Pseudo-satellite emission source high-precision clock control method

Abstract

The invention relates to a high-precision clock control method for a pseudo-satellite emission source. The high-precision clock control method for the pseudo-satellite emission source comprises the following steps: acquiring a high-precision clock source; time taming; and executing a time synchronization compensation algorithm. According to the pseudo satellite emission source high-precision clock control method, a high-precision GNSS clock source is combined with a taming constant-temperature crystal oscillator, and a time synchronization compensation algorithm is introduced for combined control, so that a pseudo satellite emission source high-precision clock is provided. After the clock control method is adopted, the clock precision of the pseudo satellite emission source reaches the nanosecond level, the positioning error is reduced to the decimeter level from the original several meters, and the requirement for high-precision positioning is met. Meanwhile, the system can still keep stable clock output under the condition that certain interference exists in GNSS signals, and continuity and reliability of positioning are guaranteed.

Description

Technical Field

[0001] This invention relates to the field of pseudo-satellite technology, and in particular to a high-precision clock control method for pseudo-satellite launch sources. Background Technology

[0002] A pseudosatellite is a ground-based transmitter that emits radio frequency signals similar to satellite navigation signals, providing users with positioning information by simulating satellite signals. Pseudosatellite technology can serve as an effective supplement to satellite navigation systems, especially in areas where satellite signals are difficult to reach, such as indoors, canyons, and densely populated urban areas with tall buildings, providing users with reliable positioning services.

[0003] In pseudosatellite systems, clock accuracy directly affects positioning accuracy. Pseudosatellites calculate the distance between the user and the pseudosatellite by measuring the time difference between signal transmission and reception, thus achieving positioning. If the clock has errors, the measured time difference will be inaccurate, leading to a discrepancy between the calculated distance and the final positioning result.

[0004] Clock errors typically originate from the following sources: (a) Long-term stability and drift issues of clocks Traditional clock sources (such as ordinary crystal oscillators) inevitably experience frequency drift during long-term operation, leading to accumulated time measurement errors and consequently affecting the positioning accuracy of pseudosatellite systems. For example, the annual drift rate of an ordinary crystal oscillator can reach 10-1. -6 The current scale is insufficient to meet the nanosecond-level time accuracy requirements of pseudosatellite systems.

[0005] (ii) Insufficient adaptability to complex environments Pseudo-satellite transmitters often operate in complex environments with temperature fluctuations, humidity changes, and electromagnetic interference, which further exacerbate clock signal instability. For example, temperature variations can cause crystal oscillator frequency shifts of up to ±5ppm, while humidity and electromagnetic interference introduce additional phase noise, making it difficult for traditional clock sources to maintain stable output in harsh environments.

[0006] (III) The problem of time synchronization among multiple pseudo-satellites In multi-pseudo-satellite systems, pseudo-satellites need to maintain nanosecond-level time synchronization to ensure the accuracy of users' position calculations based on signal time differences. However, factors such as signal propagation delay, individual device differences, and clock drift mean that traditional synchronization methods, such as the Network Time Protocol (NTP), can only achieve millisecond-level accuracy, which cannot meet the high-precision synchronization requirements of pseudo-satellite systems. Summary of the Invention

[0007] To address the shortcomings of existing technologies, this invention discloses a high-precision clock control method for pseudo-satellite launch sources, in order to solve one or more problems in the prior art.

[0008] The technical solution adopted in this invention is as follows: A high-precision clock control method for a pseudo-satellite launch source, the method comprising the following steps: Obtain a high-precision clock source; Taming time; The time synchronization compensation algorithm is executed.

[0009] Furthermore, the step of obtaining real satellite clock information includes: Receive signals from at least one satellite navigation system via a GNSS receiver antenna; Extract the satellite's navigation message and carrier phase information; Accurate time and frequency references are calculated based on navigation messages and carrier phase information.

[0010] Furthermore, the time taming step includes: Initial calibration of the local clock source; Real-time detection and calculation of the time and frequency differences between the local clock source and the high-precision clock source; Taming the algorithm execution; Perform error compensation on the local clock source and feed back the compensation information; locking.

[0011] Furthermore, the initial calibration of the local clock source includes: Using the time and frequency information of a high-precision clock source as a reference, the initial frequency of the docile cryogenic crystal oscillator is adjusted through a frequency control circuit to make the output frequency and time of the docile cryogenic crystal oscillator as close as possible to the time and frequency information of the high-precision clock source.

[0012] Furthermore, the taming algorithm performs the following steps: Based on the calculated time and frequency differences, a PID control algorithm is used to adjust the control voltage of the frequency control circuit, so that the output frequency and time of the tamed temperature-controlled crystal oscillator gradually approach the time and frequency information of the high-precision clock source.

