A GNSS satellite navigation receiver digital twin system

Abstract

The application discloses a GNSS satellite navigation receiver digital twin system, comprising: a signal data interface module, used for receiving a digitized high-frequency signal data stream input by an external simulation signal source; an antenna digital twin module, used for processing the digitized high-frequency radio frequency signal and outputting a digitized radio frequency signal simulating an antenna effect; a radio frequency channel digital twin module, used for performing complete receiver front-end processing on the processed digitized radio frequency signal and outputting a baseband digital intermediate frequency signal; a baseband processing digital twin module, used for performing software-defined signal processing on the baseband digital intermediate frequency signal to generate original observation and navigation results; and a performance evaluation module, used for evaluating the results output after the GNSS satellite navigation receiver digital twin; the application is favorable for troubleshooting and analysis of GNSS satellite navigation receiver faults, improves test efficiency, verifies sufficiency and effectiveness, and can help researchers improve the reliability of GNSS satellite navigation receivers.

Description

Technical Field

[0001] This invention belongs to the field of satellite navigation, specifically a digital twin system for a GNSS satellite navigation receiver. Background Technology

[0002] In recent years, GNSS satellite navigation receivers have been widely used in various fields such as industry, agriculture, finance, and transportation. Their small size, low cost, and wide applicability have made them an indispensable and important infrastructure for modern nations. However, the power of the GNSS satellite signals received by GNSS satellite navigation receivers is far less than the noise level, making them highly susceptible to interference, especially in complex environments such as urban canyons with tall buildings, battlefields with harsh electromagnetic environments, and poorly designed equipment.

[0003] To reduce costs, current GNSS satellite navigation receivers have generally adopted a chip-based design, using an integrated RF baseband SOC design. While this reduces costs, troubleshooting can be difficult in complex scenarios if the GNSS satellite navigation receiver malfunctions.

[0004] If a GNSS satellite navigation receiver is digitally twinned to form a digital model, it will be easier to troubleshoot and analyze faults, improve testing efficiency, verification sufficiency and effectiveness, and help R&D personnel improve the reliability of GNSS satellite navigation receivers. Summary of the Invention

[0005] To address the challenges of reproducing complex application scenarios and troubleshooting, this invention designs a digital twin system for a GNSS satellite navigation receiver. Through a visual and human-machine interface, the operating parameters of the antenna digital twin module, the radio frequency channel digital twin module, and the baseband processing digital twin module are configured to simulate the entire receiving link of the GNSS satellite navigation receiver and construct its digital twin system. This facilitates the rapid reproduction of complex application scenarios and assists researchers in solving problems such as interference, multipath propagation, and signal failures.

[0006] The technical solution of the present invention is as follows: Specifically, the following technical solution is adopted:

[0007] A GNSS satellite navigation receiver end-link digital twin system, the digital twin system taking a digitized high-frequency signal data stream as input, includes:

[0008] The signal input interface is used to receive digital high-frequency signal data streams from a simulated signal source;

[0009] The antenna digital twin module has its input end connected to the data stream of the signal input interface. It is used to process the digital high-frequency radio frequency signal according to the preset antenna pattern, phase center, VSWR and polarization characteristics, and output the digital radio frequency signal that simulates the antenna effect.

[0010] The radio frequency channel digital twin module, whose input is connected to the antenna digital twin module, is used to perform complete receiver front-end processing on the processed digitized radio frequency signal and output the baseband digital intermediate frequency signal;

[0011] The baseband processing digital twin module, whose input is connected to the radio frequency channel twin module, is used to perform software-defined signal processing on the baseband digital intermediate frequency signal to generate raw observation and navigation results;

[0012] The performance evaluation module, whose input is connected to the baseband processing digital twin module, is used to receive the raw observation and navigation results, and based on these, calculate and output a set of index data for quantitatively evaluating the full-link function and performance of the GNSS satellite navigation receiver from radio frequency to navigation solution.

[0013] Furthermore, the radio frequency channel digital twin module includes:

[0014] The low-noise amplifier unit, whose input is connected to the antenna digital twin module, is used to simulate noise figure, filter response, and amplifier nonlinear characteristics.

