Beidou communication method and system in electromagnetic suppression scene

Abstract

The application belongs to the technical field of satellite communication, and discloses a Beidou communication method and system under an electromagnetic suppression scene. The method first senses the electromagnetic environment around the Beidou terminal device; then judges whether there is electromagnetic suppression interference in the electromagnetic environment from the energy domain and the time-frequency domain, and judges whether the current communication scene is an electromagnetic suppression scene or a normal communication scene; if it is judged that the current communication scene is an electromagnetic suppression scene, the electromagnetic suppression interference is extracted and analyzed, and the type of the electromagnetic suppression interference is further judged; then countermeasures are taken according to the type of the electromagnetic suppression interference; finally, the Beidou communication configuration is adjusted according to the current communication scene, and the Beidou communication is completed. The Beidou communication method can accurately judge whether there is electromagnetic suppression in the surrounding environment, and timely countermeasures are taken to adjust the Beidou communication configuration under the electromagnetic suppression scene, so as to ensure the communication quality and system stability, and improve the accuracy and reliability of the Beidou communication.

Description

Technical Field

[0001] This invention belongs to the field of satellite communication technology, specifically relating to a BeiDou communication method and system under electromagnetic suppression scenarios. Background Technology

[0002] Global Navigation Satellite Systems (GNSS) possess unique advantages such as all-weather operation, wide coverage, and high positioning accuracy, and have become an indispensable infrastructure for modern information society. The BeiDou Navigation Satellite System is a global satellite navigation system independently developed by my country. Currently, the BeiDou-3 system has been completed, put into operation, and is running stably. This system can provide navigation, positioning, timing, and communication services to users worldwide and is widely used in many key areas such as transportation, agricultural production, and emergency rescue.

[0003] However, with the widespread adoption and in-depth application of the BeiDou Navigation Satellite System, the external challenges it faces are becoming increasingly prominent, especially the navigation countermeasures issue, which has become a significant hidden danger. Electromagnetic jamming, as one of the commonly used jamming methods in navigation countermeasures, works by transmitting high-power electromagnetic waves to cause interference. These electromagnetic waves cover the receiver's operating frequency band, causing a decline in signal reception quality and making it difficult for the receiver to extract effective information from the noise. This affects the normal operation of terminal equipment that relies on GNSS for communication and navigation services. Especially in strong electromagnetic jamming scenarios, various terminal devices using the BeiDou satellite navigation system will be unable to function properly, seriously affecting the accuracy and reliability of BeiDou communication.

[0004] Therefore, researching a communication method that can effectively resist electromagnetic suppression interference and ensure stable and reliable BeiDou communication quality under electromagnetic suppression scenarios has become an urgent technical problem to be solved. Summary of the Invention

[0005] The purpose of this invention is to propose a BeiDou communication method under electromagnetic suppression scenarios. This method can counteract electromagnetic suppression scenarios in a timely manner and adjust the BeiDou communication configuration, ensuring the communication quality of BeiDou terminal equipment and improving the accuracy and reliability of BeiDou communication.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A BeiDou communication method under electromagnetic suppression scenarios includes the following steps:

[0008] Step 1. Sensing the electromagnetic environment around the Beidou terminal device;

[0009] Step 2. Determine whether electromagnetic suppression interference exists in the electromagnetic environment from the energy domain and time-frequency domain.

[0010] If electromagnetic suppression interference exists in the electromagnetic environment, the current communication scenario is determined to be an electromagnetic suppression scenario and the process proceeds to step 3; if electromagnetic suppression interference does not exist in the electromagnetic environment, the current communication scenario is determined to be a normal communication scenario and the process proceeds to step 5.

[0011] Step 3. Separate electromagnetic suppression interference from the mixed signals of the electromagnetic environment, and extract features from the electromagnetic suppression interference to determine the type of electromagnetic suppression interference;

[0012] Step 4. Countermeasures against the types of electromagnetic suppression interference;

[0013] Step 5. Adjust the BeiDou communication configuration according to the current communication scenario and complete the BeiDou communication.

[0014] Furthermore, based on the BeiDou communication method under electromagnetic suppression scenarios, this invention also proposes a BeiDou communication system adapted to electromagnetic suppression scenarios, which adopts the following technical solution:

[0015] A BeiDou communication system under electromagnetic suppression conditions includes the following modules:

[0016] The environmental sensing module is used to sense the electromagnetic environment around the Beidou terminal equipment;

[0017] The scene judgment module is used to determine whether electromagnetic suppression interference exists in the electromagnetic environment from the energy domain and time-frequency domain.

[0018] If electromagnetic suppression interference exists in the electromagnetic environment, the current communication scenario is determined to be an electromagnetic suppression scenario and the system switches to the countermeasure adjustment module; if electromagnetic suppression interference does not exist in the electromagnetic environment, the current communication scenario is determined to be a normal communication scenario and the system switches to the Beidou communication module.

[0019] The countermeasure adjustment module is used to separate electromagnetic suppression interference from the mixed signals of the electromagnetic environment, extract features of the electromagnetic suppression interference, thereby determining the type of electromagnetic suppression interference, and counteracting the type of electromagnetic suppression interference.

[0020] The BeiDou communication module is used to adjust the BeiDou communication configuration and complete BeiDou communication according to the current communication scenario.

[0021] Furthermore, based on the BeiDou communication method under the aforementioned electromagnetic suppression scenario, this invention also proposes a computer device, which includes a memory and one or more processors.

[0022] The memory stores executable code, and when the processor executes the executable code, it implements the steps of the Beidou communication method under the electromagnetic suppression scenario described above.

