Adaptive anti-interference method and system for protecting beidou time service signal

Abstract

The application provides a Beidou time signal protection method and system based on adaptive anti-interference. First, the application receives a time signal and detects abnormal time delay introduced by multipath effect and deceptive interference. Second, according to the time domain distribution characteristics, a multi-level anti-interference strategy is generated. Then, the waveform reconstruction rule is used to compensate the phase of the chip sequence, and an anti-multipath reinforced signal is generated. Then, based on the pulse shielding rule, the injection window of the deceptive interference is identified, and random polarization filtering is introduced to suppress the deceptive component to obtain a polarization filtering signal. Finally, the polarization filtering signal is synchronized with the local clock for solution, and the anti-interference Beidou time information is output. The technical scheme provided by the application not only improves the survival and service capability of the time system in harsh environment, but also improves the anti-interference capability and time accuracy of the Beidou time signal in complex electromagnetic environment.

Description

Technical Field

[0001] This application relates to the field of signal interference protection technology, and in particular to a method and system for protecting BeiDou timing signals based on adaptive anti-interference. Background Technology

[0002] In advanced application scenarios such as drone swarm collaborative operations, autonomous precision navigation and obstacle avoidance, high-precision BeiDou satellite timing is the core foundation for ensuring multi-drone synchronization, accurate route planning and flight safety. However, when drones fly at low or ultra-low altitudes in complex environments such as cities and mountains, the BeiDou timing signals they receive are easily affected by complex multipath interference caused by building reflections, as well as deceptive interference carried out by malicious third parties. These interferences can directly cause distortion of drone positioning and timing information, which may lead to formation disorder, flight path deviation and even collision.

[0003] The existing technical solution adopts an auxiliary verification mechanism based on the time difference of arrival (TDOA). By deploying multiple ground reference stations, a verification model is built using the time difference of arrival of signals between the UAV and different reference stations. When the BeiDou timing signal received by the UAV has abnormal delay or spoofing characteristics, the model can identify the inconsistency of the timing information and attempt to correct or issue an alarm.

[0004] However, this solution still has significant drawbacks. First, it relies heavily on a pre-set network of ground reference stations, resulting in high system deployment costs and insufficient flexibility. It is unsuitable for remote areas lacking ground infrastructure or for UAV missions requiring high mobility, such as emergency reconnaissance. Second, it is essentially a back-end verification and error correction mechanism, which lacks the ability to clean up the timing signal itself in real time. When encountering continuous or complex joint interference, the timeliness and reliability of its correction will drop significantly, making it difficult to meet the stringent requirements of UAVs for continuous, real-time, and highly reliable timing. Summary of the Invention

[0005] This application provides a method and system for protecting BeiDou timing signals based on adaptive anti-interference, which solves the problems of insufficient flexibility due to reliance on fixed ground infrastructure in the prior art, and the lack of differentiation between multipath interference and deceptive interference, making it difficult to achieve reliable real-time protection in dynamic environments.

[0006] Firstly, this application provides a method for protecting BeiDou timing signals based on adaptive anti-interference, including:

[0007] It receives timing signals broadcast by BeiDou satellites and detects abnormal delays in the timing signals caused by multipath effects and deceptive interference.

[0008] Based on the time-domain distribution characteristics of abnormal delays, a multi-level anti-interference strategy matching the propagation environment of BeiDou timing signals is generated. The multi-level anti-interference strategy includes waveform reconstruction rules for multipath effects and pulse masking rules for deceptive interference.

[0009] Phase compensation is performed on the chip sequence in the timing signal affected by multipath using waveform reconstruction rules to generate an anti-multipath enhancement signal;

[0010] Based on the pulse masking rule, the injection window of deceptive interference is identified in the time-frequency domain of the anti-multipath enhancement signal, and random polarization filtering is introduced in the injection window to suppress the deceptive component, thus obtaining the polarization filtered signal.

[0011] The polarization filter signal is synchronized with the local clock to output the anti-interference BeiDou time information.

[0012] Optionally, the system receives timing signals broadcast by BeiDou satellites and detects abnormal delays in the timing signals caused by multipath effects and spoofing interference, including:

[0013] Receive the original timing signal broadcast by the BeiDou satellite and extract the chip sequence from the original timing signal;

[0014] Construct a local reference sequence that matches the chip sequence;

[0015] Perform a sliding correlation operation between the chip sequence and the local reference sequence to generate a correlation result sequence;

[0016] In the relevant result sequence, the position of the main peak is identified, and the theoretical arrival time of the direct signal component is determined based on the position of the main peak.

[0017] In the relevant result sequence, other peak points besides the main peak are searched, and these other peak points are identified as abnormal peak points.

[0018] Calculate the delay of each abnormal peak point relative to the theoretical arrival time, and record the delay as abnormal time delay.

[0019] Optionally, based on the time-domain distribution characteristics of the abnormal delay, a multi-level anti-interference strategy matching the propagation environment of the BeiDou timing signal is generated. This multi-level anti-interference strategy includes waveform reconstruction rules for multipath effects and pulse masking rules for deceptive interference, including:

[0020] A density analysis is performed on the values ​​of the abnormal delays. Based on the analysis results, abnormal delays with values ​​less than a first preset threshold and distribution less than a second preset value are classified into a first subset, and abnormal delays with values ​​greater than the first preset threshold and distribution greater than the second preset threshold are classified into a second subset.

[0021] Perform a linear mapping operation on each abnormal delay value in the first subset to generate a phase adjustment angle corresponding to each abnormal delay value, and integrate all phase adjustment angles to form a waveform reconstruction rule;

[0022] For each abnormal delay value in the second subset, a window definition operation is performed to generate a masking window of fixed time length starting from each abnormal delay value. All masking windows are then integrated to form a pulse masking rule.

[0023] The waveform reconstruction rule and the pulse masking rule are merged to generate a multi-level anti-interference strategy.

[0024] Optionally, phase compensation is performed on the chip sequence in the timing signal affected by multipath propagation using waveform reconstruction rules to generate an anti-multipath enhancement signal, including:

[0025] Read the phase adjustment angle corresponding to the value of each abnormal delay from the waveform reconstruction rules;

[0026] In the chip sequence of the timing signal, locate the delay position chip corresponding to the value of each abnormal delay;

[0027] Apply a corresponding phase adjustment angle to each of the delayed position chips to generate phase-adjusted chips;

[0028] The initial enhancement signal is generated by replacing the corresponding chip in the timing signal with a phase-adjusted chip.

[0029] The initial enhancement signal is subjected to waveform smoothing to eliminate phase jumps between chips and generate an anti-multipath enhancement signal.

[0030] Optionally, based on the pulse masking rule, the injection window for deceptive interference is identified in the time-frequency domain of the anti-multipath enhancement signal, and random polarization filtering is introduced within the injection window to suppress the deceptive component, resulting in a polarization-filtered signal, including:

[0031] Extract the start and end time information of all occlusion windows from the pulse occlusion rules;

[0032] Based on the time series of the anti-multipath enhancement signal, the start and end times of each occlusion window are marked from the start and end time information of all extracted occlusion windows.

[0033] Mark the signal segment between each start time point and end time point as the signal segment to be processed;

[0034] Perform a random number generation operation on each signal segment to be processed to generate a random number sequence equal to the number of sampling points within the signal segment to be processed;

[0035] Each random number in the random number sequence is mapped to a preset polarization angle value to generate a random polarization direction sequence;

[0036] Based on each polarization angle value in the random polarization direction sequence, the signal amplitude of the corresponding sampling point in the signal segment to be processed is proportionally adjusted to generate a random polarization signal segment.

[0037] The original signal segment corresponding to the anti-multipath enhancement signal is replaced by the random polarization signal segment to obtain the polarization filtered signal.

