Satellite navigation real-time closed loop simulation time synchronization method and system

Abstract

The application provides a satellite navigation real-time closed loop simulation time synchronization method and system, and particularly relates to the field of satellite signal transmission simulation control. The application simultaneously feeds back a periodic hardware synchronization signal generated by a measured receiver to a flight controller and a signal parameter simulation unit, and transmits receiver clock difference data to the flight controller. The flight controller locks a local time by using the hardware pulse, calculates physical deviation and frequency drift of a self clock relative to a simulator time axis according to the local time, establishes an affine time mapping model, performs time stamp marking and kinematics delay pre-compensation on trajectory data injected into the simulator through the model, and closes a time synchronization loop of the whole system in a bidirectional manner at a physical layer and an information layer.

Description

Technical Field

[0001] This invention relates to the field of satellite signal transmission simulation control, specifically to a real-time closed-loop simulation time synchronization method and system for satellite navigation. Background Technology

[0002] Hardware-in-the-loop (HIL) simulation systems for satellite navigation are crucial for verifying the positioning performance of aircraft, missiles, and various high-dynamic navigation terminals. In a typical closed-loop simulation architecture, the flight controller (e.g., a flight controller-based system) injects the vehicle's motion state information (including position, velocity, acceleration, and jerk) into the satellite navigation signal simulator in real time via fiber optic reflective memory. The simulator then generates corresponding navigation radio frequency signals based on the received motion parameters and outputs them to the receiver under test. However, this conventional closed-loop access method has significant drawbacks in terms of time consistency and frequency synchronization. Specifically, the two core simulation devices lack a unified physical time reference. The flight controller and the satellite navigation signal simulator typically use independent local time-frequency references (such as crystal oscillators or rubidium clocks). Even if the two devices perform software alignment at the start of the simulation, the time offset accumulates rapidly over time due to frequency deviations in the hardware crystal oscillators. This frequency asynchrony causes the time axis of the motion trajectory to gradually diverge from the time axis of the navigation signal. Secondly, although fiber optic reflective memory has high bandwidth and low latency, it is essentially a shared memory exchange, capable only of data transfer and unable to transmit physical time precision. The motion state frames output by the flight controller often lack high-precision hardware timestamps, and unpredictable latency jitter occurs during operating system scheduling, memory bus contention, and reflective memory network transmission. When the simulator receives a frame of trajectory data, it cannot accurately determine the corresponding physical execution time and its delay on the transmission path, introducing random phase errors and pseudorange offsets into the signal generation stage. In addition, the system lacks dedicated hardware-level synchronization interfaces between nodes, relying solely on software interaction to attempt to solve synchronization problems, which is insufficient for handling highly dynamic, long-duration simulation tasks.

[0003] To address the aforementioned issues, patent CN114706108A proposes a method that compares simulation time with external time within the simulator and performs post-event smoothing using extrapolation algorithms or speed adjustment logic. However, this method relies excessively on the timestamp accuracy inherent in the external trajectory data and does not establish a true hardware common time axis. Furthermore, when performing resynchronization operations, it is often necessary to clear higher-order motion terms, causing abrupt jumps in the frequency of the simulator's output signal, which fails to meet the testing requirements for high-precision carrier phase tracking.

[0004] Furthermore, patent CN118444338A discloses a closed-loop access system based on fiber optic reflective memory. This system uses a satellite navigation management computer, a signal generator, and testing equipment to form a local area network. It utilizes a signal receiver to parse navigation signals to obtain simulated time and position information, which is then transmitted back to the testing equipment via a serial port for latency evaluation. Firstly, this scheme's feedback link includes both serial port and network, resulting in high latency and significant uncertainty. Secondly, it requires a GNSS signal generator as an external clock source to provide a hardware clock for the relevant hardware devices. However, in practical engineering applications, the hardware architecture and interface standards related to flight controllers are typically strictly closed, generally lacking a hardware reference clock interface for receiving direct input from an external simulator. Their time-frequency operating logic often relies solely on its internal crystal oscillator as a reference. This means that in complex real-world HIL scenarios, the simulator and flight controller are often in a state of "hardware time disconnection." The hardware timing link relied upon by existing technologies is difficult to close at the physical level. Furthermore, due to the lack of a direct hardware synchronization path from the simulator to the flight controller, CN114706108A has to resort to software-level comparison, speed adjustment, and extrapolation algorithms. This solution compares the simulation time with the external trajectory time within the simulator and performs post-processing smoothing on the trajectory frames through algorithms. The limitation of this software compensation method is that it only remedies the latency result, rather than constraining the clock source. When dealing with highly dynamic, long-endurance simulation tasks, because it cannot eliminate the accumulated physical frequency deviation between the hardware crystal oscillators of the two devices, the software smoothing algorithm often causes higher-order motion terms to be cleared or velocity steps to occur during resynchronization, and it cannot eliminate the injected latency jitter caused by operating system scheduling. Summary of the Invention

[0005] The purpose of this invention is to provide a time synchronization method and system for real-time closed-loop simulation of satellite navigation. Flight controllers generally have an interface for receiving the output time and information from the satellite navigation receiver under test, but lack other external time synchronization input interfaces. This invention addresses this type of real-time closed-loop simulation system by solving the problem of establishing a true physical common time reference pointing to the flight controller's time axis without adding any dedicated time synchronization equipment between the flight controller and the satellite navigation signal simulator, and without modifying the existing flight controller's hardware and software architecture. Based on this, the clock epoch deviation and frequency drift between the two systems are eliminated, ensuring the real-time performance, realism, and continuity of the closed-loop simulation.

[0006] This invention is achieved through the following technical solution: S1. The periodic hardware synchronization signal and multi-dimensional status information output by the satellite navigation receiver are simultaneously connected to the satellite navigation signal parameter simulation unit and the flight controller through a physical transmission line. The periodic hardware synchronization signal is used as a unified hardware trigger source for the entire system to replace the original software time synchronization path in the system with hardware. Specifically, existing technologies typically use reflected memory to send synchronization messages to align the clocks of the flight controller and the simulator. This method is subject to operating system interrupt responses and bus contention, inevitably resulting in microsecond-level random jitter. This step utilizes the characteristic that the receiver's internal clock maintains physical alignment with the simulator's time-frequency reference after the lock signal is received, using the 1PPS pulse output by the receiver as the physical trigger reference for the entire system. This pulse is connected to the flight controller via a dedicated physical signal line, directly attaching the calculation steps, which originally relied on software message triggering, to the hardware level transition edge. The determinism of the physical signal avoids the latency fluctuations caused by the software protocol stack.