[0015] The downconversion unit, whose input is connected to the low-noise amplifier unit, is used to downconvert high-frequency signals to intermediate-frequency signals through digital mixing and digitally controlled oscillators.

[0016] An automatic gain control unit, whose input is connected to a downconversion unit, is used to simulate the dynamic gain adjustment of the receiving link to prevent exceeding the threshold of analog-to-digital conversion;

[0017] The analog-to-digital conversion effect simulation unit, whose input is connected to the automatic gain control unit, is used to simulate quantization noise, sampling clock jitter, and nonlinear distortion.

[0018] This module simulates the hardware characteristics of the RF front end by configuring the parameters of the above units and outputs the final baseband digital intermediate frequency signal.

[0019] Furthermore, the hardware characteristic parameters simulated by the RF channel digital twin module are configurable. By modifying these parameters, different models or different hardware states of RF channels can be simulated. The hardware characteristic parameters include, but are not limited to: local oscillator frequency and phase noise, image rejection ratio, filter bandwidth and in-band ripple, automatic gain control dynamic range and response time, and the effective number of bits, sampling rate and spurious-free dynamic range of the analog-to-digital converter.

[0020] Furthermore, the design methodology for the RF channel digital twin module is as follows:

[0021] The digital radio frequency signal first passes through a low-noise amplifier and filter model, which can amplify and filter signals at specific frequencies. At the same time, the noise figure, amplifier nonlinearity, and filter in-band flatness effects are superimposed to adjust the corresponding digital radio frequency signal strength. The automatic gain control unit can select fixed gain or automatic gain control according to the settings to prevent signal overflow or distortion.

[0022] Then, the digitized radio frequency signal is converted into a configurable digital intermediate frequency signal through the downconverter model. The analog-to-digital conversion model introduces analog quantization noise, nonlinear distortion, and quantization bit loss.

[0023] Finally, the adjusted digital intermediate frequency signal is output.

[0024] Furthermore, the baseband processing digital twin module includes:

[0025] Parallel channel processing unit is used to simulate multiple independent signal processing channels to process signals from different GNSS satellites simultaneously;

[0026] The configurable algorithm unit allows for dynamic selection and configuration of its signal acquisition algorithm, phase-locked loop bandwidth, frequency-locked loop bandwidth, and code loop discriminator algorithm.

[0027] Furthermore, the design method for the baseband processing digital twin module is as follows:

[0028] Signal acquisition and tracking of digital intermediate frequency signals: The receiver searches in a two-dimensional space of frequency and code phase, and captures visible satellite signals according to relevant calculations; then, precise tracking is performed through carrier tracking loop and code delay-locked loop to achieve carrier stripping and despreading, and to synchronize and demodulate the navigation message bit stream;

[0029] Entering the message decoding and measurement extraction stage: parsing the navigation message to obtain satellite ephemeris and clock error parameters; at the same time, using the tracking loop output, generating pseudorange and high-precision carrier phase core observation values, and calculating the precise position of each satellite;

[0030] Positioning calculation: Based on the pseudorange observation equation, the error model is used for correction; after locking on at least 4 satellites, the least squares method or Kalman filter algorithm is used to iteratively calculate the receiver's three-dimensional position, velocity and time information.

[0031] Furthermore, the functional performance metrics calculated by the performance evaluation module include:

[0032] RF link metrics include gain flatness, out-of-band rejection, and dynamic range.

[0033] Signal quality metrics: carrier-to-noise power density ratio, correlation peak shape;

[0034] Tracking performance metrics: carrier phase error, code phase error, and reacquisition time after lock-on loss;

[0035] Navigation performance indicators: positioning accuracy, speed measurement accuracy, and time synchronization accuracy.

[0036] Furthermore, digital twin systems also include:

[0037] A visualization and human-computer interaction interface is used to display the index data output by the performance evaluation module in a graphical manner in real time, and to receive configuration instructions from the user for various parameters in the antenna digital twin module, the radio frequency channel digital twin module, and the baseband processing digital twin module.

