A method for fast start taming of an aircraft atomic clock

Abstract

The present application relates to the technical field of atomic clock fast starting, and provides a kind of fast starting taming method suitable for aircraft atomic clock, comprising first incubation in multiple temperature conditions, the data of laser tube thermal ring heating current and atomic clock output frequency are collected, corresponding segment is divided according to the absolute value difference of current change rate;For each segment, the corresponding relationship between current and frequency is established, the compensation parameters for offsetting frequency drift are calculated, the characteristics of the starting segment at each temperature are extracted and a segmented feature template library is constructed, and compensation parameters are reserved in advance.Atomic clock starts, real-time data and corresponding change rate are collected and matched with the template library characteristics, the starting temperature is determined, and the corresponding segmented compensation parameters are called to compensate the frequency segment by segment;After the frequency enters the thermal equilibrium fluctuation range, the locking process is triggered, and the external reference signal is used to tame the synchronization frequency, which realizes fast starting and ensures accurate and stable output frequency.

Description

Technical Field

[0001] This invention relates to the field of atomic clock rapid start-up technology, and more specifically, to a rapid start-up and taming method adapted to the atomic clock of an aircraft. Background Technology

[0002] The content in this section only provides background information related to this invention and may not constitute prior art.

[0003] Atomic clocks, as high-precision time and frequency reference devices, play a crucial role in fields such as communication, navigation, and aerospace telemetry and control. Their startup and stabilization speed directly affects the overall system response efficiency. Especially during the operation of atomic clocks in spacecraft, the laser tube, as a core component, has its operating temperature and heating current state directly affecting the frequency output characteristics of the atomic clock. Affected by factors such as ambient temperature and the length of time the equipment has been idle, the internal temperature field distribution of the atomic clock is uneven when it is started up from a cold state. The laser tube's heating ring needs to be heated to gradually approach the operating temperature. During this process, the heating current will fluctuate continuously with the temperature change, thus causing a significant drift in the output frequency.

[0004] After the atomic clock is powered on, it outputs its own second pulse signal and simultaneously connects to an external reference source to acquire the corresponding second pulse signal. The appropriate data acquisition time needs to be determined dynamically. This acquisition time starts from the later of the atomic clock locking time and the external reference source connection time, and ends at the time after the atomic clock is powered on and a preset time interval has elapsed. Within the determined acquisition time, the phase difference between the two second pulse signals is measured second by second. The phase difference between adjacent seconds is subtracted to obtain the phase deviation value and form a phase deviation sequence. The phase deviation sequence is fitted to generate the target frequency accuracy. Then, the atomic clock is calibrated based on the target frequency accuracy to complete the rapid adaptive training of the atomic clock.

[0005] In existing technologies, atomic clock start-up control methods mostly employ constant temperature control logic and fixed frequency compensation parameters, failing to fully consider the impact of different initial start-up temperatures on heating current and frequency drift. During the start-up phase, the internal temperature and electrical parameters of the equipment exhibit strong dynamic and random variations, making it difficult for fixed compensation models to cover the frequency shift characteristics under various start-up conditions, resulting in limited frequency correction effectiveness. Furthermore, existing technologies cannot adaptively adjust the control strategy according to actual start-up conditions, relying solely on long-term natural stabilization to achieve frequency locking. Therefore, a rapid start-up and discipline method adapted to spacecraft atomic clocks is urgently needed to address these issues. Summary of the Invention

[0006] The purpose of this invention is to provide a rapid start-up and discipline method for spacecraft atomic clocks, thereby improving the aforementioned problems. To achieve this objective, the technical solution adopted by this invention is as follows: In a first aspect, this application provides a rapid start-up and discipline method for an atomic clock adapted to an aircraft, comprising: After maintaining the temperature for a preset time under multiple preset temperature conditions, the machine is powered on and the heating current value of the laser tube hot ring and the frequency value output by the atomic clock are collected after power-on to generate the original power-on dataset corresponding to each temperature condition. A point-by-point time-axis analysis was performed on the original start-up dataset to calculate the absolute value of the rate of change of heating current values ​​per unit time between adjacent time points. Based on different intervals of the absolute value of the rate of change, the original start-up dataset was divided into three continuous segments: the cold-state heating segment, the temperature transition segment, and the thermal equilibrium segment. Among them, the time period with the highest absolute value of the rate of change is the cold-state heating segment, the time period with the middle absolute value of the rate of change is the temperature transition segment, and the time period with the lowest absolute value of the rate of change is the thermal equilibrium segment. For each segment, a correspondence is established between the heating current value and the frequency value within that segment. Based on this correspondence, the frequency compensation parameters required to offset the frequency drift within that segment are calculated. Simultaneously, the heating current value, frequency value, and absolute value of the initial rate of change at the beginning of the cold-state heating segment under each temperature condition are extracted as features of the segment corresponding to that temperature condition. The segmentation results corresponding to each temperature condition, the frequency compensation parameters of each segment, and the features are integrated and stored to generate a segment feature template library. When the atomic clock is turned on, real-time data of heating current and frequency values ​​are collected, and the absolute value of the real-time rate of change of the two is calculated. The real-time data and the absolute value of the real-time rate of change are matched with the initial features of each cold-state heating segment pre-stored in the segmented feature template library to identify the initial temperature conditions corresponding to this turn-on. Based on the initial temperature conditions, the pre-stored frequency compensation parameters of each segment at the corresponding temperature are called from the segmented feature template library, and the output frequency of the atomic clock is compensated in segments in the cold heating segment, temperature transition segment and thermal equilibrium segment. During the compensation process, when the atomic clock output frequency value is detected to enter the frequency fluctuation range corresponding to the thermal equilibrium segment, the frequency locking process of the atomic clock is triggered. After the locking is completed, the discipline process of the external reference signal is started to synchronize the output frequency of the atomic clock to the external reference signal.