[0038] Optionally, based on each polarization angle value in the random polarization direction sequence, the signal amplitude of the corresponding sampling point in the signal segment to be processed is proportionally adjusted to generate a random polarization signal segment, including:

[0039] Read the original signal amplitude value of each sampling point in the order of appearance of the sampling points in the signal segment to be processed;

[0040] Simultaneously, each polarization angle value is read sequentially according to the arrangement order of the polarization angle values ​​in the random polarization direction sequence;

[0041] Each polarization angle value is converted into an amplitude scaling factor;

[0042] The original signal amplitude value of each sampling point is multiplied by the amplitude scaling factor corresponding to the polarization angle value of the sampling point in the same order position to obtain the adjusted signal amplitude value of the sampling point.

[0043] The amplitude values ​​of the adjusted signals at all sampling points are arranged in chronological order of their occurrence to form a random polarization signal segment.

[0044] Optionally, the polarization filter signal is synchronized with the local clock to output the anti-interference BeiDou time information, including:

[0045] Starting from the predetermined starting position of the polarization filter signal, a continuous sequence of chips is extracted as a synchronization comparison unit.

[0046] Each of the synchronization comparison units is compared with a preset ideal chip sequence for chip-by-chip consistency.

[0047] The number of chips in each synchronization comparison unit that match the ideal chip sequence is counted and recorded as the number of matching chips.

[0048] The maximum synchronization comparison unit that identifies the number of consistent chips is identified, and the starting position of the maximum synchronization comparison unit in the polarization filter signal is identified as the frame synchronization point.

[0049] Based on the frame synchronization point, the time information chip carried in the polarization filter signal is parsed, and the time information chip is translated into the corresponding BeiDou system time data.

[0050] The time difference is calculated by comparing the BeiDou system time data with the current time data of the local clock.

[0051] The time difference is input into the local clock adjustment mechanism to output the anti-interference BeiDou time synchronization information.

[0052] Secondly, this application provides a BeiDou timing signal protection system based on adaptive anti-interference, comprising:

[0053] The receiving module is used to receive the timing signal broadcast by the BeiDou satellite and detect abnormal delays in the timing signal caused by multipath effects and deceptive interference.

[0054] The generation module is used to generate a multi-level anti-interference strategy that matches the propagation environment of the BeiDou timing signal based on the time-domain distribution characteristics of abnormal delays. The multi-level anti-interference strategy includes waveform reconstruction rules for multipath effects and pulse masking rules for deceptive interference.

[0055] The compensation module is used to perform phase compensation on the chip sequence in the timing signal that is affected by multipath using waveform reconstruction rules, and generate an anti-multipath enhancement signal.

[0056] The suppression module is used to identify the injection window of deceptive interference in the time-frequency domain of the anti-multipath enhancement signal based on the pulse masking rule, and introduce random polarization filtering in the injection window to suppress the deceptive component, thereby obtaining the polarization filtered signal.

[0057] The calculation module is used to synchronize the polarization filter signal with the local clock and output the anti-interference BeiDou time information.

[0058] Thirdly, this application provides a computing device, including a processing component and a storage component; the storage component stores one or more computer instructions; the one or more computer instructions are to be invoked and executed by the processing component to implement the BeiDou timing signal protection method based on adaptive anti-interference as described in the first aspect above.

[0059] Fourthly, this application provides a computer storage medium storing a computer program, which, when executed by a computer, implements a BeiDou timing signal protection method based on adaptive anti-interference as described in the first aspect.

[0060] This application constructs a complete and closed-loop signal processing flow by sequentially executing a series of collaborative steps, including abnormal delay detection, adaptive strategy generation, multi-level signal enhancement, and synchronous calculation. The core benefit of this scheme is that it can autonomously and intelligently cope with the mixed threats of multipath effects and deceptive interference in complex electromagnetic environments without relying on any external auxiliary systems. Through accurate identification, classification, and hierarchical suppression of interference signals, it ultimately outputs highly reliable and complete BeiDou time service information, thereby fundamentally and significantly improving the survival and service capabilities of the time service system in harsh environments.

[0061] Furthermore, by designing a unique frame synchronization capture and time information parsing mechanism, the overall scheme is provided with the ability to acquire a precise time reference. Its beneficial effects are reflected in the fact that by using consistency comparison and peak identification methods, the accurate frame synchronization point can be robustly located from the signal after the aforementioned anti-interference processing, and the standard time data can be reliably interpreted. This data is then compared and calibrated with the local clock with high precision, ensuring that the final output time synchronization result is not only highly anti-interference, but also has extremely high time accuracy and stability.

[0062] These or other aspects of this application will become more apparent in the following description of the embodiments. Attached Figure Description

[0063] To more clearly illustrate the technical solutions in this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0064] Figure 1 A flowchart of a BeiDou timing signal protection method based on adaptive anti-interference provided in this application is shown;

[0065] Figure 2 A schematic diagram of the structure of a BeiDou timing signal protection system based on adaptive anti-interference provided in this application is shown;

[0066] Figure 3 A schematic diagram of the structure of a computing device provided in this application is shown. Detailed Implementation

[0067] To enable those skilled in the art to better understand the present application, the technical solution of the present application will be clearly and completely described below with reference to the accompanying drawings.

[0068] In some of the processes described in the specification, claims, and accompanying drawings of this application, multiple operations appearing in a specific order are included. However, it should be clearly understood that these operations may not be executed in the order they appear herein, or may be executed in parallel. The operation numbers, such as 101, 102, etc., are merely used to distinguish different operations and do not themselves represent any execution order. Furthermore, these processes may include more or fewer operations, and these operations may be executed sequentially or in parallel. It should be noted that the descriptions such as "first," "second," etc., in this document are used to distinguish different messages, devices, modules, etc., and do not represent a chronological order, nor do they limit "first" and "second" to different types.

[0069] The technical solutions of this application will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0070] Figure 1 This application provides a flowchart of a BeiDou timing signal protection method based on adaptive anti-interference, as shown in the following figure. Figure 1 As shown, the method includes:

[0071] Step 101: Receive the timing signal broadcast by the BeiDou satellite and detect abnormal delays in the timing signal caused by multipath effects and deceptive interference.

[0072] Optionally, step 101 may specifically include the following steps:

[0073] Step 1011: Receive the original timing signal broadcast by the BeiDou satellite and extract the chip sequence from the original timing signal;

[0074] Step 1012: Construct a local reference sequence that matches the chip sequence;

[0075] Step 1013: Perform a sliding correlation operation between the chip sequence and the local reference sequence to generate a correlation result sequence;

[0076] Step 1014: Identify the main peak position in the relevant result sequence, and determine the theoretical arrival time of the direct signal component based on the main peak position;

[0077] Step 1015: In the relevant result sequence, search for other peak points besides the main peak, and determine the other peak points as abnormal peak points;

[0078] Step 1016: Calculate the delay of each abnormal peak point relative to the theoretical arrival time, and record the delay as abnormal time delay.

[0079] In the above scheme, the timing signal refers to the internally encoded radio wave signal of precise standard time that the Beidou satellite continuously broadcasts to the ground, which is the source of the standard time for the receiver;

[0080] Multipath effect refers to the phenomenon that during the propagation of satellite signals, in addition to reaching the receiver through a straight path, multiple delayed copies of the signal are generated due to reflections from obstacles such as buildings and mountains. These copies of the signal can interfere with the original signal.

[0081] Deceptive interference refers to malicious third-party actions that simulate or forward false satellite signals in an attempt to trick receivers into receiving and using incorrect timing information, thereby causing them to derive incorrect time or location.

[0082] Abnormal delay refers to the abnormal amount of time delay in arrival of the received signal relative to the real signal, in addition to the direct component representing the real signal, caused by reflected signals due to multipath effects and spoofed signals caused by deceptive interference.

[0083] The raw timing signal refers to the initial, unprocessed radio waveform data captured directly from the air by the receiver antenna;

[0084] A chip sequence is a string of digital codes carried in a timing signal, arranged according to specific rules to distinguish different satellites and facilitate receiver identification. It can be understood as the "identity fingerprint" of the signal.

