Constant-temperature crystal oscillator automatic taming and calibrating method and system based on GPS pulse per second

Abstract

The invention belongs to the technical field of satellite communication, navigation and precision measurement, and discloses a constant-temperature crystal oscillator automatic taming and calibration method and system based on GPS pulse per second, which can accurately tame and calibrate internal clocks such as a rubidium atomic clock and a 10MHz constant-temperature crystal oscillator through a GPS pulse per second signal, and adopts a novel clock synchronization algorithm to realize the automatic taming and calibration of the constant-temperature crystal oscillator. Through accurate frequency calibration and phase synchronization, high-stability and high-precision second pulse signals and 10MHz frequency clock signals are output.

Description

Technical Field

[0001] The invention belongs to the technical fields of satellite communication, navigation and precision measurement, and particularly relates to a method and system for automatic taming and calibration of a constant temperature crystal oscillator based on GPS second pulses. Background Art

[0002] With the rapid development of information technology, modern communications, navigation, and measurement systems are placing increasingly stringent demands on time synchronization. This is particularly true in satellite communications, deep space exploration, astronomical observation, and various precision measurement applications, where clock synchronization accuracy directly determines system precision and reliability. Therefore, high-precision clock sources have become an indispensable and critical component in modern science and technology.

[0003] While traditional high-precision clock sources (such as rubidium atomic clocks, hydrogen clocks, and cesium clocks) have high frequency stability, they still face the problem of frequency drift over long-term use, especially for lower-precision clocks such as quartz oscillators. In this context, the Global Positioning System (GPS) provides an ideal solution for clock synchronization. GPS not only provides precise positioning information but also delivers a high-precision atomic clock-based time calibration signal, the 1 Pulse Per Second (1PPS). This has led to the widespread use of GPS-based clock synchronization methods.

[0004] Currently, most GPS-based clock synchronization systems rely on external GPS receiver modules and utilize an external clock source (such as a rubidium atomic clock) for clock synchronization. However, most existing GPS-based clock synchronization systems can only output pulse-per-second signals, but are unable to simultaneously deliver a highly stable and accurate pulse-per-second signal and a 10 MHz clock signal. Summary of the Invention

[0005] The purpose of the present invention is to provide a method and system for automatic training and calibration of a constant temperature crystal oscillator based on GPS second pulses, which can accurately train and calibrate internal clocks (rubidium atomic clocks, 10MHz constant temperature crystal oscillators, etc.) through the second pulse signals of GPS, and output high-stability, high-precision second pulse signals and 10MHz frequency clock signals through precise frequency calibration and phase synchronization.

[0006] The technical solution adopted by the present invention is a method for automatic taming and calibration of a constant temperature crystal oscillator based on GPS second pulses, comprising the following steps:

[0007] S1, GPS receiving module receives the signal from GPS satellite, decodes and obtains time information, and obtains second pulse signal;

[0008] S2, the rubidium atomic clock receives the GPS second pulse signal sent by the GPS receiving module, connects to the rubidium atomic clock frequency calibration counter to count the rising edges and averages the counting results with a sliding algorithm. The rubidium atomic clock frequency calibration counter outputs the relevant counting average results to the rubidium atomic clock frequency training and calibration module for training and calibration, and obtains the key frequency calibration parameters of the rubidium atomic clock;

[0009] S3, the rubidium atomic clock frequency adjustment loop receives the key frequency calibration parameters of the rubidium atomic clock and performs voltage conversion, directly inputs the voltage into the rubidium atomic clock for frequency control, performs frequency adjustment after the rubidium atomic clock is calibrated, and the adjusted rubidium atomic clock outputs a signal to the phase-locked loop to complete phase locking, and then locks the GPS second pulse signal through frequency and phase synchronization, finally outputting a highly stable and high-precision second pulse signal;

[0010] S4, the 10MHz oven-controlled crystal oscillator receives the second pulse signal output by the rubidium atomic clock, connects to the 10MHz oven-controlled crystal oscillator frequency calibration counter to count the rising edges and average the counting results with a sliding algorithm. The 10MHz oven-controlled crystal oscillator frequency calibration counter outputs the relevant counting average result to the 10MHz oven-controlled crystal oscillator frequency fast follower calibration module for taming and calibration, and obtains the key frequency calibration parameters of the 10MHz oven-controlled crystal oscillator;

[0011] S5, 10MHz constant temperature crystal oscillator frequency adjustment loop receives the key parameters of the frequency calibration of the 10MHz constant temperature crystal oscillator for voltage conversion, directly inputs the voltage into the 10MHz constant temperature crystal oscillator for frequency control, and adjusts the frequency after the 10MHz constant temperature crystal oscillator is calibrated. After adjustment, the 10MHz constant temperature crystal oscillator outputs a signal to the phase-locked loop to complete phase locking, and then synchronizes the frequency and phase to lock the second pulse signal output by the rubidium atomic clock, and finally outputs a highly stable, high-precision second pulse signal and a 10MHz frequency clock signal.

[0012] Furthermore, in S1, the arrival times of the four GPS satellites are used to determine the three-dimensional position and clock deviation of the receiving device. The distances between the four GPS satellites simultaneously received by the GPS receiving module at time T are P1, P2, P3, and P4, respectively. The time differences between the satellite transmission time signals and the signals received by the GPS receiving module are ΔT1, ΔT2, ΔT3, and ΔT4, respectively. The three-dimensional coordinates of the four GPS satellites are (Xi, Yi, Zi), where i = 1, 2, 3, 4. The three-dimensional coordinates of point P are (X, Y, Z). The expression for the distance between point P and the four GPS satellites is:

[0013]

[0014] Where Ti is the time when each GPS satellite transmits the time signal, i = 1, 2, 3, 4; T is the time when the GPS receiving module receives the GPS satellite signal;

[0015] ΔTi=T-Ti

[0016] The clock deviation of the GPS receiving module is calculated by the distance PRi from point P to each GPS satellite and the time difference △Ti between the satellite transmission time signal and the signal received by the GPS receiving module. Then, the second pulse system time difference is corrected according to the clock deviation and the second pulse signal is output.

[0017] Furthermore, the specific steps of S2 include:

[0018] S21, using a rubidium atomic clock as an internal clock, synchronizes the time-frequency signal output by the rubidium atomic clock with the coordinated universal time (UTC) of the GPS second pulse output, calculates the deviation of the frequency output of the rubidium atomic clock frequency standard using the GPS second pulse output, and measures the time interval ΔT between the rising edge of the GPS second pulse output and the second pulse output by the rubidium atomic clock using the rubidium atomic clock frequency calibration counter;

[0019] S22, the rubidium atomic clock frequency taming and calibration module receives the GPS time calibration signal, adjusts the rubidium atomic clock according to the signal, and performs signal processing and frequency synchronization;

[0020] S23, in each GPS time calibration cycle, the rubidium atomic clock frequency taming and calibration module calculates the frequency error △f by comparing the time difference between the GPS second pulse signal and the second pulse signal output by the rubidium atomic clock after a 2000-point sliding average. The rubidium atomic clock frequency taming and calibration module calibrates the frequency of the rubidium atomic clock based on the frequency error △f. The calibration formula is:

[0021] f0(t+1)=f0(t)+k1*Δf(t)

[0022] Among them, f0(t+1) is the reference frequency value of the rubidium atomic clock at time t+1; f0(t) is the reference frequency value of the rubidium atomic clock at time t; k1 is the key parameter for frequency calibration of the rubidium atomic clock; Δf(t) is the frequency error of the rubidium atomic clock at time t.

