Clock synchronous positioning device and method with safety protection function

Abstract

The invention belongs to the field of satellite time service, and relates to a clock synchronous positioning device and method with a safety protection function, and the device comprises a multi-frequency receiver which is used for receiving a first satellite signal and a second satellite signal of different frequency bands; the signal processor is used for performing clock synchronization and determining a first key parameter and a second key parameter; the safety protection processor is used for obtaining a first deception recognition result and a second deception recognition result, and sending a signal source switching instruction when a deception signal is recognized in the first deception recognition result and / or the second deception recognition result; the isolation controller is used for controlling to cut off the connection between the multi-frequency receiver and the abnormal Beidou signal source when receiving the signal source switching instruction, and switching to a standby signal source; and the RTK positioning module is used for generating differential correction data according to the received satellite signal and sending the differential correction data to the target moving station. According to the scheme provided by the invention, the safety and the stability of the clock synchronous positioning process are ensured.

Description

Technical Field

[0001] The present invention relates to the technical field of satellite timekeeping, and particularly to a clock synchronization and positioning device and method with a security protection function. Background Art

[0002] In today's digital age, critical industries such as power and communication have extremely high requirements for the accuracy and stability of clock synchronization. Clock synchronization is like the "pulse" of the operation of these industries, and precise timekeeping is the cornerstone for ensuring the normal and efficient operation of the system.

[0003] In the power system, the safe and stable operation of the power grid depends on precise clock synchronization. In each link from power generation, transmission, transformation to distribution, accurate time is required to ensure the accurate execution of functions such as power dispatching, fault location, and relay protection. For example, in a smart grid, the access of distributed energy, power quality monitoring, and power market transactions all require the clock synchronization accuracy between nodes to reach the microsecond or even nanosecond level. Similarly, in the communication system, the synchronization between base stations is crucial for operations such as signal transmission, handover, and data exchange. Whether it is 2G, 3G, 4G, or the currently widely deployed 5G network, precise clock synchronization is a key factor for ensuring communication quality, improving spectrum utilization, and achieving seamless communication.

[0004] For a long time, satellite timekeeping systems have been widely applied in industries such as power and communication due to their wide coverage and high accuracy. However, with the development of technology and the increasing complexity of application scenarios, the limitations and security risks of satellite timekeeping systems have gradually emerged.

[0005] On the one hand, since the satellite signal is extremely weak during transmission, it is easily interfered by various natural and human factors. On the other hand, the satellite timekeeping system faces a serious threat of spoofing attacks. Malicious attackers can transmit forged satellite signals, causing the receiving device to misjudge time and position information. In the power system, such spoofing attacks may cause the relay protection device to malfunction, trigger a power grid fault, and even cause a large-scale power outage accident. In the communication system, spoofing attacks may cause deviations in the synchronization of communication base stations, resulting in problems such as communication interruption and signal interference, seriously affecting the quality and stability of communication services.

[0006] In summary, the current clock synchronization scheme relying on satellite timekeeping has the technical problems of low reliability and stability. Summary of the Invention

[0007] The present invention provides a clock synchronization and positioning device and method with a security protection function to address the defects of low reliability and stability existing in the current clock synchronization scheme relying on satellite timekeeping.

[0008] On the one hand, the present invention provides a clock synchronization and positioning device with a security protection function, comprising: A multi-frequency receiver for receiving a first satellite signal and a second satellite signal of different frequency bands emitted by a Beidou signal source; A signal processor for performing clock synchronization according to the standard time information in at least one of the first satellite signal and the second satellite signal, determining a first key parameter according to the first satellite signal, and determining a second key parameter according to the second satellite signal; A security protection processor for respectively inputting the first key parameter and the second key parameter into a pre-established spoofing signal recognition model to obtain a first spoofing recognition result and a second spoofing recognition result, and issuing a signal source switching instruction when a spoofing signal is recognized in the first spoofing recognition result and / or the second spoofing recognition result; An isolation controller for controlling to cut off the connection between the multi-frequency receiver and the abnormal Beidou signal source and switch to a backup signal source when receiving the signal source switching instruction; An RTK positioning module for generating differential correction data according to the received first satellite signal and / or second satellite signal, and sending the differential correction data to a target rover so that the target rover corrects its own positioning information according to the differential correction data.

[0009] According to the clock synchronization and positioning device with a security protection function provided by the present invention, both the first key parameter and the second key parameter include: signal power and pseudorange; The spoofing signal recognition model is established through the following process: According to the historical satellite signals received in the historical clock synchronization link, obtaining signal power samples and pseudorange samples, and adding spoofing recognition labels to the historical satellite signals; According to the signal power samples, pseudorange samples and spoofing recognition labels, establishing a sample data set; Training and testing a pre-constructed machine learning model through the sample data set to obtain a spoofing signal recognition model.

[0010] According to the clock synchronization and positioning device with a security protection function provided by the present invention, the device further comprises: a first monitoring module; The first monitoring module is used for regularly generating and sending a heartbeat signal to the multi-frequency receiver, the signal processor, the security protection processor and the isolation controller, and generating and issuing an abnormal monitoring log after receiving a heartbeat detection abnormal signal sent by at least one of the multi-frequency receiver, the signal processor, the security protection processor and the isolation controller.

[0011] The clock synchronization and positioning device with a safety protection function provided by the present invention further includes: an inspection module; The calibration module is used to obtain the first position information of the RTK positioning module and the second position information of the target process station, calculate the position deviation between the first position information and the second position information, and issue a position anomaly warning message when the position deviation exceeds a preset position deviation threshold.