[0038] A method for creating a digital twin of the functional performance of a GNSS satellite navigation receiver using a full-link digital twin system includes the following steps: Step S1: Receive the digitized high-frequency signal data stream from the simulated signal source through the radio frequency signal input interface; Step S2: Simulate the entire process of GNSS signal being received by the antenna and down-converted to baseband digital intermediate frequency signal through the antenna digital twin module and the radio frequency channel digital twin module in sequence; Step S3: In the baseband processing digital twin module, the baseband digital intermediate frequency signal is captured, tracked, and processed; Step S4: In the performance evaluation module, based on the results of step S3, calculate the performance indicators of each function from radio frequency to navigation. Step S5: Output and display the functional performance indicators to complete the evaluation of the end-to-end performance under a specific receiver configuration.

[0039] Compared with the prior art, the advantages of the present invention are as follows:

[0040] This invention enables the configuration of antenna digital twin modules, radio frequency channel digital twin modules, baseband processing digital twin modules, and other components through a visual and human-computer interaction interface, thereby achieving a fully digital twin of the GNSS satellite navigation receiver. By continuously adjusting the parameters of different modules, the reception effect under different scenarios can be verified, which greatly reduces the testing cost of complex scenarios, improves testing efficiency, verification sufficiency and effectiveness, and can help R&D personnel improve the reliability of GNSS satellite navigation receivers.

[0041] (1) Through the antenna digital twin module, different types and sizes of antennas can be loaded onto the receiver in a simulated environment to verify the adaptability of the antenna in different scenarios. There is no need to purchase all antennas for testing, which greatly reduces the development and adaptation costs.

[0042] (2) Decouple the baseband processing process and separate the algorithms for the capture, tracking, decoding and positioning steps. These algorithms can be configured or replaced individually, and the effectiveness and reliability of different algorithms and schemes in complex environments can be quickly verified.

[0043] (3) Software-based receivers are highly scalable and can be easily integrated with anti-spoofing and anti-interference algorithm models, which is helpful for the development and verification of more complex receivers. Attached Figure Description

[0044] Figure 1 This is a schematic diagram of the system implemented according to the present invention.

[0045] Figure 2 This invention provides a specific design method for the baseband digital twin module. Detailed Implementation

[0046] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. A full-link digital twin system for a GNSS satellite navigation receiver, in which all components run on a general-purpose computer, workstation, industrial control computer, or server, is used to evaluate the functional performance indicators of a GNSS satellite navigation receiver. The system takes a digitized high-frequency signal data stream as input.

[0047] Figure 1 The schematic diagram of the system of the present invention shown illustrates a digital twin system for a GNSS satellite navigation receiver, including a signal data interface module, an antenna digital twin module, a radio frequency channel digital twin module, a baseband processing digital twin module, a performance evaluation module, and a visualization and human-computer interaction interface.

[0048] Signal data interface module: Used to receive digitized high-frequency signal data streams generated by simulated signal sources. It removes redundant information from application layer protocols and outputs the actual data stream to subsequent modules. Input data streams are either 100G optical network hardware interfaces or software interfaces for inter-process communication. Output interfaces are internal software interfaces for inter-process communication, such as shared memory or local sockets.

[0049] Antenna Digital Twin Module: Used to simulate different types of satellite receiving antennas, including but not limited to circularly polarized antennas, linearly polarized antennas, vertically polarized antennas, and horizontally polarized antennas. It has a simulation model configuration interface with parameters such as gain pattern, phase center, VSWR, and polarization characteristics. It processes the digitized high-frequency radio frequency signal and outputs a digitized radio frequency signal that simulates antenna effects.

[0050] The signal data interface module outputs digitized radio frequency (RF) signals from satellites originating from different directions. Each signal passes through an antenna digital twin module. The signal first undergoes gain pattern adjustment, ranging from -50dB to 50dB with a minimum resolution of 0.1dB, simulating the gain differences between signals at different frequencies and from different directions. The signal strengths are then superimposed. Next, polarization parameters are added; for mismatched polarizations, a fixed gain value is subtracted. Then, based on the standing wave (VSWR) parameters at different frequencies, corresponding gain values ​​are subtracted. Finally, the satellite RF signal with all these effects superimposed is output. The output interface is a software internal interface for inter-process communication, such as shared memory or local sockets.

