Time-frequency preservation method, device, and system based on dual-source discipline and drift prediction

Abstract

This invention discloses a time-frequency maintenance method, apparatus, and system based on dual-source discipline and drift prediction, relating to the field of satellite time synchronization and time transfer technology. The method includes: S1, acquiring first data and second data in real time; S2, analyzing the first frequency offset based on the first data and analyzing the cumulative phase of the second frequency offset based on the second data; S3, analyzing the target phase value based on the cumulative phase of the second frequency offset and the first data; S4, analyzing the frequency offset correction value based on the target phase value and the first frequency offset; S5, controlling the center frequency of the thermostatic crystal oscillator based on the frequency offset correction value and outputting a time-frequency signal; S6, returning to S1 and repeating S1-S5 in a loop to achieve time-frequency maintenance. By introducing the BeiDou satellite navigation system as a time-frequency reference source in addition to the cesium clock, the simultaneous operation of the two sources achieves the following objectives: reducing the frequency offset of the cesium clock, improving frequency accuracy, and significantly improving the timekeeping performance of the cesium clock.

Description

Technical Field

[0001] This invention relates to the field of satellite timing and time transfer technology, and in particular to a time-frequency preservation method, apparatus and system based on dual-source discipline and drift prediction. Background Technology

[0002] Since being defined as the "second" by the International System of Units (SI) in 1967, the cesium atomic clock has been a focal point in the field of atomic frequency standard technology. With the rapid development of information technology, especially in the digital age, the requirements for time accuracy have risen to unprecedented levels. Currently, precise time systems have become the central nervous system for information flow control, possessing irreplaceable core value in most technological fields.

[0003] It has transcended the scope of traditional measuring tools and is a fundamental guarantee for the coordinated operation and functional realization of modern technological systems. Furthermore, after decades of investment and research, remarkable achievements have been made in cesium atomic clock technology, and related products have been applied in practical engineering construction, showing broad prospects for future development.

[0004] Current cesium atomic clocks still face challenges from complex factors such as aging of internal components, fluctuations in environmental temperature and humidity, and mechanical stress disturbances.

[0005] Improving the frequency accuracy and output reliability of existing cesium atomic clocks has become a pressing issue. Summary of the Invention

[0006] The purpose of this invention is to design a time-frequency preservation method, apparatus and system based on dual-source discipline and drift prediction in order to solve the above problems.

[0007] The present invention achieves the above objectives through the following technical solutions:

[0008] Time-frequency preservation methods based on dual-source discipline and drift prediction include:

[0009] S1. Real-time acquisition of first data and second data. The first data consists of the signals of the thermostatic crystal oscillator and the cesium atomic clock. The second data consists of the signals of the thermostatic crystal oscillator, the signals of the Beidou satellite receiver, and the receiver messages.

[0010] S2. Analyze the first frequency offset based on the first data. And based on the second data, analyze the cumulative phase of the second frequency offset. First frequency deviation The first frequency offset is the frequency deviation of the thermostatic crystal oscillator relative to the cesium atomic clock, and the second frequency offset is the frequency deviation of the thermostatic crystal oscillator relative to the BeiDou satellite.

[0011] S3, based on the cumulative phase of the second frequency offset and the first data analysis target phase value ;

[0012] S4. Based on the target phase value and the first frequency offset Analysis of frequency offset correction values ;

[0013] S5. Based on the frequency offset correction value Control the center frequency of the thermostatic crystal oscillator and output a time-frequency signal;

[0014] S6, return to S1, and repeat S1-S5 in a loop to achieve time and frequency preservation.

[0015] A time-frequency preservation device based on dual-source discipline and drift prediction includes:

[0016] Storage; storage is used to store computer programs;

[0017] An actuator; the actuator is used to execute a computer program in the storage, which, when executed, implements the time-frequency preservation method based on dual-source discipline and drift prediction as described above.

[0018] A time-frequency preservation system based on dual-source discipline and drift prediction includes:

[0019] Cesium atomic clock;

[0020] Thermostatic crystal oscillator;

[0021] Beidou satellite receiver;

[0022] The first counter is used to convert the 10MHz signal of the cesium atomic clock into a 1Hz cesium atomic clock signal. The signal output terminal of the cesium atomic clock is connected to the signal input terminal of the first counter.