[0007] S2. The flight controller captures the edge of the periodic hardware synchronization signal and latches the local time of the flight controller. The flight controller then sends the received multidimensional status information and the latched local time to the satellite navigation signal parameter simulation unit through the data transmission link for sending dynamic trajectory data. Specifically, in traditional closed-loop schemes, the flight controller lacks a precise correlation with the physical timeline when sending trajectory data, causing the simulator to be unable to determine the actual execution instant corresponding to the trajectory frame. This step addresses this by immediately latching the local counter value using the underlying hardware registers at the instant the 1PPS pulse arrives at the flight controller. By encapsulating this physical timestamp along with observation data such as position and pseudorange fed back from the receiver, the flight controller transmits a deterministic slice containing the physical time and measured state to the parameter simulation unit via the data link, thus resolving the problem of asynchronous separation between time-domain characteristics and spatial-domain states between heterogeneous devices.

[0008] S3. The satellite navigation signal parameter simulation unit compares the local time of the flight controller, the local time of the signal parameter simulation, and the clock difference, as well as other multi-dimensional state information, with the theoretical reference model generated in real time during the current simulation cycle, and calculates the quantitative data reflecting the simulation link delay fluctuation and clock deviation. Specifically, existing technologies often fail to quantify the comprehensive dynamic error caused by factors such as RF cable length, filter group delay, and simulator frequency conversion loss. This step involves the satellite navigation signal parameter simulation unit performing a three-way correlation calculation: the latch time forwarded by the flight controller, the local time recorded by the unit under the same pulse, and the real-time clock difference reported by the receiver. By synchronously differentially calculating the measured values ​​from the receiver with the theoretical true values ​​generated in real-time within the parameter simulation unit, the end-to-end physical residual of the entire link is extracted, thereby constructing a multi-dimensional sensing deviation vector capable of quantifying the dynamic fluctuations and frequency drift of the simulated link.

[0009] S4. Use quantized data to perform physical compensation on the output parameters of the satellite navigation real-time signal generation unit, eliminate the time delay and phase difference in the simulation link in real time, and ensure that the satellite navigation real-time signal simulator and the flight controller are synchronized in real time. Specifically, addressing the issue that existing software smoothing algorithms can easily lead to carrier frequency jumps and receiver loss of lock, this step directly applies quantization deviations to the underlying control parameters of the signal generation unit. The parameter simulation unit, combining high-order motion parameters such as speed and acceleration provided by the flight controller, performs kinematic extrapolation prediction based on the measured total loop delay, pre-compensating for the physical offset between the dropped code phase and the carrier phase at the source of signal generation. This pre-compensation mechanism ensures that the motion state corresponding to the physical characteristics of the RF signal reaching the receiver antenna is aligned with the computational epochs of the flight controller in both spatial and temporal dimensions.

[0010] A satellite navigation real-time closed-loop simulation time synchronization system, the system being implemented based on the aforementioned satellite navigation real-time closed-loop simulation time synchronization method, comprising: The navigation signal processing module is used to acquire initial navigation information and transmit it to the satellite navigation signal parameter simulation unit. The satellite navigation real-time signal generation unit is used to receive control parameters and generate navigation radio frequency signals, which are connected to the satellite navigation receiver through a radio frequency transmission link; The satellite navigation parameter simulation unit is used to perform simulation parameter calculation. It is connected to the satellite navigation real-time signal generation unit through a two-way data link and receives the status awareness data output by the satellite navigation receiver through a feedback channel. The flight controller is used to perform motion trajectory calculation and is connected to the satellite navigation parameter simulation unit via a data interface. The satellite navigation receiver is connected to the satellite navigation signal parameter simulation unit and the flight controller through independent physical feedback lines. It is used to transmit the periodic hardware synchronization signal generated by the node under test to the two units in real time, and to use the periodic hardware synchronization signal as a unified hardware trigger source for the whole system to form a time closed-loop synchronization topology of the physical layer.

[0011] Specifically, during the simulation, the radio frequency signal generated by the satellite navigation real-time signal generation unit is injected into the satellite navigation receiver. Once the receiver locks onto and tracks this signal, its internal clock is tamed by the simulator's time axis clock through carrier and pseudorange phase locking. At this point, the periodic hardware synchronization signal (such as 1PPS) output by the satellite navigation receiver through an independent physical feedback line essentially becomes the physical projection of the simulator's time axis onto the measured node. This signal is simultaneously sent to the flight controller and the satellite navigation parameter simulation unit, serving as a unified hardware heartbeat forcibly aligning all simulation nodes in the entire system, thus constraining the originally divergent time-frequency references of each node to the same physical reference frame.

[0012] Furthermore, at the instant of the rising edge transition of the periodic hardware synchronization signal, the underlying hardware registers of the flight controller and the satellite navigation parameter simulation unit synchronously perform local count value latching to obtain their respective local physical time values. The flight controller receives the clock difference data fed back by the satellite navigation receiver in real time and algebraically couples it with the locally latched time to calculate the execution time deviation of the calculation period start point relative to the ideal epoch of the simulator. The satellite navigation parameter simulation unit synchronously extracts the position solution, pseudorange residual, and carrier phase deviation returned by the receiver, and performs differential comparison with the theoretical true value model at the same epoch to construct a quantized deviation vector reflecting the delay of the signal transmission link and the processing group.

[0013] Furthermore, the system enters a dual-domain parallel correction process: the flight controller handles the time domain logic, establishing an affine time mapping model using the execution time deviation of consecutive epochs to eliminate the frequency drift of the hardware crystal oscillator, and performing third-order kinematic extrapolation on the motion state in conjunction with the known simulation loop delay to calculate the pre-compensated motion trajectory, achieving "injection and alignment" of trajectory data on the time axis. The satellite navigation parameter simulation unit handles the spatial domain logic, using the deviation vector to correct the underlying control parameters of the satellite navigation real-time signal generation unit, directly adjusting the initial phase of the spreading code and the carrier Doppler frequency to eliminate the phase offset caused by the physical link length.

[0014] Furthermore, the control commands, after time-domain trajectory pre-compensation and spatial-domain signal parameter correction, are jointly injected into the satellite navigation real-time signal generation unit to generate a doubly corrected pre-compensated navigation radio frequency signal. Since this signal has already offset the transmission jitter, computational delay, and frequency offset present in the simulation closed loop at the transmission source, its physical characteristics upon reaching the satellite navigation receiver antenna port are in phase with the flight controller's computational intent in the spatiotemporal dimension. The receiver's new round of sensing of this pre-compensated signal is then fed back to each unit through physical and information links, driving the system error vector norm to continuously decrease and converge towards zero, ultimately achieving a high-fidelity synchronous simulation between the simulation scenario and the device under test.