[0012] The clock synchronization and positioning device with a safety protection function provided by the present invention further includes: a second monitoring module; The second monitoring module is used to respectively evaluate the quality of the first satellite signal and the second satellite signal, obtain the first signal quality evaluation result of the first satellite signal and the second signal quality evaluation result of the second satellite signal, and generate a signal adjustment strategy according to the first signal quality evaluation result and the second signal quality evaluation result.

[0013] For the clock synchronization and positioning device with a safety protection function provided by the present invention, evaluating the quality of the first satellite signal to obtain the first signal quality evaluation result of the first satellite signal includes: Obtain the received power of the first satellite signal, calculate the deviation between the received power of the first satellite signal and the standard power range of the corresponding frequency band to obtain a power deviation value; Perform normalization processing on the power deviation value to obtain the intensity evaluation value of the first satellite signal; Determine the bit error rate of the first satellite signal, calculate the deviation between the bit error rate of the first satellite signal and a preset bit error rate threshold to obtain a bit error rate deviation value; Perform normalization processing on the bit error rate deviation value to obtain the integrity evaluation value of the first satellite signal; Obtain the credible characterization parameter of the first satellite signal, and determine the credibility evaluation value of the first satellite signal based on the credible characterization parameter; Perform weighted summation on the intensity evaluation value, the integrity evaluation value, and the credibility evaluation value to obtain the measured signal quality value of the first satellite signal; Compare the measured signal quality value with a preset signal quality reference value to obtain the first signal quality evaluation result of the first satellite signal.

[0014] According to the clock synchronization and positioning device with a safety protection function provided by an embodiment of the present invention, the credible characterization parameters of the first satellite signal include: phase jitter value, signal frequency value, signal-to-noise ratio value, and signal source position; Determining the credibility evaluation value of the first satellite signal based on the credible characterization parameter includes: Calculate the deviation between the phase jitter value of the first satellite signal and a preset phase jitter threshold to obtain a phase jitter deviation value; Calculate the deviation between the signal frequency value of the first satellite signal and a standard frequency value to obtain a signal frequency deviation value; Calculate the deviation between the signal-to-noise ratio value of the first satellite signal and a preset reference signal-to-noise ratio to obtain a signal-to-noise ratio deviation value; Calculate the deviation between the signal source indication position of the first satellite signal and a signal source reference position to obtain a signal source position deviation value; Normalize the phase jitter deviation value, the signal frequency deviation value, the signal-to-noise ratio deviation value, and the signal source position deviation value respectively, and calculate a credibility evaluation value of the first satellite signal based on the normalized phase jitter deviation value, signal frequency deviation value, signal-to-noise ratio deviation value, and signal source position deviation value.

[0015] According to the clock synchronization and positioning device with a security protection function provided by the present invention, generate a signal adjustment strategy based on the first signal quality evaluation result and the second signal quality evaluation result, including: If one of the first signal quality evaluation result and the second signal quality evaluation result is a low signal quality, and the other evaluation result is a normal signal quality, determine that the signal adjustment strategy is: allocate a first preset weight value to the satellite signal with normal signal quality, and allocate a second preset weight value to the satellite signal with low signal quality, where the first preset weight value is higher than the second preset weight value; If both the first signal quality evaluation result and the second signal quality evaluation result are low signal quality, determine that the signal adjustment strategy is: start a temporary autonomous timekeeping mode, determine clock compensation parameters, and dynamically compensate the clock information in the temporary autonomous timekeeping mode according to the clock compensation parameters.

[0016] According to the clock synchronization and positioning device with a security protection function provided by the present invention, determine clock compensation parameters, including: Obtain historical clock synchronization data of a previous clock synchronization link stored in advance; Extract key features from the historical clock synchronization data, and establish a signal change prediction model based on the key features; Input the current clock signal into the signal change prediction model to obtain a synchronization error value output by the signal change prediction model; Determine clock compensation parameters according to the synchronization error value.

[0017] On the other hand, the present invention also provides a clock synchronization and positioning method with a security protection function. The method is based on any one of the above-mentioned clock synchronization and positioning devices with a security protection function, and the method includes: Receiving first satellite signals and second satellite signals of different frequency bands emitted by a Beidou signal source through a multi-frequency receiver; Performing clock synchronization by a signal processor according to the standard time information in at least one of the first satellite signal and the second satellite signal, determining a first key parameter according to the first satellite signal, and determining a second key parameter according to the second satellite signal; Inputting the first key parameter and the second key parameter into a pre-established spoofing signal recognition model by a security protection processor respectively to obtain a first spoofing recognition result and a second spoofing recognition result, and sending out a signal source switching instruction when a spoofing signal is recognized in the first spoofing recognition result and / or the second spoofing recognition result; When the isolation controller receives the signal source switching instruction, controlling to cut off the connection between the multi-frequency receiver and the abnormal Beidou signal source and switching to a backup signal source; Generating differential correction data by an RTK positioning module according to the received first satellite signal and / or second satellite signal, and sending the differential correction data to a target rover so that the target rover corrects its own positioning information according to the differential correction data.

[0018] The clock synchronization and positioning device and method with a security protection function provided by the present invention receive a first satellite signal and a second satellite signal of different frequency bands emitted by a Beidou signal source through a multi-frequency receiver. The signal processor performs clock synchronization based on the standard time information in at least one of the first satellite signal and the second satellite signal, determines a first key parameter based on the first satellite signal, determines a second key parameter based on the second satellite signal, inputs the first key parameter and the second key parameter into a pre-established spoofing signal recognition model through a security protection processor to obtain a first spoofing recognition result and a second spoofing recognition result, and when a spoofing signal is recognized in the first spoofing recognition result and / or the second spoofing recognition result, issues a signal source switching instruction. The isolation controller receives the signal source switching instruction, controls to cut off the connection between the multi-frequency receiver and the abnormal Beidou signal source, and switches to a backup signal source. The RTK positioning module generates differential correction data according to the received first satellite signal and / or second satellite signal, and sends the differential correction data to the target mobile station so that the target mobile station corrects its own positioning information according to the differential correction data. Since the security protection processor can implement the spoofing recognition function based on the key parameters corresponding to the satellite signals of two different frequency bands, and when at least one satellite signal is detected as a spoofing signal, it can jointly implement the safe cut-off of the abnormal Beidou signal source with the isolation controller and switch to the backup signal source, ensuring the safety and stability of the clock synchronization and positioning process. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained according to these drawings without creative efforts.