[0085] The local reference sequence refers to a clean copy of the chip sequence that is completely identical to the sequence of chips broadcast by the satellite to be received, which is stored in advance inside the receiver and is used as a standard template for comparison.

[0086] The related result sequence refers to a series of values ​​obtained by comparing the received actual chip sequence with the internal local reference sequence point by point and calculating the similarity. The value reflects the degree of matching between the two sequences at corresponding positions.

[0087] The main peak position refers to the position corresponding to the highest and most prominent peak point in the relevant result sequence. It usually represents the arrival time of the strongest energy and most likely direct satellite signal.

[0088] Direct signal components refer to the portion of the real signal that travels directly from the satellite to the receiver without any reflection or tampering.

[0089] The theoretical arrival time refers to the precise time point at which the direct signal component is most likely to arrive at the receiver, based on the position of the main peak in the relevant result sequence.

[0090] Abnormal peak points refer to peak points in the relevant result sequence that are significantly higher than the background noise, apart from the main peak. They are usually abnormal signal components caused by multipath reflection or deceptive interference.

[0091] The delay refers to the time difference between the time corresponding to each abnormal peak point and the theoretical arrival time, and is used to quantify the degree of lag of the abnormal signal relative to the real signal.

[0092] In this scheme, firstly, the antenna unit of the receiving device captures radio waves from the BeiDou satellite. After down-conversion and analog-to-digital conversion, a string of raw timing signals composed of digital sampling points is obtained. Subsequently, the signal processing unit, according to the known BeiDou signal structure specifications, accurately extracts and separates the core part with specific coding rules used to identify the satellite and transmit time information from this complex digital signal, namely the chip sequence. Next, in order to provide a clean comparison benchmark for subsequent signal analysis, the processor inside the device generates a perfect copy of the desired signal, completely synchronized with it and free from any interference, in real time, based on pre-stored pseudo-random code generation rules that correspond perfectly to the target BeiDou satellite. The local reference sequence, serving as a "standard ruler," has its chip arrangement perfectly consistent with the theoretically transmitted satellite signal. Then, the computing unit performs crucial similarity analysis, comparing the extracted actual chip sequence (which may contain interference) with the generated clean local reference sequence using a "sliding correlation" operation. Specifically, this involves aligning the actual chip sequence and the local reference sequence point-by-point, calculating the sum of their point-by-point products within the local reference sequence to obtain a similarity value. Then, the actual sequence is slid relative to the reference sequence by a very small fixed time interval (e.g., half a chip width), and the sum of the products is calculated again, repeating this process. The better the phase alignment of the two sequences, the larger the calculated sum of the products. Finally, this series of steps... The similarity values ​​calculated from the sliding positions, arranged sequentially, constitute the correlation result sequence. The graphical representation of this sequence typically shows a clear peak at locations of concentrated signal energy. Next, the analysis unit scans the obtained correlation result sequence to find the peak point with the highest amplitude and steepest slope; this is the main peak position. This main peak represents the portion of the received signal with the highest matching degree to the local reference sequence, usually corresponding to the strongest and most direct satellite signal path, i.e., the direct signal component. Based on the index position of this main peak in the sequence, combined with the known sampling rate, the arrival time of this direct signal component at the receiver can be accurately calculated, i.e., the theoretical arrival time. Subsequently, after determining the main peak position, the analysis unit continues to scan the sequence... The remaining part of the result sequence is searched for other peaks whose amplitudes are lower than the main peak but significantly higher than the background noise level. These peaks are considered abnormal signal components, which may originate from building reflections (multipath effect) or maliciously injected fake signals (deceptive interference), and are therefore uniformly identified as anomalous peaks. Finally, for each identified anomalous peak, the processing unit accurately calculates its corresponding time in the relevant result sequence and subtracts the theoretical arrival time determined at this time to obtain the time difference between the two. This time difference is the delay of each anomalous signal component relative to the real direct signal. All calculated delays are systematically recorded to form an anomalous time delay set for subsequent analysis.

[0093] For example, suppose a drone navigation device deployed in a complex urban area of ​​city A needs to obtain precise time. First, its receiving module captures the raw time synchronization signal from Beidou satellite B. The device's internal processor then generates a local reference sequence that perfectly matches the signal format of satellite B. Next, the processor performs a sliding similarity calculation on the actual received signal, which may contain ghosting due to reflections from surrounding buildings C or spoofing due to malicious interference from source D, with the clean internal reference sequence, resulting in an undulating curve, i.e., the correlation result sequence. Analyzing this curve, the device identifies the most significant peak, determines it to be the peak of the real signal directly transmitted from satellite B, and records its position as the theoretical arrival time. At the same time, the device discovers some smaller but obvious abnormal peaks before and after the main peak. The device then calculates the time difference between these abnormal peaks and the main peak. For example, one small peak is delayed by one millionth of a second, and another is delayed by two millionths of a second. These differences are recorded as abnormal delays representing different interference sources.

[0094] This step, by receiving the original signal and performing precise comparison and peak analysis using an internally generated clean reference sequence, can effectively distinguish between the direct component representing the real satellite signal and the anomalous signal components introduced by multipath reflection and deception interference. It also accurately quantifies the anomalous time delay of each anomalous signal relative to the real signal, providing precise input data and judgment criteria for subsequent targeted and adaptive elimination of these interferences, thus laying the foundation for the entire anti-interference processing flow.

[0095] Step 102: Based on the time-domain distribution characteristics of abnormal delay, generate a multi-level anti-interference strategy that matches the propagation environment of BeiDou timing signal. The multi-level anti-interference strategy includes waveform reconstruction rules for multipath effects and pulse masking rules for deceptive interference.

[0096] Optionally, step 102 may specifically include the following steps:

[0097] Step 1021: Perform density analysis on the values ​​of the abnormal delays. Based on the analysis results, abnormal delays with values ​​less than a first preset threshold and distribution less than a second preset value are classified into a first subset, and abnormal delays with values ​​greater than the first preset threshold and distribution greater than the second preset threshold are classified into a second subset.

[0098] Step 1022: Perform a linear mapping operation on each abnormal delay value in the first subset to generate a phase adjustment angle corresponding to each abnormal delay value, and integrate all phase adjustment angles to form a waveform reconstruction rule;

[0099] Step 1023: Perform a window definition operation on each abnormal delay value in the second subset, generate a masking window of fixed time length starting from each abnormal delay value, and integrate all the masking windows to form a pulse masking rule.

[0100] Step 1024: Merge the waveform reconstruction rule and the pulse masking rule to generate a multi-level anti-interference strategy.

[0101] In the above scheme, the time-domain distribution characteristics refer to the distribution of all detected abnormal time delay values ​​in terms of time delay magnitude, including statistical characteristics such as the degree of concentration and dispersion of these values.

[0102] The propagation environment of BeiDou timing signals refers to the total physical conditions that BeiDou satellite signals experience during their propagation from space to the ground receiver, such as whether it is in an urban canyon (significant multipath effect) or whether there are malicious interference sources (high risk of deceptive interference).

[0103] A multi-level anti-interference strategy refers to a comprehensive set of countermeasures. It sets up different levels and different principles of defense rules according to different types of interference (such as multipath effect or deceptive interference), rather than a single treatment method.

[0104] Waveform reconstruction rules are a set of specific instructions that clearly define how to adjust (i.e. reconstruct) the waveform shape at the corresponding delay position in the original signal based on the value of the abnormal delay, especially to perform phase compensation in order to correct signal distortion caused by multipath effects.

[0105] Pulse masking rules are a set of specific instructions that clearly define which specific time periods (i.e. masking windows) on the signal time axis require special filtering or shielding measures to suppress signal components that appear to be deceptive interference during these time periods.