[0015] Compared with the prior art, the present invention has the following advantages and beneficial effects: This invention feeds back the 1PPS of the receiver under test to the timing acquisition port of the flight controller via hardware pulses, and transmits the flight controller's time axis to the navigation simulator as data. The navigation simulator then measures the deviation of its own clock relative to the flight controller's time axis, estimates the deviation, drift, and overall simulation delay to establish a continuous time mapping, and uses this mapping to timestamp the trajectory data injected into the simulator and perform loop delay compensation, thereby closing the time synchronization loop between the two simulation devices. This solution does not require additional hardware time synchronization equipment or modification of the flight controller's hardware and software architecture, and can maximize compatibility and reuse of existing flight controllers, achieving stable, reliable, low-latency, and highly stable real-time closed-loop simulation. Attached Figure Description

[0016] The accompanying drawings, which are included to provide a further understanding of embodiments of the invention and form part of this application, do not constitute a limitation thereof. In the drawings: Figure 1 This is a schematic diagram of the method flow of the present invention; Figure 2 This is a structural diagram of the time system of the present invention; Figure 3 This is a schematic diagram of the system structure of the present invention; Figure 4 This invention provides a comparison of extrapolated increments from zero-order position to third-order jerk. Figure 5 This is a flowchart of the software control process of the present invention. Detailed Implementation

[0017] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments and accompanying drawings. The illustrative embodiments and descriptions of this invention are for illustrative purposes only and are not intended to limit the invention. It should be noted that this invention is already in the actual research and development stage.

[0018] Example 1 like Figure 1 As shown, a satellite navigation real-time closed-loop simulation time synchronization method and system includes the following steps: S1. The periodic hardware synchronization signal and multi-dimensional status information output by the satellite navigation receiver are simultaneously connected to the satellite navigation signal parameter simulation unit and the flight controller through a physical transmission line. The periodic hardware synchronization signal is used as a unified hardware trigger source for the entire system to replace the original software time synchronization path in the system with hardware. S2. The flight controller captures the edge of the periodic hardware synchronization signal and latches the local time of the flight controller. The flight controller then sends the received multidimensional status information and the latched local time to the satellite navigation signal parameter simulation unit through the data transmission link for sending dynamic trajectory data. S3. The satellite navigation signal parameter simulation unit compares the local time of the flight controller, the local time of the signal parameter simulation, and the clock difference, as well as other multi-dimensional state information, with the theoretical reference model generated in real time during the current simulation cycle, and calculates the quantitative data reflecting the simulation link delay fluctuation and clock deviation. S4. Use quantized data to perform physical compensation on the output parameters of the satellite navigation real-time signal generation unit, eliminate the time delay and phase difference in the simulation link in real time, and ensure that the satellite navigation real-time signal simulator and the flight controller are synchronized in real time.

[0019] Specifically, this embodiment utilizes the characteristic that the internal clock of a satellite navigation receiver is disciplined by the navigation signal source clock after capturing radio frequency signals to establish a physical layer hardware pulse feedback loop. The periodic hardware synchronization signal (such as 1PPS) output by the satellite navigation receiver represents the physical reproduction of the simulator's timeline on the terminal side. It is connected in reverse to the signal parameter simulation unit and the timing acquisition pin of the flight controller via a shielded cable independent of the data link. The transition edge of this pulse signal directly triggers the high-speed latching logic inside each simulation node to perform a hardware-level phase zeroing operation. This physical feedback mechanism avoids the protocol stack latency and operating system non-real-time scheduling jitter caused by cross-node device transmission in the reflective memory network, shifting the time synchronization of the entire link from uncertain software logic control to direct constraint by the underlying hardware pulse.

[0020] Furthermore, the flight controller's hardware capture pins monitor the level of the synchronization pulse in real time. Upon capturing the rising edge of the pulse, the flight controller's underlying register latches the current value of the local high-frequency counter. The flight controller then correlates this value with the receiver's feedback position, pseudorange / carrier observations, and other status information, and packages them together. For example, the flight controller utilizes existing trajectory injection channels (such as high-speed fiber optic links) to send status data packets containing physical time stamps to the signal parameter simulation unit, achieving high coupling between time domain (locally latched time) and spatial domain (receiver-calculated status) data at the calculation node.

[0021] Furthermore, after receiving the data packet, the satellite navigation signal parameter simulation unit simultaneously records its local time triggered by the same pulse edge. By comparing the time stamp information sent by the flight controller with the theoretical epoch it generates, and combining the real-time observations fed back by the receiver, it calculates the quantization deviation caused by the transmission path, group delay, and equipment crystal oscillator drift in the full simulation link, and senses the errors in each link of the simulator-receiver-flight controller closed-loop link.

[0022] Furthermore, after obtaining the quantization deviation data, the signal parameter simulation unit performs physical-level correction on the signal transmission parameters by adjusting the spreading code phase and carrier frequency parameters to pre-compensate the time delay introduced by the physical link length and system processing cycle at the signal generation source. This pre-compensation mechanism ensures that the motion state corresponding to the physical characteristics of the generated navigation radio frequency signal can be aligned with the calculation epoch of the flight controller when it arrives at the receiver antenna port.

[0023] Furthermore, it also includes step S0: before the satellite navigation receiver acquires the signal, a synchronization message containing the current simulation time is sent to the flight controller through the satellite navigation signal parameter simulation unit to perform preliminary alignment of the simulation task execution cycle of each node at the software level.

[0024] Furthermore, in the initial stage before the satellite navigation receiver locks onto the radio frequency signal, a physical feedback pulse is sent by the satellite navigation signal parameter simulation unit to the flight controller via fiber optic reflection memory, containing a synchronization alignment message of the current simulation time. Upon receiving the message, the flight controller initiates the trajectory calculation cycle. Although there is microsecond-level software execution jitter during this stage, it ensures that the receiver obtains the initial excitation signal and enters the acquisition state. Once the receiver achieves positioning and outputs a valid hardware pulse, the flight controller immediately switches to hardware trigger mode.

