Navigation signal seamless conversion method and device based on unified space-time information

Abstract

The application discloses a navigation signal seamless conversion method and device based on unified space-time information. The method comprises the following steps: acquiring navigation signal observation data and second pulse signals from an external signal source; determining the motion state of a carrier platform according to the observation data, and if the motion state is dynamic, acquiring inertial navigation data of the carrier platform; determining the motion trajectory of the carrier platform through a fusion algorithm; dynamically adjusting the initial value of signal parameters to obtain the target value of the signal parameters according to the motion trajectory; generating standard satellite navigation signals in the same format as the satellite navigation system adapted to the carrier navigation terminal according to the target value of the signal parameters and the motion trajectory; realizing signal seamless conversion between different navigation systems and terminal in-situ adaptation; and sending the signal to the navigation terminal after anti-hijacking processing. The application provides continuous and reliable navigation services for the carrier platform without changing the existing navigation terminal, and effectively improves the navigation continuity in the satellite navigation denial environment.

Description

Technical Field

[0001] This invention relates to the field of satellite navigation, and in particular to a method, apparatus, computer equipment, and storage medium for seamless conversion of navigation signals based on unified spatiotemporal information. Background Technology

[0002] With breakthroughs in artificial intelligence, low-cost manufacturing, and autonomous technologies, carrier platforms such as drones, manned aircraft, unmanned vehicles, manned vehicles, and unmanned vessels have been widely used in fields such as reconnaissance, logistics, and surveying, with their positioning, navigation, and timing (PNT) support systems becoming core support.

[0003] Current PNT (Portable Navigation) platforms primarily rely on satellite navigation (BeiDou, GPS), inertial navigation, and visual positioning technologies. However, satellite navigation (BeiDou, GPS) depends on space-based signals and is prone to failure in denied environments (such as urban canyons and areas with strong electromagnetic interference); inertial navigation suffers from drift errors, and its accuracy deteriorates significantly with long-term use; visual positioning is greatly affected by environmental factors such as lighting and obstruction, and its reliability is insufficient in complex scenarios. As a result, the platform lacks a continuous and reliable navigation signal, making it difficult to meet navigation requirements in denied environments. Summary of the Invention

[0004] The purpose of this invention is to propose a method and apparatus for seamless conversion of navigation signals based on unified spatiotemporal information, so as to solve the technical problem of no continuous and reliable navigation signals in satellite navigation denial environments.

[0005] To address the aforementioned technical problems, this invention provides a seamless navigation signal conversion method based on unified spatiotemporal information, comprising the following steps: Acquire observation data and second pulse signals of navigation signals from external signal sources, the navigation signals including low-orbit augmentation signals and / or pseudo-satellite ground-based augmentation signals; The motion state of the carrier platform is determined based on the observation data. The motion state includes dynamic and static states. If the motion state is dynamic, the inertial navigation data of the carrier platform is acquired. The motion trajectory of the carrier platform is determined by a fusion algorithm based on the observation data of the navigation signal, the second pulse signal, and the inertial navigation data. Based on the motion trajectory of the carrier platform, the preset initial values ​​of the signal parameters are dynamically adjusted to obtain the target values ​​of the signal parameters. Based on the target values ​​of the signal parameters and the motion trajectory of the carrier platform, a standard satellite navigation signal with the same format as the satellite navigation system adapted to the carrier navigation terminal is generated. The standard satellite navigation signal is subjected to anti-hijacking processing to obtain the target satellite navigation signal, and the target satellite navigation signal is sent to the navigation terminal of the carrier platform.

[0006] To address the aforementioned technical problems, the present invention also provides a seamless navigation signal conversion device based on unified spatiotemporal information, comprising: The acquisition module is used to acquire observation data and second pulse signals of navigation signals from external signal sources, wherein the navigation signals include low-orbit enhancement signals and / or pseudo-satellite ground-based enhancement signals; The first determining module is used to determine the motion state of the carrier platform based on the observation data. The motion state includes dynamic and static states. If the motion state is dynamic, the inertial navigation data of the carrier platform is acquired. The second determining module is used to determine the motion trajectory of the carrier platform by means of a fusion algorithm based on the observation data of the navigation signal, the second pulse signal, and the inertial navigation data. The adjustment module is used to dynamically adjust the preset initial values ​​of the signal parameters according to the motion trajectory of the carrier platform to obtain the target values ​​of the signal parameters; The generation module is used to generate a standard satellite navigation signal that is consistent with the format of the satellite navigation system adapted to the carrier navigation terminal, based on the target value of the signal parameters and the motion trajectory of the carrier platform. The security processing module is used to perform anti-hijacking processing on the standard satellite navigation signal, obtain the target satellite navigation signal, and send the target satellite navigation signal to the navigation terminal of the carrier platform.

[0007] To address the aforementioned technical problems, the present invention also provides a computer device, including a memory and a processor, wherein the memory stores computer-readable instructions, and the processor executes the computer-readable instructions to implement the steps of the seamless conversion method for navigation signals based on unified spatiotemporal information as described above.

[0008] To address the aforementioned technical problems, the present invention also provides a computer-readable storage medium storing computer-readable instructions, which, when executed by a processor, implement the steps of the seamless navigation signal conversion method based on unified spatiotemporal information as described above.

[0009] The seamless conversion method and apparatus for navigation signals based on unified spatiotemporal information disclosed in this invention have at least the following advantages compared with the prior art: 1) This invention, by introducing and integrating external signal sources (such as low-Earth orbit augmentation signals and pseudo-satellite ground-based augmentation signals), helps to compensate for the problem of missing or degraded traditional satellite signals in satellite navigation denied environments (such as urban canyons, underground areas, or areas with strong electromagnetic interference). Through the coordinated use of multi-source signals, it can provide a more continuous and stable navigation signal guarantee for the carrier platform, enhancing its navigation reliability in complex environments.

[0010] 2) This invention generates standard satellite navigation signals consistent with the format of the satellite navigation system adapted to the carrier navigation terminal, and performs format conversion when the airborne navigation terminal is detected to support different navigation systems, thus achieving seamless spatiotemporal signal conversion between different navigation systems and different navigation frequencies. This method supports in-situ adaptation of GNSS navigation terminals for various equipment systems, does not require hardware modifications to existing terminals, reduces technical deployment costs and complexity, and facilitates agile deployment with "plug and play".

[0011] 3) This invention performs anti-hijacking processing on the generated navigation signal. The anti-hijacking processing ensures the authenticity and integrity of the navigation information through encryption and other methods, which helps to improve the security of the signal in complex electromagnetic environments, thereby providing reliable signal protection for the carrier platform to operate in adversarial environments.

[0012] 4) This invention can dynamically adjust the initial values ​​of signal parameters according to the motion trajectory of the carrier platform, thereby adapting to different motion states (such as high-speed maneuvering or low-speed cruising) and external interference environments. This adaptive mechanism helps optimize signal tracking performance, multipath resistance, and power efficiency in different scenarios, improving the overall quality of navigation services.

[0013] 5) The external signal sources used in this invention are diverse and complementary, including various types such as low-Earth orbit augmentation signals and pseudo-satellite ground-based augmentation signals, and are characterized by flexible structure and strong scalability. Temporary and regional augmentation navigation systems can be constructed according to different mission requirements, suitable for various application scenarios such as military reconnaissance, emergency rescue, and precision agriculture.

[0014] In summary, this invention, through the technical approach of signal regeneration, fusion processing, and seamless conversion, enables the construction of an enhanced navigation system with anti-interference, anti-hijacking, and continuous navigation capabilities for various carrier platforms without altering existing navigation terminals, providing an effective technical solution for addressing navigation and positioning problems in denied environments. Attached Figure Description

[0015] To more clearly illustrate the solutions in this invention, the accompanying drawings used in the description of this invention will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0016] Figure 1 This is an exemplary system architecture diagram in which the present invention can be applied; Figure 2 This is a flowchart of an embodiment of the navigation signal seamless conversion method based on unified spatiotemporal information according to the present invention; Figure 3 This is a schematic diagram of an embodiment of the navigation signal seamless conversion device based on unified spatiotemporal information according to the present invention; Figure 4 This is a schematic diagram of the structure of an embodiment of a computer device according to the present invention. Detailed Implementation

[0017] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings.

[0018] like Figure 1 As shown, system architecture 100 may include terminal devices 101, 102, and 103, a network 104, and a server 105. Network 104 serves as the medium for providing communication links between terminal devices 101, 102, and 103 and server 105. Network 104 may include various connection types, such as wired or wireless communication links, or fiber optic cables, etc.