[0007] Furthermore, the steps of maintaining the machine at multiple preset temperature conditions for a preset time before turning it on specifically include: Multiple preset temperature conditions were selected, including temperatures of -40°C, 0°C, 25°C, 45°C, and 60°C. Under each temperature condition, the atomic clock was placed in a constant temperature chamber for at least two hours to ensure that the internal components of the atomic clock reached thermal equilibrium under that temperature condition before the clock was turned on for data acquisition.

[0008] Furthermore, the steps of collecting the heating current value of the laser tube's thermal ring and the frequency value output by the atomic clock after power-on specifically include: The heating current value is acquired at a fixed period, while the frequency value output by the atomic clock is continuously recorded. All acquired heating current values ​​and frequency values ​​are packaged in chronological order to generate a raw boot dataset in text format.

[0009] Furthermore, the original startup dataset is divided into three consecutive segments—a cold-state heating segment, a temperature transition segment, and a thermal equilibrium segment—based on different intervals of the absolute value of the rate of change. Specifically, this includes: Calculate the difference in heating current value at each time point relative to the previous time point, and divide the difference by the sampling time interval to obtain the absolute value of the rate of change per unit time. Analyze the continuous distribution characteristics of all absolute values ​​of rate of change, and determine two continuous rate of change thresholds, denoted as the first threshold and the second threshold, respectively, with the first threshold being greater than the second threshold. The first threshold is the critical value after the absolute value of the rate of change starts to decrease significantly from the peak, and the second threshold is the critical value when the absolute value of the rate of change tends to stabilize and the fluctuation amplitude is less than the preset fluctuation threshold. The time period in which the absolute value of the rate of change is continuously greater than or equal to the first threshold is determined as the cold state heating period; the time period in which the absolute value of the rate of change is continuously between the second threshold and the first threshold is determined as the temperature transition period; and the time period in which the absolute value of the rate of change is continuously less than the second threshold and the fluctuation range meets the preset stability requirements is determined as the thermal equilibrium period.

[0010] Furthermore, the step of calculating the frequency compensation parameters required to offset the frequency drift within the segment based on the correspondence specifically includes: During the cold heating phase, the heating current value at each time point is used as the input, and the frequency value at the corresponding time point is used as the output. A linear relationship curve is fitted using the least squares method, and the compensation value used to offset the frequency drift in the segment is calculated based on the slope of the linear relationship curve. In the temperature transition section and the thermal equilibrium section, a mapping table between the heating current value and the frequency value is established by piecewise linear interpolation, and the offset compensation value required for each discrete point is calculated based on the mapping table.

[0011] Furthermore, the steps of performing segmented compensation on the atomic clock's output frequency in the cold-state heating stage, the temperature transition stage, and the thermal equilibrium stage specifically include: The current segment is determined based on the real-time collected heating current value; From the segmented feature template library, retrieve the frequency compensation parameters corresponding to the initial temperature conditions and the current segment, and superimpose these frequency compensation parameters onto the control voltage of the voltage-controlled crystal oscillator inside the atomic clock. By changing the output frequency of the voltage-controlled crystal oscillator, the frequency drift caused by temperature changes can be offset.

[0012] Furthermore, during the segmented compensation process, when the atomic clock's operating state switches from one segment to the next adjacent segment, the frequency compensation parameters are smoothly adjusted to ensure that the compensation parameters change continuously at the boundaries of adjacent segments.