[0051] The RF channel digital twin module receives the aforementioned digitized RF signals and simulates various characteristics of components in the RF channel, including low-noise amplifiers, filters, downconverters, crystal oscillators, and analog-to-digital converters, ultimately outputting a digital intermediate frequency (IF) signal. The digitized RF signal first passes through a low-noise amplifier and filter model, which amplifies and filters signals at specific frequencies. It also incorporates noise figure, amplifier nonlinearity, and filter in-band flatness to adjust the corresponding digitized RF signal strength. The automatic gain control unit can select fixed gain or automatic gain control based on settings to prevent signal overflow or distortion. Then, the downconverter model converts the digitized RF signal into a configurable-bit digital IF signal. The analog-to-digital conversion model introduces analog quantization noise, nonlinear distortion, and quantization bit loss. Finally, the adjusted digital IF signal is output. The output interface is a software internal interface for inter-process communication, such as shared memory or local sockets.

[0052] The hardware characteristic parameters simulated by the digital twin module of the radio frequency channel are configurable. By modifying these parameters, radio frequency channels of different models or with different hardware states can be simulated. These parameters include, but are not limited to: local oscillator frequency and phase noise, image rejection ratio, filter bandwidth and in-band ripple, automatic gain control dynamic range and response time, and the effective number of bits, sampling rate and spurious-free dynamic range of the analog-to-digital converter.

[0053] The baseband processing digital twin module receives the aforementioned digital intermediate frequency signal, performs acquisition, tracking, decoding, and positioning calculations, and outputs results and process parameters. It features a configurable algorithm unit whose signal acquisition and tracking algorithm, phase-locked loop bandwidth, frequency-locked loop bandwidth, and code loop discriminator algorithms are dynamically selectable and configurable, accurately reflecting the relevant performance indicators of the actual baseband chip.

[0054] First, the digital intermediate frequency (IF) signal is acquired and tracked: the receiver searches in a two-dimensional space of frequency and code phase, and captures visible satellite signals based on relevant calculations; then, precise tracking is performed through a carrier tracking loop and a code delay-locked loop to achieve carrier stripping and despreading, synchronizing and demodulating the navigation message bitstream. Next, the message decoding and measurement extraction stage begins: the navigation message is parsed to obtain satellite ephemeris, clock bias, and other parameters; simultaneously, the tracking loop output is used to generate pseudorange and high-precision carrier phase core observations, and the precise positions of each satellite are calculated. Finally, positioning is calculated: based on the pseudorange observation equation, corrections are made using error models (such as ionosphere, troposphere, and clock bias); after at least four satellites are locked, algorithms such as least squares or Kalman filtering are used to iteratively calculate the receiver's three-dimensional position, velocity, and time information. For high-precision carrier phase positioning, integer ambiguity needs to be solved additionally. The entire process is completed by the baseband processing digital twin module, achieving real-time dynamic positioning. The output interface is a software internal interface for inter-process communication, such as shared memory or local sockets.

[0055] The baseband processing digital twin module further includes:

[0056] Parallel channel processing unit is used to simulate multiple independent signal processing channels to process signals from different GNSS satellites simultaneously;

[0057] The configurable algorithm unit allows for dynamic selection and configuration of its signal acquisition algorithm, phase-locked loop bandwidth, frequency-locked loop bandwidth, and code loop discriminator algorithm.

[0058] Performance Evaluation Module: Receives the output results and process parameters from the baseband processing digital twin module, calculates and evaluates indicators such as carrier noise power density ratio, correlation peak shape, carrier phase error, code phase error, lock-out reacquisition time, positioning accuracy, velocity measurement accuracy, and time synchronization accuracy. It then outputs the results to a visualization and human-machine interface. The output interface is a software internal interface for inter-process communication, such as shared memory or local sockets. The functional performance indicators calculated by the performance evaluation module include:

[0059] RF link metrics include gain flatness, out-of-band rejection, and dynamic range.