[0013] Furthermore, the time difference and frequency deviation between the tamed temperature-controlled crystal oscillator and the high-precision clock source are calculated using a comparator.

[0014] Furthermore, the step of performing error compensation on the local clock source and feeding back compensation information includes: During the taming process, the output signal of the taming thermostatic crystal oscillator is compensated for errors in real time, and the compensated signal is fed back to the clock signal processing and output module. At the same time, the error calculation and control parameters are continuously updated to improve the accuracy and stability of taming.

[0015] Furthermore, the locking step includes: A local high-precision clock signal is generated by a PLL phase-locked loop control circuit, which keeps the output frequency of the tamed temperature-controlled crystal oscillator synchronized with the frequency of the high-precision clock source, thus completing the taming process.

[0016] Furthermore, the calculation formula for the time synchronization correction algorithm is shown below: ; In the formula, That is, the clock difference between the satellite and the actual satellite. The pseudorange measurement values ​​obtained by pseudosatellite observation of real satellites. This refers to the ionospheric propagation delay error and pseudorange error when pseudosatellites observe real satellites. Let be the true distance between the pseudo-satellite and the real satellite. The pseudo-satellite's three-dimensional position coordinates, These are the actual three-dimensional position coordinates of the satellite.

[0017] Compared with the prior art, the beneficial technical effects of the present invention are as follows: (i) The high-precision clock control method for the pseudo-satellite transmitter of the present invention combines a high-precision GNSS clock source with a disciplined temperature-controlled crystal oscillator and introduces a time synchronization compensation algorithm for joint control, thereby providing a high-precision clock for the pseudo-satellite transmitter. After adopting the clock control method of the present invention, the clock accuracy of the pseudo-satellite transmitter reaches the nanosecond level, and the positioning error is reduced from several meters to the decimeter level, meeting the requirements for high-precision positioning. Simultaneously, the system can maintain a stable clock output even when there is some interference in the GNSS signal, ensuring the continuity and reliability of positioning.

[0018] (ii) Furthermore, high-precision atomic clocks are expensive and bulky. Combining a high-precision GNSS clock source with a temperature-controlled crystal oscillator utilizes the long-term stability (10...) of the high-precision GNSS clock source... -10 (Order-level) calibrating the frequency drift of the disciplined cryogenic crystal, using the short-term stability (10) of the disciplined cryogenic crystal. -9 This technology (on a scale of [number] orders of magnitude) compensates for the ability of a high-precision GNSS clock source signal to maintain its position when interrupted by interference. Through real-time discipline and calibration, it fully leverages the high-precision time and frequency reference of GNSS and the short-term stability advantages of a temperature-controlled crystal oscillator, achieving low-cost, high-precision clock control. Furthermore, the temperature-controlled crystal oscillator is low in cost, small in size, and low in power consumption.

[0019] In the time discipline process, the discipline unit adjusts the output frequency of the crystal oscillator in real time according to the degree to which the actual frequency deviates from the nominal value, forming a dynamic closed-loop feedback control. This ensures the accuracy and stability of the clock, improves the reliability and maintainability of the system, and has advantages in cost and size compared to atomic clock solutions.

[0020] (iii) Furthermore, the docile thermostatic crystal oscillator has temperature compensation, PID regulation error prediction, and maintains a constant temperature, which can greatly adapt to changes in the external ambient temperature. The local clock input of the docile thermostatic crystal oscillator is not affected by network transmission. Even when there is some interference or obstruction of GNSS signals, the short-term stability of the thermostatic crystal oscillator can continue to provide an accurate clock signal, ensuring the continuity and reliability of the system and solving the problem that the GNSS synchronization scheme is completely dependent on the continuity of satellite signals.

[0021] (iv) Furthermore, PID control algorithm or other adaptive control algorithm is adopted to monitor and calculate clock error in real time, and the frequency control voltage of the thermostatic crystal oscillator is dynamically adjusted according to the error situation to effectively compensate for clock drift and improve the stability and accuracy of the clock. Attached Figure Description

[0022] Figure 1 A flowchart of a high-precision clock control method for a pseudo-satellite launch source according to Embodiment 1 of the present invention is shown.