[0019] Users can use terminal devices 101, 102, and 103 to interact with server 105 via network 104 to receive or send messages, etc. Various communication client applications can be installed on terminal devices 101, 102, and 103, such as web browser applications, shopping applications, search applications, instant messaging tools, email clients, social media platform software, etc.

[0020] Terminal devices 101, 102, and 103 can be various electronic devices with displays and web browsing capabilities, including but not limited to smartphones, tablets, e-book readers, MP3 (Moving Picture Experts Group Audio Layer III) players, MP4 (Moving Picture Experts Group Audio Layer IV) players, laptops, and desktop computers, etc.

[0021] Server 105 can be a server that provides various services, such as a backend server that supports the pages displayed on terminal devices 101, 102, and 103.

[0022] It should be noted that the seamless navigation signal conversion method based on unified spatiotemporal information provided in this invention is generally executed by the terminal device, and correspondingly, the seamless navigation signal conversion device based on unified spatiotemporal information is generally installed in the terminal device. It should be understood that... Figure 1The number of terminal devices, networks, and servers shown is merely illustrative. Depending on implementation needs, any number of terminal devices, networks, and servers can be included.

[0023] like Figure 2 As shown, the seamless conversion method for navigation signals based on unified spatiotemporal information according to the present invention includes the following steps: Step S201: Obtain observation data and second pulse signals of navigation signals from external signal sources, wherein the navigation signals include low-orbit enhancement signals and / or pseudo-satellite ground-based enhancement signals.

[0024] In this invention, the navigation signal seamless conversion method based on unified spatiotemporal information operates on electronic devices (e.g., Figure 1 The terminal device shown can send or receive data via wired or wireless connection. It should be noted that the aforementioned wireless connection methods may include, but are not limited to, 3G / 4G / 5G connections, WiFi connections, Bluetooth connections, WiMAX connections, Zigbee connections, UWB (ultra wideband) connections, and other currently known or future known wireless connection methods.

[0025] In this invention, the navigation signal output from the external signal source refers to a signal originating outside the carrier platform, used to supplement navigation accuracy and improve signal continuity in denied environments. Specifically, it includes real signal enhancement signals (navigation enhancement signals broadcast by ground-based augmentation base stations, such as the BeiDou ground-based augmentation system and GPS CORS base stations), low-Earth orbit (LEO) enhancement signals (navigation enhancement signals broadcast by low Earth orbit satellites, typically at altitudes below 2000km, such as LEO navigation augmentation constellation satellites), and pseudo-satellite ground-based enhancement signals (simulated satellite navigation signals broadcast by ground-deployed pseudo-satellite base stations, which can be flexibly selected for same-frequency or different-frequency broadcasting depending on the application scenario). The observation data is extracted after the navigation receiver receives the signal, and the second pulse signal provides a precise time reference for the observation data, ensuring the synchronization and accuracy of the timestamps.

[0026] Navigation signal observation data and second pulse signals from external signal sources are acquired by a high-reliability satellite navigation regenerative anti-interference component. This component is designed for different carrier platform structures and can utilize lightweight, high-strength quick-installation clamps made of aluminum alloy and carbon fiber composites. Its three-section adjustable buckles adapt to various installation scenarios on carrier platforms such as UAVs, manned aircraft, and unmanned vehicles. The clamps have built-in buffer and shock-absorbing layers, requiring no modification to the platform itself. Furthermore, this component can be installed not only on carrier platforms but also on devices / platforms with navigation receivers. The component establishes power and signal links through standardized electrical interface modules, integrating a DC 12-24V wide-range power interface and RS485 / CAN bus dual data interfaces. It is equipped with quick-plug cables with locking mechanisms, ensuring compatibility with the power supply and communication needs of different platforms.

[0027] Optionally, a high-sensitivity pseudosatellite receiving antenna is used to receive same-frequency / different-frequency navigation signals from pseudosatellite base stations, and is compatible with low-Earth orbit satellite augmentation signals to ensure uninterrupted signal source in denial environments. The received raw signal is first filtered by an anti-interference filter to remove industrial interference, WiFi clutter, and other noise, thus improving the signal-to-noise ratio; then, a low-noise amplifier amplifies the weak signal to meet the calculation requirements. After demodulation and decoding by the analytical calculation module, the core observation data is extracted; specifically, the pseudosatellite signal includes pseudorange observations. Pseudo-satellite coordinates ( (Pre-configured by the base station) and signal propagation time Navigation messages (including base station clock bias and ionospheric delay correction parameters), ephemeris parameters, carrier phase observations, and initial Doppler frequency offset values, etc.

[0028] Step S202: Determine the motion state of the carrier platform based on the observation data. The motion state includes dynamic and static states. If the motion state is dynamic, acquire the inertial navigation data of the carrier platform.

[0029] In this invention, key feature parameters are extracted from the observation data, including pseudorange change, absolute value of Doppler frequency offset, and position coordinate fluctuation over a continuous 3-second period. Subsequently, a judgment threshold is set (e.g., pseudorange change ≤ 0.5m / 3s, absolute value of Doppler frequency offset ≤ 0.1Hz, position coordinate fluctuation ≤ 0.3m). If all the above parameters in the observation data meet the threshold conditions, the carrier platform (such as a fixed ground monitoring station or a stationary unmanned vessel) is determined to be static; if any parameter exceeds the threshold, the carrier platform is determined to be dynamic. At this time, the component reads real-time inertial navigation data (including three-dimensional velocity, acceleration, and device temperature calibration parameters) from the inertial navigation module located inside the component via the RS485 standardized interface, providing dynamic compensation data for subsequent motion trajectory fusion calculation. This inertial navigation module can be placed on a regenerative anti-interference component or a navigation receiver.

[0030] When the carrier platform is static, seamless signal conversion between different navigation systems can still be achieved without the need for inertial navigation data assistance: After determining the fixed position coordinates of the carrier based on static observation data, the component calls the satellite signal interface control file (ICD) corresponding to the satellite navigation system adapted to the carrier navigation terminal (e.g., conversion from BeiDou to GPS). The observation data of the BeiDou B1I signal (including pseudo-satellite coordinates and ionospheric correction parameters) is reconstructed according to the message structure of the GPS L1 signal. For example, BeiDou ephemeris parameters are converted to GPS ephemeris format, and the initial values ​​of the signal parameters are adjusted. A baseband signal conforming to the GPS L1 format is generated through direct digital frequency synthesis technology, and then output to the carrier navigation terminal after radio frequency front-end modulation. This achieves in-situ signal adaptation from BeiDou to GPS in static scenarios without requiring changes to the terminal hardware configuration.

[0031] Step S203: Based on the observation data of the navigation signal, the second pulse signal, and the inertial navigation data, the motion trajectory of the carrier platform is determined by a fusion algorithm.

[0032] In this invention, a fusion algorithm is used to collaboratively process navigation signal observation data, second pulse signals, and inertial navigation data. The navigation signal provides absolute position to correct inertial navigation drift, while the inertial data supplements the continuous motion state during signal interruptions or accuracy fluctuations. The second pulse serves as a unified time reference, resolving the synchronization issue between the two types of data and ultimately correcting errors from a single data source. Specifically, the timestamps of both types of data are first calibrated using the second pulse as a reference to ensure strict alignment of sampling times. The navigation signal calculates the preliminary position based on the calibrated propagation time using the pseudorange formula, and the second pulse is used to correct receiver clock errors, reducing calculation errors caused by time asynchrony. In dynamic scenarios, the inertial data, combined with the sampling time synchronized by the second pulse, derives the predicted position value through a kinematic model, avoiding sampling offset deviations. Subsequently, the fusion algorithm uses the calibrated time axis as a reference to weightedly fuse the preliminary position and predicted value, while further calibrating the clock error using the second pulse signal to improve synchronization accuracy. Continuous acquisition of synchronization data and integration of position information according to the time series generate a complete trajectory, which includes spatial dimensions (latitude / longitude / altitude) and temporal dimensions (calibrated timestamps, velocity / acceleration). Finally, after ionospheric delay correction and Kalman smoothing denoising, unified spatiotemporal information with accurate time synchronization, high spatial accuracy, and continuous state is formed, providing a unique benchmark for subsequent signal conversion and ensuring spatiotemporal consistency before and after conversion.

[0033] Step S204: Based on the motion trajectory of the carrier platform, dynamically adjust the preset initial values ​​of the signal parameters to obtain the target values ​​of the signal parameters.