[0106] The first preset threshold refers to a pre-set time threshold value used to distinguish between "small delay" and "large delay". Abnormal delays with a delay time shorter than this threshold are considered to be more likely to be caused by multipath effects.

[0107] The second preset value refers to a pre-set statistical threshold (such as standard deviation, variance, etc.) used to measure the degree of concentration of abnormal delay values. Abnormal delay sets with a distribution range smaller than this value are considered to be more concentrated.

[0108] The first subset refers to the set of abnormal time delays that, after analysis, are classified as being mainly caused by multipath effects. Its typical characteristics are that the values ​​are small (less than the first preset threshold) and the distribution is concentrated (less than the second preset value).

[0109] The second subset refers to the set of abnormal delays that, after analysis, are classified as being mainly caused by deceptive interference. Its typical characteristics are that the values ​​are large (greater than the first preset threshold) and the distribution is scattered (greater than the second preset value).

[0110] The phase adjustment angle refers to the angle value that needs to be rotated or corrected to correct the phase deviation of the signal waveform caused by multipath reflection. This phase adjustment angle is related to the value of abnormal delay through a linear mapping operation.

[0111] Fixed time length refers to a time interval length set for each abnormal delay that is determined to be a deception interference. This interval extends for a fixed period of time starting from the abnormal delay value, and anti-interference measures are activated within this interval.

[0112] A masking window refers to a specific time period on the signal time axis, starting from each abnormal delay value in the second subset and extending for a fixed length. Within this masking window, the signal will be subject to focused inspection and may be filtered.

[0113] In this scheme, firstly, a density analysis is performed on all abnormal delay values ​​obtained by the system. The system calculates the statistical characteristics of these delay values, such as the mean and standard deviation, and observes their clustering on the number axis. Then, the system uses two predefined thresholds: a first preset threshold (used to determine the magnitude of the delay) and a second preset value (used to determine the degree of dispersion of the distribution). The system filters out abnormal delays with smaller values ​​(less than the first preset threshold), smaller differences between them, and a relatively concentrated distribution (their distribution range is smaller than the second preset value), classifying them into one category, called the first subset. This category usually corresponds to multipath interference caused by reflections from nearby objects, with shorter delays and relatively stable characteristics. At the same time, abnormal delays with larger values ​​(greater than the first preset threshold), more dispersed, and a wider distribution range (greater than the second preset value) are filtered out and classified into another category, called the second subset. This category usually corresponds to deceptive interference from different directions or with different delays, with greater variation. Secondly, the system begins to create specific response rules for different types of interference subsets. For the first subset (multipath interference), the system performs a linear mapping operation on each abnormal delay value within the set. This operation is like a simple conversion table: input a time delay value, and it outputs a specific phase adjustment angle according to a preset linear ratio (for example, the larger the delay, the larger the phase angle that needs to be compensated). The system calculates a corresponding phase adjustment angle for each time delay value in the first subset, and then collects and organizes all these correspondences of "time delay value - phase angle" to form a clear instruction manual, namely waveform reconstruction rules. This set of waveform reconstruction rules specifies the specific angle of phase correction that should be performed when the signal encounters a specific multipath delay. Next, the system processes the second subset (deceptive interference). For each abnormal time delay value in this subset, the system performs a window definition operation. This window definition operation takes the time indicated by each time delay value as the starting point and draws a fixed length forward. A defined time interval is used, which is a masking window. The system defines such a masking window for each delay value in the second subset. Then, the start and end time information of all these masking windows are summarized to form another set of instructions, namely the pulse masking rules. This set of pulse masking rules indicates which specific time periods on the signal time axis require the activation of strong filtering measures against spoofing signals. Finally, the system combines the generated waveform reconstruction rules (responsible for fine correction of multipath distortion) and pulse masking rules (responsible for strong suppression of spoofing pulses) into two sets of special strategies for different interferences to form a complete, hierarchical defense scheme, namely a multi-level anti-interference strategy. This multi-level interference strategy enables the system to adaptively call the most appropriate processing means based on the actual detected interference characteristics.

[0114] Following the specific implementation of the previous solution, the UAV navigation device calculates several abnormal latency values, such as one of 0.1 microseconds, two of 0.12 microseconds and 0.15 microseconds respectively, and another of 2.5 microseconds. First, the system performs a density analysis: it finds that the values ​​of 0.1, 0.12, and 0.15 microseconds are all less than a preset threshold (e.g., 0.5 microseconds), and they are close to each other (the distribution range of 0.05 microseconds is less than the preset dispersion threshold of 0.2 microseconds). Therefore, they are classified into the first subset (determined to be multipath reflections from building C). The value of 2.5 microseconds is much greater than the 0.5 microsecond threshold and differs significantly from the other latency values, so it is separately classified into the second subset (determined to be a deceptive signal possibly from malicious interference source D). Next, the system calculates the corresponding phase adjustment angle (1 degree, 1.2 degrees, ...) for each latency value (0.1, 0.12, 0.15 microseconds) in the first subset using a linear mapping (multiplied by a coefficient). The system integrates the delay values ​​of 1.5 microseconds into waveform reconstruction rules. Then, starting from the delay value of 2.5 microseconds in the second subset, the system defines a masking window with a duration of 1 microsecond (i.e., the time period from 2.5 microseconds to 3.5 microseconds) and integrates it into pulse masking rules. Finally, the waveform reconstruction rules for multipath and the pulse masking rules for deception are merged to generate a complete multi-level anti-interference strategy.

[0115] This step intelligently classifies detected abnormal delays and generates targeted signal processing rules based on the classification results, achieving adaptive customization of anti-interference strategies. It distinguishes complex interference environments into multipath effects and deceptive interference with distinct characteristics, and equips them with two different levels of processing methods: fine waveform correction and coarse-grained pulse masking. This allows subsequent signal processing to be targeted, effectively suppressing interference while minimizing unnecessary damage to useful signals, thus improving the accuracy and overall efficiency of anti-interference processing.

[0116] Step 103: Use waveform reconstruction rules to perform phase compensation on the chip sequence in the timing signal that is affected by multipath, and generate an anti-multipath enhancement signal.

[0117] Optionally, step 103 may specifically include the following steps:

[0118] Step 1031: Read the phase adjustment angle corresponding to the value of each abnormal delay from the waveform reconstruction rules;

[0119] Step 1032: Locate the delay position chip corresponding to the value of each abnormal delay in the chip sequence of the timing signal;

[0120] Step 1033: Apply a corresponding phase adjustment angle to each delayed position chip to generate a phase-adjusted chip;

[0121] Step 1034: Replace the corresponding chip in the timing signal with the phase-adjusted chip to generate the initial enhancement signal;

[0122] Step 1035: Perform waveform smoothing on the initial enhancement signal to eliminate phase transitions between chips and generate an anti-multipath enhancement signal.

[0123] In the above scheme, the anti-multipath enhancement signal refers to the signal obtained after processing. The waveform distortion (especially phase distortion) caused by multipath effect is specifically corrected and compensated. The signal quality is significantly improved compared with the original timing signal, and the anti-multipath interference capability is enhanced.

[0124] The phase adjustment angle refers to an angle value preset from the waveform reconstruction rules for a specific abnormal delay value. This angle value is used to indicate how many degrees the waveform at the corresponding position in the original signal needs to be rotated to compensate for the phase deviation caused by multipath reflection.

[0125] Delayed position chips refer to those specific chips in the chip sequence of the timing signal that are delayed relative to the main signal (direct signal) on the time axis. Their position chips are precisely determined by the value of the abnormal time delay. These chips are the parts most directly affected by multipath.

[0126] A phase-adjusted chip refers to a new chip obtained by rotating and correcting the original delayed chip by applying its corresponding phase adjustment angle. The waveform shape of the new chip has been corrected and is closer to the ideal state.

[0127] The initial enhancement signal refers to the new signal formed by replacing all the identified delay position chips in the original timing signal with their corresponding phase-adjusted chips. At this time, the main multipath distortion of the new signal has been corrected, but the chip connection may not be smooth.