[0023] Furthermore, based on the BeiDou communication method under the aforementioned electromagnetic suppression scenario, this invention also proposes a computer-readable storage medium storing a program thereon; when executed by a processor, this program is used to implement the steps of the BeiDou communication method under the aforementioned electromagnetic suppression scenario.

[0024] The present invention has the following advantages:

[0025] As described above, this invention discloses a BeiDou communication method under electromagnetic suppression scenarios. The method first senses the electromagnetic environment surrounding the BeiDou terminal device; then, it determines whether electromagnetic suppression interference exists in the electromagnetic environment from both energy and time-frequency domains, thereby determining whether the current communication scenario is an electromagnetic suppression scenario or a normal communication scenario; if the current communication scenario is determined to be an electromagnetic suppression scenario, then the electromagnetic suppression interference is feature-extracted and analyzed, and its type is determined, followed by countermeasures against the type of electromagnetic suppression interference; finally, the BeiDou communication configuration is adjusted according to the current communication scenario, and BeiDou communication is completed. This invention employs a comprehensive energy and time-frequency domain judgment method, reducing misjudgments of electromagnetic suppression interference by single energy threshold detection and improving the accuracy of electromagnetic suppression interference detection in the electromagnetic environment. Furthermore, by extracting features from electromagnetic suppression interference, this invention achieves accurate classification of electromagnetic suppression interference and can take targeted countermeasures, adaptively adjusting communication parameters to meet the high-reliability communication requirements under complex electromagnetic environments. The method of this invention enables BeiDou terminal equipment to accurately determine whether there is electromagnetic suppression in the surrounding environment, and to counteract it in a timely manner in electromagnetic suppression scenarios, adjusting the BeiDou communication configuration to ensure communication quality and system stability, thereby improving the accuracy and reliability of BeiDou communication. Attached Figure Description

[0026] Figure 1 This is a flowchart of the BeiDou communication method under electromagnetic suppression scenario in an embodiment of the present invention.

[0027] Figure 2 This is an architecture diagram of the BeiDou communication method under electromagnetic suppression scenarios in an embodiment of the present invention. Detailed Implementation

[0028] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments:

[0029] Example 1

[0030] This embodiment proposes a BeiDou communication method under electromagnetic suppression scenarios. The method first senses the electromagnetic environment surrounding the BeiDou terminal device. Then, it determines whether electromagnetic suppression interference exists in the electromagnetic environment, thereby determining whether the current communication scenario is an electromagnetic suppression scenario or a normal communication scenario. If the current communication scenario is determined to be an electromagnetic suppression scenario, the electromagnetic suppression interference features are extracted and analyzed. Next, countermeasures are taken based on the results of the electromagnetic suppression interference feature extraction and analysis, and the BeiDou communication configuration is adjusted to the communication configuration under electromagnetic suppression scenarios. Finally, BeiDou communication is completed under electromagnetic suppression scenarios. This invention's BeiDou communication method under electromagnetic suppression scenarios enables BeiDou terminal devices to accurately determine whether electromagnetic suppression exists in the surrounding environment and to promptly counter and adjust the BeiDou communication configuration under electromagnetic suppression scenarios, thereby ensuring communication quality and system stability, and improving the accuracy and reliability of BeiDou communication.

[0031] like Figure 1 As shown, a BeiDou communication method under electromagnetic suppression scenarios specifically includes the following steps:

[0032] Step 1. Sensing the electromagnetic environment around the Beidou terminal equipment.

[0033] The electromagnetic environment surrounding BeiDou terminal equipment contains useful signals such as communication and navigation signals, as well as intentional interference signals such as suppression and deception interference. A quantitative characterization system for the electromagnetic environment typically includes six dimensions: time domain, frequency domain, spatial domain, energy domain, polarization domain, and modulation domain, to achieve a comprehensive characterization of the electromagnetic environment.

[0034] In electromagnetic suppression scenarios, the power of electromagnetic interference is significantly high, making it easily distinguishable from both energy and time-frequency domains. Therefore, this invention addresses electromagnetic suppression scenarios by monitoring the energy and time-frequency domains of real-time signals, enabling rapid perception of the electromagnetic environment in both these domains. Specifically, the energy domain perception of the electromagnetic environment surrounding the BeiDou terminal equipment can be achieved through power spectral density (PSD) analysis of the signal's frequency domain energy distribution, directly reflecting the signal's power strength. The time-frequency domain perception of the electromagnetic environment surrounding the BeiDou terminal equipment can be characterized using a time-spectrum graph.

[0035] In this embodiment, step 1 of the BeiDou communication method under electromagnetic suppression scenarios specifically includes:

[0036] Real-time signals in the electromagnetic environment are monitored and sampled, and represented in the following form:

[0037]

[0038] Where x(n) is the monitoring signal, i.e. the real-time signal in the electromagnetic environment surrounding the Beidou terminal equipment, s(n) is the useful signal, j(n) is electromagnetic suppression interference, ω(n) is noise, H0 indicates that there is no electromagnetic suppression interference in the monitoring signal, and H1 indicates that there is electromagnetic suppression interference in the monitoring signal.

[0039] Specifically, the perception of the energy domain directly reflects the power strength of the signal. In this embodiment, the power spectral density is used to analyze the frequency domain energy distribution of the signal. The PSD of the discrete signal is represented using the Welch method as follows:

[0040]

[0041] Wherein, P(f k ) indicates a frequency of f k The power spectral density at time K is the number of segments, L is the length of each segment, and x is the power spectral density at time L. i (n) represents the monitoring signal of the i-th segment, i∈[1,K], u(n) is the window function, n∈[1,L-1], U is the window energy compensation factor, j represents the imaginary unit, f k =kf s / N,f s The sampling frequency is k = 0, 1, ..., N / 2, where N is the number of sampling points. The unit of power spectral density is W / Hz. Under electromagnetic suppression conditions, the power spectral density of the monitored signal may fluctuate significantly or exhibit abnormal peaks.