[0025] Furthermore, the periodic hardware synchronization signal is a 1PPS hardware second pulse signal output by the receiver. This periodic hardware synchronization signal is characterized by two types: one is a 1PPS hardware second pulse signal synchronized with the satellite navigation signal parameter simulation unit after time calibration by the receiver's positioning calculation; the other is a 1PPS hardware second pulse signal that has not undergone time calibration, is determined by the receiver's local crystal oscillator, and is not synchronized with the satellite navigation signal parameter simulation unit's time. Specifically, this embodiment involves two types of 1PPS signal processing: one is a signal that has undergone internal time calibration by the receiver and is synchronized with the simulator's time axis; the other is a signal that has not undergone time calibration and is determined solely by the receiver's local crystal oscillator. By identifying these two characteristics in subsequent algorithms, the system can flexibly adapt to receivers under test with different technical architectures. For example, this embodiment adapts to receivers with two different operating modes. For receivers that output 1PPS of time synchronization (i.e., the pulse edge is internally aligned to the simulator time), the system directly uses its rising edge as the physical alignment point. For receivers that output 1PPS of time synchronization unequal (the pulse position is randomly generated by the local crystal oscillator), the system uses the pulse edge as a frequency reference and performs equivalent calibration by combining it with the real clock difference reported by the receiver. This design ensures that time synchronization of the entire system can be achieved under different hardware access schemes.

[0026] Furthermore, the receiver sensing observations include the three-dimensional position coordinates calculated by the satellite navigation receiver, the pseudorange residuals of each visible satellite, the carrier phase deviation, and the clock error and clock drift of the receiver relative to the simulator time axis.

[0027] Specifically, in the actual execution process, the sensed observations output by the satellite navigation receiver are the core data source for the closed-loop system to perform spatial domain correction and temporal domain synchronization. The observations include the three-dimensional position coordinates calculated in real time by the receiver. By spatially differentiating these measured coordinates with the true value of the synchronization trajectory generated within the parameter simulation unit, the offset of the positioning point in three-dimensional space can be intuitively obtained. Simultaneously, the sensed data includes pseudorange residuals for each visible satellite. These residuals reflect the comprehensive pseudorange error introduced by the navigation signal during transmission via radio frequency cables, signal processing delays, and indoor / outdoor spatial mapping.

[0028] Furthermore, the carrier phase deviation fed back by the receiver is used to monitor the tracking accuracy of the receiver tracking loop for Doppler frequency changes in real time. The most critical observations are the clock bias and clock drift data of the receiver relative to the simulator time axis. Since the signal generated by the simulator carries the standard navigation system time, the clock bias value fed back by the receiver after locking the signal actually represents the offset measure of the simulator time axis at the receiver's physical port. By combining the position offset, phase residual, and clock bias and clock drift in multiple dimensions, a perception deviation vector is constructed to reflect the end-to-end dynamic fluctuation characteristics of the simulation link.

[0029] Furthermore, step S2 specifically includes the following sub-steps: S201. The flight controller receives the periodic hardware synchronization signal output from the satellite navigation receiver and the corresponding navigation status calculation data, latches the flight controller's local time using the hardware synchronization signal, and obtains the time series. ; S202. Pack the latched flight controller local time and the received navigation status calculation data at the corresponding time into a data packet to be sent to the satellite navigation signal parameter simulation unit; S203. The packaged data packet is sent to the satellite navigation signal parameter simulation unit via a high-speed data interface.

[0030] Specifically, in the implementation process, sub-step S201 focuses on the flight controller's capture of the simulation timeline at the physical level. The flight controller monitors in real-time the periodic hardware synchronization signal (such as a 1PPS signal) output by the satellite navigation receiver in the physical feedback circuit through its underlying hardware timing capture interface or FPGA logic unit. When a level change (usually a rising edge) is detected in the pulse signal, the hardware logic immediately triggers an interrupt or register latch action, instantaneously sampling the value of the flight controller's local high-frequency counter to obtain a set of local time sequences with physical alignment characteristics. This sampling method bypasses the operating system's kernel scheduling and application layer software instruction cycles, ensuring the determinism of the time acquisition process and eliminating time noise caused by software execution jitter.

[0031] Furthermore, during sub-step S202, the flight controller deeply binds the latched local time value with the navigation status calculation data obtained from the receiver data interface (such as serial port or Ethernet port) within the same physical cycle. Specifically, the navigation status calculation data includes the epoch timescale information calculated by the receiver. By logically matching this timescale with the hardware latched time, a high-dimensional data packet with physical time and perceived state characteristics is formed. The significance of this packaging method is that it provides a time reference point for subsequent calculation units, enabling the originally isolated receiver measurement data to have coordinate mapping of the flight controller's local time axis, thereby achieving joint time-space annotation at the physical level.

[0032] Furthermore, sub-step S203 executes data transfer logic through the high-speed data link at the physical layer. The flight controller utilizes a high-speed interface (such as fiber optic reflective memory, high-speed Ethernet, or PCIe bus) connected to the satellite navigation signal parameter simulation unit to forward the encapsulated feedback data packets in real time. During this process, due to the high bandwidth and low latency characteristics of hardware such as reflective memory, data packets containing physical timestamps can be delivered to the calculation node with extremely short and constant transmission delays, enabling the signal parameter simulation unit to obtain the precise physical instant when the flight controller generates motion commands.

[0033] Furthermore, step S3 specifically includes the following sub-steps: S301. Simulate the local time of the unit using the satellite navigation signal parameters stored in the periodic hardware synchronization signal to obtain the local time series. ; S302. If the hardware time synchronization signal output by the satellite navigation receiver under test does not perform internal clock error correction, the execution time deviation between the satellite navigation signal parameter simulation unit and the flight simulator will be significant. The specific solution process is as follows: ; in, For the corresponding integer seconds, For the calibrated fixed cable delay difference, This refers to the clock bias fed back by the receiver.

[0034] If the hardware time synchronization signal output by the satellite navigation receiver under test has undergone internal clock error correction, the execution time deviation between the satellite navigation signal parameter simulation unit and the flight simulator will be... The specific solution process is as follows: ; S303. The specific calculation process for the frequency drift rate of the satellite navigation signal parameter simulation unit and flight simulator is as follows: ; S304. By using the satellite navigation signal parameter simulation unit, the associated navigation state solution data and the theoretical trajectory true value generated in real time by the satellite navigation signal parameter simulation unit at the same time are synchronously differentially calculated to extract the pseudorange phase deviation and positioning point offset of each visible satellite. The S305 integrates the calculated pseudorange phase deviation, position offset, and clock difference and frequency drift information of the simulator and flight controller time axis to construct a multi-dimensional perception deviation vector for driving simulation closed-loop correction.