[0034] In this invention, the motion trajectory accurately records the position, orientation, and state of the carrier platform at different times, reflecting processes such as acceleration, deceleration, and turning. The initial values ​​of the signal parameters are a set of analog signal characteristic parameters consistent with the target satellite signal, set based on the nominal characteristics of the target satellite system, mainly including the initial carrier frequency, initial code rate, and initial modulation depth, providing a foundation for signal generation. Specifically, motion state features such as the rate of position change, direction offset, and update frequency (reflecting the platform's dynamic requirements) are extracted from the trajectory. Because the motion state affects the adaptability of analog signal reception, the initial parameters are modified accordingly. For example, if the rate increases, the signal frequency parameter is adjusted to compensate for the deviation; if the position updates are frequent, the signal transmission efficiency parameter is optimized.

[0035] Step S205: Based on the target value of the signal parameters and the motion trajectory of the carrier platform, generate a standard satellite navigation signal that is consistent with the format of the satellite navigation system adapted to the carrier navigation terminal.

[0036] In this invention, based on the motion trajectory of the carrier platform and combined with preset signal parameter target values, a standard satellite navigation signal consistent with the format of the satellite navigation system adapted to the carrier navigation terminal is generated through the built-in signal generation module, achieving seamless signal conversion between different systems and in-situ adaptation of the terminal. The conversion process can cover all frequency points of the four major global satellite navigation systems, including B1I, B1C, B2I, B2a, B2b, and B3I of BeiDou (BDS), L1, L1C, L2C, L2P, and L5 of GPS, E1, E5A, E5B, and E6 of Galileo, and L1, L2, and L3 of GLONASS, and the frequency points of each system can be arbitrarily converted.

[0037] For example, if the terminal natively supports GPS L1 frequency signals, then when the component receives and processes the BeiDou B1C signal, the signal generation module will convert the BeiDou B1C signal parameters into GPS L1 target parameters based on the spatiotemporal reference of the motion trajectory. At the same time, it will reassemble the navigation message according to the GPS L1 encoding rules (such as converting the BeiDou ephemeris into GPS ephemeris format) to generate a standard signal that is completely consistent with the GPS L1 format. After being directly input into the terminal, the terminal can parse and locate without any modification.

[0038] Step S206: Perform anti-hijacking processing on the standard satellite navigation signal to obtain the target satellite navigation signal, and send the target satellite navigation signal to the navigation terminal of the carrier platform.

[0039] In this invention, to prevent standard satellite navigation signals from being illegally intercepted, tampered with, or forged during transmission, anti-hijacking processing is required to generate target satellite navigation signals before sending them to the navigation terminal on the carrier platform. Specifically, the anti-hijacking processing includes two layers of protection: First, based on the location information (such as latitude and longitude) in the real-time motion trajectory of the carrier platform and the system time calibrated by the second pulse, dynamic characteristic parameters bound to the current state of the carrier are generated. These parameters are integrated into the underlying modulation process of the standard signal, giving the signal a uniqueness that dynamically changes with the carrier state, reducing the risk of being copied or forged. Second, the navigation message portion of the signal containing key positioning information is encrypted and protected. A lightweight encryption mechanism ensures that the message content can only be decrypted and parsed by the compatible navigation terminal, preventing unauthorized terminals from stealing or tampering with positioning data. The target satellite navigation signal obtained after the above processing is transmitted through a dedicated communication link between the component and the terminal. The link adopts an anti-interference transmission protocol to further ensure the security of the signal transmission process, ultimately ensuring that the signal received by the navigation terminal is authentic, complete, and unhijacked, and can be directly used for positioning calculation.

[0040] In summary, this invention generates the platform's motion trajectory by fusing observation data and second pulse signals from external signal sources with the platform's inertial navigation data. Based on the trajectory, it dynamically adjusts signal parameters and generates a standard satellite navigation signal consistent with the format of the satellite navigation system adapted to the platform's navigation terminal, achieving seamless conversion between different navigation systems and in-situ terminal adaptation. Finally, it transmits the target signal to the navigation terminal through anti-hijacking processing. This invention can provide continuous and reliable navigation services to the platform without altering the existing navigation terminal, effectively improving navigation continuity in satellite navigation denied environments.

[0041] In some optional implementations of the present invention, the steps of performing anti-hijacking processing on the standard satellite navigation signal to obtain the target satellite navigation signal include: The standard satellite navigation signal is modulated using dynamic spreading code based on the real-time time and location information of the carrier platform. The sequence of the dynamic spreading code is generated by the real-time latitude and longitude coordinates and system time of the carrier platform through a hash algorithm to obtain a physical layer encrypted standard satellite navigation signal. The physical layer encrypted standard satellite navigation signal is then encrypted using the lightweight national cryptographic algorithm SM4 to encrypt the navigation message, thereby obtaining the target satellite navigation signal.

[0042] In this invention, standard satellite navigation signals are encrypted. For the physical layer, dynamic spreading code modulation based on the real-time time and location information of the carrier platform is first employed. Specifically, the platform's real-time latitude and longitude and system time are used to generate a unique and dynamically changing spreading code sequence via a hash algorithm. This sequence is then spread and modulated with the standard signal to expand the signal spectrum, achieving physical layer encryption, preventing third-party interception and forgery, and constructing a dynamic and unpredictable security barrier. This physical layer encryption method offers high security: the spreading code changes with location and time, making it difficult to predict and copy, effectively resisting eavesdropping and deception; direct sequence spreading and dynamic codes result in low power spectral density, making the signal difficult to detect and enhancing concealment; the key (spreading code) is generated from the platform's real-time motion state, eliminating the need for additional distribution and management, simplifying the design and improving security and reliability. After the physical layer encryption is completed, the transport layer uses the lightweight national cryptographic algorithm SM4 to encrypt the navigation message, extracts the core data of the message (almanac, ephemeris, time calibration parameters, etc.), splits it into fixed data blocks according to the SM4 block length, and encrypts the blocks using a preset anti-tampering key stored securely in the component; then it is integrated with the physical layer encryption signal into a complete encryption signal to prevent message tampering and theft, enhance security and trustworthiness, and ensure reliable transmission and national compliance.

[0043] As can be seen, the present invention uses SM4 to encrypt navigation messages, which can achieve: 1) High security: SM4 is a standard approved by the State Cryptography Administration, and its strength is certified, which can ensure the confidentiality and integrity of the messages and prevent tampering and forgery; 2) High efficiency of resources: Specifically, the lightweight algorithm has a small amount of computation, fast speed, and low resource consumption, which is suitable for embedded scenarios on carrier platforms and ensures real-time encryption and decryption; 3) Compliance advantages: The use of national cryptographic algorithms meets the requirements of domestic information security and independent control, and is applicable to military, government and other fields.

[0044] This invention significantly enhances the anti-hijacking capability and security of satellite navigation signals through a dual-layer protection mechanism of physical layer dynamic encryption and transmission layer national cryptographic encryption, while also ensuring adaptability and compliance. The two layers of encryption work synergistically to prevent hijacking from the physical transmission of signals to the transmission of message content, effectively guaranteeing the safe, reliable, and compliant use of satellite navigation signals.

[0045] In some optional implementations of the present invention, the method further includes, before acquiring the observation data and second pulse signal of the navigation signal from the external signal source, the following steps: An initial navigation signal from an external signal source is acquired, and real-time frequency band monitoring and interference detection are performed on the initial navigation signal to identify the type and intensity of interference. If interference is detected, an adaptive frequency switching strategy is initiated to modulate the initial navigation signal to one of a number of preset backup operating frequency bands, and the signal is reconstructed based on a signal reconstruction algorithm to obtain an anti-interference navigation signal. The signal reconstruction algorithm includes: a channel estimation and equalization algorithm based on the minimum mean square error criterion, combined with orthogonal frequency division multiplexing technology, to reconstruct the damaged signal in the frequency domain; the anti-interference navigation signal is then processed by signal purification to extract standard signal features; the standard signal features are compared with a preset satellite signal feature library, and if the features match, the navigation signal is output; if there is a deviation, the signal is corrected using digital predistortion technology before outputting the navigation signal; the observation data is extracted from the navigation signal.

[0046] In this invention, the initial satellite navigation signal is monitored in real time across the entire frequency band, with a focus on capturing abnormal electromagnetic signals within the operating frequency band. Interference types (such as narrowband and broadband interference) and their intensity can be identified through signal characteristic analysis, and information is recorded in real time to provide a basis for subsequent anti-interference efforts. Specifically, narrowband interference is characterized by strong amplitude peaks, a sudden drop in signal-to-noise ratio (e.g., ≤20dB), concentrated interference frequency bands (e.g., bandwidth ≤1MHz), and no impact on other frequency bands. Broadband interference is characterized by continuous clutter, increased signal distortion, and frequent phase drift in a wide frequency band (e.g., around 1561MHz ±5MHz in the BeiDou B1 band). Co-channel interference is characterized by complete overlap between the interfering signal and the standard signal operating frequency band, resulting in "signal confusion" at the receiver and a sudden increase in pseudorange error (e.g., >10m).