[0020] Figure 1 is a schematic structural diagram of a clock synchronization and positioning device with a security protection function; Figure 2 is a schematic flow diagram of a clock synchronization and positioning method with a security protection function provided by an embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0021] To make the objectives, technical solutions, and advantages of the present invention clearer, the following will clearly and completely describe the technical solutions in the present invention with reference to the accompanying drawings in the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art without creative efforts based on the embodiments in the present invention fall within the scope of protection of the present invention.

[0022] The following combinationFigure 1 and Figure 2 Describe the detailed solutions of the clock synchronization and positioning device and method with security protection functions provided by the embodiments of the present invention.

[0023] Figure 1 It is a schematic structural diagram of the clock synchronization and positioning device with security protection functions provided by the embodiments of the present invention.

[0024] As Figure 1 shown, the clock synchronization and positioning device with security protection functions provided by the embodiments of the present invention specifically includes: A multi-frequency receiver 110, configured to receive the first satellite signal and the second satellite signal of different frequency bands sent by a Beidou signal source.

[0025] A signal processor 120, configured to perform clock synchronization according to the standard time information in at least one of the first satellite signal and the second satellite signal, determine a first key parameter according to the first satellite signal, and determine a second key parameter according to the second satellite signal.

[0026] A security protection processor 130, configured to respectively input the first key parameter and the second key parameter into a pre-established spoofing signal recognition model to obtain a first spoofing recognition result and a second spoofing recognition result, and send a signal source switching instruction when the first spoofing recognition result indicates that the first satellite signal is a spoofing signal, and / or the second spoofing recognition result indicates that the second satellite signal is a spoofing signal.

[0027] An isolation controller 140, configured to control the disconnection of the connection between the multi-frequency receiver and the abnormal Beidou signal source and switch to a standby signal source when receiving the signal source switching instruction.

[0028] An RTK positioning module 150, configured to generate differential correction data according to the received first satellite signal and / or second satellite signal, and send the differential correction data to a target mobile station, so that the target mobile station corrects its own positioning information according to the differential correction data.

[0029] In this embodiment, a dual-frequency combination strategy can be adopted to comprehensively utilize the first satellite signal and the second satellite signal of two frequency bands for clock synchronization. The dual-frequency combination strategy can suppress multipath effects and electromagnetic interference, thereby improving the accuracy of the clock synchronization link.

[0030] In practical applications, the first satellite signal and the second satellite signal can adopt the satellite signals of the B1 frequency band and the B3 frequency band in the dual-Beidou satellite system. Among them, the frequency range of the B1 frequency band in Beidou-2 is 1561.098 MHz ± 2.046 MHz, the center frequency of B1i in Beidou-3 is 1561.098 MHz ± 2.046 MHz, and the center frequency of B1c is 1575.420 MHz ± 16 MHz. The signal propagation characteristics of the B1 frequency band are good, and it can provide relatively stable positioning and timing information. The center frequencies of the B3 frequency band in both Beidou-2 and Beidou-3 are 1268.520 MHz ± 10.23 MHz. The signals of the B3 frequency band have higher positioning accuracy and anti-interference ability, and the signal strength and stability perform excellently in complex environments.

[0031] Since the B1 and B3 frequency bands are in different frequency ranges, the electromagnetic interference characteristics they are subject to are also different. When the signal of one frequency band is interfered, the signal of the other frequency band may be less affected. In this embodiment, through dual-frequency combined reception and processing, the complementary nature of the signals of the two frequency bands can be utilized to improve the anti-interference ability of the signals in the clock synchronization link. For example, when the first satellite signal of the B1 frequency band is subject to narrowband interference, the second satellite signal of the B3 frequency band may be relatively normal. The multi-frequency receiver can perform weighted fusion processing on the signals of the two frequency bands to reduce the impact of interference on the overall signal quality. At the same time, the dual-frequency signals can also be used for interference detection and identification. Specifically, by comparing the signal characteristics of the two frequency bands, it is possible to determine whether there is interference and to identify the type and intensity of the interference, so as to take corresponding anti-interference measures.

[0032] It should be noted that in this embodiment, the multi-frequency receiver is implemented using a national Beidou timing module. Among them, the Beidou dual-mode antenna can receive the first satellite signal and the second satellite signal of the two frequency bands, and after being filtered by a low-noise amplifier, it is sent to the signal processor.

[0033] In some embodiments, the multi-frequency receiver can also adopt a triple-frequency receiver (i.e., B1I, B2a, B3I), which supports RTK (Real Time Kinematic) and PPP (Precise Point Positioning) technologies. The horizontal positioning accuracy meets ±5 mm under static conditions and ±10 mm under dynamic conditions.

[0034] In practical applications, the signal processor can be implemented using a domestic FPGA chip, such as the chips of the PG2L series from Unisoc. At the same time, in this embodiment, the timing output interface supports PTP, IRIG-B, and 1PPS protocols.

[0035] In some embodiments, the signal processor may add an FPGA coprocessor dedicated to carrier phase resolution and cycle slip detection data processing, with a data processing delay of less than 50 ms.