[0128] Phase jumps refer to a sudden, discontinuous change in the waveform phase between the adjusted chip and the unadjusted chips before and after it in the initial enhancement signal due to independent phase adjustments to individual chips. This jump itself is a distortion and requires smoothing.

[0129] In this scheme, firstly, the waveform reconstruction rules generated by the processing system (which can be viewed as a "delay-phase adjustment" lookup table) are read one by one from each abnormal delay value classified as multipath interference and its corresponding phase adjustment angle; for example, for an abnormal delay of 0.1 microseconds, an adjustment of 1 degree is required; for 0.12 microseconds, an adjustment of 1.2 degrees is required, etc., clarifying which points of the signal need to be corrected and by how much; secondly, based on each abnormal delay value read, the system performs precise... The system first locates the specific time point corresponding to each abnormal delay value and identifies the corresponding chip(s) at that time point. These chips are the delay position chips that need to be corrected, mapping the abstract delay value to specific data points in the signal that need to be processed. Next, the system performs a phase rotation operation on each located delay position chip. Specifically, the system acquires the original waveform data of that delay position chip (usually represented by a complex number, including amplitude and phase), and then adds (or subtracts, according to convention) its phase value from the waveform reconstruction rules. The system generates a new, phase-corrected chip by adjusting the corresponding phase angle. This new chip is similar to the original chip in waveform, but its phase is shifted to compensate for the phase error introduced by multipath propagation. Then, the system uses all the generated phase-corrected chips to replace the original chips at corresponding positions in the chip sequence of the original timing signal. After the replacement, the entire signal becomes the initial enhancement signal. At this point, the main multipath distortion points identified in the initial enhancement signal are directly corrected at the waveform level. Finally, the system performs waveform smoothing on the initial enhancement signal. Because the replacement is done chip by chip, there may be phase discontinuities, i.e., phase jumps, at the connection between the replaced phase-corrected chip and the unreplaced chips before and after it. The system uses signal processing techniques such as digital filtering or interpolation to smooth the transition at the boundaries of these chips, eliminating abrupt phase jumps and making the waveform of the entire signal continuous and smooth. The final output after this step is the anti-multipath enhancement signal with significantly improved quality.

[0130] Following the specific implementation of the previous solution, the UAV navigation device has generated waveform reconstruction rules, for example: a delay of 0.1 microseconds corresponds to an adjustment of 1 degree, 0.12 microseconds corresponds to 1.2 degrees, and 0.15 microseconds corresponds to 1.5 degrees. First, the system reads these delay values ​​and their corresponding phase adjustment angles from these waveform reconstruction rules. Second, in the received original timing signal chip sequence, the system finds those chips that are delayed by 0.1 microseconds, 0.12 microseconds, and 0.15 microseconds respectively, and marks them as delayed position chips. Then, the system... The system applies phase rotations of 1 degree, 1.2 degree, and 1.5 degree to these located chips, generating three phase-adjusted chips. The system then replaces the old chips at the corresponding positions in the original signal with these three new chips, forming the initial enhancement signal. At this point, the phase deviation caused by the reflection from Building C in the initial enhancement signal has been preliminarily corrected. Finally, the system performs smoothing filtering on the initial enhancement signal to eliminate the slight discontinuities (phase jumps) generated at the chip boundaries due to the phase adjustment of individual chips, ultimately outputting a smooth waveform and improved quality anti-multipath enhancement signal.

[0131] This step accurately locates the signal chip affected by multipath interference according to preset rules and applies precise phase compensation, effectively correcting the signal waveform distortion caused by multipath effects. Subsequently, waveform smoothing eliminates the connection non-smoothness problem that may be introduced by local correction, and finally generates an enhanced signal with higher waveform quality and significantly suppressed multipath interference, providing a cleaner signal foundation for further processing of deceptive interference.

[0132] Step 104: Based on the pulse masking rule, identify the injection window of the deceptive interference in the time-frequency domain of the anti-multipath enhancement signal, and introduce random polarization filtering in the injection window to suppress the deceptive component, thereby obtaining the polarization filtered signal.

[0133] Optionally, step 104 may specifically include the following steps:

[0134] Step 1041: Extract the start and end time information of all occlusion windows from the pulse occlusion rules;

[0135] Step 1042: Based on the time series of the anti-multipath enhancement signal, mark the start and end time points of each occlusion window from the start and end time information of all extracted occlusion windows;

[0136] Step 1043: Mark the signal segment between each start time point and end time point as the signal segment to be processed;

[0137] Step 1044: Perform a random number generation operation on each signal segment to be processed to generate a random number sequence equal to the number of sampling points in the signal segment to be processed;

[0138] Step 1045: Map each random number in the random number sequence to a preset polarization angle value to generate a random polarization direction sequence;

[0139] Step 1046: Based on each polarization angle value in the random polarization direction sequence, the signal amplitude of the corresponding sampling point in the signal segment to be processed is proportionally adjusted to generate a random polarization signal segment.

[0140] Step 1046 may specifically include the following steps:

[0141] According to the order of appearance of the sampling points in the signal segment to be processed, the original signal amplitude value of each sampling point is read sequentially; at the same time, according to the order of arrangement of polarization angle values ​​in the random polarization direction sequence, each polarization angle value is read sequentially; each polarization angle value is converted into an amplitude scaling factor; the original signal amplitude value of each sampling point is multiplied by the amplitude scaling factor corresponding to the polarization angle value at the same position of the sampling point to obtain the adjusted signal amplitude value of the sampling point; the adjusted signal amplitude values ​​of all sampling points are arranged according to the order of appearance of the sampling points to form a random polarization signal segment.

[0142] Step 1047: Replace the corresponding original signal segment in the anti-multipath enhancement signal with the random polarization signal segment to obtain the polarization filtered signal.

[0143] In the above scheme, the time-frequency domain refers to the field where signals are observed and analyzed simultaneously from both time and frequency dimensions. Here, it refers to focusing on the signal characteristics within a specific time period (i.e., the injection window) on the time axis of anti-multipath enhancement signals.

[0144] The injection window refers to the specific time period on the signal's time axis when a deceptive interference signal is suspected of being injected. Its location is determined by the masking window defined in the pulse masking rules.

[0145] Random polarization filtering is a signal processing technique that disrupts specific signal components by randomly changing the polarization state of a signal waveform (similar to changing the polarization direction of a light wave). In this context, it refers to randomly adjusting the signal amplitude within the injection window to suppress deceptive components.

[0146] A polarization-filtered signal refers to a signal obtained after random polarization filtering, in which deceptive interference components are effectively suppressed.

[0147] Start and end time information refers to the start and end times of each occlusion window extracted from the pulse occlusion rules;

[0148] The start time point refers to the specific time point at which each masking window begins in the time series of the anti-multipath enhancement signal;

[0149] The termination point refers to the specific time point at which each masking window ends in the time series of the anti-multipath enhancement signal;

[0150] The signal segment to be processed refers to the portion of signal data between the start and end points in the anti-multipath enhancement signal, which is the area that needs to be processed to resist spoofing.

[0151] The number of sampling points refers to the total number of discrete data points contained in the signal segment to be processed;

[0152] A random number sequence is a string of values ​​generated by a random number generator. Its length is equal to the number of sampling points of the signal segment to be processed, and each value is randomly distributed within a specific range (such as between 0 and 1).

[0153] The preset polarization angle values ​​refer to a predefined set of angle values ​​used to represent different polarization states (such as 0 degrees, 45 degrees, 90 degrees, 135 degrees, etc.).

[0154] A random polarization direction sequence refers to a sequence of polarization angles formed by mapping each random number in a random number sequence to a preset polarization angle value according to a mapping rule. The polarization direction of this polarization angle sequence is random.