[0047] Optionally, when encountering narrowband interference, an adaptive frequency switching is immediately triggered, selecting an unaffected frequency band from the backup band to modulate the signal. Simultaneously, signal reconstruction is initiated to repair damaged segments during the switching process, avoiding interference and restoring signal integrity. When encountering broadband interference, coarse filtering (broadband suppression) and fine filtering (adaptive bandpass) are applied using an anti-interference filter to reduce clutter. If the signal-to-noise ratio after filtering is still insufficient (e.g., <30dB), the signal is switched to the backup band with the lowest interference for remodulation, combined with signal reconstruction to repair attenuation. When encountering co-channel interference, after identification through phase comparison (e.g., the phase difference between the interference and the standard signal is >1°), the signal is preferentially switched to an adjacent, unaffected backup frequency band. Signal reconstruction is then used to perform frequency domain repair on the switched signal, correcting pseudorange errors and message distortion. It is worth noting that real-time frequency band monitoring and interference detection can identify the type and intensity of interference, enabling environmental awareness and proactive detection and diagnosis of interference threats, rather than passively enduring them. Subsequently, through adaptive frequency switching and signal reconstruction algorithms, a "perception-response" closed loop is formed, which can actively and quickly jump out of the interference frequency band and intelligently reconstruct the complete signal on the backup channel, significantly improving the system's survivability and stability in dynamic high-intensity confrontation environments.

[0048] The channel reconstruction algorithm is based on the minimum mean square error (MMSE) criterion for channel estimation and equalization, combined with orthogonal frequency-division multiplexing (OFDM) technology for frequency domain reconstruction. Specifically, the channel estimation module first collects the channel characteristic parameters of the damaged signal (including channel attenuation, delay spread, noise power, etc.), constructs an objective function according to the MMSE criterion, and calculates the optimal channel equalization coefficient to cancel interference. Then, OFDM technology is used to decompose the damaged signal into multiple orthogonal subcarriers, and the amplitude and phase of each subcarrier are independently corrected in the frequency domain (correcting deviations and filtering out strong interference subcarriers according to the equalization coefficient). The subcarriers are then combined and synthesized to restore a complete and stable signal, providing a high-quality signal for subsequent encryption and improving anti-interference performance. This scheme achieves optimal frequency domain reconstruction of damaged signals through MMSE and OFDM: the MMSE criterion can optimally estimate channel characteristics and compensate for distortion under noise interference to recover the original signal to the greatest extent, thereby improving reconstruction accuracy and reliability; OFDM technology decomposes high-speed data streams into low-speed subcarriers for parallel transmission, resisting frequency-selective fading and narrowband interference. The combination of the two is suitable for high-speed data signal reconstruction in complex electromagnetic environments, enhancing the system's spectrum utilization and anti-multipath interference capability.

[0049] Optionally, signal purification processing is applied to the signal after anti-interference processing. Specifically, by suppressing residual random noise and eliminating distortion components introduced during signal transmission, the signal-to-noise ratio and stability are improved, bringing the signal waveform and parameters closer to a standard state. Then, standard signal features of the purified navigation signal are extracted, including key features such as carrier frequency, code rate, modulation scheme identifier, and stable parameters of signal amplitude / phase. The extracted standard signal features are compared with a pre-set satellite signal feature library, which stores standard signal feature templates from mainstream satellite navigation systems such as BeiDou, GPS, and Galileo. If the comparison shows a perfect match, the signal is directly output as a navigation signal suitable for subsequent processing. If there are feature deviations, digital pre-distortion technology is used to dynamically adjust the amplitude, phase, and frequency parameters of the signal to correct the deviations and make it conform to the feature library standards before outputting the corrected navigation signal. Finally, observation data is extracted from the processed navigation signal to provide a basis for subsequent motion state determination and fusion processing.

[0050] This invention significantly improves the anti-interference capability and reliability of navigation signals through a full-process "perception-response-optimization" approach, laying a high-quality foundation for subsequent observation data extraction. It first monitors the initial signal in real time, accurately identifying interference types and intensities such as narrowband and broadband, achieving proactive interference detection and avoiding passive acceptance. Upon detecting interference, it adaptively switches to backup frequency bands according to the interference type, and combines signal reconstruction algorithms to repair damaged signals, quickly avoiding interference and ensuring signal integrity. Finally, through signal purification and feature comparison, it uses digital pre-distortion correction to correct deviation signals, ensuring the output signal meets standards and improving accuracy.

[0051] In some optional implementations of the present invention, the above-mentioned step of performing signal purification processing on the interference-resistant navigation signal includes: The anti-interference navigation signal is sequentially subjected to bandpass filtering and adaptive notch filtering to suppress out-of-band noise and residual interference; wavelet transform is used to perform time-frequency analysis on the signal to identify and suppress instantaneous pulse interference; Kalman filter is used to smooth the signal amplitude and phase; and automatic gain control technology is used to calibrate the intensity of the filtered signal to obtain the purified navigation signal.

[0052] In this invention, the navigation signal after interference is first subjected to bandpass filtering. The bandwidth is set according to the operating frequency band of the satellite navigation system adapted to the carrier navigation terminal, allowing only the adapted frequency band to pass through, suppressing out-of-band noise such as WiFi and industrial clutter, and initially improving the signal-to-noise ratio to over 25dB. Subsequently, adaptive notch filtering is activated, monitoring the spectrum after bandpass filtering in real time, identifying narrowband residual interference (such as electromagnetic pulse aftershocks), and automatically generating corresponding notch null points to filter out the interference, avoiding impact on signal phase stability. This achieves synergistic suppression of both broadband and narrowband interference, significantly improving signal purity. The combination of these two methods constitutes a "wideband-narrowband synergy, internal and external control" filtering system, significantly improving the signal-to-noise ratio and purity.

[0053] Optionally, wavelet transform can be used to perform time-frequency analysis on the signal, decomposing it into wavelet coefficients of different scales. Abnormal peak values ​​corresponding to instantaneous pulse interference can be identified in the coefficients. After truncating the corresponding time-frequency intervals and removing interference components, the signal can be reconstructed, eliminating pulse interference such as lightning strikes and instantaneous equipment discharges. This gives the signal control station the ability to resist strong instantaneous pulse interference, ensuring signal continuity. Pulse interference is short-lived and high-energy, making it difficult for traditional filters to handle and prone to signal loss of lock. Wavelet transform has strong time-frequency localization capabilities, accurately locating interference, suppressing and eliminating pulse spikes, avoiding receiver lock-up, and ensuring signal and location continuity.

[0054] Optionally, the signals after the first two stages of filtering are input into a Kalman filter model, and a state vector is constructed using amplitude and phase as target parameters. A state prediction equation is established based on signal continuity, and the state is updated using real-time observations. Weights are adjusted using Kalman gain to smooth amplitude jumps and phase drifts caused by device fluctuations, controlling phase deviation and ensuring signal stability and high-precision ranging. Even after the aforementioned filtering, low-frequency jitter or random fluctuations may still exist. Kalman filtering, as the optimal estimation algorithm, can recursively smooth the predicted amplitude and phase, suppressing signal fluctuations and obtaining a stable waveform. This lays the foundation for high-precision measurement in navigation terminals and directly improves positioning accuracy.

[0055] Optionally, after multi-stage filtering, the signal strength is dynamically calibrated using Automatic Gain Control (AGC) technology. Specifically, the real-time signal strength after filtering is acquired and compared with the standard signal strength range adapted to the carrier navigation terminal. If the signal strength is below the lower limit of the standard (e.g., below -120dBm), the AGC module gradually increases the signal amplification gain to bring the signal strength within the standard range; if the strength is above the upper limit of the standard (e.g., above -80dBm), the amplification gain is reduced to avoid signal saturation distortion. During calibration, gain and strength are monitored in real time, and closed-loop adjustment ensures the strength is adapted to the terminal, avoiding reception interruption or signal distortion. To address the uncertain power loss from multi-stage processing, AGC monitors the output power level in real time and adjusts the gain in a closed loop to stabilize the strength within a preset ideal range, meeting the requirements of subsequent fusion calculations and the navigation system supported by the airborne navigation terminal. This prevents signals from being too weak to capture or too strong to cause distortion, ensuring availability and reliability.

[0056] A rigorous signal quality assurance chain was established through multi-stage filtering, signal strength calibration, and feature comparison correction. Specifically, firstly, multi-stage filtering removes noise and residual interference; secondly, strength calibration ensures power stability; and finally, feature comparison and pre-distortion correction fine-tune the signal to ensure that its format, quality, and spectral characteristics are close to those of the real signal.