[0023] Furthermore, in S2, the sliding algorithm averaging specifically includes:

[0024] (1) Take the 2000-point sliding average of the time interval value △T and subtract the weakened time cumulative error;

[0025] (2) The measured value is subjected to a sliding average digital filter using the GPS pulse-per-second signal received by the GPS receiving module, and the corresponding smoothing time interval difference ΔT' is obtained by using the difference between two adjacent filtered values. Combined with the sampling time τ between two adjacent measured values, the frequency offset Δf is calculated using the frequency difference formula of the time ratio method:

[0026]

[0027] Where f0 is the 10 MHz reference frequency of the rubidium atomic clock.

[0028] Furthermore, the specific steps of S3 include:

[0029] S31, the rubidium atomic clock frequency adjustment circuit receives the key frequency calibration parameters of the rubidium atomic clock and then combines them with the voltage-controlled sensitivity coefficient of the rubidium atomic frequency standard to calculate the voltage corresponding to the voltage-controlled voltage applied to the rubidium atomic frequency standard and use it as the training parameter. The control voltage is then output through a D / A converter and directly output to the voltage-controlled pin of the rubidium atomic clock to adjust the rubidium atomic clock;

[0030] S32, after voltage control adjustment, the rubidium atomic clock outputs the signal to the phase-locked loop. In the phase-locked loop, the rubidium atomic clock is synchronized with the frequency of the GPS second pulse signal and the phase of the GPS second pulse signal.

[0031] Furthermore, in said S32, the specific steps of phase synchronization include:

[0032] (1) Whenever the GPS second pulse signal arrives, the phase-locked loop compares the phase of the rubidium atomic second pulse clock with that of the GPS clock, setting the phase of the rubidium atomic second pulse clock to φ0(t)1 and the phase of the GPS clock to φ_GPS(t)1. The phase error Δφ(t)1 is expressed as:

[0033] Δφ(t)1=φ0(t)1-φ_GPS(t)1

[0034] (2) The system adjusts the phase of the rubidium atomic second pulse clock according to the phase error Δφ(t)1 to synchronize it with the GPS second pulse signal. The phase adjustment formula is:

[0035] Φ0(t+1)1=φ0(t)1-α1*Δφ(t)1

[0036] Wherein, α1 is the phase adjustment coefficient of the rubidium atomic second pulse clock.

[0037] Furthermore, the specific steps of S4 include:

[0038] S41 uses a 10 MHz oven-controlled crystal oscillator as an internal clock, synchronizes the time-frequency signal output by the 10 MHz oven-controlled crystal oscillator with the Coordinated Universal Time (UTC) of the second pulse output by the rubidium atomic clock, calculates the deviation of the frequency output of the 10 MHz oven-controlled crystal oscillator frequency standard using the second pulse output by the rubidium atomic clock, and measures the time interval ΔTT between the rising edges of the second pulse output by the rubidium atomic clock and the second pulse output by the 10 MHz oven-controlled crystal oscillator using the 10 MHz oven-controlled crystal oscillator frequency calibration counter;

[0039] S42, 10MHz constant temperature crystal oscillator frequency fast follower calibration module receives the second pulse signal output by the rubidium atomic clock, adjusts the 10MHz constant temperature crystal oscillator according to the signal, and performs signal processing and frequency synchronization;

[0040] S43, the 10MHz constant temperature crystal oscillator frequency fast follower calibration module calculates the frequency error Δf′ by comparing the time difference between the second pulse signal output by the rubidium atomic clock and the second pulse signal output by the 10MHz constant temperature crystal oscillator after 2000 points of sliding average. The 10MHz constant temperature crystal oscillator frequency fast follower calibration module calibrates the frequency of the 10MHz constant temperature crystal oscillator based on the frequency error Δf′. The calibration formula is:

[0041] f0′(t+1)=f0′(t)+k2*Δf′(t)

[0042] Among them, f0′(t+1) is the reference frequency value of the 10MHz oven-controlled crystal oscillator at time t+1; f0′(t) is the reference frequency value of the 10MHz oven-controlled crystal oscillator at time t; k2 is the key parameter for frequency calibration of the 10MHz oven-controlled crystal oscillator; Δf′(t) is the frequency error of the 10MHz oven-controlled crystal oscillator at time t.

[0043] Furthermore, the specific steps of S5 include:

[0044] S51, the 10MHz oven-controlled crystal oscillator frequency adjustment loop receives the key frequency calibration parameters of the rubidium atomic clock and combines them with the voltage-controlled sensitivity coefficient of the 10MHz oven-controlled crystal oscillator frequency standard to calculate the voltage corresponding to the voltage-controlled voltage applied to the 10MHz oven-controlled crystal oscillator frequency standard and use it as the training parameter. The control voltage is then output through a high-resolution D / A converter and directly output to the voltage-controlled pin of the 10MHz oven-controlled crystal oscillator to adjust the 10MHz oven-controlled crystal oscillator.

[0045] S52, after voltage control adjustment of the 10MHz constant temperature crystal oscillator, outputs the signal to the phase-locked loop. In the phase-locked loop, the 10MHz constant temperature crystal oscillator is synchronized with the frequency of the second pulse signal output by the rubidium atomic clock, and at the same time, the phase is synchronized with the second pulse signal output by the rubidium atomic clock.

[0046] Furthermore, in S52, the specific steps of phase synchronization include:

[0047] (1) Whenever the second pulse signal output by the rubidium atomic clock arrives, the phase-locked loop compares the phase of the 10 MHz oven-controlled crystal oscillator clock with the rubidium atomic second pulse clock, setting the phase of the 10 MHz oven-controlled crystal oscillator clock to φ0(t)2 and the phase of the rubidium atomic second pulse clock to φ_GPS(t)2. The phase error Δφ(t)2 is expressed as:

[0048] Δφ(t)2=φ0(t)2-φ_GPS(t)2

[0049] (2) The system adjusts the phase φ0(t)2 of the 10MHz oven-controlled crystal oscillator clock according to the phase error Δφ(t)2 to synchronize it with the pulse-per-second signal output by the rubidium atomic clock. The phase adjustment formula is:

[0050] Φ0(t+1)2=φ0(t)2-α2*Δφ(t)2

[0051] Wherein, α2 is the phase adjustment coefficient of the 10 MHz oven-controlled crystal oscillator clock.