[0042] To reduce misjudgments of electromagnetic suppression interference by single energy threshold detection and improve the accuracy of electromagnetic suppression interference detection in the electromagnetic environment, the method of this invention adopts a comprehensive judgment method combining the energy domain and the time-frequency domain. Therefore, it is also necessary to sense the electromagnetic environment around the Beidou terminal equipment in the time-frequency domain.

[0043] Specifically, the perception of the time and frequency domains is represented using a time-spectrum graph. A time-spectrum graph is a two-dimensional image generated after a signal undergoes a Short-Time Fourier Transform (STFT), with time on the horizontal axis and frequency on the vertical axis, and signal strength represented by color depth. By placing time and frequency on a single image, the time-spectrum graph facilitates simultaneous observation of both time and frequency domain information.

[0044] Step 2. Determine whether electromagnetic suppression interference exists in the electromagnetic environment from the energy domain and time-frequency domain. If electromagnetic suppression interference exists in the electromagnetic environment, determine that the current communication scenario is an electromagnetic suppression scenario and proceed to Step 3. If electromagnetic suppression interference does not exist in the electromagnetic environment, determine that the current communication scenario is a normal communication scenario and proceed to Step 5.

[0045] Current communication scenarios include ordinary communication scenarios and electromagnetic suppression scenarios. Ordinary communication scenarios refer to situations where no electromagnetic suppression interference is perceived in the electromagnetic environment, and BeiDou communication terminal equipment operates normally. Electromagnetic suppression scenarios refer to communication scenarios where electromagnetic suppression interference is perceived in the electromagnetic environment, and BeiDou communication terminal equipment needs to cope with electromagnetic suppression. The determination of whether electromagnetic suppression interference exists in the electromagnetic environment, and thus whether the current communication scenario is an electromagnetic suppression scenario or an ordinary communication scenario, is based on the perception results in the energy domain and time-frequency domain. If electromagnetic suppression is detected in the electromagnetic environment, the current communication scenario is determined to be an electromagnetic suppression scenario. If electromagnetic suppression is not detected in the electromagnetic environment, the current communication scenario is determined to be an ordinary communication scenario.

[0046] In step 2 of the BeiDou communication method under electromagnetic suppression scenarios in this embodiment, the presence of electromagnetic suppression interference in the electromagnetic environment is comprehensively determined from both the energy domain and time-frequency domain perspectives. From the energy domain perspective, when the monitored signal strength is greater than the minimum suppression power threshold, or the actual value of the calculated suppression coefficient is greater than the suppression coefficient threshold, electromagnetic suppression may exist in the electromagnetic environment. To ensure the accuracy of electromagnetic suppression interference detection, it is also necessary to further determine whether electromagnetic suppression exists in the electromagnetic environment from the time-frequency domain perspective. From the time-frequency domain perspective, the presence of electromagnetic suppression in the electromagnetic environment is determined by analyzing the time-frequency spectrum. When the difference in spectrum characteristics is greater than the determination threshold, electromagnetic suppression is determined to exist in the electromagnetic environment.

[0047] Step 2, the process of initially determining whether electromagnetic suppression interference exists in the electromagnetic environment from the perspective of the energy domain, specifically involves:

[0048] Firstly, in terms of visualization, one can observe whether the power spectral density of the monitored signal fluctuates significantly or exhibits abnormal peaks, thus making a preliminary judgment on whether electromagnetic suppression interference may exist. Furthermore, the strength of the monitored signal can be further calculated from the power spectral density, using the following formula:

[0049]

[0050] Where Δf is the frequency resolution, Δf = f s / N,f s Where N is the sampling frequency and N is the number of sampling points.

[0051] In electromagnetic suppression, the suppression coefficient reflects the minimum suppression power required to electromagnetically suppress a target. The suppression coefficient is defined as the ratio of the minimum suppression power required to effectively suppress interference to the received signal power.

[0052] The average signal received power under normal communication conditions without electromagnetic interference is taken as the default value P. s And preset the minimum suppression power threshold as Thus, the suppression coefficient threshold J is calculated. th for:

[0053] When the monitoring signal strength P m Less than or equal to the minimum suppression power threshold At that time, i.e., P m ≤P jth If the electromagnetic environment does not exhibit electromagnetic suppression interference, the current communication scenario is determined to be a normal communication scenario, and the process proceeds to step 5. When the monitored signal strength P... m Greater than the minimum suppression power threshold At that time, that is If so, it can be preliminarily determined that there may be electromagnetic suppression interference in the electromagnetic environment, but further judgment from the time and frequency domain perspective is still needed.

[0054] Or calculate the actual value of the suppression coefficient J. m =P m / P s When the actual value of the suppression coefficient J m Less than or equal to the suppression coefficient threshold J th At that time, i.e., J m ≤J th If the electromagnetic environment does not exhibit electromagnetic suppression interference, then the current communication scenario is determined to be a normal communication scenario, and the process proceeds to step 5. When the actual value of the suppression coefficient J... m Greater than the suppression coefficient threshold J th At that time, i.e., J m >J th At this time, it can be preliminarily determined that there is electromagnetic suppression interference in the electromagnetic environment, and further judgment from the time and frequency domain perspective is required.

[0055] After initially determining the potential presence of electromagnetic suppression interference in the energy domain, this invention further makes an accurate determination in the time and frequency domain.