[0036] In practical applications, the security protection processor may add a national cryptography SM2 hardware acceleration chip, supporting differential data signature verification with a thousand-level QPS, and the SM2 signature speed is above 2000 times per second.

[0037] In this embodiment, the RTK positioning module may use a multi-band high-precision antenna to receive satellite signals, supporting frequency bands such as BDS B1 / B2 / B3 and GPS L1 / L2, capable of improving the carrier phase measurement accuracy and achieving centimeter-level positioning. The RTK positioning module generates differential correction data in the RTCM 3.0+ format by calculating the satellite pseudorange and carrier phase correction values in real time. At the same time, the RTK positioning module is equipped with an encrypted communication interface, integrating national cryptography SM4 / SM9 algorithms, and can encrypt the differential correction data and wirelessly transmit it to the target rover via 4G / 5G or LoRa.

[0038] In practical applications, an RTK antenna array may be set in the RTK positioning module, specifically using a choke antenna design, which can suppress the multipath effect and has higher phase center stability.

[0039] In some embodiments, the isolation controller may add a dual-band Wi-Fi 6+UWB hybrid networking interface, supporting multi-mode positioning data transmission, with a transmission distance of 300 m in Wi-Fi mode and 100 m in UWB mode.

[0040] In one embodiment, both the first key parameter and the second key parameter include signal power and pseudorange.

[0041] It can be understood that during the propagation of satellite signals sent by the normal Beidou satellite system, their signal power will have a certain attenuation law with the propagation distance and environmental factors. The spoofing signal may exhibit abnormal power, such as a sudden increase in power or a situation that does not conform to the normal attenuation pattern. In addition, the pseudorange is the measured distance from the Beidou satellite system to the multi-frequency receiver, and the spoofing signal may cause the pseudorange to jump, not conforming to the normal change law. Based on the above signal characteristics, the spoofing signal can be identified.

[0042] In this embodiment, the spoofing signal recognition model can be specifically established through the following process: First, based on the historical satellite signals received in the historical clock synchronization link, obtain the signal power samples and pseudorange samples, and add spoofing recognition labels to the historical satellite signals.

[0043] Then, based on the signal power samples, pseudorange samples, and spoofing recognition labels, establish a sample data set.

[0044] Finally, the pre-constructed machine learning model is trained and tested using a sample data set to obtain a spoofing signal recognition model.

[0045] In this embodiment, the machine learning model is trained using a sample data set established by signal power samples, pseudorange samples, and spoofing recognition labels, enabling the machine learning model to learn the recognition ability of spoofing signal features. Subsequently, spoofing signals can be accurately recognized based on signal power and pseudorange. In practical applications, the machine learning model can be a deep learning model built with a neural network architecture.

[0046] In some embodiments, considering the characteristics of dual-system redundant timekeeping, cross-checks can be performed on the satellite signals of two Beidou satellite systems, comparing parameters such as time information, pseudorange measurement values, and signal characteristics of the two satellite signals. If there are significant differences in the above parameters between the two satellite signals and they exceed the normal error range, it is possible that a spoofing signal has affected one of the Beidou satellite systems. Through this cross-checking method, the detection ability for spoofing signals can be improved.

[0047] In one embodiment, the above clock synchronization and positioning device with security protection functions may further include: a first monitoring module.

[0048] The first monitoring module is configured to periodically generate and send heartbeat signals to the multi-frequency receiver, signal processor, security protection processor, and isolation controller, and generate and issue an abnormal monitoring log after receiving a heartbeat detection abnormal signal sent by at least one of the multi-frequency receiver, signal processor, security protection processor, and isolation controller.

[0049] In this embodiment, a fixed time period can be preset, such as generating a heartbeat signal every second or every few seconds. The heartbeat signal can be a simple digital pulse signal or a data packet containing specific information (such as device status and timestamp, etc.).

[0050] After the heartbeat signal is generated, the first monitoring module can send the generated heartbeat signal to each part of the device structure simultaneously. Under normal circumstances, each part of the structure can receive the heartbeat signal.

[0051] In practical applications, a heartbeat monitoring unit can be set inside each structure to continuously monitor the received heartbeat signal. If the heartbeat signal is not received within the expected time period, a heartbeat detection abnormal signal can be immediately sent to the first monitoring module.

[0052] In one embodiment, the above clock synchronization and positioning device with security protection functions may further include: an inspection module.

[0053] The verification module is used to obtain the first position information of the RTK positioning module and the second position information of the target mobile station, calculate the position deviation between the first position information and the second position information, and issue a position anomaly warning message when the position deviation exceeds the preset position deviation threshold.

[0054] In this embodiment, the preset position deviation threshold can be set to 10 cm. In practical applications, the encryption key of the differential correction data can be updated every hour to prevent replay attacks.

[0055] In practical applications, the clock synchronization signal after clock synchronization can be aligned with the timestamp of the differential correction data to generate position information with accurate time tags.

[0056] In some embodiments, an ARIMA (Autoregressive Integrated Moving Average Model) can be established based on historical positioning data to real-time verify whether the movement trajectory of the personnel or vehicle corresponding to the target mobile station is reasonable, and automatically mark the abnormal trajectories with unreasonable inspection results.

[0057] In practical applications, a dynamic electronic fence function can also be set. Specifically, it can be based on the GIS engine to real-time render the three-dimensional safety area of the monitoring target, support hierarchical control and adaptive boundary adjustment functions, and can automatically shrink or expand the boundary according to the operation stage.

[0058] The physical layer of the clock synchronization positioning device adopts a design of anti-disassembly shell combined with a fiber optic vibration sensor. When an illegal opening is detected, the differential correction data of the key data layer can be immediately erased, supporting triple verification of CRC32 + HMAC-SHA256 + timestamp, and implementing RBAC permission control at the application layer. Double authentication is required for accessing positioning data.