[0023] The second counter is used to convert the 10MHz signal of the thermostatic crystal oscillator into a 1Hz thermostatic crystal oscillator signal. The signal output terminal of the thermostatic crystal oscillator is connected to the signal input terminal of the second counter.

[0024] The first phase detector is used to measure the time difference between the isothermal crystal oscillator signal and the cesium atomic clock signal, and serves as the first phase. The signal output terminals of the first counter and the second counter are connected to the signal input terminal of the first phase detector.

[0025] The second phase detector is used to measure the time difference between the isothermal crystal oscillator signal and the Beidou satellite receiver signal and use it as the second phase. The signal output terminal of the second counter is connected to the signal output terminal of the Beidou satellite receiver and the signal input terminal of the second phase detector.

[0026] Central processing unit (CPU); the data signal input terminal of the CPU is connected to the data output terminals of the first phase detector and the second phase detector. When the CPU performs time-frequency maintenance based on the first phase and the second phase, it implements the time-frequency maintenance method based on dual-source discipline and drift prediction as described above.

[0027] The beneficial effects of this invention are as follows: by introducing the BeiDou satellite navigation system as a time and frequency reference source in addition to the cesium clock, the dual sources operate simultaneously, achieving the following objectives: reducing the frequency offset of the cesium clock, improving frequency accuracy, and significantly improving the timekeeping performance of the cesium clock.

[0028] Reducing Cesium Atomic Clock Frequency Offset and Improving Frequency Accuracy: This method involves a system that includes a BeiDou receiver and a cesium atomic clock. Leveraging the unique advantages of the BeiDou space-based spatiotemporal system and the frequency stability of the cesium clock, through long-term observation (3 days, 72 hours) data accumulation, an estimate of the cesium atomic clock frequency offset based on the time and frequency measurement benchmark (BeiDou's time source) can be obtained, with an accuracy better than 1E-14. Furthermore, by finely controlling the cryogenic crystal oscillator, a correction factor for the cesium atomic clock frequency offset is added to the oscillator based on the cesium atomic clock frequency standard, ultimately obtaining an output signal with higher frequency accuracy than the cesium atomic clock itself.

[0029] Improving the Reliability of Cesium Atomic Clock Output: During long-term operation, cesium atomic clocks may exhibit anomalies due to various factors, such as phase jumps, frequency jumps, and noise spikes. These anomalies severely affect their accuracy and stability. This method does not directly utilize the cesium clock but ultimately outputs the frequency signal through a temperature-controlled crystal oscillator (OCXO). The manufacturing process of OCXOs is highly mature, with core processes achieving standardized mass production. Their applications are widespread, and the output signal is stable and reliable.

[0030] Significantly improves the timekeeping performance of cesium clocks: The system involved in this method can still operate even when the BeiDou receiver is unavailable. By utilizing the cesium clock frequency offset obtained from simultaneous operation of dual sources, the cesium clock can be continuously corrected, ensuring that the output frequency accuracy remains at a high level. At the same time, the introduction of a temperature-controlled crystal oscillator avoids abnormal phenomena of the cesium clock. Attached Figure Description

[0031] Figure 1 This is a schematic diagram of the time-frequency preservation method based on dual-source discipline and drift prediction of the present invention;

[0032] Figure 2 This is a schematic diagram of the time-frequency preservation system based on dual-source discipline and drift prediction of the present invention. Detailed Implementation

[0033] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0034] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0035] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0036] In the description of this invention, it should be understood that the terms "upper," "lower," "inner," "outer," "left," "right," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of this invention is in use, or the orientation or positional relationship commonly understood by those skilled in the art. They are only used to facilitate the description of this invention and to simplify 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.

[0037] Furthermore, the terms "first," "second," etc., are used only to distinguish descriptions and should not be interpreted as indicating or implying relative importance.

[0038] In the description of this invention, it should also be noted that, unless otherwise explicitly specified and limited, terms such as "set" and "connection" should be interpreted broadly. For example, "connection" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can be a connection within two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0039] The specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0040] like Figure 1 As shown, the time-frequency preservation method based on dual-source discipline and drift prediction includes:

[0041] S1. Real-time acquisition of first data and second data. The first data consists of the signals of the thermostatic crystal oscillator and the cesium atomic clock. The second data consists of the signals of the thermostatic crystal oscillator, the signals of the Beidou satellite receiver, and the receiver messages.