[0056] Step 2, the process of determining whether electromagnetic suppression interference exists in the electromagnetic environment from the time-frequency domain perspective, specifically involves:

[0057] The presence of electromagnetic suppression in the electromagnetic environment can be further determined by analyzing the time-frequency spectrum. Using the time-frequency spectrum of a typical communication scenario as a reference, and the time-frequency spectrum of the real-time monitored signal as the real-time spectrum, a preliminary observation and analysis can be performed by comparing the real-time spectrum with the reference spectrum to preliminarily determine whether electromagnetic suppression is possible. Besides visually observing the time-frequency changes of the electromagnetic signal, since the time-frequency spectrum is a two-dimensional image, feature extraction and matching techniques from image processing are also employed to make accurate judgments in the time-frequency domain. For example, the Scale-Invariant Feature Transform (SIFT) method can be used for feature extraction and matching of the time-frequency spectrum.

[0058] In this embodiment, the process of SIFT feature extraction and matching is as follows:

[0059] (1) Time-frequency spectrum preprocessing: The real-time spectrum and the reference spectrum are preprocessed, the spectrum power values ​​are mapped to grayscale images from 0 to 255, and Gaussian blur noise reduction and edge enhancement are performed.

[0060] (2) Key point detection and descriptor generation: By constructing a Gaussian pyramid at multiple scales to capture the features of useful and interference signals, by performing extreme value detection to locate power mutation points, by performing direction allocation to reflect the time-frequency change trend, and by generating descriptors to encode the local power distribution features of key points.

[0061] (3) Feature matching and difference quantification: Nearest neighbor approximate matching is used to bidirectionally match key points of the reference spectrum and the real-time spectrum. Difference is determined by the proportion of unmatched key points and the average Euclidean distance between matched key points.

[0062] The thresholds for determining the proportion of unmatched keypoints and the average Euclidean distance between matched keypoints in a preset electromagnetic suppression scenario are set.

[0063] If the spectral features between the reference spectrum and the real-time spectrum differ significantly, i.e., the proportion of unmatched key points and the average Euclidean distance between matched key points are both greater than the judgment threshold, then it is determined that there is electromagnetic suppression interference in the electromagnetic environment, and the current communication scenario is determined to be an electromagnetic suppression scenario, and the process proceeds to step 3; otherwise, it is determined that there is no electromagnetic suppression interference in the electromagnetic environment, and the current communication scenario is determined to be a normal communication scenario, and the process proceeds to step 5.

[0064] Step 3. Separate electromagnetic suppression interference from the mixed signals of the electromagnetic environment, and extract features from the electromagnetic suppression interference to determine the type of electromagnetic suppression interference.

[0065] Based on the frequency band and bandwidth of electromagnetic suppression (ESS), EES is classified into blocking interference, targeting interference, and frequency sweeping interference. If the current communication scenario is determined to be an EES scenario, EES characteristics are extracted and analyzed to further determine the type of EES.

[0066] In step 3 of the BeiDou communication method under electromagnetic suppression scenarios in this embodiment, electromagnetic suppression interference (ESI) first needs to be separated from the mixed signal, and then features of ESI are extracted. Since the real-time monitoring signal in an ESI scenario is a mixture of ESI and useful signals, it is necessary to first separate the ESI from the mixed signal. Then, feature extraction and analysis are performed on the ESI. ESI feature extraction and analysis further extracts features from the ESI in the ESI scenario. The features of the ESI need to be extracted from the time domain, frequency domain, and time-frequency domain, thus laying the foundation for timely and accurate countermeasures against ESI. This embodiment performs peak-to-average power ratio (PAPR) feature extraction and analysis in the time domain, bandwidth ratio and spectral entropy feature extraction and analysis in the frequency domain, and time-frequency distribution feature extraction and analysis in the time-frequency domain.

[0067] Specifically, in step 3, electromagnetic suppression interference is first separated from the mixed signal. This embodiment uses a suppression interference signal separation technology based on STFT-ICA joint processing, and its specific process includes:

[0068] (1) STFT time-frequency transformation: Extract the amplitude spectrum from the time spectrum of the real-time monitoring signal after STFT and construct the amplitude spectrum matrix. The time spectrum of the real-time monitoring signal has been obtained in step 2.

[0069] (2) ICA Independent Component Separation: The amplitude spectrum matrix is ​​used as input, and after fast independent component analysis, the time-frequency distribution of the independent components is obtained.

[0070] (3) Identification of interference components: Calculate the peak-to-average power ratio (PAPR). The PAPR calculation formula is as follows:

[0071]

[0072] Among them, PAPR i S represents the peak-to-average power ratio. i Indicates the independent components after separation.

[0073] The component with the highest PAPR is selected as the electromagnetic suppression interference, and the time-frequency distribution matrix of the electromagnetic suppression interference is output.

[0074] (4) Inverse STFT recovery of time-domain electromagnetic suppression interference: Perform inverse STFT on the time-frequency distribution matrix of electromagnetic suppression interference to obtain the time-frequency spectrum of electromagnetic suppression interference.

[0075] Step 3, the process of extracting features from electromagnetic suppression interference and determining the type of electromagnetic suppression interference, is as follows:

[0076] For the electromagnetic suppression interference separated from the mixed signal, peak-to-average power ratio (PAPR) features are extracted in the time domain, bandwidth ratio and spectral entropy features are extracted in the frequency domain, and time-frequency distribution features are extracted in the time-frequency domain.

[0077] Preset thresholds for peak-to-average power ratio, bandwidth ratio, and spectral entropy to determine the type of electromagnetic suppression interference.