[0052] A GPS pulse-second-based oven-controlled crystal oscillator automatic taming and calibration system is implemented according to the GPS pulse-second-based oven-controlled crystal oscillator automatic taming and calibration method, comprising a GPS receiving module, a rubidium atomic clock frequency calibration counter, a rubidium atomic clock frequency taming and calibration module, a rubidium atomic clock frequency regulation loop, a rubidium atomic clock, a rubidium atomic clock phase-locked loop, a 10 MHz oven-controlled crystal oscillator frequency calibration counter, a 10 MHz oven-controlled crystal oscillator frequency fast-following calibration module, a 10 MHz oven-controlled crystal oscillator frequency regulation loop, a 10 MHz oven-controlled crystal oscillator, and a 10 MHz oven-controlled crystal oscillator phase-locked loop, wherein:

[0053] The GPS receiving module is used to receive the GPS pulse-per-second signal provided by the GPS satellite outside the system;

[0054] The rubidium atomic clock frequency calibration counter is used to accurately measure and compare the frequency signal output by the rubidium atomic clock to achieve calibration and stable control of the clock frequency;

[0055] The rubidium atomic clock frequency taming and calibration module is used to precisely control the frequency signal output by the rubidium atomic clock and optimize its long-term stability;

[0056] The rubidium atomic clock frequency regulation loop is used to precisely regulate the output signal of the rubidium atomic clock oscillator to ensure that its frequency is stable over a long period of time and close to the ideal reference value.

[0057] Rubidium atomic clocks are used to provide high-precision, high-stability time and frequency standards;

[0058] The rubidium atomic clock phase-locked loop is used to achieve frequency synchronization and phase tracking of GPS second pulse signals;

[0059] 10MHz Oven-Controlled Crystal Oscillator Frequency Calibration Counter is used to accurately measure the deviation between the 10MHz Oven-Controlled Crystal Oscillator output frequency and the standard reference source;

[0060] The 10MHz oven-controlled crystal oscillator frequency fast follow-up calibration module is used to quickly capture, detect and automatically calibrate the 10MHz oven-controlled crystal oscillator frequency;

[0061] The 10MHz constant temperature crystal oscillator frequency adjustment loop is used to achieve closed-loop control and fine-tuning of the crystal oscillator frequency output;

[0062] 10MHz oven-controlled crystal oscillator is used to provide a stable and accurate reference frequency signal;

[0063] The 10MHz oven-controlled crystal oscillator phase-locked loop is used to achieve frequency and phase synchronization control between the rubidium atomic clock and the 10MHz oven-controlled crystal oscillator.

[0064] The beneficial effects of the present invention are:

[0065] The present invention can accurately tame and calibrate the internal clock (rubidium atomic clock, 10MHz constant temperature crystal oscillator, etc.) through the second pulse signal of GPS, and output high-stability, high-precision second pulse signal and 10MHz frequency clock signal through precise frequency calibration and phase synchronization. The present invention has broad application prospects and has important application value in the fields of communication, navigation, measurement and other fields with high precision requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0066] Figure 1 Schematic diagram of the process of the automatic training and calibration method of the constant temperature crystal oscillator based on GPS second pulse of the present invention;

[0067] Figure 2 The figure is a schematic diagram of the structure of the automatic training and calibration system of the constant temperature crystal oscillator based on GPS second pulse of the present invention. DETAILED DESCRIPTION

[0068] In order to make the objectives, technical solutions and advantages of the present invention clearer and more understandable, the technical solutions of the present invention will be further described in detail below with reference to the accompanying drawings.

[0069] A method for automatic training and calibration of constant temperature crystal oscillators based on GPS second pulses, such as Figures 1 to 2 As shown, the specific steps include:

[0070] S1, the GPS receiving module receives signals from GPS satellites, decodes and obtains time information, and obtains data such as second pulse signals.

[0071] GPS uses the arrival time ranging principle to locate and time the receiving device. Specifically, the present invention uses the arrival time of four GPS satellites to determine the three-dimensional position and clock deviation of the receiving device. At time T, the distances between the four GPS satellites simultaneously received by the GPS receiving module are P1, P2, P3, and P4, respectively. The time differences between the satellite transmission time signal and the signal received by the GPS receiving module are △T1, △T2, △T3, and △T4, respectively. The three-dimensional coordinates of the four GPS satellites are (Xi, Yi, Zi), where i = 1, 2, 3, 4. The three-dimensional coordinates of point P are (X, Y, Z). The expression for the distance between point P and the four GPS satellites is:

[0072]

[0073] Wherein, Ti, i=1, 2, 3, 4 is the time of each GPS satellite transmitting time signal; T is the time of GPS receiving module receiving GPS satellite signal.

[0074] ΔTi=T-Ti Formula 5

[0075] The clock deviation of GPS receiving module is calculated by the distance PRi from P point to each GPS satellite, the time difference △Ti between satellite transmitting time signal and GPS receiving module receiving signal, and then the time difference of second pulse system is corrected according to the clock deviation, and the high-precision second pulse signal is output.

[0076] The standard GPS receiving module can receive signals of multiple frequency bands such as L1 frequency band. The GPS receiving module receives signals from GPS satellites, and extracts second pulse signal and time information, the rising edge of the second pulse signal represents a time of coordinated universal time UTC, and the GPS receiving module outputs time information and second pulse signal. Since the ground control system synchronizes the coordinated universal time UTC of each atomic clock observatory, the explicit relationship between GPS and coordinated universal time UTC is established, and the long-term stability of the second pulse signal output by all GPS receiving modules is very good. The second pulse signal is used as a time calibration signal, and an accurate time reference is provided once per second.

[0077] The GPS receiving module supports receiving signals emitted by multiple GPS satellites, and outputs three-dimensional positioning information, time information and satellite state after signal transformation, amplification and processing, and obtains time information, position information and speed information provided by GPS. The time information includes output year, month, day, hour, minute, second and second pulse signal with a frequency of 1Hz (the accuracy can reach 10-12~10-13 order of magnitude). The core of GPS time service principle is to calculate the time error in the satellite signal and correct it to the same order of magnitude as the GPS signal.

[0078] S2, the GPS second pulse signal sent by the GPS receiving module is received by the rubidium atomic clock, the rising edge is counted by the rubidium atomic clock frequency calibration counter, and the counting result is averaged by the sliding algorithm, and the related counting average result is output to the rubidium atomic clock frequency taming calibration module for taming and calibration, and the frequency calibration key parameter of the rubidium atomic clock is obtained, and the specific steps include:

[0079] S21, the rubidium atomic clock is used as an internal clock in the application, the time-frequency signal output by the rubidium atomic clock is synchronized with the coordinated universal time UTC output by the GPS second pulse, the deviation of the frequency output by the rubidium atomic clock is calculated by the GPS output second pulse, and the time interval value △T between the rising edge of the GPS output second pulse and the rising edge of the second pulse output by the rubidium atomic clock is measured by the rubidium atomic clock frequency calibration counter.

[0080] The rubidium atomic clock frequency calibration counter counts and measures the time interval △T between the second pulse signal output by the rubidium atomic frequency standard and the second pulse signal of the GPS. That is, the second pulse signal output by the GPS receiving module and the second pulse signal output by the rubidium atomic clock phase-locked are input into the rubidium atomic clock frequency calibration counter to calculate the time interval △T between the two. Although the external GPS second pulse signal received by the GPS receiving module has high stability and high accuracy, it has a certain amount of random jitter. In order to eliminate the influence of random jumps in the GPS second pulse signal, the statistical time interval value △T is smoothed and the arithmetic average of multiple measurement data is used to eliminate the influence of its random jumps. Specifically:

[0081] (1) Take the 2000-point sliding average of the time interval value △T and subtract the weakened time accumulation error.