[0023] Figure 2 A flowchart of the time discipline step in the high-precision clock control method for pseudo-satellite launch sources according to Embodiment 1 of the present invention is shown. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of this invention clearer, the device proposed by this invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. The advantages and features of this invention will become clearer from the following description. It should be noted that the drawings are in a very simplified form and use non-precise proportions, only for the purpose of conveniently and clearly illustrating the embodiments of this invention. Please refer to the accompanying drawings to make the objectives, features, and advantages of this invention more apparent and understandable. It should be understood that the structures, proportions, sizes, etc., depicted in the accompanying drawings are only for the purpose of assisting those skilled in the art in understanding and reading the content disclosed in the specification, and are not intended to limit the implementation conditions of this invention. Therefore, they have no substantial technical significance. Any modifications to the structure, changes in the proportional relationships, or adjustments to the size, without affecting the effects and objectives achieved by this invention, should still fall within the scope of the technical content disclosed in this invention.

[0025] In the description of this invention, the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "top," "bottom," "inner," "outer," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0026] Example 1 Please refer to Figure 1 The high-precision clock control method for pseudo-satellite launch sources includes the following steps: Step S1: Obtain a high-precision clock source. The step of obtaining real satellite clock information includes: Step S11: Receive signals from at least one satellite navigation system via the GNSS receiver antenna.

[0027] Specifically, a high-precision GNSS (Global Navigation Satellite System) clock source module is introduced. This module can receive clock information from real satellites. The module receives signals from one or more satellite navigation systems (such as GPS, BeiDou, GLONASS, etc.) through a GNSS receiver and transmits them to the receiver front end for amplification, filtering and other preprocessing.

[0028] In this step, signals from multiple satellite navigation systems are received simultaneously, improving signal availability and reliability. In the multi-pseudo-satellite system, clock synchronization among multiple pseudo-satellite transmitters is achieved, ensuring the positioning accuracy and consistency of the entire system.

[0029] Step S12: Extract the satellite's navigation message and carrier phase information.

[0030] Specifically, the signal processing unit of the GNSS high-precision clock source module acquires, tracks, and demodulates the pre-processed signal to extract the satellite's navigation message and carrier phase information.

[0031] Step S13: Calculate the accurate time and frequency reference based on the navigation message and carrier phase information.

[0032] Specifically, the time and frequency extraction unit of the GNSS high-precision clock source module calculates an accurate time and frequency reference based on the navigation message and carrier phase information. It then outputs a precise PPS signal for use by the second part of the disciplined clock and the third part of the time synchronization compensation algorithm.

[0033] Step S2, time taming. Please refer to [link / reference]. Figure 2 The time taming steps include: Step S21: Initially calibrate the local clock source.

[0034] Specifically, using the time and frequency information of a high-precision clock source as a reference, the initial frequency of the disciplined cryogenic crystal oscillator is adjusted through a frequency control circuit. This ensures that the output frequency and time of the disciplined cryogenic crystal oscillator are as close as possible to the time and frequency information of the high-precision clock source, achieving an error accuracy level of ±10°C compared to traditional crystal oscillators. -6 .

[0035] Step S22: Real-time detection and calculation of the time difference and frequency difference between the local clock source and the high-precision clock source.

[0036] Specifically, the time and frequency signals of the GNSS high-precision clock source and the output signal of the disciplined cryogenic crystal are continuously monitored, and the time difference and frequency deviation between the disciplined cryogenic crystal and the high-precision clock source are calculated by a comparator.

[0037] Step S23: The taming algorithm is executed.

[0038] Specifically, the PID controller adjusts the control voltage of the frequency control circuit based on the calculated time difference and frequency difference, using a PID control algorithm to gradually bring the output frequency and time of the docile temperature-controlled crystal oscillator closer to the time and frequency information of the high-precision clock source.

[0039] Step S24: Perform error compensation on the local clock source and feed back the compensation information.

[0040] Specifically, during the training process, the output signal of the training thermostatic crystal oscillator is compensated for errors in real time, and the compensated signal is fed back to the clock signal processing and output module. That is, the compensated signal is input into the PLL phase-locked loop to adjust the local clock signal. At the same time, the error calculation and control parameters are continuously updated, that is, the adjusted clock signal is continuously compared with the Beidou high-precision time synchronization module, forming a dynamic closed-loop feedback control to improve the accuracy and stability of training.

[0041] Throughout the training process, the training unit adjusts the crystal oscillator's output frequency in real time based on the degree to which the actual frequency deviates from the nominal value. This is a dynamic process of closed-loop feedback adjustment. In this way, training the crystal oscillator can significantly improve the system's time measurement accuracy and timekeeping stability.

[0042] Step S25, lock.

[0043] Specifically, a local high-precision clock signal is generated through control circuits such as a PLL phase-locked loop, so that the output frequency of the tamed temperature-controlled crystal oscillator is synchronized with the frequency of the high-precision clock source, thus completing the taming process.