[0078] If the characteristics of electromagnetic suppression interference simultaneously satisfy the following conditions: dynamic change in bandwidth ratio, periodic fluctuation of spectral entropy value, peak-to-average ratio higher than the preset peak-to-average ratio threshold and periodic fluctuation, and time-frequency distribution as a slanted or curved time-frequency trajectory, then the type of electromagnetic suppression interference is determined to be frequency sweep interference.

[0079] If the electromagnetic suppression interference characteristics simultaneously meet the following conditions: the bandwidth ratio is wider than the preset bandwidth ratio threshold, the spectral entropy value is greater than the preset spectral entropy value threshold, the peak-to-average ratio is lower than the preset peak-to-average ratio threshold, and the time-frequency distribution is uniformly distributed across the entire frequency band, then the electromagnetic suppression interference is determined to be a blocking interference.

[0080] If the electromagnetic suppression interference characteristics simultaneously meet the following conditions: the bandwidth ratio is narrower than a preset bandwidth ratio threshold, the spectral entropy value is less than a preset spectral entropy value threshold, the peak-to-average power ratio is higher than a preset peak-to-average power ratio threshold, and the time-frequency distribution is a fixed narrowband focusing, then the electromagnetic suppression interference is determined to be targeting interference.

[0081] Table 1. Characteristics of the three types of suppression interference under different feature dimensions.

[0082] Feature Dimension Blocking interference Targeting jamming Frequency sweeping interference Bandwidth percentage Width narrow Dynamic changes Spectral entropy big Small Periodic fluctuations Peak-to-average ratio Low high High and cyclical fluctuations Time-frequency distribution Uniform distribution across the entire frequency band Fixed narrowband focusing Sloping / curved time-frequency trajectories

[0083] Specifically, feature extraction analysis is performed on electromagnetic suppression interference (ESI) to determine its type and select appropriate countermeasures. In this embodiment, ESI is categorized into blocking interference, targeting interference, and frequency sweeping interference based on its suppression frequency band and bandwidth. Table 1 shows the characteristics of these three types of ESI under different feature dimensions. Blocking interference has a wide bandwidth, targeting interference is narrow-band and specific to a particular frequency, and frequency sweeping interference varies with time.

[0084] The characteristics of electromagnetic suppression interference need to be extracted from the time domain, frequency domain, and time-frequency domain.

[0085] In the time domain, peak-to-average power ratio (PAPR) feature extraction analysis is performed to calculate the PAPR of the suppressed interference signal. Blocking interference exhibits a low PAPR with uniform energy distribution. Aiming or sweeping interference shows a high PAPR with concentrated energy; sweeping interference also exhibits periodic amplitude fluctuations due to frequency changes.

[0086] In the frequency domain, bandwidth proportion and spectral entropy feature extraction analysis are performed. In this embodiment, bandwidth proportion is analyzed by calculating the power spectral density (PSD) of the suppressed interference signal. Blocking interference has a wide bandwidth proportion, while targeting interference has a narrow bandwidth proportion. Spectral entropy describes the complexity and randomness of a signal in the frequency domain; a higher entropy value means the signal contains more frequency components, and its changes are more complex and disordered. The formula for spectral entropy is:

[0087] H(f) = -∑P(f)log(P(f)).

[0088] Where H(f) represents the spectral entropy and P(f) represents the power spectral density. Blocking interference has a larger spectral entropy, aiming interference has a smaller spectral entropy, and sweeping interference exhibits periodic entropy fluctuations.

[0089] In the time-frequency domain, the time-frequency distribution needs to be extracted, which was obtained synchronously during the separation and suppression of interference. By capturing the frequency change over time through time-frequency analysis, linear / nonlinear frequency changes are detected, and frequency sweep interference will show a slanted / curved time-frequency trajectory.

[0090] Step 4. Countermeasures are taken based on the results of the electromagnetic suppression interference feature extraction and analysis, i.e., the type of electromagnetic suppression interference.

[0091] After analyzing the characteristics of electromagnetic suppression interference, the types of suppression interference are identified, and targeted countermeasures are then implemented. Adaptive zeroing techniques are used for targeting interference, while adaptive cancellation techniques are employed for jamming and frequency sweeping interference.

[0092] Adaptive nulling is used to target interference. It utilizes the beamforming capability of an array antenna to create nulls in the direction of interference by adjusting the weights of the antenna array, thereby suppressing the interference. Adaptive cancellation is suitable for blocking and frequency-sweeping interference. It achieves interference cancellation by generating a reconstructed signal with the same amplitude but opposite phase to the interference. Table 2 provides a comparison between adaptive nulling and adaptive cancellation techniques.

[0093] Table 2 Comparison of Adaptive Zeroing and Adaptive Cancellation Techniques

[0094] Dimension Adaptive zeroing Adaptive cancellation Suppression Dimension airspace Frequency domain / Time domain Applicable Scenarios Narrowband directional interference Broadband / Dynamic Interference Real-time requirements High (requires rapid weight updates) Medium (depending on filter convergence speed) Hardware costs High (requires array antenna) Low (single-channel operation possible)

[0095] Specifically, adaptive nulling technology is used to target interference. It utilizes the beamforming capability of an array antenna to create nulls in the direction of interference by adjusting the weights of the antenna array, thereby suppressing the interference. The steps of adaptive nulling technology include:

[0096] (1) Signal reception: Signals are acquired through a multi-channel array antenna.

[0097] (2) Interference localization: Based on spatial spectrum estimation, such as the MUSIC algorithm, the direction of interference is determined.

[0098] (3) Weight calculation: The optimal weight is calculated by using the sampling matrix inversion (SMI) or the least mean square (LMS) algorithm.

[0099] (4) Beamforming: Adjust the array weights to generate nulls in the direction of interference.