[0035] It should be noted that, as Figure 2 As shown, Figure 2 This is a time system structure diagram of the present invention. The flight controller is the core of the system simulation control, and its hardware modification and expansion are the most difficult. Using the flight controller's time axis as a reference, the satellite navigation simulator's time axis is adjusted, and delay prediction compensation is performed. Here, b represents the deviation between the starting points of the two time axes, and fM and fS represent the frequencies of the two time axes, respectively. Due to the frequency deviation between their different sources, long-term simulations will result in the accumulation of deviations. This refers to all the uncertainties and delays that occur when the trajectory simulation commands issued by the flight controller reach the satellite navigation simulator for execution via fiber optic reflection. This delay needs to be compensated for by the satellite navigation simulator through extrapolation. These time and frequency variables are coupled, and the method of this invention allows for real-time dynamic estimation and calibration of these parameters, thereby achieving strict time synchronization in the simulation process.

[0036] Specifically, on the satellite navigation signal parameter simulation unit side, sub-step S301 synchronously executes hardware latching logic. By connecting to the same periodic hardware synchronization signal line, the signal parameter simulation unit synchronously records its local time series on the pulse transition edge. This action ensures that both the parameter simulation unit and the flight controller leave their own time records at the same physical "jump point." Specifically, by comparing the difference in count values ​​between these two nodes under the same physical pulse, the system can quantify the basis of the phase offset between the two heterogeneous hardware systems. This synchronization capture mechanism is the physical prerequisite for subsequent frequency normalization and affine mapping, ensuring that subsequent calculations are performed under a unified physical excitation source.

[0037] Furthermore, sub-steps S302 and S303 perform differentiated quantitative calculations based on the time-frequency reference. Specifically, if the satellite navigation receiver outputs a 1PPS signal without internal time calibration, then the formula is used... By substituting the real-time clock difference data reported by the receiver and the calibrated physical cable delay, random frequency offsets generated at the receiver end are eliminated. If the signal has already undergone time synchronization, the calculation process is simplified. Simultaneously, the frequency drift rate is calculated by determining the ratio of the difference in local time between the two simulation devices within adjacent pulse periods. This calculation effectively outlines the dynamic evolution between the simulator's time axis and the flight controller's time axis, capturing subtle frequency contractions caused by crystal oscillator aging and environmental temperature fluctuations, thus eliminating drift accumulation in long-term simulations.

[0038] Furthermore, sub-steps S304 and S305 perform the synthesis of spatial and temporal domain features. The signal parameter simulation unit performs high-precision differential calculations on the receiver observations (position coordinates, pseudorange, carrier phase) forwarded by the flight controller and the theoretical reference true values ​​generated in real time at the same simulation epoch. Specifically, by extracting the phase residuals and position deviations of each visible satellite, the system senses the dynamic physical offset introduced during transmission by the simulation link. The system integrates the calculated spatial residuals, positioning offsets, clock errors, and frequency drift information between the two devices to construct a multi-dimensional sensing deviation vector that drives the self-stabilizing correction of the entire system. This vector serves as the control source for the full closed-loop simulation, transmitted to the execution stage via a high-speed bus, directly guiding the signal parameters for compensation, so that the generated RF waveform continuously converges to the receiver's actual sensing state at the physical level.

[0039] Furthermore, step S4 specifically includes the following sub-steps: S401. By filtering the phase alignment residual deviation of multiple consecutive simulation cycles, a time mapping relationship is established between the flight controller and the satellite navigation signal parameter simulation unit, thereby eliminating the time and frequency drift during the simulation calculation process; S402. The injected trajectory of the flight controller is timestamped by time mapping relationship, and the kinematic extrapolation algorithm is used to pre-compensate for position offset, and synchronous control is performed on the navigation signal transmission time and the motion trajectory effective time.

[0040] Specifically, during the closed-loop synchronization correction phase, the system eliminates link drift through the synergistic effect of the time and spatial domains. Specifically, in sub-step S401, the parameter simulation unit extracts stable clock bias and frequency change rate by performing loop filtering or Kalman smoothing on the phase alignment residual deviations of multiple consecutive simulation cycles. Using these parameters, a time mapping relationship is established between the flight controller and the parameter simulation unit. Disciplined elimination is performed on the accumulated frequency error caused by differences in the physical characteristics of the hardware crystal oscillators, which diverges continuously over time, ensuring that the two heterogeneous devices maintain a high degree of frequency coherence on the logic timeline.

[0041] Furthermore, in sub-step S402, the flight controller uses the established time mapping relationship to add precise simulator timestamps to the motion trajectory frames of the injected parameter simulation unit, achieving deep binding between information flow and time flow. For the pre-calibrated full closed-loop simulation loop delay, the flight controller calls a kinematic extrapolation algorithm to perform pre-compensation calculations on the position data based on the vehicle's current real-time motion state. Specifically, by directly injecting the extrapolated and corrected position parameters into the signal generation logic, physical synchronization control is performed on the navigation signal transmission time and the actual effective time of the trajectory, enabling the indoor-generated navigation radio frequency signal to converge in real-time to the receiver's actual perception state at the physical level.

[0042] Furthermore, in step S302, the process for establishing the affine time mapping relationship is as follows: ; in, For simulator time axis coordinates, For the flight controller time axis coordinates, For frequency drift rate, For time offset.

[0043] Furthermore, in step S303, the output position after pre-compensation The specific solution process is as follows: ; in, These are the theoretical position, velocity, acceleration, and jerk of the trajectory, respectively. The simulation loop delay is known.

[0044] Specifically, such as Figure 4 When performing application-layer closed-loop correction, kinematic feedforward compensation is performed to address the inherent delay in the simulation loop. Specifically, this is achieved through the formula... By using trajectory theory position, real-time velocity, acceleration, and jerk to perform high-order kinematic extrapolation, the pre-compensated output position is calculated. The total known loop delay includes the time it takes for data to be transmitted in the reflective memory, the time it takes for the flight controller's algorithm to process the data, and the hardware group delay for the simulator to generate the radio frequency signal.

[0045] Furthermore, by introducing a third-order extrapolation model, the system can cover the complex motion characteristics of the carrier in high-dynamic, high-turn-rate scenarios. Specifically, the calculated pre-compensated displacement increment can offset the signal "expiration" problem caused by link delay in real time. After injecting the extrapolated and corrected position parameters into the satellite navigation real-time signal generation unit, the simulator will adjust the initial phase of the spreading code and the Doppler carrier parameters accordingly. This physical parameter-level pre-compensation ensures that the physical phase of the RF signal when it arrives at the receiver antenna port is aligned with the flight controller's calculated intent on the time axis, effectively solving the measurement errors and receiver positioning jump phenomena commonly caused by dynamic lag in closed-loop simulations.