[0042] The first data meets the first requirement, which is: the first data is data extracted from the current time back over a first preset time period, and the number of data meets the preset number; the first data comes from the first phase detector, the input signals of the first phase detector are the 1pps signal from the temperature-controlled crystal oscillator and the 1pps signal from the cesium atomic clock, the first phase detector can measure once per second and output a (time) phase difference value between the two input signals; the first phase detector collects a set of data every 120 seconds, and the data window duration is 120 seconds; the analysis of the first frequency offset and steps S3-S5 are executed once every 120 seconds, extracting data from the current time back over 120 seconds, for a total of 120 phase difference value data.

[0043] The second data meets the second requirement: the second data is data extracted from the current time back over a second preset time period. Specifically, the second data comes from the second phase detector, derived from the 1pps signal of the temperature-controlled crystal oscillator and the 1pps signal of the Beidou satellite receiver. The second phase detector can measure once per second and output a (time) phase difference value between the two input signals; if the Beidou satellite receiver signal is missing, no data is generated for the current second; a set of data is collected every 2 hours, with a data window duration of 3 days; the second frequency offset calculation process is executed every 2 hours, extracting data from the current time back over 3 days, totaling 259,200 phase difference value data. This data set is allowed a maximum of 6% missing or abnormal data; if the data does not meet the quantity requirement, it is necessary to wait until the phase detector's phase data accumulates to meet the requirement before proceeding with the second frequency offset calculation process;

[0044] S1', Perform outlier filtering on the first and second data:

[0045] The specific steps for filtering out outliers from the first data are as follows:

[0046] The first outlier of the isothermal crystal oscillator signal is screened out using the Laida criterion. The first outlier is the phase difference between adjacent time points. The phase correction values ​​of the two signals associated with the first outlier are used as outliers, marked as outliers, and then discarded.

[0047] The specific steps for filtering out outliers in the second data are as follows:

[0048] The second outlier of the isothermal crystal oscillator signal and the Beidou satellite receiver signal was screened out using the Laida criterion. The second outlier is the phase difference between adjacent time points. The phase correction values ​​of the two signals associated with the second outlier are used as outliers, marked as outliers, and then removed.

[0049] Check whether the timing validity flag and the number of available satellites in the receiver message meet the retention requirements. If so, retain the BeiDou satellite receiver signal; otherwise, the corresponding BeiDou satellite receiver signal is an abnormal signal. Mark the second data of the time corresponding to the abnormal signal as abnormal and discard it.

[0050] S2. Analyze the first frequency offset based on the first data. And based on the second data, analyze the cumulative phase of the second frequency offset. First frequency deviation The first frequency offset is the frequency deviation of the thermostatic crystal oscillator relative to the cesium atomic clock, and the second frequency offset is the frequency deviation of the thermostatic crystal oscillator relative to the BeiDou satellite.

[0051] Based on the first data analysis, the first frequency offset Specifically, the first frequency offset is analyzed using the least squares method, and expressed as: ,in, for The first data at any given moment This represents the number of data points removed from the first set of data.

[0052] Based on the second data analysis, the cumulative phase of the second frequency offset Specifically:

[0053] (1) Analyze the second frequency offset of the current cesium atomic clock using the least squares method. , represented as: ,in, for The second data point at time, This represents the number of data points removed from the second set of data.

[0054] (2) Utilizing the second frequency offset The cumulative phase of the second frequency offset from the previous cycle is updated as the current cumulative phase of the second frequency offset. , represented as: .

[0055] S3, based on the cumulative phase of the second frequency offset and the first data analysis target phase value Specifically, it includes:

[0056] S31. Analyze the average value of the current phase. , represented as: , As the first data, This represents the number of data points removed from the first set of data.