[0057] This invention significantly improves the purity, stability, and adaptability of navigation signals through multi-level filtering and dynamic calibration signal purification processing, forming a strict signal quality assurance chain as a whole. This provides a high-quality signal foundation for subsequent processing, making it suitable for military, government, and other fields with high signal quality requirements. It also provides reliable signal support for the precise positioning of carrier platforms in complex environments.

[0058] In some optional implementations of the present invention, the step of determining the motion trajectory of the carrier platform by means of a fusion algorithm based on the observation data of the navigation signal, the second pulse signal, and the inertial navigation data includes: Based on the observation data of the navigation signal and the second pulse signal, the position observation value of the carrier platform is determined; based on the inertial navigation data and the second pulse signal, the position prediction value of the carrier platform is determined; using a fusion algorithm based on adaptive weighted Kalman filtering, the position observation value and the position prediction value are weighted and error corrected to obtain adaptation weights; based on the adaptation weights, the position observation value and the position prediction value are weighted and fused to obtain the real-time time and position information of the carrier platform; based on the real-time time and position information, the motion trajectory of the carrier platform is generated.

[0059] In this invention, the core of the navigation signal observation data includes pseudorange observations. Pseudo-satellite / low-Earth orbit satellite coordinates Signal propagation time The navigation message (including delay correction parameters) requires the signal propagation time to be calibrated based on the second pulse signal. The receiver clock error is corrected using the second pulse to ensure a unified measurement standard for the signal propagation time. Then, the position observation value of the carrier platform is determined using the following pseudorange formula:

[0060] in, For pseudorange observations, For pseudo-satellite / low-Earth orbit satellite coordinates, At the speed of light, To correct observation errors for ionospheric and tropospheric delay parameters in navigation messages, The term is used to quantize the signal propagation time after second-pulse calibration. The corresponding distance. Solve for the coordinates of the desired position by simultaneously using pseudorange data from at least three different signal sources. The final position observation value of the carrier platform is obtained. This observation value has absolute position reference characteristics, but may fluctuate under strong electromagnetic interference.

[0061] Optionally, a position prediction value can be generated based on inertial navigation data and a second pulse signal. This is achieved by deriving a matrix-based mathematical model adapted to Kalman filtering, which transforms kinematic principles into the model. The inertial navigation data includes real-time raw position and three-dimensional velocity. Three-dimensional acceleration and device operating state parameters. First, define the state vector containing the key motion parameters of the carrier platform as:

[0062] in, The position parameters to be derived are... and These are the velocity and acceleration parameters output by the inertial navigation system, respectively. The receiver clock bias, calibrated by a second pulse (used to correct time synchronization deviations), is used to comprehensively describe the motion state of the carrier platform. The kinematic principles of position change derivation based on velocity and acceleration are transformed into a matrix expression, establishing the state prediction equation:

[0063] in, The state transition matrix is ​​implicitly defined through its elements. Isokinetic relationships; Used to establish the dimensional matching relationship between control input and state vector, ensuring that velocity and acceleration parameters can effectively affect position deduction; To control the input, the three-dimensional velocity and acceleration from the inertial navigation data are directly substituted in; To account for process noise, quantify inertial device errors (such as accelerometer bias and gyroscope drift). Substitute the state estimate from the previous moment into the input. With current control input The state vector containing the current position prediction information is obtained through equation operations. The position parameters are extracted from this data to obtain the predicted position value of the carrier platform. This predicted value can continuously reflect the platform's motion trajectory, but it is affected by... The effect is that there is a cumulative deviation when used alone.

[0064] Optionally, a fusion algorithm based on the Adaptive Weighted Kalman Filter (AWKF) can be used to achieve optimized fusion of location observations and predictions. Specifically, based on the state prediction equation, an observation equation is established:

[0065] in These are location observations. For the observation matrix, establish the mapping relationship between the observed values ​​and the state vector. To mitigate observation noise (from atmospheric delay in the calculation of observations, receiver noise, etc.), the observation equation matches the data dimension of the position observations with the position predictions. Next, the signal-to-noise ratio and frequency deviation of the navigation signal are obtained to assess the reliability of the position observations, and the position prediction error is calculated using the drift rate of the inertial navigation data. Based on the assessment results, adaptation weights are dynamically allocated, and the error covariance matrix is ​​updated. Correcting prediction errors and observation errors, among which To achieve dynamic adaptation of weights and error states, Kalman gain is used. The observed and predicted positions are weighted according to the adapted weights to obtain the real-time time and position information of the platform. This real-time time and position information is continuously collected in a time series to form the raw motion trajectory data. The final generated trajectory clearly reflects the platform's positional changes in space. Kalman filtering is essentially an optimal estimator. Based on the system model and historical data, it predicts the current state and fuses it with the observed values. This process itself is a denoising and smoothing process. Therefore, the final generated trajectory is highly accurate and smooth, avoiding trajectory jumps caused by observation noise, and providing high-quality, high-confidence input for higher-level applications such as path planning and decision control.

[0066] It is worth noting that the fusion algorithm based on AWKF overcomes the limitations of a single navigation source. Inertial navigation data can provide high-frequency, short-term, high-precision relative displacement but has cumulative errors. Navigation signal observation data can provide absolute position reference and is less prone to drift, but is susceptible to obstruction, interference, or temporary loss. AWKF can dynamically evaluate the reliability of the two types of data sources to achieve optimal fusion. When the signal is reliable, the observation values ​​are used to correct inertial navigation drift; when unreliable, short-term inertial navigation is used for estimation. This complementary mechanism can output a continuous, smooth, and high-precision motion trajectory, improving positioning accuracy and reliability. Its core advantage is "adaptive weighting." Traditional filters often have fixed observation noise matrices, but AWKF can dynamically adjust them in real time according to the observation residual sequence. When the signal is abnormal, it automatically reduces the weight of unreliable observation values ​​to prevent contamination; when the quality recovers, it increases the weight. This intelligent fault tolerance significantly improves the system's robustness in complex environments.

[0067] This invention utilizes AWKF (Automatic Array of Sources) to achieve multi-source data fusion, effectively improving the accuracy and continuity of the platform's motion trajectory. The smooth trajectory clearly reflects changes in the platform's spatial position, providing a reliable positional reference for subsequent signal parameter adjustments and standard navigation signal generation, thus enhancing system adaptability and environmental resilience. Instead of using a fixed set of parameters that may perform poorly in certain scenarios, the system forms a closed loop of perception-evaluation-adjustment. This allows the navigation system to automatically adapt to environments such as open skies, urban canyons, and varying levels of interference, maintaining optimal performance at all times, reducing reliance on manual parameter tuning, and achieving a higher level of intelligence.

[0068] In some optional implementations of the present invention, the initial values ​​of the signal parameters include an initial carrier frequency, an initial code rate, and an initial modulation depth, and the target values ​​of the signal parameters include a target carrier frequency, a target code rate, and a target modulation depth. The step of dynamically adjusting the preset initial values ​​of the signal parameters according to the motion trajectory of the carrier platform to obtain the target values ​​of the signal parameters includes: Real-time motion feature parameters are extracted from the motion trajectory of the carrier platform, including instantaneous velocity, acceleration, and maneuvering mode. Based on the real-time motion feature parameters, a preset mapping table is queried to dynamically adjust the initial carrier frequency and the initial modulation depth to obtain the target carrier frequency and the target modulation depth. The position update rate of the carrier platform navigation system is acquired in real time, and the electromagnetic interference level in the environment is detected. Based on the position update rate and the environmental interference level, the initial code rate is adaptively adjusted to obtain the target code rate.

[0069] In this invention, instantaneous velocity is determined based on the position coordinates of two consecutive moments in the trajectory, acceleration is calculated using the difference in instantaneous velocity between adjacent moments and the time interval, and maneuver pattern recognition is based on different carrier platforms combined with instantaneous velocity and acceleration thresholds to classify patterns, such as when... When the instantaneous speed is between 5 m / s and 15 m / s and the acceleration is between 0.2 m / s² and 1 m / s², it is determined to be a medium-speed cruise mode; when the instantaneous speed is greater than 15 m / s and the acceleration is greater than 0.5 m / s², it is determined to be a high-speed acceleration maneuver mode; when the instantaneous speed is between 5 and 12 m / s and the acceleration is greater than 1 m / s² and the velocity direction change angle is greater than 15°, it is determined to be a sharp turn maneuver mode. This achieves optimal matching between navigation signal generation and the dynamic characteristics of the carrier platform, significantly improving signal tracking performance. For example, in high-dynamic scenarios (such as high speed, high acceleration, and violent maneuvers), by increasing the carrier frequency and modulation depth, the tracking bandwidth and anti-Doppler frequency shift capability of the signal are effectively improved, preventing receiver lock-up and ensuring signal continuity and stability under high-maneuver conditions. In low-dynamic scenarios (such as low-speed, constant-speed cruise), by reducing the carrier frequency and modulation depth, the power efficiency of the signal is optimized, unnecessary power consumption is reduced, and sufficient signal stability is maintained. This adaptive matching ensures that the navigation terminal can obtain the highest quality and easiest-to-track satellite navigation signals under different motion conditions.