[0046] Additionally, it should be noted that, It refers to the nanosecond-level flight time of a high-precision hardware second pulse in the physical transmission cable, primarily used to calibrate the timing deviation of the pulse captured by the flight controller, ensuring that the trigger times of the calculation cycles of all nodes in the entire system are physically and strictly aligned; while It is the total closed-loop latency of the entire link from flight controller calculation, reflection memory transmission, simulator synthesis to the activation of radio frequency signal. It is usually on the order of microseconds to milliseconds. It is used to predict the spatial location of the data activation time in advance through high-order kinematic extrapolation to compensate for the dynamic motion lag caused by the time consumption of data flow.

[0047] Example 2 Furthermore, as a preferred embodiment of the above embodiments, a real-time closed-loop simulation time synchronization system for satellite navigation is proposed, such as... Figure 3 The system is implemented based on the satellite navigation real-time closed-loop simulation time synchronization method described in Embodiment 1 above, including: The navigation signal processing module is used to acquire initial navigation information and transmit it to the satellite navigation signal parameter simulation unit. The satellite navigation real-time signal generation unit is used to receive control parameters and generate navigation radio frequency signals, which are connected to the satellite navigation receiver through a radio frequency transmission link; The satellite navigation parameter simulation unit is used to perform simulation parameter calculation. It is connected to the satellite navigation real-time signal generation unit through a two-way data link and receives the status awareness data output by the satellite navigation receiver through a feedback channel. The flight controller is used to perform motion trajectory calculation and is connected to the satellite navigation parameter simulation unit via a data interface. The satellite navigation receiver is connected to the satellite navigation signal parameter simulation unit and the flight controller through independent physical feedback lines. It is used to transmit the periodic hardware synchronization signal generated by the node under test to the two units in real time, and to use the periodic hardware synchronization signal as a unified hardware trigger source for the whole system to form a time closed-loop synchronization topology of the physical layer.

[0048] Furthermore, the satellite navigation receiver, as a physical layer time transfer node, after locking the navigation radio frequency signal, disciplines its internal clock to the time axis of the satellite navigation parameter simulation unit, or the internal clock is not disciplined, but can be equivalently software locked to the time axis of the satellite navigation parameter simulation unit in combination with clock difference data; by feeding back the output periodic hardware synchronization signal to the flight controller, physical synchronization of the time reference between the satellite navigation parameter simulation unit and the flight controller is achieved.

[0049] Furthermore, the satellite navigation parameter simulation unit includes an error history database, which records the state perception data and corresponding parameter corrections for each simulation cycle, and provides online calibration data for simulation link delay fluctuations.

[0050] In practical implementation, the operating principles of this system's physical connection architecture, time synchronization mechanism, and data calibration process are as follows: In the physical layer topology, each module executes signal flow and timing constraints through dedicated physical links. The navigation signal processing module performs RF front-end processing on the captured external navigation signals, demodulates the time parameters, and sends the stabilized reference frequency signal to the external reference source interface of the satellite navigation parameter simulation unit via a coaxial cable as the system's main time-frequency reference. The satellite navigation parameter simulation unit interacts with the satellite navigation real-time signal generation unit via a bidirectional high-speed bus (such as a PCIe bus), calculating and sending control parameters such as code phase and Doppler frequency in real time. The satellite navigation real-time signal generation unit synthesizes high-frequency navigation RF signals based on these control parameters and injects them into the satellite navigation receiver via a high-frequency cable. The satellite navigation receiver, through a power divider or two independent physical coaxial cables, simultaneously connects the generated periodic hardware synchronization signal (such as a 1PPS pulse per second) to the external capture interface of the satellite navigation parameter simulation unit and the hardware interrupt pin of the flight controller. Through this physical topology, the rising edge of the hardware second pulse simultaneously triggers the underlying latch registers inside the flight controller and the satellite navigation parameter simulation unit, directly attaching the start point of the calculation cycle of the two independent devices to the hardware pulse level transition edge of the receiver.

[0051] During the physical transfer of the time reference, the satellite navigation receiver acts as the time reference node. Once the carrier and pseudorange tracking loop within the satellite navigation receiver locks onto the radio frequency signal generated by the real-time satellite navigation signal generation unit, the receiver's local crystal oscillator frequency and phase are disciplined by the radio frequency signal clock. The transition position of its output periodic hardware synchronization signal is physically aligned with the simulator's internal master clock. At this point, the flight controller is triggered in reverse by this hardware pulse, synchronizing its logical time axis with the simulator's time axis. If the receiver's internal clock is undisciplined, its output hardware pulse will have a random phase offset. The system then synchronously acquires the real-time clock difference data calculated by the receiver through the data feedback channel. After receiving the rising edge of the undisciplined pulse and latching the local time, the flight controller substitutes this real-time clock difference data into its local time deviation calculation algorithm for algebraic compensation, thereby mathematically equivalently recovering the simulator's master time node and completing the physical alignment of the time-frequency reference between the flight controller and the parameter simulation unit.

[0052] The error history database is integrated into the storage medium of the satellite navigation parameter simulation unit, performing online calibration of closed-loop error characteristics during simulation operation. In each solution cycle, the satellite navigation parameter simulation unit reads the pseudorange residual, position offset, and clock difference of the two time axes transmitted back from the satellite navigation receiver, and correlates them with the control parameter corrections (such as code phase pre-compensation values) output in that cycle, writing them into the error history database. During operation, the simulation calculation unit calls upon data from consecutive epochs in this database to perform differential estimation of physical delay fluctuations caused by data link communication delays, simulator frequency conversion group delays, and transmission cable lengths, calculating the comprehensive physical delay drift curve. The system extracts the systematic constant deviation from this curve, converts it into fixed delay pre-compensation parameters, and directly superimposes them into the baseband generation control logic of the satellite navigation real-time signal generation unit. Without adding hardware peripherals, it performs online physical elimination of the inherent delay and dynamic drift of the system's physical topology.

[0053] Example 3 Furthermore, as a preferred embodiment of the above embodiments, this embodiment provides a detailed description of the signal flow and collaborative processing logic in the fully simulated link: During the simulation mission startup phase, the system executes a software alignment process. Since the satellite navigation receiver has not yet locked onto the navigation radio frequency signal in the initial cold start phase and cannot provide a physical synchronization reference, a synchronization message containing the initial simulation time is sent to the flight controller via the satellite navigation signal parameter simulation unit. Upon receiving the message, the flight controller initiates the trajectory calculation task and injects the initial motion state into the satellite navigation signal parameter simulation unit via a high-speed data link, driving the satellite navigation real-time signal generation unit to generate preliminary radio frequency signals. As the satellite navigation receiver completes signal acquisition and enters a stable tracking state, its internal clock is clock-disciplined by the simulator's time axis, and it begins to output 1PPS hardware pulse signals with nanosecond-level precision through the physical feedback circuit.