[0060] Signal quality metrics: carrier-to-noise power density ratio, correlation peak shape;

[0061] Tracking performance metrics: carrier phase error, code phase error, and reacquisition time after lock-on loss;

[0062] Navigation performance indicators: positioning accuracy, speed measurement accuracy, and time synchronization accuracy.

[0063] Visualization and human-computer interaction interface: used to display the index data output by the performance evaluation module in a graphical manner in real time, and to receive user configuration instructions for various parameters in the antenna digital twin module, radio frequency channel digital twin module and baseband processing digital twin module.

[0064] In summary, this digital twin system can meet the performance evaluation and problem diagnosis needs of GNSS satellite navigation receivers in various simulated application scenarios, improve testing efficiency, verification sufficiency and effectiveness, and help R&D personnel improve the reliability of GNSS satellite navigation receivers.

[0065] This invention also provides a method for digital twinning the functional performance of a GNSS satellite navigation receiver, the method comprising the following steps: Step S1: Receive the digitized high-frequency signal data stream from the simulated signal source through the radio frequency signal input interface; Step S2: Simulate the entire process of GNSS signal being received by the antenna and down-converted to baseband digital intermediate frequency signal through the antenna digital twin module and the radio frequency channel digital twin module in sequence; Step S3: In the baseband processing digital twin module, the baseband digital intermediate frequency signal is captured, tracked, and processed; Step S4: In the performance evaluation module, based on the results of step S3, calculate the performance indicators of each function from radio frequency to navigation. Step S5: Output and display the functional performance indicators to complete the evaluation of the end-to-end performance under a specific receiver configuration.

[0066] While the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the invention. Any person skilled in the art can make many possible variations and modifications to the technical solutions of the present invention, or modify them into equivalent embodiments, without departing from the scope of the present invention. Therefore, any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention, without departing from the scope of the present invention, should fall within the protection scope of the present invention.

Claims

1. A full-link digital twin system for a GNSS satellite navigation receiver, characterized in that, Digital twin systems take digitized high-frequency signal data streams as input, including: The signal input interface is used to receive digital high-frequency signal data streams from a simulated signal source; The antenna digital twin module has its input end connected to the data stream of the signal input interface. It is used to process the digital high-frequency radio frequency signal according to the preset antenna pattern, phase center, VSWR and polarization characteristics, and output the digital radio frequency signal that simulates the antenna effect. The radio frequency channel digital twin module, whose input is connected to the antenna digital twin module, is used to perform complete receiver front-end processing on the processed digitized radio frequency signal and output the baseband digital intermediate frequency signal; The baseband processing digital twin module, whose input is connected to the radio frequency channel twin module, is used to perform software-defined signal processing on the baseband digital intermediate frequency signal to generate raw observation and navigation results; The performance evaluation module, whose input is connected to the baseband processing digital twin module, is used to receive the raw observation and navigation results, and based on these, calculate and output a set of index data for quantitatively evaluating the full-link function and performance of the GNSS satellite navigation receiver from radio frequency to navigation solution.

2. The GNSS satellite navigation receiver end-link digital twin system according to claim 1, characterized in that, The radio frequency channel digital twin module includes: The low-noise amplifier unit, whose input is connected to the antenna digital twin module, is used to simulate noise figure, filter response, and amplifier nonlinear characteristics. The downconversion unit, whose input is connected to the low-noise amplifier unit, is used to downconvert high-frequency signals to intermediate-frequency signals through digital mixing and digitally controlled oscillators. An automatic gain control unit, whose input is connected to a downconversion unit, is used to simulate the dynamic gain adjustment of the receiving link to prevent exceeding the threshold of analog-to-digital conversion; The analog-to-digital conversion effect simulation unit, whose input is connected to the automatic gain control unit, is used to simulate quantization noise, sampling clock jitter and nonlinear distortion; This module simulates the hardware characteristics of the RF front end by configuring the parameters of the above units and outputs the final baseband digital intermediate frequency signal.

3. The GNSS satellite navigation receiver end-link digital twin system according to claim 1, characterized in that, The hardware characteristic parameters simulated by the RF channel digital twin module are configurable. By modifying these parameters, different models or different hardware states of RF channels can be simulated. The hardware characteristic parameters include, but are not limited to: local oscillator frequency and phase noise, image rejection ratio, filter bandwidth and in-band ripple, automatic gain control dynamic range and response time, and the effective number of bits, sampling rate and spurious-free dynamic range of the analog-to-digital converter.