[0059] In some embodiments, the above-mentioned clock synchronization positioning device with security protection functions can further include: a space-time adaptive filtering module and a pulse interference suppression module. The space-time adaptive filtering module is used to perform 24-hour spectrum monitoring on the 1560 - 1610 MHz frequency band and can dynamically adjust the anti-interference parameters of the multi-frequency receiver. The deployment of the pulse interference suppression module is based on a deep learning-based interference recognition model, and specifically, an architecture combining CNN (Convolutional Neural Network) and GRU (Gated Recurrent Unit) can be adopted.

[0060] In one embodiment, the above-mentioned clock synchronization positioning device with security protection functions can further include: a field alarm module.

[0061] The security protection processor is further configured to generate and issue a first warning instruction when the first spoofing recognition result is that the first satellite signal is a spoofed signal, and / or the second spoofing recognition result is that the second satellite signal is a spoofed signal.

[0062] The first monitoring module is further configured to generate and issue a second warning instruction after receiving a heartbeat detection abnormal signal sent by at least one of the multi-frequency receiver, the signal processor, the security protection processor, and the isolation controller.

[0063] The on-site warning module is configured to perform acoustic and optical warnings after receiving the first warning instruction and / or the second warning instruction.

[0064] In this embodiment, the on-site warning module mainly realizes the on-site warning function. Specifically, it can achieve a prominent prompt effect through synchronous acoustic and optical warnings, so as to facilitate on-site operation and maintenance personnel to take measures to handle abnormal situations in a timely manner.

[0065] In one embodiment, the above clock synchronization and positioning device with security protection functions may further include: a second monitoring module.

[0066] The second monitoring module is configured to respectively evaluate the quality of the first satellite signal and the second satellite signal to obtain a first signal quality evaluation result of the first satellite signal and a second signal quality evaluation result of the second satellite signal, and generate a signal adjustment strategy according to the first signal quality evaluation result and the second signal quality evaluation result.

[0067] In one embodiment, evaluating the quality of the first satellite signal to obtain a first signal quality evaluation result of the first satellite signal specifically includes: On the one hand, first, obtain the received power of the first satellite signal, and calculate the deviation between the received power of the first satellite signal and the standard power range of the corresponding frequency band to obtain a power deviation value.

[0068] By measuring the signal power of the received first satellite signal, the received power can be obtained. The received power is generally in units of dBm. In this embodiment, the received power of the satellite signal sent by the Beidou satellite system is usually within the standard power range of -120dBm to -130dBm. By subtracting the upper limit or lower limit of the standard power range from the received power of the first satellite signal, the power deviation value can be obtained.

[0069] Then, perform normalization processing on the power deviation value to obtain an intensity evaluation value of the first satellite signal.

[0070] On the other hand, determine the bit error rate of the first satellite signal, and calculate the deviation between the bit error rate of the first satellite signal and a preset bit error rate threshold to obtain a bit error rate deviation value.

[0071] In this embodiment, the bit error rate of the first satellite signal can be obtained by comparing the signal data at the sending end and the receiving end, and counting the ratio of the number of error bits to the total number of bits. For example, in the Beidou satellite navigation signal, if the bit error rate exceeds a preset bit error rate threshold, such as 10 -6 , it may affect the accuracy of clock synchronization. In practical applications, the bit error rate of the first satellite signal can be subtracted from the preset bit error rate threshold to obtain the bit error rate deviation value.

[0072] Then, the bit error rate deviation value is normalized to obtain the integrity evaluation value of the first satellite signal.

[0073] In this embodiment, the normalization process can be implemented by using the maximum-minimum normalization function.

[0074] On the other hand, obtain the credible characterization parameters of the first satellite signal, and determine the credibility evaluation value of the first satellite signal based on the credible characterization parameters.

[0075] It can be understood that the credible characterization parameters can characterize the credibility of the first satellite signal.

[0076] Subsequently, the intensity evaluation value, the integrity evaluation value, and the credibility evaluation value are weighted and summed to obtain the measured signal quality value of the first satellite signal.

[0077] Finally, the measured signal quality value is compared with the preset signal quality reference value to obtain the first signal quality evaluation result of the first satellite signal.

[0078] In this embodiment, the first signal quality evaluation result can be set to multiple levels, such as excellent, good, general, poor, and extremely poor. The multiple levels can be determined according to several ranges divided by a plurality of preset signal quality reference values.

[0079] In one embodiment, the credible characterization parameters of the first satellite signal include: phase jitter value, signal frequency value, signal-to-noise ratio value, and signal source location.

[0080] In this embodiment, determining the credibility evaluation value of the first satellite signal based on the credible characterization parameters specifically includes: On the one hand, a deviation calculation is performed on the phase jitter value of the first satellite signal and the preset phase jitter threshold to obtain the phase jitter deviation value.

[0081] In practical applications, the phase jitter of the signal is usually represented by the root mean square phase jitter. If the phase jitter exceeds ±10°, it will affect the accuracy of clock synchronization. Therefore, the preset phase jitter threshold can be set to 10°. Specifically, the absolute value of the phase jitter value of the first satellite signal is subtracted from the preset phase jitter threshold to obtain the phase jitter deviation value.

[0082] In a second aspect, a deviation calculation is performed between the signal frequency value of the first satellite signal and a standard frequency value to obtain a signal frequency deviation value.