[0054] Furthermore, during the hardware takeover phase, the flight controller monitors the level status of the hardware acquisition interface in real time. Once a valid rising edge transition of a 1PPS pulse is detected, the flight controller immediately triggers the internal low-level register to latch the current value of the local high-frequency counter, obtaining the local time sequence. During this process, the flight controller timestamps and packages the real-time received multi-dimensional status information of the satellite navigation receiver (including three-dimensional position coordinates, pseudorange residuals, carrier phase deviation, and clock error) with the corresponding latched time. Using the data transmission link for transmitting dynamic trajectory data (such as fiber optic reflective memory), this composite data packet is forwarded to the satellite navigation signal parameter simulation unit, realizing the initial correlation between time-domain timestamps and spatial-domain observation data.

[0055] Furthermore, in the deviation quantization and parameter correction logic, the satellite navigation signal parameter simulation unit receives the composite data packet forwarded by the flight controller and extracts the latch time, receiver clock error, and space observation measurements. The satellite navigation signal parameter simulation unit synchronously records its local time triggered by the same hardware pulse edge and compares this multi-dimensional information with the theoretical reference model generated in real-time during the current simulation cycle. By performing differential calculations, the satellite navigation signal parameter simulation unit calculates the quantization deviation vector reflecting the end-to-end delay fluctuations of the simulation link, and accordingly calculates the spreading code phase correction and carrier frequency correction. Simultaneously, this deviation vector is fed back to the flight controller to establish an affine time mapping relationship and perform trajectory extrapolation compensation.

[0056] Furthermore, the kinematically extrapolated and pre-compensated trajectory output by the flight controller, along with the signal parameter compensation calculated by the satellite navigation signal parameter simulation unit, is jointly injected into the satellite navigation real-time signal generation unit. Based on the integrated control parameters, the satellite navigation real-time signal generation unit generates a navigation radio frequency signal that has undergone dual correction for time-domain synchronization and spatial-domain deviation. This clearly defined closed-loop flow mechanism ensures that the generated navigation signal converges in real-time to the receiver's actual perceived state in terms of physical characteristics, guaranteeing the self-stable alignment of the entire system's time and spatial dimensions under closed-loop simulation conditions.

[0057] Example 4 Furthermore, as a preferred embodiment of the above embodiments, a software control flow description based on the method described in Embodiment 1 or the system described in Embodiment 2 is proposed, according to... Figure 5 The provided synchronization control flow and system execution logic are as follows: During the initial cold start phase of the system, the satellite navigation receiver is in the acquisition phase, unable to achieve positioning and output a 1PPS signal. At this time, the system automatically enters software alignment mode, where the satellite navigation signal parameter simulation unit sends an initial alignment message to the flight controller via the reflective memory network to establish the initial simulation clock axis. The flight controller uses this message as a trigger to start the trajectory calculation step, guiding the satellite navigation receiver to complete signal acquisition and carrier tracking in the closed loop.

[0058] Once the satellite navigation receiver successfully positions itself and begins outputting a 1PPS hardware pulse signal, the system enters a two-way synchronization mode. The flight controller and the satellite navigation signal parameter simulation unit capture this pulse edge via a hardware interrupt. The flight controller performs local time latching and packages it with the receiver status data for forwarding. The satellite navigation signal parameter simulation unit calculates the physical execution time deviation by comparing the latched times at both ends and the receiver clock difference. The system uses this hardware pulse to physically zero the microsecond-level phase deviation caused by the aforementioned software alignment. The reference seamlessly switches from software message triggering to hardware pulse driving, achieving physical layer time alignment.

[0059] After the entire system enters a stable synchronization phase, the flight controller and the satellite navigation signal parameter simulation unit collaboratively perform dual-domain parallel correction. The flight controller establishes an affine time mapping model. The system performs disciplined hardware crystal oscillator frequency drift and, combined with known loop delays, performs third-order kinematic extrapolation to calculate the pre-compensated position parameters. Meanwhile, the satellite navigation signal parameter simulation unit synchronously executes spatial domain logic to calculate pseudorange and phase corrections. This real-time feedback correction ensures physical alignment between the navigation signal transmission time and the trajectory activation time at the receiver antenna port.

[0060] If a brief loss of lock-on occurs in the satellite navigation receiver, causing a 1PPS signal interruption, the system enters a brief timekeeping maintenance phase. During this time, the flight controller and the satellite navigation signal parameter simulation unit cease parameter updates and autonomously calculate the timekeeping of both clocks using the mapping model established before the lock-on loss, maintaining the continuity of trajectory extrapolation and signal generation. If the lock-on time exceeds a preset threshold (determined as a long-term lock-on loss), the system executes a software reset procedure, reverting to the initial software synchronization state, re-injecting alignment messages into the flight controller, guiding the receiver to re-acquire and establish a new physical synchronization reference, ensuring the system's robustness for long-endurance closed-loop operation.

[0061] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A real-time closed-loop simulation time synchronization method for satellite navigation, characterized in that, Includes the following steps: S1. The periodic hardware synchronization signal and multi-dimensional status information output by the satellite navigation receiver are simultaneously connected to the satellite navigation signal parameter simulation unit and the flight controller through a physical transmission line. The periodic hardware synchronization signal is used as a unified hardware trigger source for the entire system to replace the original software time synchronization path in the system with hardware. S2. The flight controller captures the edge of the periodic hardware synchronization signal and latches the local time of the flight controller. The flight controller then sends the received multidimensional status information and the latched local time to the satellite navigation signal parameter simulation unit through the data transmission link for sending dynamic trajectory data. S3. The satellite navigation signal parameter simulation unit compares the local time of the flight controller's time stamp, the local time of the signal parameter simulation, and the multi-dimensional state information with the theoretical reference model generated in real time during the current simulation cycle, and calculates the quantitative data reflecting the simulation link delay fluctuation and clock deviation. S4. Use quantized data to perform physical compensation on the output parameters of the satellite navigation real-time signal generation unit, eliminate the time delay and phase difference in the simulation link in real time, and ensure that the satellite navigation real-time signal simulator and the flight controller are synchronized in real time.

2. The satellite navigation real-time closed-loop simulation time synchronization method as described in claim 1, characterized in that, It also includes step S0: before the satellite navigation receiver acquires the signal, a synchronization message containing the current simulation time is sent to the flight controller through the satellite navigation signal parameter simulation unit to perform preliminary software-level alignment of the simulation task execution cycle of each node.

3. The satellite navigation real-time closed-loop simulation time synchronization method as described in claim 1, characterized in that, The periodic hardware synchronization signal is a 1PPS hardware pulse signal output by the receiver.