[0013] The beneficial effects of this invention are as follows: This invention employs a heat preservation start-up process under varying temperature conditions, collecting data on the heating current of the laser tube's thermal ring and the atomic clock's output frequency. Time-axis analysis of the data is performed, and different temperature stages are defined based on the differences in the absolute value of the heating current's rate of change. A correspondence between heating current and frequency is established for each stage, and compensation parameters to offset frequency drift are calculated. Simultaneously, features of the initial stage under each temperature condition are extracted and integrated into a segmented feature template library, thus pre-stocking compensation data for different temperatures and laying the foundation for rapid compensation after start-up. During start-up, real-time heating current, frequency data, and corresponding absolute values ​​of their rates of change are collected. The collected data is then matched with the initial features in the template library to determine the current starting temperature. The compensation parameters for each stage at the corresponding temperature are then invoked, and frequency compensation is performed sequentially for each temperature stage, effectively shortening the time it takes for the atomic clock to reach a stable state. During the compensation process, when frequency fluctuations within the thermal equilibrium stage are detected, a frequency locking process is triggered. After locking, external reference signal discipline is initiated, synchronizing the atomic clock's output frequency to the external reference signal. This combination of segmented compensation and locking discipline enables rapid start-up of the atomic clock while ensuring the accuracy and stability of its output frequency. Attached Figure Description

[0014] Figure 1 A flowchart of a rapid start-up and discipline method for an atomic clock of an aircraft provided by the present invention; Figure 2 This is a schematic diagram of an atomic clock rapid start-up system provided by the present invention.

[0015] In the diagram: 201, Data Acquisition Module; 202, Segmentation Module; 203, Template Generation Module; 204, Temperature Matching Module; 205, Segment Compensation Module; 206, Frequency Locking Module. Detailed Implementation

[0016] 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 embodiments of the present invention, and not all embodiments. 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.

[0017] like Figure 1 As shown in the embodiment of the present invention, a rapid start-up and discipline method for an atomic clock adapted to a spacecraft includes: S101 is powered on after maintaining the temperature for a preset time under multiple preset temperature conditions. It collects the heating current value of the laser tube heat ring and the frequency value output by the atomic clock after power-on, and generates the original power-on dataset corresponding to each temperature condition.

[0018] Specifically, this step involves conducting standardized power-on experiments under multiple temperature conditions to collect correlation data between the laser tube's heating current and the atomic clock's output frequency, generating a raw power-on dataset. The principle is based on the core characteristic of the CPT atomic clock: its output frequency is significantly affected by temperature. After the CPT atomic clock is powered on from a cold state, temperature changes in core components such as the laser tube, absorber, and temperature-compensated crystal oscillator directly or indirectly cause frequency drift in the entire system. Furthermore, the temperature rise process and frequency drift pattern of each component differ significantly under different initial temperature conditions. Only by obtaining real power-on data under various temperature conditions through standardized experiments can an objective and effective data source be provided for subsequent temperature segmentation and compensation parameter modeling. The detailed process is as follows: First, the process of maintaining the clock at preset temperatures for predetermined durations before powering on aims to standardize the initial experimental conditions for data acquisition. Its core principle is to ensure the validity and repeatability of the acquired data by identifying typical temperature zones and maintaining initial thermal balance. Temperature points including -40°C, 0°C, 25°C, 45°C, and 60°C are selected as the preset temperature conditions. The principle behind this design is that these five temperature points fully cover the typical operating temperature range of the CPT atomic clock, from the low-temperature operating limit of -40°C to the high-temperature operating limit of 60°C. This includes the standard operating point of 25°C and also covers the critical transition points of 0°C and 45°C, comprehensively simulating various initial temperature conditions of the CPT atomic clock in actual engineering applications. This avoids situations where the original dataset cannot reflect the frequency drift patterns under complex actual power-on environments due to the selection of only one temperature point or incomplete coverage. The atomic clock is placed in a constant temperature chamber for at least two hours under each temperature condition to ensure that all internal components reach thermal equilibrium before powering on and collecting data. The principle behind this is that the CPT atomic clock integrates multiple core components, including an absorber heat exchanger, a laser tube heat exchanger, a temperature-compensated crystal oscillator, and a microwave source. These components have significant differences in heat capacity, thermal conductivity, and temperature response characteristics. If data is collected before thermal equilibrium is reached, the initial temperature state of the internal components will be random, and the collected temperature changes and frequency drift data will contain irregular initial fluctuations, failing to accurately reflect the inherent startup pattern of the atomic clock under that temperature condition. Therefore, this method eliminates the randomness of the initial temperature of the internal components, ensuring a high degree of consistency in the initial state of each power-on under the same temperature condition.

[0019] The subsequent steps involve collecting the heating current value of the laser tube's thermal ring and the frequency value output by the atomic clock after power-on. The core of this process is to establish a temporal correlation between these two parameters by simultaneously acquiring temperature-related indicators and frequency output indicators. Specifically, the heating current value is acquired at fixed intervals, while the frequency value output by the atomic clock is continuously recorded. The principle is that the heating current value of the laser tube's thermal ring is a direct quantitative indicator reflecting the temperature change of the laser tube. The laser tube in the CPT atomic clock is a VCSEL laser tube, and its operating temperature fluctuations directly affect the wavelength and intensity of the output laser, thereby changing the center frequency of the CPT peak and ultimately causing a drift in the overall output frequency. The change in the heating current of the laser tube's thermal ring is strongly correlated with the change in the laser tube's temperature. Acquiring this parameter at fixed intervals allows for precise capture of the dynamic temperature change process of the laser tube. Simultaneously, continuously recording the frequency value output by the atomic clock establishes a real-time correlation between the laser tube's temperature change and the overall frequency drift. Furthermore, the fixed-period acquisition method avoids timeline data distortion caused by uneven acquisition intervals, and continuous recording of frequency values ​​ensures the continuity of frequency drift data without missing crucial data. All acquired heating current and frequency values ​​are packaged in chronological order to generate a raw startup dataset in text format. The principle behind this is that text-format datasets have the technical advantages of strong hardware compatibility, easy data reading, and easy subsequent processing. Integrating all acquired parameters in chronological order can completely preserve the dynamic change time sequence characteristics of each parameter during the CPT atomic clock startup process, ensuring that the correspondence between heating current and output frequency at each time point can be accurately traced when performing time-axis point-by-point analysis of the data. At the same time, all acquired data under the same temperature condition are packaged and stored, which facilitates the classification, comparative analysis, and unified retrieval of datasets under different temperature conditions.