[0083] In practical applications, the signal frequency deviation value can be obtained by subtracting the standard frequency value from the signal frequency value. If the signal frequency deviation value is within ±10 Hz, it can be considered that the frequency consistency is good and the signal credibility is high; if the signal frequency deviation value exceeds ±50 Hz, the signal may be interfered with or there may be a fault, and the signal credibility is reduced.

[0084] In a third aspect, a deviation calculation is performed between the signal-to-noise ratio value of the first satellite signal and a preset reference signal-to-noise ratio to obtain a signal-to-noise ratio deviation value.

[0085] In this embodiment, the signal-to-noise ratio value can be calculated by calculating the ratio of the signal power to the noise power. Generally speaking, when the signal-to-noise ratio value is lower than 10 dB, the signal is easily interfered by noise and the signal credibility is reduced. Therefore, the reference signal-to-noise ratio can be taken as 10 dB.

[0086] In a fourth aspect, a deviation calculation is performed between the signal source indication position of the first satellite signal and a signal source reference position to obtain a signal source position deviation value.

[0087] In practical applications, the signal source position deviation value is obtained by calculating the error between the signal source indication position of the Beidou satellite signal source indicated by the received first satellite signal and the known signal source reference position. If the signal source position deviation value is within a certain range, such as less than 1 km, the signal credibility is high; if the signal source position deviation value exceeds 5 km, the signal credibility is reduced, and there may be signal spoofing or interference.

[0088] Finally, normalization processing is respectively performed on the phase jitter deviation value, the signal frequency deviation value, the signal-to-noise ratio deviation value, and the signal source position deviation value, and a credibility evaluation value of the first satellite signal is calculated based on the normalized phase jitter deviation value, signal frequency deviation value, signal-to-noise ratio deviation value, and signal source position deviation value.

[0089] In practical applications, the normalized phase jitter deviation value, signal frequency deviation value, signal-to-noise ratio deviation value, and signal source position deviation value can be multiplied to obtain a deviation product value, and then the fourth root of the deviation product value is taken to obtain the credibility evaluation value of the first satellite signal.

[0090] Similarly, the implementation process of performing quality evaluation on the second satellite signal to obtain the second signal quality evaluation result of the second satellite signal is basically the same as the above instruction evaluation process of the first satellite signal, and will not be repeated here.

[0091] In one embodiment, according to the first signal quality evaluation result and the second signal quality evaluation result, a signal adjustment strategy is generated, which specifically includes: In one case, if one of the first signal quality evaluation result and the second signal quality evaluation result is that the signal quality is low, and the other evaluation result is that the signal quality is normal, then it is determined that the signal adjustment strategy is: allocate the first preset weight value to the satellite signal with normal signal quality, and allocate the second preset weight value to the satellite signal with low signal quality, where the first preset weight value is higher than the second preset weight value.

[0092] In this case, there is exactly one signal with low signal quality among the first satellite signal and the second satellite signal. Since the other signal has normal quality and can meet the clock synchronization accuracy requirements, therefore, in the dual-frequency combination strategy, a higher weight value can be allocated to the satellite signal with normal signal quality, and a lower weight value can be allocated to the satellite signal with low signal quality, so as to ensure the clock synchronization accuracy.

[0093] In practical applications, the specific value of the weight can be reasonably set according to the clock synchronization accuracy requirements and will not be specifically limited here.

[0094] In another case, if both the first signal quality evaluation result and the second signal quality evaluation result are that the signal quality is low, then it is determined that the signal adjustment strategy is: start the temporary autonomous timekeeping mode, and determine the clock compensation parameter, and dynamically compensate the clock information in the temporary autonomous timekeeping mode according to the clock compensation parameter.

[0095] In this case, the signal quality of both satellite signals is low. At this time, the dual-frequency combination strategy is difficult to meet the normal clock synchronization accuracy requirements. In this embodiment, the temporary autonomous timekeeping mode is started to meet the normal clock synchronization process and ensure the uninterrupted clock synchronization.

[0096] It should be noted that since the signal quality can be divided into multiple levels, such as four levels: excellent, good, average, poor, and extremely poor, where the normal signal quality can correspond to the levels of excellent, good, and average, and the low signal quality can correspond to the two levels of poor and extremely poor.

[0097] In one embodiment, determining the clock compensation parameter includes: First, obtain the historical clock synchronization data of the previous clock synchronization link stored in advance.

[0098] In the process of clock synchronization, the historical clock synchronization data can be continuously recorded, such as information such as the time stamp, synchronization error value, and signal strength of each synchronization.

[0099] In some embodiments, the collected historical clock synchronization data can be preprocessed, including operations such as removing outliers and data smoothing, to improve the quality and reliability of the historical clock synchronization data. For example, a moving average filtering algorithm can be used to smooth the synchronization error data and eliminate short-term noise interference.

[0100] Then, extract the key features from the historical clock synchronization data and establish a signal change prediction model based on the key features.

[0101] In this embodiment, useful key features can be extracted from the historical clock synchronization data, such as the error mean, error variance, signal change trend, etc., in order to analyze the operating rules of the clock and the change characteristics of the signal, so as to provide accurate data basis for the establishment of the signal change prediction model.

[0102] In this embodiment, the signal change prediction model can adopt a linear model, a polynomial model, an ARIMA model, etc., to predict the future change trend of the signal. For example, if it is found that the synchronization error shows an approximately linear change trend over time, a linear regression model can be established as the signal change prediction model.

[0103] Subsequently, input the current clock signal into the signal change prediction model to obtain the synchronization error value output by the signal change prediction model.

[0104] Finally, determine the clock compensation parameter based on the synchronization error value.