[0082] Using a 2000-point sliding average, the number of sampling points is N, the sampling values ​​are △T1, △T2, ..., △T2000, and the number of sampling points 2000 is regarded as a sliding window. The sliding average of array N is:

[0083]

[0084] Among them, P N is the sliding average of the Nth sampling point; P N+1 is the sliding average of the N+1th sampling point; i is the i-th sampling point among 2000 points; △Ti is the sampling value corresponding to the i-th sampling point.

[0085] A rubidium atomic clock frequency calibration counter accumulates time differences and calculates the cumulative time error within a specific time range. This cumulative error is divided by 150, reducing the 1σ jitter of the GPS pulse-per-second reference signal, which is 50 ppb / s, to 0.33 ppb / s. The 1σ jitter amplitude is proportional to the bandwidth; a 150-fold reduction in bandwidth results in a proportional reduction. Time averaging of the output data using a filter effectively eliminates the inherent jitter transients of the GPS pulse-per-second reference signal.

[0086] (2) The measured value is subjected to a sliding average digital filter using the GPS pulse-per-second signal received by the GPS receiving module, and the corresponding smoothing time interval difference ΔT' is obtained by using the difference between two adjacent filtered values. Combined with the sampling time τ between two adjacent measured values, the frequency offset Δf is calculated using the frequency difference formula of the time ratio method:

[0087]

[0088] Where f0 is the 10 MHz reference frequency of the rubidium atomic clock.

[0089] S22, the rubidium atomic clock frequency taming and calibration module receives the GPS time calibration signal, adjusts the internal clock (rubidium atomic clock) according to the signal, and performs signal processing and frequency synchronization.

[0090] S23, within each GPS time calibration period (usually 1 second), the rubidium atomic clock frequency taming and calibration module calculates the frequency error △f by comparing the time difference between the GPS second pulse signal and the second pulse signal output by the rubidium atomic clock after a 2000-point sliding average. The rubidium atomic clock frequency taming and calibration module calibrates the frequency of the rubidium atomic clock based on the frequency error △f, which can effectively reduce clock drift and ensure that the frequency of the rubidium atomic clock is synchronized with the GPS clock. The calibration formula is:

[0091] f0(t+1)=f0(t)+k1*Δf(t) Formula 9

[0092] Among them, f0(t+1) is the reference frequency value of the rubidium atomic clock at time t+1; f0(t) is the reference frequency value of the rubidium atomic clock at time t; k1 is the key parameter for frequency calibration of the rubidium atomic clock, and the optimal value is obtained through debugging; Δf(t) is the frequency error of the rubidium atomic clock at time t.

[0093] A rubidium atomic clock is used as the internal clock source, providing a highly stable and accurate time reference. Based on the rubidium atomic clock as the reference source, a highly stable second pulse signal is output after phase locking.

[0094] S3, the rubidium atomic clock frequency adjustment circuit receives the key frequency calibration parameters of the rubidium atomic clock and performs voltage conversion. The voltage is directly input into the rubidium atomic clock for frequency control. The frequency is adjusted after the rubidium atomic clock is calibrated. After adjustment, the rubidium atomic clock outputs a signal to the phase-locked loop to complete phase lock. The GPS second pulse signal is then locked through frequency and phase synchronization. Finally, a highly stable and high-precision second pulse signal is output. The specific steps include:

[0095] S31, the rubidium atomic clock frequency adjustment circuit receives the key parameters of the frequency calibration of the rubidium atomic clock and then combines it with the voltage-controlled sensitivity coefficient of the rubidium atomic frequency standard to calculate the voltage corresponding to the voltage-controlled voltage that should be added to the rubidium atomic frequency standard and use it as the training parameter. The control voltage is then output through a high-resolution D / A converter and directly output to the voltage-controlled pin of the rubidium atomic clock to adjust the rubidium atomic clock and achieve the purpose of correcting the output frequency of the rubidium atomic frequency standard.

[0096] S32, after voltage control adjustment, the rubidium atomic clock outputs the signal to the phase-locked loop. In the phase-locked loop, the rubidium atomic clock needs to be synchronized with the frequency of the GPS second pulse signal, and also needs to be phase-synchronized with the GPS second pulse signal to ensure the accuracy of the second pulse signal output by the rubidium atomic clock.

[0097] The specific steps of phase synchronization include:

[0098] (1) Whenever the GPS second pulse signal arrives, the phase-locked loop compares the phase of the rubidium atomic second pulse clock with that of the GPS clock, setting the phase of the rubidium atomic second pulse clock to φ0(t)1 and the phase of the GPS clock to φ_GPS(t)1. The phase error Δφ(t)1 is expressed as:

[0099] Δφ(t)1=φ0(t)1-φ_GPS(t)1 Formula 10

[0100] (2) The system adjusts the phase of the rubidium atomic second pulse clock according to the phase error Δφ(t)1 to synchronize it with the GPS second pulse signal. The phase adjustment formula is:

[0101] Φ0(t+1)1=φ0(t)1-α1*Δφ(t)1 Formula 11

[0102] Here, α1 is the phase adjustment coefficient of the rubidium atomic second pulse clock, typically a constant less than 1. An appropriate value is obtained through debugging. The phase synchronization process ensures the accuracy of the second pulse signal output by the rubidium atomic clock and reduces the system's time error.

[0103] The rubidium atomic clock phase-locked loop consists of three parts: a phase detector, a filter, and a voltage-controlled oscillator. The phase detector calculates the phase difference between two second pulse signals (GPS satellite and rubidium atomic clock); the loop filter receives the time measurement value of the previous level, filters out the noise it contains, and outputs the result to the controller, which calculates the control quantity; the voltage-controlled oscillator outputs an analog voltage within the voltage-controlled range, and the voltage-controlled end is used to adjust the voltage control adjustment of the rubidium atomic clock frequency standard.

[0104] A phase-locked loop (PLL) is a closed-loop feedback system that transmits phase information. Rubidium atomic clocks use this loop to adjust frequency accuracy and stability. The phase difference between the input signal of the standard second pulse output by the rubidium atomic clock and the output signal of the voltage-controlled oscillator is compared. The resulting phase difference adjusts the output voltage of the phase detector, controlling the oscillation frequency of the voltage-controlled oscillator to ensure that the output frequency matches the frequency and phase of the input signal.

[0105] In step S4, the 10MHz oven-controlled crystal oscillator receives the pulse-per-second signal output by the rubidium atomic clock, connects to the 10MHz oven-controlled crystal oscillator frequency calibration counter to count rising edges and averages the counting results using a sliding algorithm. The 10MHz oven-controlled crystal oscillator frequency calibration counter outputs the relevant counting average results to the 10MHz oven-controlled crystal oscillator frequency fast follower calibration module for taming and calibration, and obtains the key frequency calibration parameters of the 10MHz oven-controlled crystal oscillator. The specific steps include:

[0106] S41 uses a 10MHz oven-controlled crystal oscillator as its internal clock, synchronizes the time-frequency signal output by the 10MHz oven-controlled crystal oscillator with the Coordinated Universal Time (UTC) of the second pulse output by the rubidium atomic clock, calculates the frequency deviation of the 10MHz oven-controlled crystal oscillator frequency standard output using the second pulse output by the rubidium atomic clock, and measures the time interval ΔTT between the rising edge of the second pulse output by the rubidium atomic clock and the second pulse output by the 10MHz oven-controlled crystal oscillator through the 10MHz oven-controlled crystal oscillator frequency calibration counter.