[0155] A random polarization signal segment refers to a new signal segment obtained after applying a random polarization direction sequence to the signal segment to be processed for amplitude adjustment;

[0156] The order of appearance refers to the order in which the sampling points in the signal are arranged according to time.

[0157] The original signal amplitude value refers to the signal strength value of each sampling point in the signal segment to be processed before processing;

[0158] The amplitude scaling factor is a scaling factor obtained from the polarization angle value, used to scale the amplitude value of the original signal.

[0159] Adjusting the signal amplitude value refers to multiplying the original signal amplitude value by the corresponding amplitude scaling factor to obtain the new signal amplitude value.

[0160] In this scheme, firstly, the start and end time information of all predefined masking windows for combating deception interference is extracted from the pulse masking rules generated by the processing system. This start and end time information clarifies which time periods on the signal time axis require special attention and processing. Secondly, the system maps the start and end times of each extracted masking window onto the discrete time series of the anti-multipath enhancement signal, precisely marking the specific index positions of the start and end times of each window in the signal data array. Next, based on each marked start and end time point, the system extracts the signal data between the two points from the anti-multipath enhancement signal and marks these signal data segments as follows: The system identifies the signal segments to be processed, each segment being a local signal region requiring anti-spoofing filtering. For each segment, the system independently generates a random number sequence. This sequence contains the same number of random numbers as the number of sampling points within the segment, ensuring that each point can be processed subsequently. Then, the system converts each random number in the generated sequence into a specific polarization angle value based on a preset mapping (e.g., uniformly mapping random numbers between 0 and 1 to angles between 0 and 180 degrees). All these polarization angle values ​​are then processed sequentially. The sequential arrangement forms a random polarization direction sequence, which assigns a random polarization adjustment direction to each sampling point in the signal segment to be processed. Then, the system begins substantive filtering of the signal segment. It reads the original signal amplitude value of each sampling point sequentially according to their appearance time; simultaneously, it reads the corresponding polarization angle value for each point sequentially according to the random polarization direction sequence. The system then converts each polarization angle value into an amplitude scaling factor (e.g., through a cosine function transformation), and multiplies the original signal amplitude value of each sampling point by the amplitude scaling factor corresponding to the polarization angle value in the same sequential position. The system obtains the amplitude value of the adjusted signal at the sampling point. Finally, the amplitude values ​​of the adjusted signals at all sampling points are rearranged strictly according to their original time sequence to form the processed random polarization signal segment. This random polarization signal segment maintains the basic timing structure of the original signal, but the amplitude is randomly modulated. Finally, the system replaces the corresponding original signal segment to be processed in the anti-multipath enhancement signal with the generated random polarization signal segment. After the replacement, random polarization filtering is only performed in the time window where deception interference is suspected, while the signal in other parts remains unchanged. The final signal obtained in this way is the polarization filtered signal, in which the deception component is effectively suppressed.

[0161] Following the specific implementation of the previous solution, the UAV equipment already has pulse masking rules, specifying that there is a masking window from 2.5 microseconds to 3.5 microseconds on the signal time axis (corresponding to suspected interference source D). First, the system extracts the start and end times of this masking window (2.5µs, 3.5µs). Second, the system finds the start and end times corresponding to 2.5µs and 3.5µs on the time series of the anti-multipath enhancement signal (assumed to be the 2501st and 3501st sampling points). Then, the system extracts the 1001 sampling points between these two points and marks them as the signal segment to be processed. Then, the system generates a random number sequence containing 1001 random numbers between 0 and 1. Subsequently, these random numbers are mapped to polarization angles (e.g., 0->0°, 0.25->45°, 0.5->90°, 0.75->135°). (1.0->180°), generating a random polarization direction sequence; then the system sequentially reads the original signal amplitude values ​​of 1001 sampling points in the signal segment to be processed, and simultaneously reads 1001 angle values ​​in the random polarization direction sequence, converting each angle value into an amplitude scaling factor (such as cos(angle)), and then multiplying the amplitude value of each sampling point by the corresponding coefficient to obtain 1001 adjusted signal amplitude values, which are then arranged in the original order into a random polarization signal segment; finally, this new signal segment replaces the 2.5us to 3.5us portion of the original signal to obtain the polarization filtered signal, and the deception interference within this time period is suppressed by randomization processing.

[0162] This step accurately locates the signal time periods suspected of being spoofing interference based on preset rules, and introduces amplitude modulation based on random polarization direction within these specific windows, effectively destroying the structural correlation of the spoofing signal. At the same time, due to the randomness of the modulation mode, the spoofing source is difficult to predict and adapt to. Thus, while preserving the basic framework of the useful signal, the spoofing interference components are significantly suppressed, generating a filtered signal with enhanced anti-spoofing capability.

[0163] Step 105: Synchronize the polarization filter signal with the local clock and output the anti-interference BeiDou time information.

[0164] Optionally, step 105 may specifically include the following steps:

[0165] Step 1051: Starting from the predetermined starting position of the polarization filter signal, extract consecutive chip sequences as synchronization comparison units.

[0166] Step 1052: Perform a chip-by-chip consistency comparison between each of the synchronization comparison units and the preset ideal chip sequence;

[0167] Step 1053: Count the number of chips in each synchronization comparison unit that match the ideal chip sequence, and record them as the number of matching chips;

[0168] Step 1054: Identify the maximum synchronization comparison unit of the number of consistent chips, and identify the starting position of the maximum synchronization comparison unit in the polarization filter signal as the frame synchronization point;

[0169] Step 1055: Based on the frame synchronization point, parse the time information chip carried in the polarization filter signal and translate the time information chip into the corresponding BeiDou system time data;

[0170] Step 1056: Compare the BeiDou system time data with the current time data of the local clock to calculate the time difference;

[0171] Step 1057: Input the time difference value into the adjustment mechanism of the local clock and output the anti-interference BeiDou time information.

[0172] In the above scheme, the BeiDou time synchronization information refers to the highly reliable standard time information finally recovered from the BeiDou signal after anti-interference processing, which can be used to accurately synchronize various devices;

[0173] Synchronous comparison units refer to a sequence of consecutive chips extracted sequentially from the polarized filtered signal in chronological order. These comparison units are used to match the signal with the ideal signal in order to find the starting position of the signal frame.

[0174] The preset ideal chip sequence refers to a known, pure chip sequence that is pre-stored inside the receiver and is completely consistent with a specific field (such as the frame header or synchronization code) used for synchronization in the BeiDou satellite signal frame structure, serving as a standard template for comparison;

[0175] Consistency comparison refers to the process of comparing each chip in the synchronization comparison unit with the chips in the same position in the preset ideal chip sequence one by one to determine whether they are the same (consistent).

[0176] The number of consistent chips refers to the total number of chips in a synchronization comparison unit that are completely consistent with the chips at the corresponding positions of the preset ideal chip sequence. This number reflects the degree of matching between the signal segment and the ideal synchronization sequence.

[0177] The maximum synchronization alignment unit refers to the unit with the maximum number of consistent chips among all the synchronization alignment units in the sliding truncation, indicating that the alignment unit has the highest matching degree with the ideal synchronization sequence;

[0178] The frame synchronization point refers to the starting position of the maximum synchronization comparison unit in the polarization filter signal. This frame synchronization point marks the beginning of a complete data frame of the BeiDou signal and is the basis for subsequent time information analysis.

[0179] Time information chips refer to those specific chips that follow the frame synchronization header and are used to carry precise time data in the BeiDou signal frame structure.

[0180] BeiDou system time data refers to the specific date, hour, minute, second, and other time values ​​obtained after decoding the time information chip according to the BeiDou signal protocol;

[0181] Current time data refers to the time reading currently maintained by the device's local clock;

[0182] The time difference refers to the difference between the decoded BeiDou system time data and the current time data of the local clock.