[0100] Specifically, adaptive cancellation technology is used for blocking and frequency sweeping interference, both of which cover a wide range in the frequency or time domain. Adaptive cancellation technology achieves interference cancellation by generating a reconstructed signal with the same amplitude but opposite phase as the interference. The steps of adaptive cancellation technology include:

[0101] (1) Reference signal extraction: Obtain the interference reference signal through auxiliary channels or separation algorithms.

[0102] (2) Adaptive filtering: The filter coefficients are trained using LMS or recursive least squares (RLS) algorithm.

[0103] (3) Interference reconstruction: generating an accurate copy of the interference is called interference reconstruction.

[0104] (4) Cancellation: Subtract the reconstructed interference from the main signal. Furthermore, the variable step-size algorithm VSS-LMS is used to achieve dynamic interference tracking for frequency sweeping interference, and sub-band decomposition technology is combined to address the broadband characteristics of blocking interference.

[0105] In mixed interference scenarios that include jamming interference, aiming interference, and frequency sweeping interference, strong aiming interference can be suppressed first by adaptive zeroing technology, and then residual jamming / frequency sweeping interference can be handled by adaptive cancellation technology.

[0106] Step 5. Adjust the BeiDou communication configuration according to the current communication scenario and complete the BeiDou communication.

[0107] In this embodiment, the communication configuration of the BeiDou terminal device includes communication configuration under normal scenarios and communication configuration under suppression scenarios. These two scenarios correspond to two communication channels: the initial communication channel and the suppression communication channel. The communication configuration of both types of BeiDou terminal devices includes five parameters: operating frequency band, modulation scheme, transmit power, channel coding, and beam pattern. Specific configuration information is shown in Table 3, where BPSK is Binary Phase Shift Keying, QPSK is Quadrature Phase Shift Keying, FHSS is Frequency Hopping Spread Spectrum, LDPC is Low-Density Parity-Check Code, and Polar is Polar Code.

[0108] Table 3 Communication Configuration for Normal and Suppression Scenarios

[0109] parameter Standard scenario configuration (default) Suppression Scene Configuration Related interference types Operating frequency band B2a: 1176.45MHz B2b: 1207.14MHz General Modulation method BPSK QPSK+FHSS Frequency sweeping / blocking interference Transmit power Fixed power Adaptive power boost Blocking interference Channel coding LDPC code Polar codes General Beam mode Omnidirectional beam Directional beam Targeting jamming

[0110] Set the initial default communication configuration for BeiDou communication and allocate an initial communication channel for it. If the current communication scenario is a normal communication scenario, the default communication configuration is directly adopted as the normal communication scenario configuration, and the initial communication channel is used for BeiDou communication. If the current communication scenario is an electromagnetic suppression scenario, the suppression communication channel is switched, and the suppression scenario communication configuration is completed according to Table 3 before BeiDou communication is initiated.

[0111] For targeted jamming scenarios, the B2b band is activated and directional beams are used to suppress directional interference. For frequency sweeping jamming scenarios, frequency hopping mode is adopted to dynamically match the jamming frequency sweep rate. For jamming blocking scenarios, transmit power is adaptively increased.

[0112] The BeiDou terminal device using the method of this invention will adjust the BeiDou communication configuration according to the current communication scenario and select the corresponding communication channel for subsequent communication, tracking, positioning, etc. The method of this invention can promptly counteract and adjust the BeiDou communication configuration under electromagnetic suppression scenarios, thereby ensuring communication quality and system stability, and improving the accuracy and reliability of BeiDou communication.

[0113] This invention reduces the misjudgment of electromagnetic suppression interference by single energy threshold detection through a comprehensive energy domain and time-frequency domain judgment method, thereby improving the detection accuracy of electromagnetic suppression interference in electromagnetic environments. By extracting the features of electromagnetic suppression interference, it achieves accurate classification of suppression interference and takes corresponding countermeasures accordingly, realizing a technological shift from passive defense to active confrontation. It can adaptively adjust communication parameters and is particularly suitable for the high-reliability communication requirements in complex electromagnetic environments.

[0114] Example 2

[0115] This embodiment 2 describes a Beidou communication system under electromagnetic suppression scenarios. This system is based on the same inventive concept as the Beidou communication method under electromagnetic suppression scenarios in embodiment 1.

[0116] Specifically, the BeiDou communication system under this electromagnetic suppression scenario includes the following modules:

[0117] The environmental sensing module is used to sense the electromagnetic environment around the Beidou terminal equipment.

[0118] The scenario judgment module is used to determine whether electromagnetic suppression interference exists in the electromagnetic environment from the energy domain and time-frequency domain.

[0119] If electromagnetic suppression interference exists in the electromagnetic environment, the current communication scenario is determined to be an electromagnetic suppression scenario and the system switches to the countermeasure adjustment module; if electromagnetic suppression interference does not exist in the electromagnetic environment, the current communication scenario is determined to be a normal communication scenario and the system switches to the BeiDou communication module.

[0120] The countermeasure adjustment module is used to separate electromagnetic suppression interference from the mixed signals of the electromagnetic environment, extract features of the electromagnetic suppression interference, thereby determining the type of electromagnetic suppression interference, and counteracting the type of electromagnetic suppression interference.

[0121] The BeiDou communication module is used to adjust the BeiDou communication configuration and complete BeiDou communication according to the current communication scenario.

[0122] It should be noted that in the BeiDou communication system under electromagnetic suppression scenarios, the implementation process of the functions and roles of each functional module is detailed in the corresponding steps of the method in Example 1, and will not be repeated here.

[0123] Example 3

[0124] This embodiment 3 describes a computer device that includes a memory and one or more processors.

[0125] The memory stores executable code, which, when executed by the processor, implements the steps of the Beidou communication method under the electromagnetic suppression scenario in Embodiment 1 above.