[0107] The 10MHz OOC frequency calibration counter counts and measures the time interval △TT between the pulse-per-second signal output by the 10MHz OOC and the rubidium atomic clock. That is, the pulse-per-second signal output by the rubidium atomic clock and the pulse-per-second signal output by the 10MHz OOC are input into the 10MHz OOC frequency calibration counter, and the time interval △TT between the two is calculated. To avoid the influence of random jitter of the pulse-per-second signal output by the rubidium atomic clock, the statistical time interval △TT is smoothed, and the arithmetic average of multiple measurement data is used to eliminate the influence of its random jumps. Specifically:

[0108] (1) Take the 2000-point sliding average of the time interval value △TT and subtract the weakened time accumulation error.

[0109] A 2000-point sliding average is used. The number of sampling points is N, which is 2000 in this paper. The sampling values ​​are △TT1, △TT2, ..., △TT2000. The number of sampling points 2000 is regarded as a sliding window. The sliding average of the array N is:

[0110]

[0111] A 10MHz oven-controlled crystal counter accumulates time differences and calculates the cumulative time error within a specific time range. This cumulative error is divided by 150, reducing the 1σ jitter of the 50ppb / s GPS pulse-per-second reference signal to 0.33ppb / s. The 1σ jitter amplitude is proportional to the bandwidth; a 150-fold reduction in bandwidth results in a proportional reduction. A filter then performs time averaging on the output data, effectively eliminating the inherent jitter transients of the GPS pulse-per-second reference signal.

[0112] (2) The measured value is digitally filtered by sliding average using the pulse-per-second signal output by the rubidium atomic clock, and the corresponding smoothed time interval difference △TT' is obtained by using the difference between two adjacent filtered values. Combined with the sampling time τ' between two adjacent measured values, the frequency offset Δf' is calculated using the frequency difference formula of the time ratio method:

[0113]

[0114] Where f0′ is the 10 MHz reference frequency of the 10 MHz oven-controlled crystal oscillator.

[0115] S42, 10MHz constant temperature crystal oscillator frequency fast follower calibration module receives the second pulse signal output by the rubidium atomic clock, adjusts the internal clock (10MHz constant temperature crystal oscillator) according to the signal, and performs signal processing and frequency synchronization.

[0116] S43, the 10MHz oven-controlled crystal oscillator frequency fast following calibration module calculates the frequency error Δf′ by comparing the time difference between the second pulse signal output by the rubidium atomic clock and the second pulse signal output by the 10MHz oven-controlled crystal oscillator after a 2000-point sliding average. The 10MHz oven-controlled crystal oscillator frequency fast following calibration module calibrates the frequency of the 10MHz oven-controlled crystal oscillator based on the frequency error Δf′, which can effectively reduce clock drift and ensure that the frequency of the 10MHz oven-controlled crystal oscillator is synchronized with the second pulse clock output by the rubidium atomic clock. The calibration formula is:

[0117] f0′(t+1)=f0′(t)+k2*Δf′(t) Formula 15

[0118] Among them, f0′(t+1) is the reference frequency value of the 10MHz oven-controlled crystal oscillator at time t+1; f0′(t) is the reference frequency value of the 10MHz oven-controlled crystal oscillator at time t; k2 is the key parameter for frequency calibration of the 10MHz oven-controlled crystal oscillator, and the optimal value is obtained through debugging; Δf′(t) is the frequency error of the 10MHz oven-controlled crystal oscillator at time t.

[0119] A 10MHz oven-controlled crystal oscillator (OCR) serves as an internal clock source, providing a standard-frequency clock signal with high short-term stability. Because the output frequency and phase of a 10MHz OCR drift over time, the present invention uses a stable pulse-second frequency standard generated by a trained rubidium atomic clock to calibrate the 10MHz OCR. Using phase-locked loop (PLL) technology, the OCR precisely synchronizes the pulse-second signal output by the rubidium atomic clock with the short-term stability of the OCR. After phase locking, the OCR outputs a highly stable pulse-second signal, ultimately achieving synchronization with the GPS pulse-second signal.

[0120] S5, the 10MHz constant temperature crystal oscillator frequency adjustment loop receives the key parameters of the frequency calibration of the 10MHz constant temperature crystal oscillator and performs voltage conversion. The voltage is directly input into the 10MHz constant temperature crystal oscillator for frequency control. The 10MHz constant temperature crystal oscillator is calibrated and the frequency is adjusted. After adjustment, the 10MHz constant temperature crystal oscillator outputs a signal to the phase-locked loop to complete phase locking. The second pulse signal output by the rubidium atomic clock is then locked through frequency and phase synchronization. Finally, a high-stability, high-precision second pulse signal and a 10MHz frequency clock signal are output. The specific steps include:

[0121] S51, the 10MHz oven-controlled crystal oscillator frequency adjustment loop receives the key frequency calibration parameters of the rubidium atomic clock and then combines them with the voltage-controlled sensitivity coefficient of the 10MHz oven-controlled crystal oscillator frequency standard to calculate the voltage corresponding to the voltage-controlled voltage that should be added to the 10MHz oven-controlled crystal oscillator frequency standard and use it as the training parameter. The control voltage is then output through a high-resolution D / A converter and directly output to the voltage-controlled pin of the 10MHz oven-controlled crystal oscillator to adjust the 10MHz oven-controlled crystal oscillator to achieve the purpose of correcting the output frequency of the 10MHz oven-controlled crystal oscillator frequency standard.

[0122] S52, after voltage control adjustment of the 10MHz constant temperature crystal oscillator, the signal is output to the phase-locked loop. In the phase-locked loop, the 10MHz constant temperature crystal oscillator needs to be synchronized with the frequency of the second pulse signal output by the rubidium atomic clock. At the same time, it also needs to be phase-synchronized with the second pulse signal output by the rubidium atomic clock to ensure the accuracy of the final output second pulse signal.

[0123] The specific steps of phase synchronization include:

[0124] (1) Whenever the second pulse signal output by the rubidium atomic clock arrives, the phase-locked loop compares the phase of the 10 MHz oven-controlled crystal oscillator clock with the rubidium atomic second pulse clock, setting the phase of the 10 MHz oven-controlled crystal oscillator clock to φ0(t)2 and the phase of the rubidium atomic second pulse clock to φ_GPS(t)2. The phase error Δφ(t)2 is expressed as:

[0125] Δφ(t)2=φ0(t)2-φ_GPS(t)2 Formula 12

[0126] (2) The system adjusts the phase φ0(t)2 of the 10MHz oven-controlled crystal oscillator clock according to the phase error Δφ(t)2 to synchronize it with the pulse-per-second signal output by the rubidium atomic clock. The phase adjustment formula is:

[0127] Φ0(t+1)2=φ0(t)2-α2*Δφ(t)2 Formula 13

[0128] Wherein, α2 is the phase adjustment coefficient of the 10 MHz oven-controlled crystal oscillator clock, which is usually a constant less than 1 and a suitable value is obtained through debugging.