[0020] The specific implementation method is as follows: An XHTF1040B-M type CPT atomic clock was selected as the experimental object. A temperature-controlled constant temperature chamber, a general-purpose serial communication device, and an XHTF3596 frequency acquisition device were prepared. First, the temperature control parameter of the constant temperature chamber was set to -40℃. The CPT atomic clock to be tested was placed inside the constant temperature chamber. After closing the chamber door, the temperature holding timer was started. After 2 hours of continuous temperature holding, it was confirmed that the temperature inside the constant temperature chamber was stable at -40℃ and that all components inside the atomic clock, including the absorber, laser tube, temperature-compensated crystal oscillator, and microwave source, had reached thermal equilibrium under this temperature condition. Then, the CPT atomic clock was powered on. Simultaneously, the data acquisition program was started, with a fixed acquisition cycle of 1 second. HEX commands (21 83 0D) were continuously sent to the atomic clock via a general-purpose serial communication program. 0A: Obtain the heating current DA value of the laser tube hot ring as the heating current value for each command feedback. Simultaneously, continuously record the 10MHz standard frequency value output by the atomic clock using the XHTF3596 frequency acquisition device. Stop the acquisition operation after 30 minutes of continuous acquisition. Arrange the heating current values ​​and corresponding frequency values ​​of a total of 1800 time points in order from 0 seconds to 1800 seconds after power-on, and finally package all the data into a text file named "-40℃ original power-on dataset.txt". Following the same experimental operation procedure, set the temperature control parameters of the constant temperature chamber to 0℃, 25℃, 45℃, and 60℃ respectively. After holding at each temperature for 2 hours, complete the power-on and data acquisition operations, generating text files named "0℃ original power-on dataset.txt", "25℃ original power-on dataset.txt", "45℃ original power-on dataset.txt", and "60℃ original power-on dataset.txt" respectively. This completes the construction of the original power-on dataset under the full typical operating temperature range of the CPT atomic clock, thus completing all the implementation operations of step S101.

[0021] S102, perform time-axis point-by-point analysis on the original start-up dataset, calculate the absolute value of the rate of change of heating current value per unit time between adjacent time points; divide the original start-up dataset into three continuous segments: cold state heating segment, temperature transition segment, and thermal equilibrium segment according to different intervals of the absolute value of the rate of change.

[0022] Specifically, by analyzing the timeline of the original startup dataset point by point, the precise division of temperature change stages is achieved. The core principle is that the absolute value of the unit time change rate of the heating current of the laser tube's hot ring is strongly positively correlated with the temperature change rate of the hot ring. The continuous evolution of the temperature change rate of the hot ring corresponds one-to-one with the physical states of the CPT atomic clock after startup: cold-state heating, temperature transition, and thermal equilibrium. Through this quantitative analysis, the physical temperature state of the atomic clock can be transformed into calculable and determinable dataset features, providing a precise stage division basis for subsequent segmented frequency compensation and effectively avoiding the problem of compensation parameter mismatch caused by ambiguous stage division.

[0023] First, the difference in heating current value at each time point relative to the previous time point is calculated sequentially. This difference is then divided by the acquisition time interval to obtain the absolute value of the rate of change per unit time. The principle is that the original power-on dataset uses a fixed 1-second acquisition period. This equal-interval acquisition characteristic provides a unified benchmark for calculating the rate of change per unit time. The adjacent differences in heating current values ​​directly reflect the fluctuation amplitude of the current within a single second. The absolute value of the rate of change obtained by dividing by the acquisition time interval can accurately quantify the real-time change rate of the laser tube's thermal ring temperature, eliminating the influence of the time dimension and enabling a horizontal comparison of temperature change characteristics at different time points.