[0126] In this embodiment, the computer device can be any device or apparatus with data processing capabilities, and will not be described in detail here.

[0127] Example 4

[0128] This embodiment 4 describes a computer-readable storage medium storing a program that, when executed by a processor, implements the steps of a BeiDou communication method under electromagnetic suppression scenarios.

[0129] The computer-readable storage medium can be an internal storage unit of any device or apparatus with data processing capabilities, such as a hard disk or memory, or an external storage device of any device with data processing capabilities, such as a plug-in hard disk, smart media card (SMC), SD card, flash card, etc.

[0130] Of course, the above description is only a preferred embodiment of the present invention. The present invention is not limited to the above-described embodiments. It should be noted that any equivalent substitutions or obvious modifications made by those skilled in the art under the guidance of this specification fall within the scope of this specification and should be protected by the present invention.

Claims

1. A method for Beidou communication in an electromagnetic suppression scene, characterized in that, Comprising the following steps: Step 1. Sensing the electromagnetic environment around the Beidou terminal device; Step 2. Judging whether there is electromagnetic suppression jamming in the electromagnetic environment from the energy domain and the time-frequency domain; If there is electromagnetic suppression jamming in the electromagnetic environment, it is determined that the current communication scene is an electromagnetic suppression scene and goes to step 3; If there is no electromagnetic suppression jamming in the electromagnetic environment, it is determined that the current communication scene is a normal communication scene and goes to step 5; Step 3. Separate the electromagnetic suppression jamming from the mixed signal of the electromagnetic environment, and extract the features of the electromagnetic suppression jamming, so as to judge the type of the electromagnetic suppression jamming; Step 4. Countermeasure for the type of electromagnetic suppression jamming; Step 5. Adjust the Beidou communication configuration according to the current communication scene and complete the Beidou communication; The step 2 is specifically: From the energy domain point of view, the signal strength is obtained by calculating the power spectral density The formula is: ； wherein, represents the power spectral density at a frequency , , is the sampling frequency, , is the number of sampling points, is the frequency resolution, ; The preset minimum suppression power threshold is When the monitoring signal strength is less than or equal to the minimum suppression power threshold , it is judged that there is no electromagnetic suppression interference in the electromagnetic environment, it is determined that the current communication scenario is a normal communication scenario, and step 5 is turned to; when the monitoring signal strength is greater than the minimum suppression power threshold , it is further judged from the time-frequency domain whether there is electromagnetic suppression interference in the electromagnetic environment; From the perspective of time-frequency domain, the time-frequency spectrum of the real-time monitoring signal, that is, the real-time spectrum, is compared with the reference spectrum in the normal communication scene, and the scale invariant feature transform (SIFT) method is used for time-frequency spectrum feature extraction and matching. The process of SIFT feature extraction and matching is specifically: Pretreatment is performed on the real-time spectrum and the reference spectrum, the spectrum power value is mapped to a 0-255 gray image, and Gaussian blur noise reduction and edge enhancement processing are performed; Key point detection and descriptor generation are performed, the useful signal and interference signal features of the real-time spectrum and the reference spectrum are captured through the construction of a Gaussian pyramid, the power mutation points are located through extreme value detection, the time-frequency change trend is reflected through direction assignment, and the local power distribution features of the key points are encoded through descriptor generation; Feature matching and difference quantization are performed, the nearest neighbor approximation matching is used, the key points of the reference spectrum and the real-time spectrum are matched in both directions, and the difference is determined through the proportion of unmatched key points and the average Euclidean distance between matched key points; The determination threshold of the proportion of unmatched key points and the average Euclidean distance between matched key points in the electromagnetic suppression scene is preset; If the spectrum feature difference between the reference spectrum and the real-time spectrum is large, that is, the proportion of unmatched key points and the average Euclidean distance between matched key points are both greater than the determination threshold, it is judged that there is electromagnetic suppression jamming in the electromagnetic environment, and the current communication scene is determined to be an electromagnetic suppression scene and goes to step 3; Otherwise, it is judged that there is no electromagnetic suppression jamming in the electromagnetic environment, and the current communication scene is determined to be a normal communication scene and goes to step 5.

2. The Beidou communication method in the electromagnetic suppression scene according to claim 1, characterized in that: The step 1 is specifically: The real-time signal in the electromagnetic environment around the Beidou terminal device is monitored and sampled, which is expressed as follows: ； wherein, is a monitoring signal, i.e. a real-time signal in the electromagnetic environment surrounding the Beidou terminal device, is a useful signal, is an electromagnetic suppression jamming, is noise, indicates that there is no electromagnetic suppression jamming in the monitoring signal, indicates that there is electromagnetic suppression jamming in the monitoring signal; The frequency energy distribution of the monitoring signal is analyzed by power spectral density (PSD) in the energy domain, and the PSD of the discrete signal is expressed by using Welch method as follows: ； wherein is the number of segments, is the length of each segment, denotes the monitoring signal of the th segment, , , is a window function, is a window energy compensation factor, denotes the imaginary unit; The electromagnetic environment around the Beidou terminal device is characterized by the time-frequency spectrum of the monitoring signal in the time-frequency domain, and the time-frequency spectrum is a two-dimensional image obtained after the signal is subjected to short-time Fourier transform (STFT), in which the horizontal axis is time and the vertical axis is frequency. The time-frequency spectrum represents the signal intensity through color depth.