[0129] The phase synchronization process ensures the accuracy of the pulse-per-second signal and reduces the timing error of the system.

[0130] The 10MHz oven-controlled crystal oscillator phase-locked loop consists of three parts: a phase detector, a filter, and a voltage-controlled oscillator. The phase detector calculates the phase difference between two second pulse signals (rubidium atomic clock and 10MHz oven-controlled crystal oscillator); the filter receives the time measurement value of the previous level, filters out the noise it contains, and outputs the result to the controller, which calculates the control quantity; the voltage-controlled oscillator outputs an analog voltage within the voltage-controlled range, and the voltage-controlled end is used to adjust the voltage control adjustment of the 10MHz oven-controlled crystal oscillator frequency standard.

[0131] A phase-locked loop (PLL) is a closed-loop feedback system that transfers phase. A 10MHz oven-controlled crystal oscillator (OCO) uses the PLL to adjust its frequency accuracy and stability. The phase difference between the input signal (the standard pulse per second output of the 10MHz OOCO) and the output signal of the voltage-controlled oscillator (VCO) is compared. The resulting phase difference adjusts the output voltage of the phase detector, controlling the oscillation frequency of the VCO to match the output frequency and phase of the input signal.

[0132] A GPS pulse-second-based oven-controlled crystal oscillator automatic taming and calibration system is implemented by the GPS pulse-second-based oven-controlled crystal oscillator automatic taming and calibration method, comprising a GPS receiving module, a rubidium atomic clock frequency calibration counter, a rubidium atomic clock frequency taming and calibration module, a rubidium atomic clock frequency regulation loop, a rubidium atomic clock, a rubidium atomic clock phase-locked loop, a 10 MHz oven-controlled crystal oscillator frequency calibration counter, a 10 MHz oven-controlled crystal oscillator frequency fast-following calibration module, a 10 MHz oven-controlled crystal oscillator frequency regulation loop, a 10 MHz oven-controlled crystal oscillator, and a 10 MHz oven-controlled crystal oscillator phase-locked loop, wherein:

[0133] The GPS receiving module is used to receive GPS pulse-per-second signals provided by GPS satellites outside the system.

[0134] The Rubidium Atomic Clock Frequency Calibration Counter is used to precisely measure and compare the frequency signal output by the Rubidium Atomic Clock, thereby achieving clock frequency calibration and stable control. Using high-precision counting technology, the Rubidium Atomic Clock Frequency Calibration Counter monitors the frequency changes of the Rubidium Atomic Clock in real time, compares the frequency with a standard reference frequency, and calculates the frequency deviation. Based on this deviation data, automatic or manual calibration adjustments can be made to ensure the high stability and accuracy of the Rubidium Atomic Clock during long-term operation.

[0135] The rubidium atomic clock frequency taming and calibration module is used to precisely control the frequency signal output by the rubidium atomic clock and optimize its long-term stability. The rubidium atomic clock frequency is tamed by introducing an external, highly stable GPS reference source. By comparing the frequency deviation between the rubidium atomic clock and the reference source, a control signal is generated to adjust the rubidium atomic clock output, ensuring that it maintains a consistent frequency standard with the reference source over the long term.

[0136] The frequency regulation loop of a rubidium atomic clock precisely controls the oscillator's output signal, ensuring long-term frequency stability and proximity to the ideal reference value. This loop monitors the error between the oscillation frequency and the atomic transition reference signal and uses a feedback control mechanism to adjust the operating parameters of the voltage-controlled crystal oscillator (VCXO) or voltage-controlled oscillator (VCO) to correct for frequency offset. The regulation loop is one of the core control units of a rubidium atomic clock, responsible for frequency lock, frequency stabilization, and fine-tuning compensation, ensuring the clock's output complies with international time and frequency standards.

[0137] Rubidium atomic clocks are used to provide a highly accurate and stable time and frequency reference. Using the energy level transition frequency of rubidium atoms as a reference, they employ phase-locking technology to output an extremely stable frequency signal. Compared to quartz oscillators, rubidium atomic clocks offer superior short-term stability and lower long-term drift. By providing a unified time and frequency reference, rubidium atomic clocks ensure precise synchronization between subsystems, thereby improving overall system performance and reliability.

[0138] A rubidium atomic clock phase-locked loop (PLL) is used to synchronize the frequency and phase of GPS pulse-per-second signals. By comparing the phase difference between the input signal and the local oscillator (LO), an error signal is generated. This error signal is then passed through a loop filter to adjust the control voltage, driving the voltage-controlled oscillator (VCO) so that its output frequency gradually locks to the frequency and phase of the input signal.

[0139] The 10MHz Oven-Controlled Crystal Oscillator Frequency Calibration Counter is used to accurately measure the deviation between the output frequency of a 10MHz Oven-Controlled Crystal Oscillator and a standard reference source, providing data support for subsequent frequency calibration. By performing real-time sampling and periodic analysis of the crystal's 10MHz output signal through a high-precision counter, the system can detect the effects of minute frequency drift and temperature fluctuations on crystal performance. Typically used in conjunction with a high-stability time reference, the system generates frequency error data by comparing it with the reference frequency for automatic or manual adjustment of the crystal.

[0140] The 10MHz Oven-Controlled Crystal Oscillator (OCO) Fast Frequency Follower Calibration Module rapidly captures, detects, and automatically calibrates the 10MHz OOC crystal frequency to address drift caused by sudden frequency changes or environmental variations. By quickly comparing the frequency of an external reference source with the crystal output, the module rapidly calculates the deviation. Internal control logic drives the regulation loop, meticulously adjusting the voltage-controlled crystal oscillator (VCXO) to quickly restore the output frequency to the desired value.

[0141] The 10MHz OCXO frequency regulation loop provides closed-loop control and fine-tuning of the 10MHz OCXO frequency output, ensuring high stability under a wide range of operating conditions. By monitoring the error signal between the 10MHz OCXO output and the reference frequency in real time, the VCXO control voltage is dynamically adjusted to correct the output frequency.

[0142] A 10MHz oven-controlled crystal oscillator (OCXO) provides a stable and accurate reference frequency signal. By maintaining a stable operating temperature within a constant temperature-controlled environment, an oven-controlled crystal oscillator (OCXO) significantly reduces frequency drift caused by ambient temperature changes, thereby improving the long-term stability and short-term frequency accuracy of the output signal.

[0143] A 10MHz oven-controlled crystal oscillator (OCC) phase-locked loop (PLL) synchronizes the frequency and phase of a rubidium atomic clock and a 10MHz oven-controlled crystal oscillator (OCC). By comparing the phase of the input signal with the local oscillator (LO), the PLL generates an error signal. This error signal is then fed back through a filtering and control loop to adjust the voltage-controlled oscillator (VCO), gradually locking the output to the input signal. This ensures the long-term stability of the output clock, consistent with global time standards.

[0144] The contents not described in detail in the specification of the present invention belong to the existing public technologies in this technical field.