[0070] Optionally, the mapping table explicitly defines the correspondence between motion characteristic parameter thresholds and adjustment strategies. For example, when in a uniform / low-speed stable mode, the carrier frequency adjustment strategy is to minimize frequency offset compensation, taking the average of 5 velocity values ​​to calculate the Doppler frequency offset. ), Fixed at 0°; the modulation depth adjustment strategy is to optimize power and speed coefficient at depth. Set to 0.01, initial modulation depth The reduction is 0.05, etc., with specific values ​​depending on the carrier platform. For the calculation of the target carrier frequency, the Doppler frequency offset is calculated based on the instantaneous velocity. To compensate for the influence of motion on the signal frequency, according to the formula... Calculate the target value, where The initial carrier frequency; The angle between the direction of relative motion and the direction of signal propagation; For example, the signal wavelength, such as the BeiDou B1 band. ≈0.19m. For the calculation of the target modulation depth, the modulation depth is optimized based on the absolute value of the relative velocity to ensure signal demodulation performance. The formula is: , of which Initial modulation depth; The velocity coefficient; Let k be the absolute value of the relative velocity at time k. For the calculation of the target code rate, the code rate is dynamically matched based on the position update rate; the target code rate formula is... ,in, This is the initial code rate, such as 1.023 Mbps; The update interval for the base position is 1 second; Let k be the actual position update interval at time k, such as 0.5s. Simultaneously, the target code rate is determined according to a two-factor adjustment rule based on environmental interference level and update rate. Specifically, under high update rate and strong interference, the code rate is increased to 1.5~2.0 times the initial value to enhance signal timeliness and robustness; under medium update rate and medium interference, it is maintained at 1.0~1.2 times the initial value to balance real-time performance and bandwidth usage; under low update rate and weak interference, it is reduced to 0.6~0.8 times the initial value to save bandwidth and improve signal-to-noise ratio. This achieves the following: under high update rate / strong interference, a high code rate can carry more navigation messages, meet high-frequency positioning requirements, and has stronger wide-spectrum anti-narrowband interference capability; under low update rate / weak interference, a low code rate saves bandwidth, concentrates signal energy to improve signal-to-noise ratio, is easier to acquire and maintain, and ultimately improves the overall system efficiency.

[0071] After the above adjustments, the target carrier frequency, target modulation depth, and target code rate form a parameter combination adapted to the platform's motion state and environmental interference. By independently and collaboratively adjusting the three core signal parameters, the system obtains multi-dimensional optimization methods, which can flexibly adapt to various mission scenarios, including but not limited to: prioritizing high dynamic tracking and high update rate for reconnaissance and surveillance missions (high mobility, high real-time performance); prioritizing power consumption and signal stability for long-duration cruise missions (low mobility, long endurance); and prioritizing anti-jamming and anti-interception capabilities in electronic warfare environments. This flexible parameter reconfigurability allows a single system to meet various differentiated needs, thus broadening its application range.

[0072] It is worth noting that the core of this adjustment mechanism lies in its closed-loop automated process of "perception-decision-execution". Specifically, perception involves the system monitoring its own motion state, positioning requirements (update rate), and external electromagnetic environment (interference level) in real time. Decision-making involves automatically making optimal parameter adjustment decisions based on a preset mapping table and optimization criteria. Execution involves dynamically configuring the parameters of the signal generator. This transforms the system from a static and passive entity into an intelligent agent capable of understanding itself and its environment and proactively optimizing, significantly improving its applicability and performance in complex scenarios, while also enhancing the environmental perception and autonomous decision-making capabilities of the navigation augmentation system.

[0073] This invention significantly improves the matching degree between standard satellite navigation signals and the carrier platform status and environment by dynamically adapting the core parameters of the signal. Through precise dynamic control of multiple parameters, it generates a highly adaptable signal that is consistent with the format of the target satellite navigation system, ensuring the signal reception quality of the navigation terminal in complex motion and interference environments.

[0074] In some optional implementations of the present invention, the step of generating a standard satellite navigation signal consistent with the format of the satellite navigation system adapted to the carrier navigation terminal based on the target value of the signal parameters and the motion trajectory of the carrier platform includes: According to the satellite signal interface control file corresponding to the satellite navigation system adapted to the carrier navigation terminal, a target navigation message conforming to the standard format is generated; according to the target navigation message and the target value of the signal parameters, a baseband digital signal is generated using direct digital frequency synthesis technology; the baseband digital signal is converted into an analog signal through a high-speed digital-to-analog converter; the analog signal is modulated to a preset working frequency band through a radio frequency front end to generate the standard satellite navigation signal.

[0075] In this invention, the interface control file of the satellite navigation system adapted to the carrier navigation terminal, such as the BeiDou satellite navigation system signal interface control file, is used. According to the ICD (Integrated Device Code) specification, a three-level structure of "frame-subframe-word" is adopted. Each frame contains 5 subframes, each subframe contains 10 words, and each word contains 30 bits (including 1 bit parity check). Subframes 1-3 are real-time frames, and subframes 4-5 are non-real-time frames. The frame period is 2 seconds, which matches the actual BeiDou timing and ensures consistency of the information layer. Ephemeris parameters can be obtained and filled into subframes 1-2 in the following ways: first, by obtaining the latest global ephemeris from the satellite navigation data center via the Internet; second, by extracting the enhanced ephemeris information broadcast by external signals (such as low-orbit augmentation signals and pseudo-satellite ground-based augmentation signals). The obtained ephemeris data will be used as "raw material" and written into subframes 1-2 of the target navigation message to ensure the accuracy and timeliness of the ephemeris parameters and provide reliable satellite orbit information for the navigation terminal. Errors during signal propagation are corrected by receiver clock bias and written into the clock correction field of subframe 3. Standardized fields such as signal health status and ionospheric delay correction parameters are filled in to ensure complete consistency with the field definitions and data accuracy of the satellite navigation system message adapted to the carrier navigation terminal. The structure, content, encoding format (such as BCD code, convolutional code), and frame structure of the navigation message are completely consistent with the satellite navigation system signal adapted to the carrier navigation terminal, ensuring 100% format compatibility with existing terminals and achieving seamless replacement. This enables any existing navigation terminal that conforms to this standard to correctly parse, decode, and use the navigation information (such as ephemeris, time, satellite health status, etc.) in the signal, which is the technological cornerstone for achieving the core advantage of "no need to modify existing terminals".

[0076] Optionally, based on the target code rate, a standard-compliant spreading code is generated via a linear feedback shift register, with the generation rate of the spreading code strictly synchronized with the target code rate. The bit stream of the target navigation message (each bit duration adapted to the spreading code period, e.g., 1ms corresponds to 1 bit of message data) is modulo-2 added to the generated spreading code; that is, when a message bit is 1, the spreading code remains unchanged; when a message bit is 0, the spreading code is inverted. The low-rate message is loaded onto the high-speed spreading code to achieve spreading, outputting a spread digital code stream. Using a phase accumulator of Direct Digital Frequency Synthesis (DDS), based on a preset frequency control word value, the phase increment is first accumulated every clock cycle to output a 32-bit phase code (corresponding to the baseband carrier phase, ensuring frequency accuracy). The phase code is then looked up in a sine / cosine waveform ROM to output a 16-bit digital amplitude value, generating the I-channel (sine) and Q-channel (cosine) baseband carriers. Finally, the spread-spectrum navigation message code stream is modulated with the baseband carrier generated by DDS, and the signal amplitude is controlled by the target modulation depth to form the final baseband digital signal. Specifically, the amplitude of the baseband carrier output by DDS is adjusted by a digital multiplier according to the target modulation depth; the spread-spectrum digital code stream is multiplied by the I-channel and Q-channel amplitude-adjusted baseband carriers respectively to achieve double-sideband amplitude modulation; since the phase difference between the I / Q carriers is 90°, the final output baseband digital signal is an orthogonal dual-channel (I / Q) digital signal. By using DDS technology to generate baseband digital signals, high precision, high stability, and high flexibility are maintained, giving the signal extremely high frequency resolution and extremely fast frequency switching speed. It can accurately achieve the target values ​​of signal parameters (such as target carrier frequency and code rate), and the frequency and phase noise performance of the generated signal is excellent. High sensitivity refers to the fact that the core of DDS is a programmable phase accumulator and waveform lookup table. By simply changing the control word, signals of different frequencies and phases can be generated instantly, providing a hardware foundation for adaptive signal generation.

