliable positioning information. Comprehensive monitoring of spoofing interference is carried out, and key information about interference events is recorded in detail, providing strong support for subsequent analysis and resolution. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 Schematic diagram of a flow chart of a method for preventing forwarding satellite navigation deception according to an embodiment of the present invention;

[0039] Figure 2 Schematic diagram of preliminary detection of multiple correlation peaks according to an embodiment of the present invention. DETAILED DESCRIPTION

[0040] To facilitate understanding of the present invention, the present application will be described more comprehensively below with reference to the relevant drawings; the drawings show preferred embodiments of the present invention, but the present invention can be implemented in many different forms and is not limited to the embodiments described herein; on the contrary, the purpose of providing these embodiments is to enable a more thorough and comprehensive understanding of the disclosed content of the present invention.

[0041] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this invention pertains; the terms used herein in the specification of the present invention are for the purpose of describing specific embodiments only and are not intended to limit the present invention; the term "and / or" used herein includes any and all combinations of one or more of the associated listed items.

[0042] Example 1: Figure 1 The present invention is a flowchart of a method for preventing forwarding satellite navigation deception according to an embodiment of the present invention.

[0043] like Figure 1 As shown, a method for preventing forwarding satellite navigation deception includes the following steps:

[0044] S1, performing preliminary multi-correlation peak detection on the signal layer of the navigation satellite signal received by the satellite navigation to identify possible abnormal signal characteristics.

[0045] Specifically, in a satellite navigation system, a receiver receives signals from multiple navigation satellites. These signals may be subject to various interferences during transmission, including spoofing interference. Therefore, it is necessary to first perform preliminary multi-correlation peak detection on the received signals to identify possible interfering signals. This preliminary multi-correlation peak detection typically involves performing correlation processing on the signals and observing the peaks in the correlation results. If multiple significant peaks appear in the correlation results, this may indicate the presence of spoofing interference.

[0046] Among them, such as Figure 2 The schematic diagram of preliminary detection of multiple correlation peaks shown includes the following steps:

[0047] S11, performing the first capture processing on the intermediate frequency signal to narrow the range of the capture window.

[0048] The search window time is set to 2 seconds, and the first capture attempt is started. It is determined whether the peak value of the first capture exceeds the preset threshold. If not, the first capture is repeated; if so, S12 is executed.

[0049] The preset threshold refers to the number of correlation peaks exceeding this threshold during the acquisition process. This threshold is set based on factors such as system performance requirements, signal characteristics, and environmental noise. When the height or intensity of a correlation peak exceeds this threshold, the peak is considered valid and may correspond to a real signal.

[0050] Specifically, initial capture is a critical step for a satellite navigation receiver to acquire satellite signals. During initial capture, the receiver searches for possible code phases and Doppler shifts to find a satellite signal that matches the received signal. To narrow the capture window, the search window can be set to 2 seconds. This means that within the 2-second window, the receiver will attempt to match all possible combinations of code phase and Doppler shift. A determination is made as to whether the peak value of the initial capture exceeds a preset threshold. The threshold is a threshold value set based on system requirements and signal characteristics and is used to determine the validity of the capture result. If the threshold is not exceeded, the initial capture is repeated; if it is exceeded, step S12 is executed. The threshold setting can be based on parameters such as the signal-to-noise ratio (SNR) and the bit error rate (BER).

[0051] Among them, the calculation formula related to the capture process is: R(τ,∫ d ) is the correlation result, which indicates that the received signal and the local reference signal are at a specific code phase τ and Doppler frequency shift ∫ ds(t) is the received signal, that is, the signal from the navigation satellite received by the satellite navigation receiver. The received signal usually contains navigation data, carrier and pseudo code (or spread spectrum code) and other components. During the capture process, the receiver needs to try to match the pseudo code and carrier frequency in the received signal. * (t-τ) is the conjugate of the local reference signal, representing the complex conjugate of the pseudocode and carrier signal generated by the receiver to match the received signal. t-τ represents the time offset of the local reference signal relative to the received signal, that is, the code phase difference. By adjusting the code phase τ, the receiver can search for and find the pseudocode sequence that matches the received signal. τ is the code phase, which represents the time offset between the local reference signal and the received signal. In satellite navigation, due to reasons such as signal propagation delay and receiver clock error, the pseudocode sequence in the received signal may be offset in time from the locally generated pseudocode sequence. By searching for different code phase values, the receiver can find the pseudocode sequence that matches the received signal. d Is Doppler shift, which indicates the change in signal frequency due to the relative motion between the receiver and the satellite. When there is relative motion between the receiver and the satellite, the received signal frequency will shift. This shift is called Doppler shift. During the acquisition process, the receiver needs to try different Doppler shift values ​​to find the carrier frequency that matches the received signal. T dt is an integral operation, which means integrating the correlation function over a period of time T. The integral operation can smooth the noise in the signal and improve the accuracy of the correlation result. Through the integral operation, the receiver can obtain the correlation result under a specific code phase and Doppler frequency shift.