3. The Beidou communication method in the electromagnetic suppression scene according to claim 2, characterized in that, in step 3, the suppression jamming signal separation technology based on STFT-ICA joint processing is used to separate the electromagnetic suppression jamming from the mixed signal, i.e. the monitoring signal, of the electromagnetic environment, and the process is specifically as follows: the amplitude spectrum of the time-frequency spectrogram of the real-time monitoring signal subjected to STFT is extracted to construct an amplitude spectrum matrix; the amplitude spectrum matrix is taken as input, and the time-frequency distribution of the independent component is obtained after ICA independent component separation; the jamming component is identified by calculating the peak-to-average power ratio (PAPR), and the calculation formula is: ； wherein indicates the peak-to-average ratio, indicates the separated individual components; the component with the highest PAPR is selected as the electromagnetic suppression jamming, and the time-frequency distribution matrix of the electromagnetic suppression jamming is output; inverse STFT is performed on the time-frequency distribution matrix of the electromagnetic suppression jamming to obtain the time-frequency spectrogram of the electromagnetic suppression jamming.

4. The Beidou communication method in the electromagnetic suppression scene according to claim 3, characterized in that, in step 3, the process of feature extraction and type judgment of the electromagnetic suppression jamming is specifically as follows: the electromagnetic suppression jamming separated from the mixed signal is subjected to peak-to-average power ratio feature extraction in the time domain, bandwidth ratio and spectral entropy feature extraction in the frequency domain, and time-frequency distribution feature extraction in the time-frequency domain; preset peak-to-average power ratio threshold, bandwidth ratio threshold and spectral entropy value threshold are used to judge the type of the electromagnetic suppression jamming; if the electromagnetic suppression jamming features satisfy the following conditions simultaneously, i.e. the bandwidth ratio dynamically changes, the spectral entropy value periodically fluctuates, the peak-to-average power ratio is higher than the preset peak-to-average power ratio threshold and periodically fluctuates, and the time-frequency distribution is a slant or curved time-frequency trajectory, it is determined that the type of the electromagnetic suppression jamming is sweep jamming; if the electromagnetic suppression jamming features satisfy the following conditions simultaneously, i.e. the bandwidth ratio is wider than the preset bandwidth ratio threshold, the spectral entropy value is greater than the preset spectral entropy value threshold, the peak-to-average power ratio is lower than the preset peak-to-average power ratio threshold, and the time-frequency distribution is uniformly distributed in the full frequency band, it is determined that the type of the electromagnetic suppression jamming is blocking jamming; if the electromagnetic suppression jamming features satisfy the following conditions simultaneously, i.e. the bandwidth ratio is narrower than the preset bandwidth ratio threshold, the spectral entropy value is less than the preset spectral entropy value threshold, the peak-to-average power ratio is higher than the preset peak-to-average power ratio threshold, and the time-frequency distribution is fixed narrowband focusing, it is determined that the type of the electromagnetic suppression jamming is aiming jamming.

5. The Beidou communication method in the electromagnetic suppression scene according to claim 4, characterized in that, step 4 is specifically as follows: for aiming jamming, adaptive nulling technology is used for countermeasures, which uses the beamforming capability of the array antenna to form a null in the direction of the jamming by adjusting the weight of the antenna array, thereby suppressing the jamming; for blocking jamming and sweep jamming, adaptive cancellation technology is used for countermeasures, which generates a reconstructed signal with equal amplitude and opposite phase to the jamming to achieve jamming cancellation.

6. The Beidou communication method in the electromagnetic suppression scene according to claim 5, characterized in that, step 5 is specifically as follows: the communication configuration of the Beidou terminal device includes a default communication configuration and a suppression scene communication configuration, wherein the default communication configuration corresponds to an initial communication channel, and the suppression scene communication configuration corresponds to a suppression communication channel; Parameters of the default communication configuration and the suppression scenario communication configuration are respectively preset, and the parameters include a working frequency band, a modulation mode, a transmission power, a channel coding, and a beam mode; If the current communication scenario is a normal communication scenario, the default communication configuration is adopted to occupy an initial communication channel to complete the Beidou communication; if the current communication scenario is an electromagnetic suppression scenario, the suppression scenario communication configuration is adopted to switch to a suppression communication channel to complete the Beidou communication in the electromagnetic suppression scenario. 7.A Beidou communication system in an electromagnetic suppression scenario for implementing the Beidou communication method in an electromagnetic suppression scenario according to claim 1, characterized in that, The Beidou communication system in an electromagnetic suppression scenario comprises: an environment sensing module for sensing an electromagnetic environment around the Beidou terminal device; a scenario judgment module for judging whether there is electromagnetic suppression interference in the electromagnetic environment from an energy domain and a time-frequency domain; if there is electromagnetic suppression interference in the electromagnetic environment, it is determined that the current communication scenario is an electromagnetic suppression scenario and the scenario judgment module is switched to a countermeasure adjustment module; if there is no electromagnetic suppression interference in the electromagnetic environment, it is determined that the current communication scenario is a normal communication scenario and the scenario judgment module is switched to a Beidou communication module; the countermeasure adjustment module is used for separating the electromagnetic suppression interference from a mixed signal of the electromagnetic environment, extracting features of the electromagnetic suppression interference, judging a type of the electromagnetic suppression interference, and taking countermeasures against the type of the electromagnetic suppression interference; the Beidou communication module is used for adjusting a Beidou communication configuration according to the current communication scenario and completing the Beidou communication.

8. A computer device comprising a memory and one or more processors, the memory having stored therein executable code, the computer device characterized in that, The processor implements the steps of the Beidou communication method in an electromagnetic suppression scenario according to any one of claims 1 to 6 when executing the executable code.

9. A computer-readable storage medium having stored thereon a program, characterized in that, The program implements the steps of the Beidou communication method in an electromagnetic suppression scenario according to any one of claims 1 to 6 when executed by the processor.

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