[0044] Step S3: The time synchronization compensation algorithm is executed.

[0045] Specifically, the calculation formula for the time synchronization correction algorithm is shown below: ; In the formula, That is, the clock difference between the satellite and the actual satellite. The pseudorange measurement values ​​obtained by pseudosatellite observation of real satellites. This refers to the ionospheric propagation delay error and pseudorange error when pseudosatellites observe real satellites. Let be the true distance between the pseudo-satellite and the real satellite. The pseudo-satellite's three-dimensional position coordinates, These are the actual three-dimensional position coordinates of the satellite.

[0046] Since the location of the pseudosatellite can be predetermined, meaning its precise position is known, and the pseudosatellite has a built-in high-precision timing module that can receive signals from the real satellite, the above formula can be used to calculate the result by observing only one real satellite. When receiving signals from multiple satellites, it can also monitor the position changes of pseudo-satellite stations in real time and calculate the clock bias. .

[0047] Practical use shows that the above time synchronization method can achieve time synchronization accuracy at the nanosecond level. For different applications, the required time synchronization accuracy, i.e., the time deviation ∆T between the pseudo-satellite and the real satellite, may be different. Usually, 20 nanoseconds can meet the needs of most applications.

[0048] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. 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 shall still fall within the scope of the present invention.

Claims

1. A high-precision clock control method for a pseudo-satellite launch source, characterized in that, The high-precision clock control method for the pseudo-satellite launch source includes the following steps: Obtain a high-precision clock source; Taming time; The time synchronization compensation algorithm is executed.

2. The high-precision clock control method for a pseudo-satellite launch source according to claim 1, characterized in that, The steps for obtaining real satellite clock information include: Receive signals from at least one satellite navigation system via a GNSS receiver antenna; Extract the satellite's navigation message and carrier phase information; Accurate time and frequency references are calculated based on navigation messages and carrier phase information.

3. The high-precision clock control method for a pseudo-satellite launch source according to claim 1, characterized in that, The time taming steps include: Initial calibration of the local clock source; Real-time detection and calculation of the time and frequency differences between the local clock source and the high-precision clock source; Taming the algorithm execution; Perform error compensation on the local clock source and feed back the compensation information; locking.

4. The high-precision clock control method for a pseudo-satellite launch source according to claim 1, characterized in that, The initial calibration of the local clock source includes the following steps: Using the time and frequency information of a high-precision clock source as a reference, the initial frequency of the docile cryogenic crystal oscillator is adjusted through a frequency control circuit to make the output frequency and time of the docile cryogenic crystal oscillator as close as possible to the time and frequency information of the high-precision clock source.

5. The high-precision clock control method for a pseudo-satellite launch source according to claim 1, characterized in that, The taming algorithm performs the following steps: Based on the calculated time and frequency differences, a PID control algorithm is used to adjust the control voltage of the frequency control circuit, so that the output frequency and time of the tamed temperature-controlled crystal oscillator gradually approach the time and frequency information of the high-precision clock source.

6. The high-precision clock control method for a pseudo-satellite launch source according to claim 1, characterized in that, The time difference and frequency deviation between the tamed temperature-controlled crystal oscillator and the high-precision clock source are calculated using a comparator.

7. The high-precision clock control method for a pseudo-satellite launch source according to claim 1, characterized in that, The steps of performing error compensation on the local clock source and feeding back compensation information include: During the taming process, the output signal of the taming thermostatic crystal oscillator is compensated for errors in real time, and the compensated signal is fed back to the clock signal processing and output module. At the same time, the error calculation and control parameters are continuously updated to improve the accuracy and stability of taming.

8. The high-precision clock control method for a pseudo-satellite launch source according to claim 1, characterized in that: The locking steps include: A local high-precision clock signal is generated by a PLL phase-locked loop control circuit, which keeps the output frequency of the tamed temperature-controlled crystal oscillator synchronized with the frequency of the high-precision clock source, thus completing the taming process.

9. The high-precision clock control method for a pseudo-satellite launch source according to claim 7, characterized in that, The calculation formula for the time synchronization correction algorithm is shown below: ； In the formula, That is, the clock difference between the satellite and the actual satellite. The pseudorange measurement values ​​obtained by pseudosatellite observation of real satellites. This refers to the ionospheric propagation delay error and pseudorange error when pseudosatellites observe real satellites. Let be the true distance between the pseudo-satellite and the real satellite. The pseudo-satellite's three-dimensional position coordinates, These are the actual three-dimensional position coordinates of the satellite.

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