[0077] Optionally, the I / Q dual-channel baseband digital signals output from the DDS are synchronously input into a high-speed analog-to-digital converter (DAC). A synchronous clock (from the same source as the DDS reference clock) controls the conversion timing, ensuring that the phase difference between the I and Q channels is strictly maintained at 90°. The high-speed, high-resolution DAC can distortion-freely reconstruct the high-precision digital signal generated by the DDS into an analog signal, precisely controlling the amplitude, zero-crossing points, and waveform smoothness of the analog waveform. This avoids the distortion and quantization noise introduced by the digital-to-analog conversion stage, ensuring that the final generated analog baseband signal has high purity and fidelity, providing high-quality material for subsequent RF modulation.

[0078] The converted analog signal is filtered by an RC low-pass filter to remove high-frequency quantization noise. The filtered analog baseband signal and the RF local oscillator signal (generated by a phase-locked loop, PLL) are input into a quadrature mixer. The target RF signal is generated through the phase quadrature characteristics of the I / Q signals. After the above-described full-process processing, the generated standard satellite navigation signal meets the standards of the satellite navigation system compatible with the carrier navigation terminal in terms of format compatibility, frequency stability, and signal quality. "RF front-end modulation to the preset operating frequency band" is a crucial step in converting the baseband signal into airborne radio waves. The modulation process accurately shifts the baseband signal to the standard frequency of satellite navigation. This ensures that the generated RF signal is consistent with the satellite signal compatible with the carrier navigation terminal in all RF specifications, including center frequency, bandwidth, and modulation method. This allows the carrier platform's navigation antenna and RF front-end to normally receive, amplify, and down-convert the signal, completing the final link from signal generation to terminal reception.

[0079] This invention, through standardized end-to-end signal generation, ensures that the output satellite navigation signal is highly consistent with the satellite navigation system adapted to the carrier navigation terminal. It defines a complete, precise, and fully standardized signal generation pipeline from "information generation" to "RF transmission." By strictly adhering to international standards, employing advanced digital signal generation technology, high-precision digital-to-analog conversion, and standard RF modulation, it ultimately produces a "standard product" that is indistinguishable from the target satellite navigation signal in three dimensions: "information content," "baseband waveform," and "RF characteristics." This ensures that it can be easily recognized and used by the vast number of existing navigation terminals on the market, achieving maximum technological compatibility and practical value.

[0080] Those skilled in the art will understand that all or part of the processes in the methods of the above embodiments can be implemented by instructing related hardware through computer-readable instructions. These computer-readable instructions can be stored in a computer-readable storage medium. When the program is executed, it can include the processes of the embodiments of the above methods. The aforementioned storage medium can be a non-volatile storage medium such as a magnetic disk, optical disk, or read-only memory (ROM), or random access memory (RAM).

[0081] It should be understood that although the steps in the flowcharts of the accompanying figures are shown sequentially as indicated by the arrows, these steps are not necessarily executed in the order indicated by the arrows. Unless explicitly stated herein, there is no strict order restriction on the execution of these steps, and they can be executed in other orders. Moreover, at least some steps in the flowcharts of the accompanying figures may include multiple sub-steps or multiple stages. These sub-steps or stages are not necessarily completed at the same time, but can be executed at different times, and their execution order is not necessarily sequential, but can be performed alternately or in turn with other steps or at least some of the sub-steps or stages of other steps.

[0082] Further reference Figure 3 As a response to the above Figure 2 The present invention provides an embodiment of a navigation signal seamless conversion device based on unified spatiotemporal information, which is implemented by the method shown. Figure 2 Corresponding to the method embodiments shown, this device can be specifically applied to various electronic devices.

[0083] like Figure 3 As shown, the seamless navigation signal conversion device 300 based on unified spatiotemporal information of the present invention includes: an acquisition module 301, a first determination module 302, a second determination module 303, an adjustment module 304, a generation module 305, and a safety processing module 306. Wherein: The acquisition module 301 is used to acquire observation data and second pulse signals of navigation signals from external signal sources; the navigation signals include low-orbit enhancement signals and / or pseudo-satellite ground-based enhancement signals; The first determining module 302 is used to determine the motion state of the carrier platform based on the observation data. The motion state includes dynamic and static states. If the motion state is dynamic, the inertial navigation data of the carrier platform is acquired. The second determining module 303 is used to determine the motion trajectory of the carrier platform by means of a fusion algorithm based on the observation data of the navigation signal, the second pulse signal and the inertial navigation data; The adjustment module 304 is used to dynamically adjust the preset initial values ​​of the signal parameters according to the motion trajectory of the carrier platform to obtain the target values ​​of the signal parameters; The generation module 305 is used to generate a standard satellite navigation signal that is consistent with the format of the satellite navigation system adapted to the carrier navigation terminal, based on the target value of the signal parameters and the motion trajectory of the carrier platform. The security processing module 306 is used to perform anti-hijacking processing on the standard satellite navigation signal to obtain the target satellite navigation signal, and send the target satellite navigation signal to the navigation terminal of the carrier platform.

[0084] Figure 3 The specific implementation of each module in the device can be referred to the foregoing method embodiments, and will not be repeated here. It should also be noted that the module names described in the device embodiments of the present invention do not necessarily constitute a limitation on the module itself under certain circumstances.

[0085] To address the aforementioned technical problems, the present invention also provides a computer device. Please refer to the following for details. Figure 4 , Figure 4 This is a basic structural block diagram of the computer device of the present invention.

[0086] The computer device 4 includes a memory 41, a processor 42, and a network interface 43 that are interconnected via a system bus. It should be noted that only the computer device 4 with components 41-43 is shown in the figure; however, it should be understood that it is not required to implement all the shown components, and more or fewer components can be implemented alternatively. Those skilled in the art will understand that the computer device described here is a device capable of automatically performing numerical calculations and / or information processing according to pre-set or stored instructions, and its hardware includes, but is not limited to, microprocessors, application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), digital signal processors (DSPs), embedded devices, etc.

[0087] The computer device can be a desktop computer, laptop, handheld computer, or cloud server, etc. The computer device can interact with the user via a keyboard, mouse, remote control, touchpad, or voice control.

[0088] The memory 41 includes at least one type of readable storage medium, including flash memory, hard disk, multimedia card, card-type memory (e.g., SD or DX memory), random access memory (RAM), static random access memory (SRAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), programmable read-only memory (PROM), magnetic memory, magnetic disk, optical disk, etc. In some embodiments, the memory 41 may be an internal storage unit of the computer device 4, such as the hard disk or memory of the computer device 4. In other embodiments, the memory 41 may also be an external storage device of the computer device 4, such as a plug-in hard disk, smart media card (SMC), secure digital (SD) card, flash card, etc. Of course, the memory 41 may include both the internal storage unit and the external storage device of the computer device 4. In this invention, the memory 41 is typically used to store the operating system and various application software installed on the computer device 4, such as computer-readable instructions for a seamless conversion method of navigation signals based on unified spatiotemporal information. In addition, the memory 41 can also be used to temporarily store various types of data that have been output or will be output.

[0089] In some embodiments, the processor 42 may be a central processing unit (CPU), controller, microcontroller, microprocessor, or other data processing chip. The processor 42 is typically used to control the overall operation of the computer device 4. In this invention, the processor 42 is used to execute computer-readable instructions stored in the memory 41 or to process data, for example, to execute computer-readable instructions for the seamless conversion method of navigation signals based on unified spatiotemporal information.

[0090] The network interface 43 may include a wireless network interface or a wired network interface, which is typically used to establish communication connections between the computer device 4 and other electronic devices.

[0091] The computer device provided by this invention ensures positioning continuity by fusing low-Earth orbit / pseudo-satellite augmentation signals with inertial navigation data. Simultaneously, it dynamically adjusts signal parameters based on real-time trajectory to adapt to platform motion requirements, resulting in a standard satellite navigation signal consistent with the target satellite navigation system format. Furthermore, anti-interference and encryption protection ensure signal reliability, allowing for zero-modification adaptation to existing terminals, strong compatibility, reduced costs, and improved adaptability to complex scenarios on the carrier platform.

[0092] The present invention also provides another embodiment, namely, providing a computer-readable storage medium storing computer-readable instructions that can be executed by at least one processor to cause the at least one processor to perform the steps of the navigation signal seamless conversion method based on unified spatiotemporal information as described above.