4. The satellite navigation real-time closed-loop simulation time synchronization method as described in claim 1, characterized in that, The multidimensional state information output by the receiver consists of receiver-sensed observations, including the three-dimensional position coordinates calculated by the satellite navigation receiver, the pseudorange residuals of each visible satellite, the carrier phase deviation, and the clock error and clock drift of the receiver relative to the simulator time axis.

5. The satellite navigation real-time closed-loop simulation time synchronization method as described in claim 4, characterized in that, Step S2 specifically includes the following sub-steps: S201. The flight controller receives the periodic hardware synchronization signal output from the satellite navigation receiver and the corresponding navigation status calculation data, latches the flight controller's local time using the hardware synchronization signal, and obtains the time series. The This represents the time axis coordinate of the flight controller at time k; S202. Pack the latched flight controller local time and the received navigation status calculation data at the corresponding time into a data packet to be sent to the satellite navigation signal parameter simulation unit; S203. The packaged data packet is sent to the satellite navigation signal parameter simulation unit via a high-speed data interface.

6. The satellite navigation real-time closed-loop simulation time synchronization method as described in claim 4, characterized in that, Step S3 specifically includes the following sub-steps: S301. Latch the local time of the satellite navigation signal parameter simulation unit using a periodic hardware synchronization signal to obtain the local time series. ; The periodic hardware synchronization signal is characterized by including two types: one is a 1PPS hardware second pulse signal that is synchronized with the time of the satellite navigation signal parameter simulation unit after being timed by the receiver positioning calculation; the other is a 1PPS hardware second pulse signal that is not timed, is determined by the receiver's local crystal oscillator, and is not synchronized with the time of the satellite navigation signal parameter simulation unit. S302. If the hardware time synchronization signal output by the satellite navigation receiver under test does not perform internal clock error correction, the execution time deviation between the satellite navigation signal parameter simulation unit and the flight controller will be... The specific solution process is as follows: ； in, For the corresponding integer seconds, The flight time of a 1PPS hardware pulse in a calibrated fixed cable is used to calibrate the timing deviation of the pulse captured by the flight controller. The fixed cable is the physical transmission line. The clock bias fed back by the receiver, the This represents the time axis coordinate of the flight controller at time k; If the hardware time synchronization signal output by the satellite navigation receiver under test has undergone internal clock error correction, the time deviation between the satellite navigation signal parameter simulation unit and the flight controller will be... The specific solution process is as follows: ； S303. The specific calculation process for the frequency drift rate of the satellite navigation signal parameter simulation unit and flight controller is as follows: ； Among them, the Indicates the frequency drift rate, the The time axis coordinate of the simulator at time k is represented by the following. This represents the simulator time axis coordinate of the previous time step at time k. Represents the time axis coordinates of the flight controller at the time preceding time k; S304. By using the satellite navigation signal parameter simulation unit, the associated navigation state solution data and the theoretical trajectory true value generated in real time by the satellite navigation signal parameter simulation unit at the same time are synchronously differentially calculated to extract the pseudorange phase deviation and positioning point offset of each visible satellite. S305. Integrate the calculated pseudorange phase deviation, position offset, and clock difference and frequency drift information of the simulator and flight controller time axis to construct a multi-dimensional perception deviation vector for driving simulation closed-loop correction.

7. The satellite navigation real-time closed-loop simulation time synchronization method as described in claim 4, characterized in that, Step S4 specifically includes the following sub-steps: S401. By filtering the phase alignment residual deviation of multiple consecutive simulation cycles, a time mapping relationship between the flight controller and the satellite navigation signal parameter simulation unit is established to eliminate the time frequency drift in the simulation calculation process; S402. The injected trajectory of the flight controller is timestamped by time mapping relationship, and the position offset is pre-compensated by kinematic extrapolation algorithm. Synchronization control is performed on the navigation signal transmission time and the motion trajectory effective time.

8. The satellite navigation real-time closed-loop simulation time synchronization method as described in claim 7, characterized in that, In step S401, the process for establishing the time mapping relationship between the flight controller and the satellite navigation signal parameter simulation unit is as follows: ； in, For simulator time axis coordinates, For the flight controller time axis coordinates, For frequency drift rate, For time offset.

9. The satellite navigation real-time closed-loop simulation time synchronization method as described in claim 7, characterized in that, In step S402, the output position after pre-compensation The specific solution process is as follows: ； in, These are the theoretical position, velocity, acceleration, and jerk of the trajectory, respectively. The known simulation loop delay is the total closed-loop delay of the motion trajectory data from flight controller calculation, reflection memory transmission, simulator synthesis, to the activation of the radio frequency signal.

10. A satellite navigation real-time closed-loop simulation time synchronization system, the system being implemented based on the satellite navigation real-time closed-loop simulation time synchronization method according to any one of claims 1-9, characterized in that, include: The navigation signal processing module is used to acquire initial navigation information and transmit it to the satellite navigation signal parameter simulation unit. The satellite navigation real-time signal generation unit is used to receive control parameters and generate navigation radio frequency signals, which are connected to the satellite navigation receiver through a radio frequency transmission link; The satellite navigation parameter simulation unit is used to perform simulation parameter calculation. It is connected to the satellite navigation real-time signal generation unit through a two-way data link and receives the status awareness data output by the satellite navigation receiver through a feedback channel. The flight controller is used to perform motion trajectory calculation and is connected to the satellite navigation parameter simulation unit via a data interface. The satellite navigation receiver is connected to the satellite navigation signal parameter simulation unit and the flight controller through independent physical feedback lines. It is used to transmit the periodic hardware synchronization signal generated by the node under test to the two units in real time, and to use the periodic hardware synchronization signal as a unified hardware trigger source for the whole system to form a time closed-loop synchronization topology of the physical layer.

11. A satellite navigation real-time closed-loop simulation time synchronization system as described in claim 10, characterized in that, The satellite navigation receiver, acting as a physical layer time transfer node, tames its internal clock to the time axis of the satellite navigation parameter simulation unit after locking onto the navigation radio frequency signal. Alternatively, if the internal clock is not tamed, it can be equivalent to software locking onto the time axis of the satellite navigation parameter simulation unit in conjunction with clock difference data. By feeding back the output periodic hardware synchronization signal to the flight controller, physical synchronization of the time reference between the satellite navigation parameter simulation unit and the flight controller is achieved.

12. A satellite navigation real-time closed-loop simulation time synchronization system as described in claim 10, characterized in that, The satellite navigation parameter simulation unit includes an error history database, which records the state perception data and corresponding parameter corrections for each simulation cycle, and provides online calibration data for simulation link delay fluctuations.

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