[0024] Secondly, the continuous distribution characteristics of all absolute values ​​of the rate of change are analyzed to determine two continuous rate of change thresholds, denoted as the first threshold and the second threshold, with the first threshold being greater than the second threshold. The first threshold is the critical value after the absolute value of the rate of change significantly decreases from its peak, while the second threshold is the critical value when the absolute value of the rate of change tends to stabilize and the fluctuation amplitude is less than a preset fluctuation threshold. The principle is that after the CPT atomic clock is powered on in a cold state, the temperature of the laser tube's thermal ring follows a continuous change pattern of "rapid rise - rate slowdown - basic stabilization," corresponding to a distribution characteristic of "high peak - continuous decline - small fluctuations" in the absolute value of the heating current's rate of change. The thresholds determined based on the inherent distribution characteristics of the data can accurately match the critical states of temperature change stages. The first threshold defines the boundary between rapid heating and slow transition, while the second threshold defines the boundary between slow transition and stable equilibrium.

[0025] Finally, the time period in which the absolute value of the rate of change is consistently greater than or equal to the first threshold is defined as the cold-state heating phase; the time period in which the absolute value of the rate of change is consistently between the second and first thresholds is defined as the temperature transition phase; and the time period in which the absolute value of the rate of change is consistently less than the second threshold and the fluctuation range meets the preset stability requirements is defined as the thermal equilibrium phase. The principle is that the range of absolute values ​​of the rate of change corresponds one-to-one with the physical temperature state of the CPT atomic clock after startup. In the cold-state heating phase, the temperature of the laser tube's thermal ring and related core components rises rapidly, and the heating current is adjusted significantly, so the absolute value of the rate of change is in the highest range. In the temperature transition phase, the rate of temperature rise slows significantly, the heating current is finely adjusted, and the fluctuation range decreases, so the absolute value of the rate of change is in the middle range. In the thermal equilibrium phase, the temperature is basically stable, and the heating current fluctuates only slightly, so the absolute value of the rate of change is in the lowest range, and the fluctuation meets the stability requirements. This achieves a precise mapping between the physical temperature state of the atomic clock and the characteristics of the dataset, allowing subsequent segmented frequency compensation to strictly match the frequency drift patterns of different startup stages of the atomic clock, laying the foundation for the accurate use of compensation parameters.

[0026] S103, for each segment, establish the correspondence between the heating current value and the frequency value within the segment, and calculate the frequency compensation parameter required to offset the frequency drift within the segment based on the correspondence; at the same time, extract the heating current value, frequency value and the absolute value of the initial rate of change at the beginning of the cold-state heating segment under each temperature condition, as the feature of the segment corresponding to that temperature condition; integrate and store the segmentation results corresponding to each temperature condition, the frequency compensation parameter and the feature of each segment to generate a segment feature template library; Specifically, during the startup of the CPT atomic clock, the heating current of the laser tube's thermal ring directly reflects the temperature change of the components. Temperature fluctuations are the core cause of frequency drift in the overall output. Establishing a quantitative correspondence between current and frequency can accurately characterize the frequency drift pattern at different heating stages, providing an objective basis for frequency compensation and significantly improving compensation accuracy. Simultaneously, the heating current value, frequency value, and absolute value of the initial rate of change at the start of the cold-state heating segment under each temperature condition are extracted as features corresponding to that temperature segment. This set of features uniquely identifies the initial startup state at different initial temperatures, laying the foundation for quickly matching temperature conditions and calling appropriate compensation parameters during subsequent startup, effectively avoiding compensation failures caused by parameter mismatches. The segmentation results corresponding to each temperature condition, the frequency compensation parameters for each segment, and the features are integrated and stored to generate a segment feature template library. This template library enables standardized management and rapid retrieval of compensation data across the entire temperature range, ensuring that the atomic clock can perform compensation operations in real time at different initial temperatures, meeting the real-time requirements for rapid startup.

[0027] The step of calculating the frequency compensation parameters required to offset the frequency drift within a segment, based on the corresponding relationship, specifically includes: During the cold-state heating segment, the heating current value at each time point is used as input, and the corresponding frequency value at that time point is used as output. A linear relationship curve is fitted using the least squares method, and the compensation value used to offset the frequency drift within that segment is calculated based on the slope of this linear relationship curve. During the cold-state heating segment, the heating current and output frequency are approximately linearly related. The least squares method can eliminate random noise in the experimental data and fit the optimal linear curve that closely matches the actual drift pattern. The slope of the curve directly reflects the drift rate of the frequency with the change in current. The compensation value calculated accordingly can linearly offset the frequency drift in this stage. The calculation is simple and the compensation response is rapid. In the temperature transition and thermal equilibrium sections, a mapping table between heating current and frequency values ​​is established using piecewise linear interpolation. The offset compensation value required for each discrete point is calculated based on the mapping table. The nonlinear correlation between current and frequency is more significant in these two sections. Piecewise linear interpolation can accurately fit the local change trend, and the mapping table can achieve a precise correspondence between discrete current values ​​and compensation values, balancing compensation accuracy and calculation efficiency, thus adapting to the stable operating conditions of gradual temperature change and thermal equilibrium.

[0028] S104 When the atomic clock is turned on, it collects real-time data of heating current and frequency values ​​and calculates the absolute value of the real-time rate of change of the two. It then matches the real-time data and the absolute value of the real-time rate of change with the pre-stored starting features of each cold-state heating segment in the segmented feature template library to identify the starting temperature conditions corresponding to this turn-on.