[0052] S12: Based on the code phase obtained in the first capture, the search window time is set to 40 milliseconds, and a second capture is performed.

[0053] Based on the result of the first capture, it is determined whether the peak value of the second capture exceeds the threshold. If not, the second capture is performed again; if it exceeds, S13 is executed.

[0054] Specifically, after a successful first capture, the receiver obtains a preliminary code phase estimate. To further improve capture accuracy, a second capture can be performed based on the code phase obtained in the first capture, with the search window set to 40 milliseconds. The second capture uses a narrower search range, allowing it to more quickly find a code phase and Doppler shift combination that better matches the received signal. A determination is then made as to whether the peak value of the second capture exceeds a threshold. If it does not, a second capture is repeated; if it does, the process proceeds to S13.

[0055] S13, according to the code phase obtained in the second capture, the search starting point is offset by 2046 chips to perform a third capture.

[0056] Specifically, after the second successful acquisition, the receiver obtains a more accurate code phase estimate. To further verify the accuracy of the acquisition, the search starting point is adjusted based on the code phase information obtained in the second acquisition, and a third acquisition is performed at the new starting point. The search range for this third acquisition is 2046 base codes, which is sufficient to cover possible code phase deviations.

[0057] S14, analyzing the second and third capture results.

[0058] The analysis of the second and third capture results includes:

[0059] S141, if the second capture is successful and the third capture is unsuccessful, and on the premise that the third capture condition is confirmed to be reasonable, it is considered that the second capture is a real signal, and the result is transferred to tracking processing.

[0060] Among them, reasonable conditions refer to the general rationality of settings such as search range and threshold settings.

[0061] Specifically, if the second acquisition is successful but the third is unsuccessful, this may mean that there is no code phase and Doppler shift combination that matches the received signal within the search range of the third acquisition. Therefore, the second acquisition can be considered to be a real signal and the result can be transferred to the tracking process.

[0062] S142: If both the second and third captures are successful, after comparing the consistency of the two capture results, it is considered that the third capture is a real signal, and the tracking process is performed.

[0063] Specifically, if both the second and third acquisitions are successful and the results are consistent to a certain extent, this likely means that a code phase and Doppler shift combination that better matches the received signal exists within the search range of the third acquisition. Therefore, the third acquisition can be considered the true signal (or a more accurate signal than the second) and tracking can be performed.

[0064] S143 , in each capture attempt, record all peak values ​​exceeding a preset threshold.

[0065] S144, counting the number of peaks exceeding the threshold. If multiple independent correlation peaks greater than the threshold are detected, it is preliminarily determined that deceptive interference exists.

[0066] If multiple correlation peaks greater than the threshold and independent of each other are detected, they are not consecutive peaks caused by accidental factors such as noise in the same capture attempt or adjacent capture attempts.

[0067] It's important to note that after recording all peaks exceeding the threshold, the number of these peaks needs to be counted. If multiple correlation peaks exceeding the threshold are detected, this may indicate the presence of a spoofing interference signal. Normally, only one significant peak should match the received signal. Therefore, a preliminary determination of spoofing interference can be made, allowing appropriate action to be taken.

[0068] S2 uses the power estimation module in the receiver to estimate the power of the received navigation satellite signal and sets a reasonable power threshold. It identifies the spoofing signal by comparing the signal power with the threshold.

[0069] Specifically, spoofing signals are identified through signal power detection, including:

[0070] S21, the power estimation module integrates the signal for a period of time, calculates and outputs its signal power.

[0071] Calculating the signal power includes estimating the navigation satellite signal power based on the integrated value of the relevant channel, i.e., the relevant channel output power (COP). Specifically, the power of the navigation satellite signal is estimated by using the ratio of the power (the sum of the squares of the integrated values) of the current branch in the three-way product branch to the noise power.