[0093] The computer-readable storage medium provided by this invention ensures positioning continuity by fusing low-Earth orbit / pseudo-satellite augmentation signals with inertial navigation data. Simultaneously, it dynamically adjusts signal parameters based on real-time trajectory to adapt to platform motion requirements, resulting in a standard satellite navigation signal consistent with the target satellite navigation system format. Furthermore, anti-interference and encryption protection ensure signal reliability, and it adapts to existing terminals with zero modifications, exhibiting strong compatibility, reducing costs, and improving the adaptability of the carrier platform to complex scenarios.

[0094] Through the above description of the embodiments, those skilled in the art can clearly understand that the methods of the above embodiments can be implemented by means of software plus necessary general-purpose hardware platforms. Of course, they can also be implemented by hardware, but in many cases the former is a better implementation method. Based on this understanding, the technical solution of the present invention, or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product is stored in a storage medium (such as ROM / RAM, magnetic disk, optical disk) and includes several instructions to cause a terminal device (which may be a mobile phone, computer, server, air conditioner, or network device, etc.) to execute the methods described in the various embodiments of the present invention.

Claims

1. A method for seamless conversion of navigation signals based on unified spatiotemporal information, characterized in that, Includes the following steps: Acquire observation data and second pulse signals of navigation signals from external signal sources, the navigation signals including low-orbit augmentation signals and / or pseudo-satellite ground-based augmentation signals; The motion state of the carrier platform is determined based on the observation data. The motion state includes dynamic and static states. If the motion state is dynamic, the inertial navigation data of the carrier platform is acquired. The motion trajectory of the carrier platform is determined by a fusion algorithm based on the observation data of the navigation signal, the second pulse signal, and the inertial navigation data. Based on the motion trajectory of the carrier platform, the preset initial values ​​of the signal parameters are dynamically adjusted to obtain the target values ​​of the signal parameters. Based on the target values ​​of the signal parameters and the motion trajectory of the carrier platform, a standard satellite navigation signal with a format consistent with the satellite navigation system adapted to the carrier navigation terminal is generated; The standard satellite navigation signal is subjected to anti-hijacking processing to obtain the target satellite navigation signal, and the target satellite navigation signal is sent to the navigation terminal of the carrier platform.

2. The seamless conversion method for navigation signals based on unified spatiotemporal information according to claim 1, characterized in that, The process of performing anti-hijacking processing on the standard satellite navigation signal to obtain the target satellite navigation signal includes: The standard satellite navigation signal is modulated using dynamic spreading code based on the real-time time and location information of the carrier platform. The sequence of the dynamic spreading code is generated by the real-time latitude and longitude coordinates of the carrier platform and the system time through a hash algorithm to obtain a physical layer encrypted standard satellite navigation signal. The standard satellite navigation signal encrypted at the physical layer is encrypted using the lightweight national cryptographic algorithm SM4 to encrypt the navigation message, thereby obtaining the target satellite navigation signal.

3. The seamless conversion method for navigation signals based on unified spatiotemporal information according to claim 1, characterized in that, Before acquiring the observation data and second pulse signal of the navigation signal from the external signal source, the method further includes: The system acquires initial navigation signals from external signal sources, performs real-time frequency band monitoring and interference detection on the initial navigation signals, and identifies the type and intensity of interference. If interference is detected, an adaptive frequency switching strategy is initiated, modulating the initial navigation signal to one of a number of preset backup operating frequency bands, and reconstructing the signal based on a signal reconstruction algorithm to obtain an anti-interference navigation signal; the signal reconstruction algorithm includes: a channel estimation and equalization algorithm based on the minimum mean square error criterion, combined with orthogonal frequency division multiplexing technology, to reconstruct the damaged signal in the frequency domain; The anti-interference navigation signal is then purified to extract the standard signal features of the purified navigation signal. The standard signal features are compared with a preset satellite signal feature library. If the features match, the navigation signal is output. If there is a deviation, the navigation signal is output after signal correction using digital predistortion technology. The observation data is extracted from the navigation signal.

4. The seamless conversion method for navigation signals based on unified spatiotemporal information according to claim 3, characterized in that, The signal purification process for the interference-resistant navigation signal includes: The anti-interference navigation signal is sequentially subjected to bandpass filtering and adaptive notch filtering to suppress out-of-band noise and residual interference; Wavelet transform is used to perform time-frequency analysis on signals to identify and suppress transient pulse interference; A Kalman filter is used to smooth the signal amplitude and phase; The filtered signal is calibrated using automatic gain control technology to obtain the purified navigation signal.

5. The seamless conversion method for navigation signals based on unified spatiotemporal information according to claim 1, characterized in that, The step of determining the motion trajectory of the carrier platform using a fusion algorithm based on the observed data of the navigation signal, the second pulse signal, and the inertial navigation data includes: The position observation value of the carrier platform is determined based on the observation data of the navigation signal and the second pulse signal; Based on the inertial navigation data and the second pulse signal, the predicted position of the carrier platform is determined; A fusion algorithm based on adaptive weighted Kalman filtering is used to assign weights and correct errors in the location observations and location predictions to obtain the appropriate weights. Based on the adaptation weights, the location observations and the location predictions are weighted and fused to obtain the real-time time and location information of the carrier platform. The motion trajectory of the carrier platform is generated based on the real-time time and location information.

6. The seamless conversion method for navigation signals based on unified spatiotemporal information according to claim 1, characterized in that, The initial values ​​of the signal parameters include an initial carrier frequency, an initial code rate, and an initial modulation depth. The target values ​​of the signal parameters include a target carrier frequency, a target code rate, and a target modulation depth. The step of dynamically adjusting the preset initial values ​​of the signal parameters according to the motion trajectory of the carrier platform to obtain the target values ​​of the signal parameters includes: Real-time motion feature parameters are extracted from the motion trajectory of the carrier platform, including instantaneous velocity, acceleration, and maneuvering mode; Based on the real-time motion characteristic parameters, a preset mapping table is queried to dynamically adjust the initial carrier frequency and the initial modulation depth, thereby obtaining the target carrier frequency and the target modulation depth; The position update rate of the carrier platform navigation system is acquired in real time, and the electromagnetic interference level in the environment is detected. Based on the position update rate and the environmental interference level, the initial code rate is adaptively adjusted to obtain the target code rate.

7. The seamless conversion method for navigation signals based on unified spatiotemporal information according to claim 1, characterized in that, The step of generating a standard satellite navigation signal consistent with the format of the satellite navigation system adapted to the carrier navigation terminal, based on the target value of the signal parameters and the motion trajectory of the carrier platform, includes: Based on the satellite signal interface control file corresponding to the satellite navigation system adapted to the carrier navigation terminal, a target navigation message conforming to the standard format is generated; Based on the target navigation message and the target value of the signal parameters, a baseband digital signal is generated using direct digital frequency synthesis technology; The baseband digital signal is converted into an analog signal using a high-speed digital-to-analog converter; The analog signal is modulated to a preset operating frequency band by a radio frequency front end to generate the standard satellite navigation signal.

8. A seamless navigation signal conversion device based on unified spatiotemporal information, characterized in that, include: The acquisition module is used to acquire observation data and second pulse signals of navigation signals from external signal sources, wherein the navigation signals include low-orbit enhancement signals and / or pseudo-satellite ground-based enhancement signals; The first determining module is used to determine the motion state of the carrier platform based on the observation data. The motion state includes dynamic and static states. If the motion state is dynamic, the inertial navigation data of the carrier platform is acquired. The second determining module is used to determine the motion trajectory of the carrier platform by means of a fusion algorithm based on the observation data of the navigation signal, the second pulse signal, and the inertial navigation data. The adjustment module is used to dynamically adjust the preset initial values ​​of the signal parameters according to the motion trajectory of the carrier platform to obtain the target values ​​of the signal parameters; The generation module is used to generate a standard satellite navigation signal that is consistent with the format of the satellite navigation system adapted to the carrier navigation terminal, based on the target value of the signal parameters and the motion trajectory of the carrier platform. The security processing module is used to perform anti-hijacking processing on the standard satellite navigation signal, obtain the target satellite navigation signal, and send the target satellite navigation signal to the navigation terminal of the carrier platform.

9. A computer device, characterized in that, The system includes a memory and a processor, wherein the memory stores computer-readable instructions, and the processor executes the computer-readable instructions to implement the steps of the navigation signal seamless conversion method based on unified spatiotemporal information as described in any one of claims 1 to 7.

10. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores computer-readable instructions, which, when executed by a processor, implement the steps of the navigation signal seamless conversion method based on unified spatiotemporal information as described in any one of claims 1 to 7.

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