[0183] In this scheme, firstly, the processing system starts from a predetermined starting point of the polarization-filtered signal (usually the beginning of the signal buffer) and sequentially extracts a continuous sequence of chips of the same length as the ideal synchronization header using a sliding window approach. Each extracted segment is called a synchronization comparison unit, and the system continuously generates multiple such units. Each comparison unit slides one or several chip positions relative to the previous comparison unit. Secondly, the system performs a consistency comparison between each generated synchronization comparison unit and a pre-stored preset ideal chip sequence (i.e., a standard frame synchronization header pattern). This process is performed chip by chip, comparing the two sequences... The system checks if the chips at the first position match, then the second position, and so on, until the entire sequence length is compared. Next, it counts the number of chips in each synchronization comparison unit that perfectly match the preset ideal chip sequence at the corresponding position during the comparison process, and records this number as the number of matching chips for that comparison unit. The higher this number, the higher the similarity between the signal segment and the ideal synchronization header. Then, among all the slidingly generated synchronization comparison units, the system finds the unit with the maximum number of matching chips, i.e., the maximum synchronization comparison unit. This maximum synchronization unit is considered to be the part that best matches the satellite signal frame header, and the system places this maximum synchronization unit in... The precise start position of the polarization-filtered signal data stream is recorded, and this position is identified as the frame synchronization point. Finding the frame synchronization point is equivalent to finding the "beginning" of the signal data frame. Subsequently, based on the found frame synchronization point and according to the BeiDou signal frame format protocol, the system extracts the time information chips specifically used for transmitting time from the specified positions after the frame synchronization point in the polarization-filtered signal. Then, according to the BeiDou signal encoding rules, the system translates (decodes) these time information chips into specific, readable BeiDou system time data, such as "2023 Year X Month Y Day Z Hour W Minute V Second". Afterward, the system decodes the BeiDou system time data from the signal... The system compares the current time data displayed by the device's own local clock with the actual time data and calculates the difference between the two, i.e., the time difference. This time difference quantifies the deviation of the local clock from the BeiDou standard time. Finally, the system uses the calculated time difference as input to the local clock's adjustment mechanism (e.g., a phase-locked loop or software calibration algorithm). This adjustment mechanism will fine-tune the local clock's running rate or directly correct its time reading based on this difference, so that the local clock keeps synchronized with the BeiDou standard time. At this point, the time output by the local clock, or the time given by the system based on the synchronized local clock, is the final, interference-resistant BeiDou time information.

[0184] Following the specific implementation of the previous solution, the UAV equipment obtains a polarized filtered signal that suppresses multipath effects and spoofing interference. First, starting from the beginning of the signal, the system extracts 100 chips at a time as a synchronization comparison unit (assuming the synchronization header is 100 chips long). Then, it slides one chip and extracts the next 100-chip unit, repeating this process. Next, each extracted unit is compared for consistency with the internally stored standard synchronization header pattern of 100 chips, checking for identical patterns chip by chip. Then, the number of chips in each unit that match the standard pattern is counted; for example, the first unit has 30 identical chips, the second has 35, and so on... The Nth unit has 95 consistent chips; then it is found that the number of consistent chips in the Nth unit is the largest, so it is determined as the largest synchronization comparison unit, and its starting position is recorded as the frame synchronization point; then, according to the protocol, starting from the 101st chip after the frame synchronization point, the subsequent 50 time information chips are parsed, and the BeiDou time "October 27, 2023, 10:30:00:100 milliseconds" is obtained after decoding; then, this time is compared with the local clock "October 27, 2023, 10:30:00:30 milliseconds", and the time difference is calculated to be 200 milliseconds (the local clock is 200 milliseconds fast); finally, this 200-millisecond difference is sent to the clock adjustment module to fine-tune the local clock, making it slow down a little, and finally outputting the BeiDou time information synchronized with BeiDou time and anti-interference.

[0185] This step successfully recovered standard BeiDou time information from the interfered signal by accurately capturing and decoding the purified signal frame synchronization. By comparing and calibrating the recovered time with the local clock, the accumulated error of the local clock was effectively eliminated. Finally, a high-precision and high-reliability time synchronization result was output, which resisted the effects of multipath and deception interference during transmission and corrected the local clock drift. This completed the entire recovery process from the damaged signal to reliable time information.

[0186] Figure 2 This application provides a schematic diagram of the structure of a BeiDou timing signal protection system based on adaptive anti-interference, as shown below. Figure 2 As shown, the system includes:

[0187] The receiving module 21 is used to receive the timing signal broadcast by the Beidou satellite and detect abnormal delays in the timing signal caused by multipath effects and deceptive interference.

[0188] The generation module 22 is used to generate a multi-level anti-interference strategy that matches the propagation environment of the BeiDou timing signal based on the time-domain distribution characteristics of the abnormal delay. The multi-level anti-interference strategy includes waveform reconstruction rules for multipath effects and pulse masking rules for deceptive interference.

[0189] Compensation module 23 is used to perform phase compensation on the chip sequence affected by multipath in the timing signal using waveform reconstruction rules, and generate an anti-multipath enhancement signal;

[0190] The suppression module 24 is used to identify the injection window of the deceptive interference in the time-frequency domain of the anti-multipath enhancement signal based on the pulse masking rule, and introduce random polarization filtering in the injection window to suppress the deceptive component, thereby obtaining the polarization filtered signal.

[0191] The calculation module 25 is used to synchronize the polarization filter signal with the local clock and output the anti-interference BeiDou time information.

[0192] Figure 2 The aforementioned BeiDou timing signal protection system based on adaptive anti-interference can perform... Figure 1 The implementation principle and technical effects of the BeiDou timing signal protection method based on adaptive anti-interference described in the illustrated embodiment will not be repeated here. The specific operation methods of each module and unit in the BeiDou timing signal protection system based on adaptive anti-interference in the above embodiments have been described in detail in the embodiments related to this method, and will not be elaborated upon here.

[0193] In one possible design, Figure 2 The BeiDou timing signal protection system based on adaptive anti-interference in the illustrated embodiment can be implemented as a computing device, such as... Figure 3 As shown, the computing device may include a storage component 31 and a processing component 32;

[0194] The storage component 31 stores one or more computer instructions, wherein the one or more computer instructions are invoked and executed by the processing component 32.

[0195] The processing component 32 is used for the above Figure 1 The embodiment describes a method for protecting BeiDou timing signals based on adaptive anti-interference.

[0196] The processing component 32 may include one or more processors to execute computer instructions to complete all or part of the steps in the above-described method. Alternatively, the processing component may be implemented as one or more application-specific integrated circuits (ASICs), digital signal processors (DSPs), digital signal processing devices (DSPDs), programmable logic devices (PLDs), field-programmable gate arrays (FPGAs), controllers, microcontrollers, microprocessors, or other electronic components to perform the above-described method.

[0197] Storage component 31 is configured to store various types of data to support operations at the terminal. The storage component can be implemented by any type of volatile or non-volatile storage device or a combination thereof, such as static random access memory (SRAM), electrically erasable programmable read-only memory (EEPROM), erasable programmable read-only memory (EPROM), programmable read-only memory (PROM), read-only memory (ROM), magnetic storage, flash memory, magnetic disk, or optical disk.

[0198] Of course, computing devices may also include other components, such as input / output interfaces, display components, communication components, etc.

[0199] Input / output interfaces provide interfaces between processing components and peripheral interface modules, which can be output devices, input devices, etc.

[0200] The communication components are configured to facilitate wired or wireless communication between computing devices and other devices.

[0201] The computing device can be a physical device or an elastic computing host provided by a cloud computing platform. In this case, the computing device can refer to a cloud server, and the aforementioned processing components, storage components, etc., can be basic server resources rented or purchased from the cloud computing platform.

[0202] This application also provides a computer storage medium storing a computer program, which, when executed by a computer, can perform the above-described functions. Figure 1 The embodiment shown is a method for protecting BeiDou timing signals based on adaptive anti-interference.