[0105] In this embodiment, in the process of dynamically compensating the clock information in the temporary autonomous timing mode using the clock compensation parameter, an appropriate compensation algorithm can be selected, such as a compensation algorithm based on Kalman filtering, a compensation algorithm based on neural network, or a compensation algorithm based on fuzzy control, etc. For example, for a clock synchronization scenario with noise interference and uncertain factors, the Kalman filtering algorithm can be used, which can effectively estimate and compensate for errors.

[0106] It can be understood that the clock compensation parameter can be the output frequency or phase of the clock source. By adjusting the output frequency or phase of the clock source, the running time of the clock can be made closer to the ideal time, thus achieving the effect of dynamic compensation.

[0107] It should be noted that in the temporary autonomous timing mode, autonomous timing is mainly achieved through domestic rubidium atomic clocks, and domestic rubidium atomic clocks can meet the higher-precision autonomous timing requirements.

[0108] In practical applications, the RTK positioning module can continuously output encrypted differential correction data to the target rover station. The target rover station can calculate the precise position by combining its own positioning information. The signal processor can align the positioning data with the timing data in the clock synchronization link. The security protection processor can identify spoofing signals in real time and switch to the backup signal source in case of abnormal situations.

[0109] In a specific implementation, when a spoofing attack is detected, a phased response mechanism can be adopted for processing, as follows: The first stage: Switch to the backup frequency band, for example, replace the B1 frequency band with the B3 frequency band.

[0110] The second stage: Turn off the differential service and enable the GNSS / INS integrated navigation.

[0111] The third stage: Activate the quantum random number generator and dynamically reconstruct the communication key.

[0112] Through the above solutions, the entire device can maintain the original timing function (the clock synchronization accuracy meets ±10 ns), while adding centimeter-level positioning capabilities, and meet the three-level protection requirements for high-precision positioning security in the relevant standard requirements, and can provide safe and reliable spatio-temporal reference services for on-site personnel and equipment.

[0113] Based on the same general inventive concept, the present invention also protects a clock synchronization and positioning method with a security protection function. The clock synchronization and positioning method with a security protection function provided by the present invention will be described below. The clock synchronization and positioning method with a security protection function described below can be mutually referred to the clock synchronization and positioning device with a security protection function described above.

[0114] As Figure 2 shown, the clock synchronization and positioning method with a security protection function provided by the embodiments of the present invention can be implemented based on the clock synchronization and positioning device with a security protection function provided by the above embodiments. The method mainly includes the following steps: Step 210: Receive the first satellite signal and the second satellite signal of different frequency bands sent by the Beidou signal source through a multi-frequency receiver.

[0115] Step 220: Perform clock synchronization through the signal processor according to the standard time information in at least one of the first satellite signal and the second satellite signal, determine the first key parameter according to the first satellite signal, and determine the second key parameter according to the second satellite signal.

[0116] Step 230: Input the first key parameter and the second key parameter into a pre-established spoofing signal recognition model through a security protection processor, obtain a first spoofing recognition result and a second spoofing recognition result, and issue a signal source switching instruction when a spoofing signal is recognized in the first spoofing recognition result and / or the second spoofing recognition result.

[0117] Step 240: When the isolation controller receives the signal source switching instruction, control to cut off the connection between the multi-frequency receiver and the abnormal Beidou signal source, and switch to the standby signal source.

[0118] Step 250: Generate differential correction data according to the received first satellite signal and / or second satellite signal through the RTK positioning module, and send the differential correction data to the target rover station, so that the target rover station corrects its own positioning information according to the differential correction data.

[0119] In the clock synchronization and positioning method with a security protection function provided by the embodiments of the present invention, since the security protection processor can implement the spoofing recognition function based on the key parameters corresponding to the satellite signals of two different frequency bands, when at least one satellite signal is detected as a spoofing signal, it can jointly implement the safe cut-off of the abnormal Beidou signal source with the isolation controller and switch to the standby signal source, ensuring the safety and stability of the clock synchronization and positioning process.

[0120] Regarding the method in the above embodiments, the specific manners of each step have been described in detail in the embodiments related to the device, and will not be elaborated here.

[0121] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A clock synchronization and positioning device with a safety protection function, characterized in that, Including: A multi-frequency receiver for receiving a first satellite signal and a second satellite signal of different frequency bands emitted by a Beidou signal source; A signal processor for performing clock synchronization based on the standard time information in at least one of the first satellite signal and the second satellite signal, determining a first key parameter based on the first satellite signal, and determining a second key parameter based on the second satellite signal; A security protection processor for respectively inputting the first key parameter and the second key parameter into a pre-established spoofing signal recognition model to obtain a first spoofing recognition result and a second spoofing recognition result, and issuing a signal source switching instruction when a spoofing signal is recognized in the first spoofing recognition result and / or the second spoofing recognition result; An isolation controller for controlling to cut off the connection between the multi-frequency receiver and the abnormal Beidou signal source and switch to a backup signal source when receiving the signal source switching instruction; An RTK positioning module for generating differential correction data according to the received first satellite signal and / or second satellite signal, and sending the differential correction data to a target rover so that the target rover corrects its own positioning information according to the differential correction data.

2. The clock synchronization and positioning device with a safety protection function according to claim 1, characterized in that, Both the first key parameter and the second key parameter include: signal power and pseudorange; The spoofing signal recognition model is established through the following process: Obtaining a signal power sample and a pseudorange sample according to the historical satellite signals received in the historical clock synchronization link, and adding a spoofing recognition label to the historical satellite signals; Establishing a sample data set according to the signal power sample, the pseudorange sample and the spoofing recognition label; Training and testing a pre-constructed machine learning model through the sample data set to obtain a spoofing signal recognition model.