[0057] S32, Based on the initial phase value ,average value The cumulative phase of the current second frequency offset Analyze target phase value , represented as: Where time represents the duration of the current time period. This is the second frequency offset; the average value from the first analysis... As the initial phase value Initial phase value Compared with the average The difference is to control the time phase of the isothermal crystal oscillator output to be consistent with the time phase of the cesium atomic clock; The integral of the second frequency deviation of the cesium atomic clock over time is used as the cumulative phase of the second frequency deviation. Each time slot is fixed at 120 seconds. The second frequency offset of the cesium atomic clock. The integral over time accumulates continuously as the system runs; similarly, the average value... The two will also be adjusted accordingly, and they will continuously offset and cancel each other out during operation, resulting in the target phase value. It remains at a very small level (nanosecond level).

[0058] S4. Based on the target phase value and the first frequency offset Analysis of frequency offset correction values Frequency offset correction value Represented as: While correcting the frequency offset of the cryogenic crystal oscillator, a small frequency offset is introduced to slowly correct the output phase, achieving high-quality output. 120 represents the duration of the cryogenic crystal oscillator control value calculation process; the 15% and 20% parameters are derived from the steady-state simplification results of the alpha-beta filter. The filter parameters are mainly related to the frequency stability of the cryogenic crystal oscillator.

[0059] This allows the frequency of the temperature-controlled crystal oscillator to be corrected to be very close to that of a cesium atomic clock; the principle behind this is the Kalman filter.

[0060] In the system described in this method, the prediction is made by using the optimal estimate of the center phase of the cryogenic crystal oscillator in the previous stage to predict the center phase of the cryogenic crystal oscillator in the next stage. The prediction essentially assumes that the center phase of the cryogenic crystal oscillator in the previous stage is the same as the center phase of the cryogenic crystal oscillator in the next stage, only with reduced confidence (quantified by "covariance"). This is because temperature is the most significant factor affecting the center frequency of the cryogenic crystal oscillator. The cryogenic crystal oscillator includes a dual-temperature bath and temperature compensation circuitry, and the overall equipment design fully considers minimizing the impact of temperature changes on the cryogenic crystal oscillator. In actual operation, the change in the crystal oscillator's center frequency can be considered a completely random process around its original center frequency.

[0061] Measurement: In the system involved in the method, These are the actual observed values; Simplification of the Kalman filter: This method discards the initial recursive process and directly uses the Kalman filter in steady state. At this point, the Kalman filter is simplified to an Alpha-Beta filter. By sacrificing a small amount of accuracy, it pursues lightweight computation, allowing this invention to be implemented on embedded devices or even microcontrollers and other platforms without strong computing power. This is the final iterative calculation form under steady-state conditions. It is jointly determined by the system model prediction of this method (assuming that the center phase of the cryogenic crystal oscillator in the previous stage is the same as the center phase of the cryogenic crystal oscillator in the next stage, only with reduced confidence (quantified by "covariance")) and the covariance of the actual observed values ​​(which is related to the specific equipment). During continuous operation, this value can be considered as the best estimate of the frequency offset of the cryogenic crystal oscillator.

[0062] The goal is to control the time phase of the output of the thermostatic crystal oscillator to the target phase. The target phase value in this method... It remains at a very small level (nanosecond level). This corresponds to the target value of the superimposed frequency offset. Since the time phase is the integral of the center frequency, future time phase changes can be considered as a completely random process near its original time phase. This can also be handled using the Kalman filter approach, by predicting that the time phase of the next stage of the cryogenic crystal oscillator will be the same as this stage, but with a different covariance. Therefore, the Kalman filter is used. The final iterative computation form.

[0063] The 15% parameter needs to be intentionally lowered: this can be achieved by using a high-performance temperature-controlled crystal oscillator. The mathematical principle is that the higher the performance of the crystal oscillator, the higher the reliability of the prediction if the time phase of the temperature-controlled crystal oscillator in the next stage is the same as that in the current stage. Since the Kalman filter is one-dimensional, the covariance simplifies to a smaller variance, and the 15% term can be smaller in the final simplified Alpha-Beta filter.

[0064] S5. Based on the frequency offset correction value Control the center frequency of the temperature-controlled crystal oscillator and output a time-frequency signal; frequency offset correction value. This is a relative value. When converting it to the output DA voltage control value of the temperature-controlled crystal oscillator, the current DA voltage control value must be taken into account, and the frequency offset correction value must be added. For example, a 10MHz temperature-controlled crystal oscillator has a draw range of 1ppm and a control voltage range of 0-5V. Within this draw range, the voltage and center frequency exhibit a linear relationship of over 90%. This indicates that a 5V change in control voltage (DA voltage control value) corresponds to a 10Hz change in center frequency, 0.5V corresponds to 1Hz, and so on.