[0029] Specifically, after the CPT atomic clock is powered on, it acquires the real-time values ​​of the heating current of the laser tube's hot ring and the atomic clock's output frequency at a preset fixed acquisition period. Based on the real-time data from adjacent sampling points, it calculates the absolute values ​​of the real-time change rates of the heating current and frequency, respectively. The principle is that the heating current of the laser tube's hot ring and the atomic clock's output frequency are core parameters characterizing the initial thermal and frequency states upon startup. The absolute values ​​of their real-time change rates quantify the initial parameter change rates, collectively forming a set of initial characteristic parameters that accurately reflect the initial operating conditions of the atomic clock upon startup. The beneficial effects of this operation are: no additional temperature detection devices are required; characteristic parameters can be acquired using the existing acquisition unit of the atomic clock, ensuring the real-time and completeness of parameter acquisition and avoiding lag or distortion in initial characteristic acquisition.

[0030] The real-time data and absolute value of the real-time rate of change are matched with the pre-stored initial features of each cold-state heating segment in the segmented feature template library to identify the initial temperature condition corresponding to this startup. In this step, the real-time collected heating current value, frequency value, and absolute value of the real-time rate of change are used as the matching basis. Numerical matching is performed with the initial features of the cold-state heating segment corresponding to five typical temperature conditions (-40℃, 0℃, 25℃, 45℃, and 60℃) pre-stored in the segmented feature template library. By calculating the deviation between the real-time parameters and the pre-stored features, the temperature corresponding to the pre-stored feature with the smallest deviation is selected as the initial temperature condition for this startup. The principle is that under the same initial temperature conditions, the initial features of the CPT atomic clock startup have stable reproducibility, and numerical matching can achieve automatic and accurate determination of the initial temperature. This allows for rapid identification of the initial temperature conditions across the entire temperature range, providing a basis for the accurate subsequent use of segmented compensation parameters.

[0031] S105, based on the initial temperature conditions, calls the pre-stored frequency compensation parameters of each segment at the corresponding temperature in the segmented feature template library, and sequentially performs segmented compensation on the output frequency of the atomic clock in the cold state heating segment, temperature transition segment and thermal equilibrium segment.

[0032] Specifically, under different initial temperature conditions, the rate of temperature change and frequency drift characteristics of the CPT atomic clock differ in the three stages of cold-state heating, temperature transition, and thermal equilibrium. The segmented feature template library has pre-stored the three-stage compensation parameters for each temperature condition. The dedicated parameters can be called according to the stage, which can avoid the adaptation error of the general compensation scheme. It can achieve a two-way accurate matching between the compensation parameters and the initial temperature and the start-up stage, avoid the failure of frequency drift suppression due to parameter mismatch, and provide core compensation support for the rapid start-up of the atomic clock.

[0033] In the specific execution of segmented compensation, the current segment is first determined based on the real-time collected heating current value. This step relies on the correspondence between the absolute value of the heating current change rate and the thermal state of the atomic clock. By using real-time heating current data, it can be determined whether the current segment is in the cold heating stage, the temperature transition stage, or the thermal equilibrium stage. No additional temperature detection device is required, which simplifies the state determination logic in principle. The beneficial effect is that segmented real-time determination can be achieved by relying on the existing acquisition unit of the atomic clock, ensuring the real-time performance and continuity of compensation execution.

[0034] Subsequently, frequency compensation parameters corresponding to the initial temperature conditions and the current segment are retrieved from the segmented feature template library. These parameters are then superimposed on the control voltage of the voltage-controlled crystal oscillator (VCO) inside the atomic clock. By changing the output frequency of the VCO, the frequency drift caused by temperature changes is offset. The principle is that the output frequency of the VCO can be linearly adjusted with the control voltage. Previously, appropriate compensation parameters were obtained for different segments using least squares fitting and piecewise linear interpolation. These compensation parameters are converted into voltage superposition values, which can inversely offset the frequency shift caused by temperature fluctuations. The beneficial effect is that it accurately matches the frequency drift pattern of each segment, quickly corrects the output frequency deviation, and significantly shortens the frequency stabilization time after the atomic clock is turned on.

[0035] Furthermore, during the segmented compensation process, when the atomic clock switches its operating state from one segment to the next adjacent segment, the frequency compensation parameters are smoothly adjusted to ensure continuous variation at the boundaries of adjacent segments. The principle behind this operation is that a direct abrupt change in the compensation parameters at the segment boundaries would cause a step jump in the voltage-controlled crystal oscillator's output frequency. A smooth transition eliminates such disturbances, ensuring a continuous compensation process without abrupt changes, avoiding secondary frequency fluctuations caused by parameter switching, and maintaining the stability of the atomic clock's output frequency.

[0036] S106 During the compensation process, when the atomic clock output frequency value is detected to enter the frequency fluctuation range corresponding to the thermal equilibrium segment, the frequency locking process of the atomic clock is triggered. After the locking is completed, the discipline process of the external reference signal is started to synchronize the output frequency of the atomic clock to the external reference signal.