[0072] S22 , setting the normal operating range to -110 dBm to -133 dBm, comparing the calculated signal power with the normal operating range, and performing spoof signal identification if the signal power exceeds the normal operating range.

[0073] Among them, deception signal identification includes:

[0074] S221 , compare the current branch power in the three-way product branch with the noise power.

[0075] The noise power is calculated by averaging multiple statistical calculations. The noise power calculation method is as follows: In a navigation receiver, the front end of the A / D converter incorporates automatic gain control (AGC) to maintain a constant input signal strength. If the A / D converter uses 3-bit quantization, a probability distribution is set for the amplitude of the quantized analog input signal, and the mean squared value of the product of the local carrier signal and the input signal is calculated based on this probability distribution. Because a single calculation may fluctuate significantly due to noise, multiple statistical calculations are performed to obtain a more accurate noise power estimate.

[0076] S222: If the current branch power is higher than the noise power threshold and the signal power is greater than the normal operating range, it is determined that deceptive interference exists.

[0077] The noise power threshold uses statistical methods to analyze historical data and determine a reasonable power difference range as a judgment standard.

[0078] S223: When it is detected that the absolute power of the signal exceeds the preset enhanced signal power threshold, it is considered that suppressive deception interference currently exists.

[0079] S224: A corresponding interference identifier is given according to the detection result, and the anti-interference antenna can start space-time anti-interference processing according to the interference identifier to deal with the detected deceptive signal.

[0080] S3 uses the known constellation layout and satellite orbit parameters to establish a constellation model. On this basis, it adopts two methods, arrival time monitoring and autonomous integrity detection, to comprehensively identify and respond to forwarding deception interference.

[0081] Specifically, arrival time monitoring includes:

[0082] S3A1, through simulation calculation, obtains the theoretical normal range of the relative time difference between different satellite signals reaching the target receiver antenna, such as 3 to 5 code chips.

[0083] S3A2 monitors the arrival time of received satellite signals in real time and calculates the difference between the arrival time of each satellite signal and the arrival time of other satellite signals.

[0084] S3A3: If the difference between the arrival time of a certain satellite signal and the arrival time of other satellite signals exceeds the normal range (3 to 5 chips) obtained by simulation, it is preliminarily determined that the signal may be subject to deceptive interference.

[0085] It should be noted that, considering the deviation between the satellite and ground receiver clocks, the absolute value of the signal arrival cannot be effectively limited, but the relative value (i.e. the difference in arrival time) is reasonable and is therefore used as a basis for judgment.

[0086] Specifically, autonomous integrity testing includes:

[0087] S3B1, randomly select 4 satellites from the 5 received satellites to perform position, velocity, and time (PVT) calculations, and obtain the current position estimate of the target receiver through the calculations.

[0088] S3B2, repeat the above process, perform five different combination solutions on the five satellites, obtain five position results, and compare the consistency of these five solution results; if there are obvious differences, and such differences cannot be explained by normal measurement errors, it indicates that deception interference may exist.

[0089] S3B3, based on abnormal information, identifies and eliminates interfering satellites to ensure the accuracy of the solution results of the remaining satellite signals and provide reliable positioning information.

[0090] S4, combining the results of arrival time monitoring and autonomous integrity testing, if both methods indicate the presence of deceptive interference, then it is determined that deceptive behavior exists.

[0091] S5. If deceptive interference is confirmed through the above steps, anti-interference measures should be initiated immediately and key information of the interference event should be recorded in detail.

[0092] Among them, anti-interference measures include adjusting receiver parameters, switching antennas, etc. Key information includes: time, location and type of interference.

[0093] The technical solutions in the above embodiments of the present application have at least the following technical effects or advantages:

[0094] Through a variety of methods, including preliminary detection of multiple correlation peaks, power estimation and threshold comparison, arrival time monitoring, and autonomous integrity testing, the system comprehensively identifies spoofing signals, significantly improving identification accuracy and reliability. Once spoofing interference is detected, anti-interference measures are immediately initiated, such as adjusting receiver parameters and switching antennas, effectively countering various spoofing attacks and ensuring normal system operation. Autonomous integrity testing eliminates anomalous satellite signals, ensuring the accuracy of the remaining satellite signal solutions and providing users with reliable positioning information. Comprehensive monitoring of spoofing interference is carried out, and key information about interference events is recorded in detail, providing strong support for subsequent analysis and resolution.