[0065] S6, return to S1, and repeat S1-S5 in a loop to achieve time and frequency preservation.

[0066] Frequency offset correction value By applying this principle to a temperature-controlled crystal oscillator and controlling its frequency, the following two objectives can be achieved:

[0067] ① This process corrects the frequency of the oven-controlled crystal oscillator to be very close to that of a cesium atomic clock: In the field of time and frequency transmission, this is generally referred to as locking. Because oven-controlled crystal oscillators are affected by external environmental factors, such as temperature, their center frequency, while relatively stable, is, from a higher precision perspective, an unpredictable time-varying parameter. It requires repeated steps S3-S5 to maintain the frequency of the oven-controlled crystal oscillator at a level very close to that of a cesium atomic clock.

[0068] ② This ensures that the time phase of the output of the thermostatic crystal oscillator is controlled at the target phase; the locked center frequency of the thermostatic crystal oscillator is still a time-varying value under high precision measurement and needs to be constantly corrected; in fact, it can be considered that the center frequency of the thermostatic crystal oscillator fluctuates slightly and irregularly around the output frequency of the cesium clock.

[0069] Frequency offset correction value This method causes the time-frequency signal output by this method to be superimposed with a frequency offset of an order of magnitude smaller and discontinuous within this small, irregular fluctuation, in order to purposefully control the time phase of the output of the thermostatic crystal oscillator; and since the frequency offset amplitude is an order of magnitude smaller than the fluctuation in the locking process and is discontinuous, it does not have a significant impact on the locking state.

[0070] A time-frequency preservation device based on dual-source discipline and drift prediction includes:

[0071] Storage; storage is used to store computer programs;

[0072] An actuator; the actuator is used to execute a computer program in the storage, which, when executed, implements the time-frequency preservation method based on dual-source discipline and drift prediction as described above.

[0073] like Figure 2 As shown, the time-frequency preservation system based on dual-source discipline and drift prediction includes:

[0074] Cesium atomic clock;

[0075] Thermostatic crystal oscillator;

[0076] Beidou satellite receiver;

[0077] The first counter is used to convert the 10MHz signal of the cesium atomic clock into a 1Hz cesium atomic clock signal. The signal output terminal of the cesium atomic clock is connected to the signal input terminal of the first counter.

[0078] The second counter is used to convert the 10MHz signal of the thermostatic crystal oscillator into a 1Hz thermostatic crystal oscillator signal. The signal output terminal of the thermostatic crystal oscillator is connected to the signal input terminal of the second counter.

[0079] The first phase detector is used to measure the time difference between the isothermal crystal oscillator signal and the cesium atomic clock signal, and serves as the first phase. The signal output terminals of the first counter and the second counter are connected to the signal input terminal of the first phase detector.

[0080] The second phase detector is used to measure the time difference between the isothermal crystal oscillator signal and the Beidou satellite receiver signal and use it as the second phase. The signal output terminal of the second counter is connected to the signal output terminal of the Beidou satellite receiver and the signal input terminal of the second phase detector.

[0081] Central processing unit (CPU); the data signal input terminal of the CPU is connected to the data output terminals of the first phase detector and the second phase detector. When the CPU performs time-frequency maintenance based on the first phase and the second phase, it implements the time-frequency maintenance method based on dual-source discipline and drift prediction as described above.

[0082] System operation flow: The 10MHz signal output from the cesium atomic clock and the 10MHz signal output from the oven-controlled crystal oscillator are converted into 1pps signals by the first counter and the second counter, respectively. The system has three 1pps signals, originating from the cesium atomic clock, the oven-controlled crystal oscillator, and the GNSS satellite receiver. The 1pps signals from the cesium atomic clock and the oven-controlled crystal oscillator are input to the first phase detector, while the 1pps signals from the oven-controlled crystal oscillator and the GNSS satellite receiver are input to the second phase detector. The phase detection data from the first and second phase detectors are processed by the central processing unit to obtain the DA voltage control value. This DA voltage control value controls the center frequency of the oven-controlled crystal oscillator.