[0037] Specifically, the thermal equilibrium stage is the stage after the CPT atomic clock is turned on, in which the absolute value of the rate of change of heating current is continuously less than the second threshold, and the temperature of core components such as the internal laser tube, absorption bulb, and temperature-compensated crystal oscillator tends to stabilize. During this stage, the output frequency fluctuation has converged to the preset stable range, which meets the prerequisite for frequency control locking. At this time, triggering the lock can avoid the lock loss and frequency drift exceeding the tolerance caused by unstable temperature, thus improving the rationality of the locking process and the success rate of execution.

[0038] After the CPT atomic clock completes frequency control locking, the servo circuit locks the voltage-controlled crystal oscillator (VCXO) output frequency to the frequency stability characteristic corresponding to the atomic energy level difference. At this point, it enters the disciplined state according to the frequency calibration command. By calculating the frequency adjustment amount and converting it into the control amount of the XN407 chip, the VCXO output frequency is adjusted to keep the 10MHz standard frequency consistent with the external reference signal. This step combines short-term frequency stabilization through segmented rapid compensation with long-term calibration through external discipline, providing dual protection for the stability and accuracy of the output frequency.

[0039] like Figure 2 As shown, based on the same inventive concept, this embodiment provides an atomic clock rapid start-up system, including: The data acquisition module 201 is used to power on the laser tube after keeping it warm for a preset time according to multiple preset temperature conditions, and to collect the heating current value of the laser tube hot ring and the frequency value output by the atomic clock after power-on, and generate the original power-on dataset corresponding to each temperature condition. The segmentation module 202 is used to perform time-axis point-by-point analysis on the original start-up dataset, calculate the absolute value of the rate of change of the heating current value per unit time between adjacent time points, and divide the original start-up dataset into three continuous segments based on different intervals of the absolute value of the rate of change: cold-state heating segment, temperature transition segment, and thermal equilibrium segment; among them, the time period with the highest absolute value of the rate of change is the cold-state heating segment, the time period with the middle absolute value of the rate of change is the temperature transition segment, and the time period with the lowest absolute value of the rate of change is the thermal equilibrium segment. The template generation module 203 is used to establish a correspondence between the heating current value and the frequency value in each segment, and calculate the frequency compensation parameters required to offset the frequency drift in the segment based on the correspondence. At the same time, it extracts the heating current value, frequency value and the absolute value of the initial rate of change of the cold state heating segment at the beginning of each temperature condition as the feature of the segment corresponding to that temperature condition. The segmentation results corresponding to each temperature condition, the frequency compensation parameters and features of each segment are integrated and stored to generate a segment feature template library. The temperature matching module 204 is used to collect real-time data of heating current and frequency values ​​when the atomic clock is turned on, and calculate the absolute value of the real-time rate of change of the two. The real-time data and the absolute value of the real-time rate of change are matched with the starting features of each cold-state heating segment pre-stored in the segmented feature template library to identify the starting temperature conditions corresponding to this turn-on. The segmented compensation module 205 is used to call the pre-stored frequency compensation parameters of each segment at the corresponding temperature in the segmented feature template library according to the initial temperature conditions, and to perform segmented compensation on the output frequency of the atomic clock in the cold heating segment, temperature transition segment and thermal equilibrium segment in sequence. The frequency locking module 206 is used to trigger the frequency locking process of the atomic clock when the output frequency value of the atomic clock enters the frequency fluctuation range corresponding to the thermal equilibrium segment during the compensation process. After the locking is completed, the disciplining process of the external reference signal is started to synchronize the output frequency of the atomic clock to the external reference signal.

[0040] It should be noted that the specific methods by which each module performs operations in the system described in the above embodiments have been described in detail in the embodiments related to the method, and will not be elaborated here.

[0041] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. 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 rapid start-up and discipline method for an aircraft atomic clock, characterized in that, include: After maintaining the temperature for a preset time under multiple preset temperature conditions, the machine is powered on and the heating current value of the laser tube hot ring and the frequency value output by the atomic clock are collected after power-on to generate the original power-on dataset corresponding to each temperature condition. The original start-up dataset is analyzed point-by-point along the time axis to calculate the absolute value of the rate of change of the heating current value per unit time between adjacent time points. Based on the different intervals of the absolute value of the rate of change, the original start-up dataset is divided into three continuous segments: cold-state heating segment, temperature transition segment, and thermal equilibrium segment. Among them, the time period with the highest absolute value of the rate of change is the cold-state heating segment, the time period with the middle absolute value of the rate of change is the temperature transition segment, and the time period with the lowest absolute value of the rate of change is the thermal equilibrium segment. For each segment, a correspondence is established between the heating current value and the frequency value within that segment. Based on this correspondence, the frequency compensation parameters required to offset the frequency drift within that segment are calculated. Simultaneously, the heating current value, frequency value, and absolute value of the initial rate of change at the beginning of the cold-state heating segment under each temperature condition are extracted as features of the segment corresponding to that temperature condition. The segmentation results corresponding to each temperature condition, the frequency compensation parameters of each segment, and the features are integrated and stored to generate a segment feature template library. When the atomic clock is turned on, real-time data of heating current and frequency values ​​are collected, and the absolute value of the real-time rate of change of the two is calculated. The real-time data and the absolute value of the real-time rate of change are matched with the starting features of each cold-state heating segment pre-stored in the segmented feature template library to identify the starting temperature conditions corresponding to this turn-on. Based on the initial temperature conditions, the pre-stored frequency compensation parameters of each segment at the corresponding temperature are called from the segmented feature template library, and the output frequency of the atomic clock is compensated in segments in the cold heating segment, temperature transition segment and thermal equilibrium segment in sequence. During the compensation process, when the atomic clock output frequency value is detected to enter the frequency fluctuation range corresponding to the thermal equilibrium segment, the frequency locking process of the atomic clock is triggered. After the locking is completed, the discipline process of the external reference signal is started to synchronize the output frequency of the atomic clock to the external reference signal.