[0203] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the specific working processes of the systems, devices, and units described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here.

[0204] The device embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs. Those skilled in the art can understand and implement this without any creative effort.

[0205] Through the above description of the embodiments, those skilled in the art can clearly understand that each embodiment can be implemented by means of software plus necessary general-purpose hardware platforms, and of course, it can also be implemented by hardware. Based on this understanding, the above technical solutions, in essence or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, magnetic disk, optical disk, etc., and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute the methods described in the various embodiments or some parts of the embodiments.

[0206] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application.

Claims

1. A method for protecting BeiDou timing signals based on adaptive anti-interference, characterized in that, include: Receiving timing signals broadcast by BeiDou satellites and detecting abnormal delays in the timing signals introduced by multipath effects and spoofing interference includes: receiving the original timing signal broadcast by BeiDou satellites and extracting the chip sequence from the original timing signal; constructing a local reference sequence to match the chip sequence; performing a sliding correlation operation on the chip sequence and the local reference sequence to generate a correlation result sequence; identifying the main peak position in the correlation result sequence and determining the theoretical arrival time of the direct signal component based on the main peak position; searching for other peak points besides the main peak in the correlation result sequence and identifying the other peak points as abnormal peak points; calculating the delay of each abnormal peak point relative to the theoretical arrival time and recording the delay as an abnormal delay. Based on the time-domain distribution characteristics of abnormal delays, a multi-level anti-interference strategy matching the propagation environment of BeiDou timing signals is generated. The multi-level anti-interference strategy includes waveform reconstruction rules for multipath effects and pulse masking rules for deceptive interference. Phase compensation is performed on the chip sequence in the timing signal affected by multipath using waveform reconstruction rules to generate an anti-multipath enhancement signal; Based on the pulse masking rule, injection windows for deceptive interference are identified in the time-frequency domain of the anti-multipath enhancement signal. Random polarization filtering is introduced within these injection windows to suppress deceptive components, resulting in a polarization-filtered signal. The process includes: extracting the start and end time information of all masking windows from the pulse masking rule; marking the start and end times of each masking window from the extracted start and end time information based on the time series of the anti-multipath enhancement signal; marking the signal segment between each start and end time point as a signal segment to be processed; performing a random number generation operation on each signal segment to generate a random number sequence equal to the number of sampling points within the signal segment; mapping each random number in the random number sequence to a preset polarization angle value to generate a random polarization direction sequence; proportionally adjusting the signal amplitude of the corresponding sampling point in the signal segment to be processed according to each polarization angle value in the random polarization direction sequence to generate a random polarization signal segment; and replacing the corresponding original signal segment in the anti-multipath enhancement signal with the random polarization signal segment to obtain the polarization-filtered signal. The polarization filter signal is synchronized with the local clock to output the anti-interference BeiDou time information.

2. The method according to claim 1, characterized in that, Based on the time-domain distribution characteristics of abnormal delays, a multi-level anti-interference strategy matching the propagation environment of BeiDou timing signals is generated. This multi-level anti-interference strategy includes waveform reconstruction rules for multipath effects and pulse masking rules for deceptive interference, including: A density analysis is performed on the values ​​of the abnormal delays. Based on the analysis results, abnormal delays with values ​​less than a first preset threshold and distribution less than a second preset value are classified into a first subset, and abnormal delays with values ​​greater than the first preset threshold and distribution greater than the second preset threshold are classified into a second subset. Perform a linear mapping operation on each abnormal delay value in the first subset to generate a phase adjustment angle corresponding to each abnormal delay value, and integrate all phase adjustment angles to form a waveform reconstruction rule; For each abnormal delay value in the second subset, a window definition operation is performed to generate a masking window of fixed time length starting from each abnormal delay value. All masking windows are then integrated to form a pulse masking rule. The waveform reconstruction rule and the pulse masking rule are merged to generate a multi-level anti-interference strategy.

3. The method according to claim 1, characterized in that, Phase compensation is performed on the chip sequence in the timing signal affected by multipath propagation using waveform reconstruction rules to generate an anti-multipath enhancement signal, including: Read the phase adjustment angle corresponding to the value of each abnormal delay from the waveform reconstruction rules; In the chip sequence of the timing signal, locate the delay position chip corresponding to the value of each abnormal delay; Apply a corresponding phase adjustment angle to each of the delayed position chips to generate phase-adjusted chips; The initial enhancement signal is generated by replacing the corresponding chip in the timing signal with a phase-adjusted chip. The initial enhancement signal is subjected to waveform smoothing to eliminate phase jumps between chips and generate an anti-multipath enhancement signal.

4. The method according to claim 1, characterized in that, Based on each polarization angle value in the random polarization direction sequence, the signal amplitude of the corresponding sampling point in the signal segment to be processed is proportionally adjusted to generate a random polarization signal segment, including: Read the original signal amplitude value of each sampling point in the order of appearance of the sampling points in the signal segment to be processed; Simultaneously, each polarization angle value is read sequentially according to the arrangement order of the polarization angle values ​​in the random polarization direction sequence; Each polarization angle value is converted into an amplitude scaling factor; The original signal amplitude value of each sampling point is multiplied by the amplitude scaling factor corresponding to the polarization angle value of the sampling point in the same order position to obtain the adjusted signal amplitude value of the sampling point. The amplitude values ​​of the adjusted signals at all sampling points are arranged in chronological order of their occurrence to form a random polarization signal segment.

5. The method according to claim 1, characterized in that, The polarization-filtered signal is synchronized with the local clock to output the anti-interference BeiDou time information, including: Starting from the predetermined starting position of the polarization filter signal, a continuous sequence of chips is extracted as a synchronization comparison unit. Each of the synchronization comparison units is compared with a preset ideal chip sequence for chip-by-chip consistency. The number of chips in each synchronization comparison unit that match the ideal chip sequence is counted and recorded as the number of matching chips. The maximum synchronization comparison unit that identifies the number of consistent chips is identified, and the starting position of the maximum synchronization comparison unit in the polarization filter signal is identified as the frame synchronization point. Based on the frame synchronization point, the time information chip carried in the polarization filter signal is parsed, and the time information chip is translated into the corresponding BeiDou system time data. The time difference is calculated by comparing the BeiDou system time data with the current time data of the local clock. The time difference is input into the local clock adjustment mechanism to output the anti-interference BeiDou time synchronization information.

6. A BeiDou timing signal protection system based on adaptive anti-interference, applied to the BeiDou timing signal protection method based on adaptive anti-interference as described in any one of claims 1-5, characterized in that, include: The receiving module is used to receive the timing signal broadcast by the BeiDou satellite and detect abnormal delays in the timing signal caused by multipath effects and deceptive interference. The generation module is used to generate a multi-level anti-interference strategy that matches the propagation environment of the BeiDou timing signal based on the time-domain distribution characteristics of abnormal delays. The multi-level anti-interference strategy includes waveform reconstruction rules for multipath effects and pulse masking rules for deceptive interference. The compensation module is used to perform phase compensation on the chip sequence in the timing signal that is affected by multipath using waveform reconstruction rules, and generate an anti-multipath enhancement signal. The suppression module is used to identify the injection window of deceptive interference in the time-frequency domain of the anti-multipath enhancement signal based on the pulse masking rule, and introduce random polarization filtering in the injection window to suppress the deceptive component, thereby obtaining the polarization filtered signal. The calculation module is used to synchronize the polarization filter signal with the local clock and output the anti-interference BeiDou time information.

7. A computing device, characterized in that, It includes a processing component and a storage component; the storage component stores one or more computer instructions; the one or more computer instructions are invoked and executed by the processing component to implement the BeiDou timing signal protection method based on adaptive anti-interference as described in any one of claims 1 to 5.

8. A computer storage medium, characterized in that, The system contains a computer program that, when executed by a computer, implements a BeiDou timing signal protection method based on adaptive anti-interference as described in any one of claims 1 to 5.

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