[0145] Finally, it should be noted that the above description is a preferred embodiment of the present invention. It should be understood that the present invention is not limited to the form disclosed herein and should not be construed as excluding other embodiments. Instead, the present invention can be used in other combinations, modifications, and environments and can be modified within the scope of the concept described herein through the above teachings or techniques or knowledge in the relevant field. Modifications and variations made by those skilled in the art that do not depart from the spirit and scope of the present invention are intended to be protected by the appended claims.

Claims

1. A method for automatic training and calibration of an oven controlled crystal oscillator based on GPS second pulse, characterized in that: The following steps are involved: S1, GPS receiving module receives the signal from GPS satellite, decodes and obtains time information, and obtains second pulse signal; S2, the rubidium atomic clock receives the GPS second pulse signal sent by the GPS receiving module, connects to the rubidium atomic clock frequency calibration counter to count the rising edges and averages the counting results with a sliding algorithm. The rubidium atomic clock frequency calibration counter outputs the relevant counting average results to the rubidium atomic clock frequency training and calibration module for training and calibration, and obtains the key frequency calibration parameters of the rubidium atomic clock; S3, the rubidium atomic clock frequency adjustment loop receives the key frequency calibration parameters of the rubidium atomic clock and performs voltage conversion, directly inputs the voltage into the rubidium atomic clock for frequency control, performs frequency adjustment after the rubidium atomic clock is calibrated, and the adjusted rubidium atomic clock outputs a signal to the phase-locked loop to complete phase locking, and then locks the GPS second pulse signal through frequency and phase synchronization, finally outputting a highly stable and high-precision second pulse signal; S4, the 10MHz oven-controlled crystal oscillator receives the second pulse signal output by the rubidium atomic clock, connects to the 10MHz oven-controlled crystal oscillator frequency calibration counter to count the rising edges and average the counting results with a sliding algorithm. The 10MHz oven-controlled crystal oscillator frequency calibration counter outputs the relevant counting average result to the 10MHz oven-controlled crystal oscillator frequency fast follower calibration module for taming and calibration, and obtains the key frequency calibration parameters of the 10MHz oven-controlled crystal oscillator; S5, 10MHz constant temperature crystal oscillator frequency adjustment loop receives the key parameters of the frequency calibration of the 10MHz constant temperature crystal oscillator for voltage conversion, directly inputs the voltage into the 10MHz constant temperature crystal oscillator for frequency control, and adjusts the frequency after the 10MHz constant temperature crystal oscillator is calibrated. After adjustment, the 10MHz constant temperature crystal oscillator outputs a signal to the phase-locked loop to complete phase locking, and then synchronizes the frequency and phase to lock the second pulse signal output by the rubidium atomic clock, and finally outputs a highly stable, high-precision second pulse signal and a 10MHz frequency clock signal.

2. The method for automatic training and calibration of an oven controlled crystal oscillator based on GPS pulse-seconds according to claim 1, characterized in that: In S1, the arrival times of the four GPS satellites are used to determine the three-dimensional position and clock deviation of the receiving device. The distances between the four GPS satellites simultaneously received by the GPS receiving module at time T are P1, P2, P3, and P4, respectively. The time differences between the satellite transmission time signals and the signals received by the GPS receiving module are ΔT1, ΔT2, ΔT3, and ΔT4, respectively. The three-dimensional coordinates of the four GPS satellites are (Xi, Yi, Zi), where i = 1, 2, 3, 4. The three-dimensional coordinates of point P are (X, Y, Z). The expression for the distance between point P and the four GPS satellites is: Where Ti is the time when each GPS satellite transmits the time signal, i = 1, 2, 3, 4; T is the time when the GPS receiving module receives the GPS satellite signal; ΔTi=T-Ti The clock deviation of the GPS receiving module is calculated by the distance PRi from point P to each GPS satellite and the time difference △Ti between the satellite transmission time signal and the signal received by the GPS receiving module. Then, the second pulse system time difference is corrected according to the clock deviation and the second pulse signal is output.

3. The method for automatic training and calibration of an oven controlled crystal oscillator based on GPS pulse-seconds according to claim 1, wherein: The specific steps of S2 include: S21, using a rubidium atomic clock as an internal clock, synchronizes the time-frequency signal output by the rubidium atomic clock with the coordinated universal time (UTC) of the GPS second pulse output, calculates the deviation of the frequency output of the rubidium atomic clock frequency standard using the GPS second pulse output, and measures the time interval ΔT between the rising edge of the GPS second pulse output and the second pulse output by the rubidium atomic clock using the rubidium atomic clock frequency calibration counter; S22, the rubidium atomic clock frequency taming and calibration module receives the GPS time calibration signal, adjusts the rubidium atomic clock according to the signal, and performs signal processing and frequency synchronization; S23, in each GPS time calibration cycle, the rubidium atomic clock frequency taming and calibration module calculates the frequency error △f by comparing the time difference between the GPS second pulse signal and the second pulse signal output by the rubidium atomic clock after a 2000-point sliding average. The rubidium atomic clock frequency taming and calibration module calibrates the frequency of the rubidium atomic clock based on the frequency error △f. The calibration formula is: f0(t+1)=f0(t)+k1*Δf(t) Among them, f0(t+1) is the reference frequency value of the rubidium atomic clock at time t+1; f0(t) is the reference frequency value of the rubidium atomic clock at time t; k1 is the key parameter for frequency calibration of the rubidium atomic clock; Δf(t) is the frequency error of the rubidium atomic clock at time t.

4. The method for automatic training and calibration of an oven controlled crystal oscillator based on GPS pulse-seconds according to claim 1, wherein: In S2, the sliding algorithm averaging specifically includes: (1) Take the 2000-point sliding average of the time interval value △T and subtract the weakening time cumulative error; (2) The GPS pulse signal received by the GPS receiving module is used to perform sliding average digital filtering on the measured value, and the difference between two adjacent filtered values ​​is used to obtain the corresponding smoothing time interval difference ΔT ′ , combined with the sampling time τ between two adjacent measurement values, the frequency offset Δf is calculated using the frequency difference measurement formula using the time ratio method: Where f0 is the 10 MHz reference frequency of the rubidium atomic clock.

5. The method for automatic training and calibration of an oven controlled crystal oscillator based on GPS pulse-seconds according to claim 1, wherein: The specific steps of S3 include: S31, the rubidium atomic clock frequency adjustment circuit receives the key frequency calibration parameters of the rubidium atomic clock and then combines them with the voltage-controlled sensitivity coefficient of the rubidium atomic frequency standard to calculate the voltage corresponding to the voltage-controlled voltage applied to the rubidium atomic frequency standard and use it as the training parameter. The control voltage is then output through a D / A converter and directly output to the voltage-controlled pin of the rubidium atomic clock to adjust the rubidium atomic clock; S32, after voltage control adjustment, the rubidium atomic clock outputs the signal to the phase-locked loop. In the phase-locked loop, the rubidium atomic clock is synchronized with the frequency of the GPS second pulse signal and the phase of the GPS second pulse signal.