[0095] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Various modifications and variations are readily apparent to those skilled in the art. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A method for preventing forwarding satellite navigation deception, characterized in that: include: S1, performing preliminary multi-correlation peak detection on the signal layer of the navigation satellite signal received by the satellite navigation to identify possible abnormal signal characteristics; S2 uses the power estimation module in the receiver to estimate the power of the received navigation satellite signal and set a reasonable power threshold. It then identifies spoofing signals by comparing the signal power with the threshold. S3 uses the known constellation layout and satellite orbit parameters to build a constellation model. Based on this model, it uses arrival time monitoring and autonomous integrity monitoring to comprehensively identify and respond to forwarding deceptive interference. S4, combining the results of arrival time monitoring and autonomous integrity testing, if both methods indicate the presence of deception interference, then deception is determined to have occurred; S5. If deceptive interference is confirmed through the above steps, anti-interference measures should be initiated immediately and key information of the interference event should be recorded in detail.

2. The method for preventing forwarding satellite navigation deception according to claim 1, wherein: The preliminary detection of multiple correlation peaks specifically includes: S11, performing the first capture process on the intermediate frequency signal and narrowing the range of the capture window; wherein, the search window time is set to 2 seconds to start the first capture attempt; determining whether the peak value of the first capture exceeds the preset threshold; if not, re-capture the first time; if so, executing S12; S12, based on the code phase obtained in the first capture, the search window time is set to 40 milliseconds and a second capture is performed; based on the result of the first capture, whether the peak value of the second capture exceeds the threshold is determined; if not, the second capture is repeated; if so, S13 is executed; S13, based on the code phase obtained in the second capture, the search starting point is offset by 2046 chips to perform a third capture; S14, analyzing the second and third capture results.

3. The method for preventing forwarding satellite navigation deception according to claim 2, wherein: The step S14, analyzing the second and third capture results, includes: S141, if the second capture is successful and the third capture is unsuccessful, and if the third capture conditions are confirmed to be reasonable, the second capture is considered to be a real signal, and the result is transferred to tracking processing; S142, if both the second and third captures are successful, after comparing the consistency of the two capture results, it is considered that the third capture is a real signal, and the tracking process is performed; S143, in each capture attempt, recording all peak values ​​exceeding a preset threshold; S144, counting the number of peaks exceeding the threshold. If multiple independent correlation peaks greater than the threshold are detected, it is preliminarily determined that deceptive interference exists.

4. The method for preventing forwarding satellite navigation deception according to claim 1, wherein: The step S2, identifying a spoof signal through signal power detection, includes: S21, the power estimation module integrates the signal over a period of time, calculates and outputs its signal power; S22 , setting the normal operating range to -110 dBm to -133 dBm, comparing the calculated signal power with the normal operating range, and performing spoof signal identification if the signal power exceeds the normal operating range.

5. The method for preventing forwarding satellite navigation deception according to claim 4, wherein: The step S22, identifying a fraudulent signal, includes: S221, comparing the current branch power in the three-way product branch with the noise power; S222, if the current branch power is higher than the noise power threshold and the signal power is greater than the normal operating range, it is determined that deceptive interference exists; S223, when it is detected that the absolute power of the signal exceeds the preset enhanced signal power threshold, it is considered that suppressive deception interference is currently present; S224: A corresponding interference identifier is given according to the detection result, and the anti-interference antenna can start space-time anti-interference processing according to the interference identifier to deal with the detected deceptive signal.

6. The method for preventing forwarding satellite navigation deception according to claim 1, wherein: The S3, arrival time monitoring, includes: S3A1, through simulation calculation, obtain the theoretical normal range of the relative time difference between different satellite signals reaching the target receiver antenna; S3A2 monitors the arrival time of received satellite signals in real time and calculates the difference between the arrival time of each satellite signal and the arrival time of other satellite signals; S3A3, if the difference between the arrival time of a certain satellite signal and the arrival time of other satellite signals exceeds the normal range obtained by simulation, it is preliminarily determined that the signal has deceptive interference.

7. The method for preventing forwarding satellite navigation deception according to claim 1, wherein: In S3, autonomous integrity detection includes: S3B1, randomly select 4 satellites from the 5 received satellites to calculate the position, velocity, and time, and obtain the current position estimate of the target receiver through the calculation; S3B2: Repeat the above process and perform five different combined calculations on the five satellites to obtain five position results. Compare the consistency of these five calculation results. If there is a difference, it indicates the presence of deception interference. S3B3, based on abnormal information, identifies and eliminates interfering satellites.

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