2. The rapid start-up and discipline method for an atomic clock adapted to an aircraft according to claim 1, characterized in that, The step of maintaining the device at multiple preset temperature conditions for a preset time before powering it on specifically includes: Temperature points including -40°C, 0°C, 25°C, 45°C, and 60°C were selected as the preset multiple temperature conditions. Under each temperature condition, the atomic clock was placed in a constant temperature chamber for at least two hours to ensure that the internal components of the atomic clock reached the thermal equilibrium state under that temperature condition before the clock was turned on for data acquisition.

3. The rapid start-up and discipline method for an atomic clock adapted to an aircraft according to claim 1, characterized in that, The steps of collecting the heating current value of the laser tube's thermal ring and the frequency value output by the atomic clock after power-on specifically include: The heating current value is acquired at a fixed period, and the frequency value output by the atomic clock is continuously recorded. All the acquired heating current values ​​and frequency values ​​are packaged in chronological order to generate the original power-on dataset in text format.

4. The rapid start-up and discipline method for an atomic clock adapted to an aircraft according to claim 1, characterized in that, The step of dividing the original startup dataset into three consecutive segments—a cold-state heating segment, a temperature transition segment, and a thermal equilibrium segment—based on different intervals of the absolute value of the rate of change specifically includes: Calculate the difference in heating current value at each time point relative to the previous time point, and divide the difference by the sampling time interval to obtain the absolute value of the rate of change per unit time. Analyze the continuous distribution characteristics of all absolute values ​​of rate of change, and determine two continuous rate of change thresholds, denoted as the first threshold and the second threshold, respectively, with the first threshold being greater than the second threshold; wherein, the first threshold is the critical value after the absolute value of the rate of change significantly decreases from the peak, and the second threshold is the critical value when the absolute value of the rate of change tends to stabilize and the fluctuation amplitude is less than the preset fluctuation threshold. The time period in which the absolute value of the rate of change is continuously greater than or equal to the first threshold is determined as the cold-state heating segment; the time period in which the absolute value of the rate of change is continuously between the second threshold and the first threshold is determined as the temperature transition segment; and the time period in which the absolute value of the rate of change is continuously less than the second threshold and the fluctuation range meets the preset stability requirements is determined as the thermal equilibrium segment.

5. The rapid start-up and discipline method for an atomic clock adapted to an aircraft according to claim 1, characterized in that, The step of calculating the frequency compensation parameters required to offset the frequency drift within the segment based on the correspondence specifically includes: Within the cold-state heating segment, the heating current value at each time point is used as the input, and the frequency value at the corresponding time point is used as the output. A linear relationship curve is fitted using the least squares method, and the compensation value used to offset the frequency drift within the segment is calculated based on the slope of the linear relationship curve. Within the temperature transition zone and the thermal equilibrium zone, a mapping table between the heating current value and the frequency value is established using piecewise linear interpolation, and the offset compensation value required for each discrete point is calculated based on the mapping table.

6. The rapid start-up and discipline method for an atomic clock adapted to an aircraft according to claim 1, characterized in that, The step of performing segmented compensation of the atomic clock's output frequency in the cold-state heating stage, the temperature transition stage, and the thermal equilibrium stage specifically includes: The current segment is determined based on the real-time collected heating current value; From the segmented feature template library, frequency compensation parameters corresponding to the initial temperature condition and the current segment are retrieved. These frequency compensation parameters are then superimposed onto the control voltage of the voltage-controlled crystal oscillator inside the atomic clock. By changing the output frequency of the voltage-controlled crystal oscillator, the frequency drift caused by temperature changes is offset.

7. The rapid start-up and discipline method for an atomic clock adapted to an aircraft according to claim 6, characterized in that, Also includes: During the segmented compensation process, when the atomic clock switches from one segment to the next adjacent segment, the frequency compensation parameters are smoothly adjusted to ensure that the compensation parameters change continuously at the boundaries of adjacent segments.

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