[0083] When the equipment uses the BeiDou system and satellite observation is good, after the data window duration in the calculation process is reached, the system can complete the assessment and correction of the frequency offset of the access cesium atomic clock.

[0084] The above process can run continuously, obtaining corrected frequency signals over a long period of time, and its frequency accuracy can be traced back to the time and frequency reference.

[0085] After the frequency offset of the cesium atomic clock is assessed, its state after being disconnected from the BeiDou satellite receiver is called "holding". Our company has applied this technology to cesium clocks such as the 5071A (Microsemi), TA-1000 (Chengdu Tian'ao), and Cs-3000 (Institute 510), achieving a holding accuracy of 100ns within 14 days. This represents a significant improvement compared to the previous holding accuracy (ranging from 400ns to 1000ns within 14 days).

[0086] By introducing the BeiDou satellite navigation system as a time and frequency reference source in addition to the cesium clock, the dual sources operate simultaneously, achieving the following objectives: reducing the frequency offset of the cesium clock, improving frequency accuracy, and significantly enhancing the timekeeping performance of the cesium clock.

[0087] Reducing Cesium Atomic Clock Frequency Offset and Improving Frequency Accuracy: This method involves a system that includes a BeiDou receiver and a cesium atomic clock. Leveraging the unique advantages of the BeiDou space-based spatiotemporal system and the frequency stability of the cesium clock, through long-term observation (3 days, 72 hours) data accumulation, an estimate of the cesium atomic clock frequency offset based on the time and frequency measurement benchmark (BeiDou's time source) can be obtained, with an accuracy better than 1E-14. Furthermore, by finely controlling the cryogenic crystal oscillator, a correction factor for the cesium atomic clock frequency offset is added to the oscillator based on the cesium atomic clock frequency standard, ultimately obtaining an output signal with higher frequency accuracy than the cesium atomic clock itself.

[0088] Improving the Reliability of Cesium Atomic Clock Output: During long-term operation, cesium atomic clocks may exhibit anomalies due to various factors, such as phase jumps, frequency jumps, and noise spikes. These anomalies severely affect their accuracy and stability. This method does not directly utilize the cesium clock but ultimately outputs the frequency signal through a temperature-controlled crystal oscillator (OCXO). The manufacturing process of OCXOs is highly mature, with core processes achieving standardized mass production. Their applications are widespread, and the output signal is stable and reliable.

[0089] Significantly improves the timekeeping performance of cesium clocks: The system involved in this method can still operate even when the BeiDou receiver is unavailable. By utilizing the cesium clock frequency offset obtained from simultaneous operation of dual sources, the cesium clock can be continuously corrected, ensuring that the output frequency accuracy remains at a high level. At the same time, the introduction of a temperature-controlled crystal oscillator avoids abnormal phenomena of the cesium clock.

[0090] The technical solutions of the present invention are not limited to the specific embodiments described above. Any technical modifications made in accordance with the technical solutions of the present invention fall within the protection scope of the present invention.