3. The clock synchronization and positioning device with a safety protection function according to claim 1, characterized in that, The device further includes: a first monitoring module; The first monitoring module is used to regularly generate and send a heartbeat signal to the multi-frequency receiver, the signal processor, the security protection processor and the isolation controller, and generate and issue an abnormal monitoring log after receiving a heartbeat detection abnormal signal sent by at least one of the multi-frequency receiver, the signal processor, the security protection processor and the isolation controller.

4. The clock synchronization and positioning device with a safety protection function according to claim 1, characterized in that, The device further includes: an inspection module; The verification module is used to obtain a first position information of the RTK positioning module and a second position information of the target rover, calculate a position deviation between the first position information and the second position information, and issue a position abnormal warning information when the position deviation exceeds a preset position deviation threshold.

5. The clock synchronization and positioning device with a safety protection function according to claim 1, characterized in that, The device further includes: a second monitoring module; The second monitoring module is used to respectively perform quality evaluation on the first satellite signal and the second satellite signal to obtain a first signal quality evaluation result of the first satellite signal and a second signal quality evaluation result of the second satellite signal, and generate a signal adjustment strategy according to the first signal quality evaluation result and the second signal quality evaluation result.

6. The clock synchronization and positioning device with a safety protection function according to claim 5, characterized in that, Performing quality evaluation on the first satellite signal to obtain a first signal quality evaluation result of the first satellite signal, including: Obtain the received power of the first satellite signal, and calculate the deviation between the received power of the first satellite signal and the standard power range of the corresponding frequency band to obtain a power deviation value; Perform normalization processing on the power deviation value to obtain an intensity evaluation value of the first satellite signal; Determine the bit error rate of the first satellite signal, and calculate the deviation between the bit error rate of the first satellite signal and a preset bit error rate threshold to obtain a bit error rate deviation value; Perform normalization processing on the bit error rate deviation value to obtain an integrity evaluation value of the first satellite signal; Obtain the credible characterization parameters of the first satellite signal, and determine the credibility evaluation value of the first satellite signal based on the credible characterization parameters; Perform weighted summation on the intensity evaluation value, the integrity evaluation value, and the credibility evaluation value to obtain an actual measured value of the signal quality of the first satellite signal; Compare the actual measured value of the signal quality with a preset signal quality reference value to obtain a first signal quality evaluation result of the first satellite signal.

7. The clock synchronization and positioning device with a safety protection function according to claim 6, characterized in that, The credible characterization parameters of the first satellite signal include: phase jitter value, signal frequency value, signal-to-noise ratio value, and signal source position; Determining the credibility evaluation value of the first satellite signal based on the credible characterization parameters includes: Calculate the deviation between the phase jitter value of the first satellite signal and a preset phase jitter threshold to obtain a phase jitter deviation value; Calculate the deviation between the signal frequency value of the first satellite signal and a standard frequency value to obtain a signal frequency deviation value; Calculate the deviation between the signal-to-noise ratio value of the first satellite signal and a preset reference signal-to-noise ratio to obtain a signal-to-noise ratio deviation value; Calculate the deviation between the indicated signal source position of the first satellite signal and a signal source reference position to obtain a signal source position deviation value; Perform normalization processing on the phase jitter deviation value, the signal frequency deviation value, the signal-to-noise ratio deviation value, and the signal source position deviation value respectively, and calculate the credibility evaluation value of the first satellite signal based on the normalized phase jitter deviation value, signal frequency deviation value, signal-to-noise ratio deviation value, and signal source position deviation value.

8. The clock synchronization and positioning device with a safety protection function according to claim 5, characterized in that, Generate a signal adjustment strategy according to the first signal quality evaluation result and the second signal quality evaluation result, including: If one of the first signal quality evaluation result and the second signal quality evaluation result is that the signal quality is low, and the other evaluation result is that the signal quality is normal, then determine the signal adjustment strategy as: allocate a first preset weight value to the satellite signal with normal signal quality, and allocate a second preset weight value to the satellite signal with low signal quality, where the first preset weight value is higher than the second preset weight value; If both the first signal quality evaluation result and the second signal quality evaluation result are that the signal quality is low, then determine the signal adjustment strategy as: start a temporary autonomous timing mode, and determine a clock compensation parameter, and dynamically compensate the clock information in the temporary autonomous timing mode according to the clock compensation parameter.

9. The clock synchronization and positioning device with a safety protection function according to claim 8, characterized in that Determining the clock compensation parameter includes: Obtain the historical clock synchronization data of the previous clock synchronization link stored in advance; Extract the key features from the historical clock synchronization data, and establish a signal change prediction model based on the key features; Input the current clock signal into the signal change prediction model to obtain the synchronization error value output by the signal change prediction model; Determine the clock compensation parameter according to the synchronization error value.

10. A clock synchronization and positioning method with a security protection function, characterized in that, The method is based on the clock synchronization and positioning device with a security protection function according to any one of claims 1 to 9, and the method includes: Receive the first satellite signal and the second satellite signal of different frequency bands sent by the Beidou signal source through a multi-frequency receiver; Perform clock synchronization by a signal processor according to the standard time information in at least one of the first satellite signal and the second satellite signal, determine a first key parameter according to the first satellite signal, and determine a second key parameter according to the second satellite signal; Input the first key parameter and the second key parameter into a pre-established spoofing signal recognition model by a security protection processor to obtain a first spoofing recognition result and a second spoofing recognition result, and issue a signal source switching instruction when a spoofing signal is recognized in the first spoofing recognition result and / or the second spoofing recognition result; When the isolation controller receives the signal source switching instruction, control to cut off the connection between the multi-frequency receiver and the abnormal Beidou signal source and switch to a backup signal source; Generate differential correction data by an RTK positioning module according to the received first satellite signal and / or second satellite signal, and send the differential correction data to a target rover so that the target rover corrects its own positioning information according to the differential correction data.

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