4. The GNSS satellite navigation receiver end-link digital twin system according to claim 3, characterized in that, The design methodology for the radio frequency channel digital twin module is as follows: The digital radio frequency signal first passes through a low-noise amplifier and filter model, which can amplify and filter signals at specific frequencies. At the same time, the noise figure, amplifier nonlinearity, and filter in-band flatness effects are superimposed to adjust the corresponding digital radio frequency signal strength. The automatic gain control unit can select fixed gain or automatic gain control according to the settings to prevent signal overflow or distortion. Then, the digitized radio frequency signal is converted into a configurable digital intermediate frequency signal through the downconverter model. The analog-to-digital conversion model introduces analog quantization noise, nonlinear distortion, and quantization bit loss. Finally, the adjusted digital intermediate frequency signal is output.

5. The GNSS satellite navigation receiver end-link digital twin system according to claim 1, characterized in that, The baseband processing digital twin module includes: Parallel channel processing unit is used to simulate multiple independent signal processing channels to process signals from different GNSS satellites simultaneously; The configurable algorithm unit allows for dynamic selection and configuration of its signal acquisition algorithm, phase-locked loop bandwidth, frequency-locked loop bandwidth, and code loop discriminator algorithm.

6. The GNSS satellite navigation receiver end-link digital twin system according to claim 5, characterized in that, The design methodology for the baseband processing digital twin module is as follows: Signal acquisition and tracking of digital intermediate frequency signals: The receiver searches in a two-dimensional space of frequency and code phase, and captures visible satellite signals according to relevant calculations; then, precise tracking is performed through carrier tracking loop and code delay-locked loop to achieve carrier stripping and despreading, and to synchronize and demodulate the navigation message bit stream; Entering the message decoding and measurement extraction stage: parsing the navigation message to obtain satellite ephemeris and clock error parameters; at the same time, using the tracking loop output, generating pseudorange and high-precision carrier phase core observation values, and calculating the precise position of each satellite; Positioning calculation: Based on the pseudorange observation equation, the error model is used for correction; after locking on at least 4 satellites, the least squares method or Kalman filter algorithm is used to iteratively calculate the receiver's three-dimensional position, velocity and time information.

7. The GNSS satellite navigation receiver end-link digital twin system according to claim 1, characterized in that, The functional performance metrics calculated by the performance evaluation module include: RF link metrics include gain flatness, out-of-band rejection, and dynamic range. Signal quality metrics: carrier-to-noise power density ratio, correlation peak shape; Tracking performance metrics: carrier phase error, code phase error, and reacquisition time after lock-on loss; Navigation performance indicators: positioning accuracy, speed measurement accuracy, and time synchronization accuracy.

8. The GNSS satellite navigation receiver end-link digital twin system according to claim 1, characterized in that, Digital twin systems also include: A visualization and human-computer interaction interface is used to display the index data output by the performance evaluation module in a graphical manner in real time, and to receive configuration instructions from the user for various parameters in the antenna digital twin module, the radio frequency channel digital twin module, and the baseband processing digital twin module.

9. A method for performing a digital twin of the functional performance of a GNSS satellite navigation receiver using a full-link digital twin system as described in any one of claims 1-8, characterized in that, Includes the following steps: Step S1: Receive the digitized high-frequency signal data stream from the simulated signal source through the radio frequency signal input interface; Step S2: Simulate the entire process of GNSS signal being received by the antenna and down-converted to baseband digital intermediate frequency signal through the antenna digital twin module and the radio frequency channel digital twin module in sequence; Step S3: In the baseband processing digital twin module, the baseband digital intermediate frequency signal is captured, tracked, and processed; Step S4: In the performance evaluation module, based on the results of step S3, calculate the performance indicators of each function from radio frequency to navigation. Step S5: Output and display the functional performance indicators to complete the evaluation of the end-to-end performance under a specific receiver configuration.

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