Claims

1. A time-frequency preservation method based on dual-source discipline and drift prediction, characterized in that, include: S1. Real-time acquisition of first data and second data. The first data consists of the signals of the thermostatic crystal oscillator and the cesium atomic clock. The second data consists of the signals of the thermostatic crystal oscillator, the signals of the Beidou satellite receiver, and the receiver messages. S1', Perform outlier filtering on the first and second data: The specific steps for filtering out outliers from the first data are as follows: The first outlier of the isothermal crystal oscillator signal is screened out using the Laida criterion. The first outlier is the phase difference between adjacent time points. The phase correction values ​​of the two signals associated with the first outlier are used as outliers, marked as outliers, and then discarded. The specific steps for filtering out outliers in the second data are as follows: The second outlier of the isothermal crystal oscillator signal and the Beidou satellite receiver signal was screened out using the Laida criterion. The second outlier is the phase difference between adjacent time points. The phase correction values ​​of the two signals associated with the second outlier are used as outliers, marked as outliers, and then removed. Check whether the timing validity flag and the number of available satellites in the receiver message meet the retention requirements. If so, retain the BeiDou satellite receiver signal; otherwise, the corresponding BeiDou satellite receiver signal is an abnormal signal. Mark the second data of the time corresponding to the abnormal signal as abnormal and discard it. S2. Analyze the first frequency offset based on the first data. And based on the second data, analyze the cumulative phase of the second frequency offset. First frequency deviation The first frequency offset is the frequency deviation of the thermostatic crystal oscillator relative to the cesium atomic clock, and the second frequency offset is the frequency deviation of the thermostatic crystal oscillator relative to the BeiDou satellite. S3, based on the cumulative phase of the second frequency offset and the first data analysis target phase value Specifically, it includes: S31. Analyze the average value of the current phase. , represented as: , As the first data, This represents the number of data points removed from the first set of data. S32, Based on the initial phase value ,average value The cumulative phase of the current second frequency offset Analyze target phase value , represented as: ; S4. Based on the target phase value and the first frequency offset Analysis of frequency offset correction values ; S5. Based on the frequency offset correction value Control the center frequency of the thermostatic crystal oscillator and output a time-frequency signal; S6, return to S1, and repeat S1-S5 in a loop to achieve time and frequency preservation.

2. The time-frequency preservation method based on dual-source discipline and drift prediction according to claim 1, characterized in that, In S1, the first data satisfies the first requirement, and the second data satisfies the second requirement. The first requirement is that the first data is data extracted from the current time back to the first preset time period, and the number of data meets the preset number. The second requirement is that the second data is data extracted from the current time back to the second preset time period.

3. The time-frequency preservation method based on dual-source discipline and drift prediction according to claim 1, characterized in that, Based on the first data analysis, the first frequency offset Specifically, the first frequency offset is analyzed using the least squares method, and expressed as: ,in, for The first data at any given moment This represents the number of data points removed from the first set of data.

4. The time-frequency preservation method based on dual-source discipline and drift prediction according to claim 1, characterized in that, Based on the second data analysis, the cumulative phase of the second frequency offset is specifically as follows: (1) Analyze the second frequency offset of the current cesium atomic clock using the least squares method. , represented as: ,in, for The second data point at time, This represents the number of data points removed from the second set of data. (2) Utilizing the second frequency offset The cumulative phase of the second frequency offset from the previous cycle is updated as the current cumulative phase of the second frequency offset. , represented as: Where time represents the duration of the current time period.

5. The time-frequency preservation method based on dual-source discipline and drift prediction according to claim 1, characterized in that, In S4, the frequency offset correction value Represented as: .

6. A time-frequency holding device based on dual-source discipline and drift prediction, characterized in that, include: Storage; Storage is used to store computer programs; Actuator; The actuator is used to execute a computer program in the storage, which, when executed, implements the time-frequency preservation method based on dual-source discipline and drift prediction as described in any one of claims 1-5.

7. A time-frequency preservation system based on dual-source discipline and drift prediction, characterized in that, include: Cesium atomic clock; Thermostatic crystal oscillator; Beidou satellite receiver; First counter; The first counter is used to convert the 10MHz signal of the cesium atomic clock into a 1Hz cesium atomic clock signal. The signal output terminal of the cesium atomic clock is connected to the signal input terminal of the first counter. The second counter is used to convert the 10MHz signal of the thermostatic crystal oscillator into a 1Hz thermostatic crystal oscillator signal. The signal output terminal of the thermostatic crystal oscillator is connected to the signal input terminal of the second counter. The first phase detector is used to measure the time difference between the isothermal crystal oscillator signal and the cesium atomic clock signal, and serves as the first phase. The signal output terminals of the first counter and the second counter are connected to the signal input terminal of the first phase detector. Second phase detector; The second phase detector is used to measure the time difference between the isothermal crystal oscillator signal and the Beidou satellite receiver signal and to use it as the second phase. The signal output terminal of the second counter is connected to the signal output terminal of the Beidou satellite receiver and the signal input terminal of the second phase detector. Central processing unit; the data signal input terminal of the central processing unit is connected to the data output terminals of the first phase detector and the second phase detector. When the central processing unit performs time-frequency maintenance based on the first phase and the second phase, it implements the time-frequency maintenance method based on dual-source discipline and drift prediction as described in any one of claims 1-5.

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