6. The method for automatic training and calibration of an oven controlled crystal oscillator based on GPS pulse-seconds according to claim 5, characterized in that: In S32, the specific steps of phase synchronization include: (1) Whenever the GPS second pulse signal arrives, the phase-locked loop compares the phase of the rubidium atomic second pulse clock with that of the GPS clock, setting the phase of the rubidium atomic second pulse clock to φ0(t)1 and the phase of the GPS clock to φ_GPS(t)1. The phase error Δφ(t)1 is expressed as: Δφ(t)1=φ0(t)1-φ_GPS(t)1 (2) The system adjusts the phase of the rubidium atomic second pulse clock according to the phase error Δφ(t)1 to synchronize it with the GPS second pulse signal. The phase adjustment formula is: Φ0(t+1)1=φ0(t)1-α1*Δφ(t)1 Wherein, α1 is the phase adjustment coefficient of the rubidium atomic second pulse clock.

7. The method for automatic training and calibration of an oven controlled crystal oscillator based on GPS pulse-seconds according to claim 1, characterized in that: The specific steps of S4 include: S41 uses a 10 MHz oven-controlled crystal oscillator as an internal clock, synchronizes the time-frequency signal output by the 10 MHz oven-controlled crystal oscillator with the Coordinated Universal Time (UTC) of the second pulse output by the rubidium atomic clock, calculates the deviation of the frequency output of the 10 MHz oven-controlled crystal oscillator frequency standard using the second pulse output by the rubidium atomic clock, and measures the time interval ΔTT between the rising edges of the second pulse output by the rubidium atomic clock and the second pulse output by the 10 MHz oven-controlled crystal oscillator using the 10 MHz oven-controlled crystal oscillator frequency calibration counter; S42, 10MHz oven-controlled crystal oscillator frequency fast follower calibration module receives the second pulse signal output by the rubidium atomic clock, adjusts the 10MHz oven-controlled crystal oscillator according to the signal, and performs signal processing and frequency synchronization; S43, 10MHz constant temperature crystal oscillator frequency fast follow calibration module calculates the frequency error Δf by comparing the time difference between the second pulse signal output by the rubidium atomic clock and the second pulse signal output by the 10MHz constant temperature crystal oscillator after 2000 points of sliding average ′ , the 10MHz constant temperature crystal oscillator frequency fast follower calibration module calibrates the frequency of the 10MHZ constant temperature crystal oscillator according to the frequency error Δf′. The calibration formula is: f0′(t+1)=f0′(t)+k2*Δf′(t) Among them, f0′(t+1) is the reference frequency value of the 10MHz oven-controlled crystal oscillator at time t+1; f0′(t) is the reference frequency value of the 10MHz oven-controlled crystal oscillator at time t; k2 is the key parameter for frequency calibration of the 10MHz oven-controlled crystal oscillator; Δf′(t) is the frequency error of the 10MHz oven-controlled crystal oscillator at time t.

8. The method for automatic training and calibration of an oven controlled crystal oscillator based on GPS pulse-seconds according to claim 1, wherein: The specific steps of S5 include: S51, the 10MHz oven-controlled crystal oscillator frequency adjustment loop receives the key frequency calibration parameters of the rubidium atomic clock and combines them with the voltage-controlled sensitivity coefficient of the 10MHz oven-controlled crystal oscillator frequency standard to calculate the voltage corresponding to the voltage-controlled voltage applied to the 10MHz oven-controlled crystal oscillator frequency standard and use it as the training parameter. The control voltage is then output through a high-resolution D / A converter and directly output to the voltage-controlled pin of the 10MHz oven-controlled crystal oscillator to adjust the 10MHz oven-controlled crystal oscillator. S52, after voltage control adjustment of the 10MHz constant temperature crystal oscillator, outputs the signal to the phase-locked loop. In the phase-locked loop, the 10MHz constant temperature crystal oscillator is synchronized with the frequency of the second pulse signal output by the rubidium atomic clock, and at the same time, the phase is synchronized with the second pulse signal output by the rubidium atomic clock.

9. The method for automatic training and calibration of an oven controlled crystal oscillator based on GPS pulse-seconds according to claim 8, characterized in that: In S52, the specific steps of phase synchronization include: (1) Whenever the second pulse signal output by the rubidium atomic clock arrives, the phase-locked loop compares the phase of the 10 MHz oven-controlled crystal oscillator clock with the rubidium atomic second pulse clock, setting the phase of the 10 MHz oven-controlled crystal oscillator clock to φ0(t)2 and the phase of the rubidium atomic second pulse clock to φ_GPS(t)2. The phase error Δφ(t)2 is expressed as: Δφ(t)2=φ0(t)2-φ_GPS(t)2 (2) The system adjusts the phase φ0(t)2 of the 10MHz oven-controlled crystal oscillator clock according to the phase error Δφ(t)2 to synchronize it with the pulse-per-second signal output by the rubidium atomic clock. The phase adjustment formula is: Φ0(t+1)2=φ0(t)2-α2*Δφ(t)2 Wherein, α2 is the phase adjustment coefficient of the 10 MHz oven-controlled crystal oscillator clock.

10. A system for automatically taming and calibrating an oven-controlled crystal oscillator based on GPS pulse-seconds, implemented according to the method for automatically taming and calibrating an oven-controlled crystal oscillator based on GPS pulse-seconds according to any one of claims 1 to 9, characterized in that: It includes a GPS receiving module, a rubidium atomic clock frequency calibration counter, a rubidium atomic clock frequency taming calibration module, a rubidium atomic clock frequency adjustment loop, a rubidium atomic clock, a rubidium atomic clock phase-locked loop, a 10MHz constant-temperature crystal oscillator frequency calibration counter, a 10MHz constant-temperature crystal oscillator frequency fast following calibration module, a 10MHz constant-temperature crystal oscillator frequency adjustment loop, a 10MHz constant-temperature crystal oscillator, and a 10MHz constant-temperature crystal oscillator phase-locked loop, wherein: The GPS receiving module is used to receive the GPS pulse-per-second signal provided by the GPS satellite outside the system; The rubidium atomic clock frequency calibration counter is used to accurately measure and compare the frequency signal output by the rubidium atomic clock to achieve calibration and stable control of the clock frequency; The rubidium atomic clock frequency taming and calibration module is used to precisely control the frequency signal output by the rubidium atomic clock and optimize its long-term stability; The rubidium atomic clock frequency regulation loop is used to precisely regulate the output signal of the rubidium atomic clock oscillator to ensure that its frequency is stable over a long period of time and close to the ideal reference value. Rubidium atomic clocks are used to provide high-precision, high-stability time and frequency standards; The rubidium atomic clock phase-locked loop is used to achieve frequency synchronization and phase tracking of GPS second pulse signals; 10MHz Oven-Controlled Crystal Oscillator Frequency Calibration Counter is used to accurately measure the deviation between the 10MHz Oven-Controlled Crystal Oscillator output frequency and the standard reference source; The 10MHz oven-controlled crystal oscillator frequency fast follow-up calibration module is used to quickly capture, detect and automatically calibrate the 10MHz oven-controlled crystal oscillator frequency; The 10MHz constant temperature crystal oscillator frequency adjustment loop is used to achieve closed-loop control and fine-tuning of the crystal oscillator frequency output; 10MHz oven-controlled crystal oscillator is used to provide a stable and accurate reference frequency signal; The 10MHz oven-controlled crystal oscillator phase-locked loop is used to achieve frequency and phase synchronization control between the rubidium atomic clock and the 10MHz oven-controlled crystal oscillator.

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