High-stability crystal oscillator taming device, system and method

Abstract

The embodiment of the invention provides a high-stability crystal oscillator taming device, system and method, and solves the problems that in the prior art, the precision is insufficient, the stability is insufficient, and the time cannot be kept at high precision by depending on a GPS (Global Positioning System) or under a specific condition. The high-stability crystal oscillator taming equipment comprises a judgment module which is used for receiving the time signal of the satellite and carrying out validity judgment; and the phase detection module is used for receiving a second signal sent by the high-stability crystal oscillator to be detected and performing phase difference detection on the second signal and a time signal of a satellite to obtain a comparison signal. And the aging module and the temperature module respectively carry out aging compensation and temperature compensation on the comparison signal and then send the comparison signal to the adjusting module. And the adjusting module is used for converting the comparison signal into an adjusting signal and sending the adjusting signal to the to-be-tested high-stability crystal oscillator, and is used for adjusting the output frequency of the high-stability crystal oscillator. The frequency accuracy and the long-term frequency stability of the high-stability crystal oscillator are effectively improved by combining Kalman filtering, aging compensation, temperature compensation, PID (Proportion Integration Differentiation) adjustment and other technologies.

Description

Technical Field

[0001] The present application relates to the field of time and frequency technology, and in particular to a high-stability crystal oscillator taming device, system and method. Background Art

[0002] In the fields of timing, positioning navigation, clock synchronization, and measurement, there are extremely high requirements for the accuracy and stability of time and frequency. As a device that provides high-precision frequency, high-stability crystal oscillators play an important role in these applications. However, the frequency of high-stability crystal oscillators will be affected by environmental factors (such as temperature) and its own aging, resulting in poor frequency accuracy and long-term frequency stability. In order to improve the performance of high-stability crystal oscillators, it is necessary to tame and correct the high-stability crystal oscillator when external signals such as navigation systems are valid. When the external signal is invalid, the temperature and aging data are used for continuous correction to ensure that the crystal oscillator always has good frequency accuracy and long-term stability.

[0003] The high-precision timekeeping system based on constant temperature crystal oscillator in the prior art does not consider the temperature compensation of the constant temperature crystal oscillator when facing complex environmental changes, resulting in a certain impact on the temperature stability of the crystal oscillator. The equipment for satellite clock taming in the prior art proposes to tame the crystal oscillator with the satellite's 1PPS, but does not consider aging compensation and temperature compensation in the non-taming stage, which has the problem of low efficiency and affects the time keeping effect in special circumstances (such as when 1PPS is invalid).

[0004] This technology aims to solve the deficiencies of the above existing technologies. The existing training technology has the problems of insufficient accuracy, insufficient stability, dependence on GPS or inability to maintain time with high accuracy under certain conditions (such as when 1PPS is invalid). Summary of the invention

[0005] The embodiments of the present application provide a high-stability crystal oscillator taming device, system and method, which solve the problems of existing taming technologies such as insufficient accuracy, insufficient stability, dependence on GPS or inability to maintain time with high precision under specific conditions.

[0006] In a first aspect, an embodiment of the present application provides a high-stability crystal oscillator taming device, comprising a judgment module, a phase detection module, an aging module, a temperature module and an adjustment module. The judgment module is used to receive the time signal of the satellite and make a validity judgment; the phase detection module is used to receive the second signal sent by the high-stability crystal oscillator to be tested and perform phase difference detection with the satellite time signal to obtain a comparison signal. The aging module and the temperature module respectively perform aging compensation and temperature compensation on the comparison signal and then send the comparison signal to the adjustment module. The adjustment module is used to convert the comparison signal into an adjustment signal and send it to the high-stability crystal oscillator to be tested, so as to adjust the output frequency of the high-stability crystal oscillator.

[0007] Preferably, a Kalman filter module is further included to filter the measurement noise of the comparison signal.

[0008] In one embodiment, a temperature sensor is also included, which is used to detect the internal and external temperatures of the high-stability crystal oscillator and transmit the temperature data to the temperature module.

[0009] In one embodiment, the regulation module comprises: a PID control unit and a DAC data conversion unit. The PID control unit is used to receive the compensated comparison signal and convert it into a voltage-controlled voltage value. The DAC data conversion unit is used to convert the voltage-controlled voltage value into a regulation signal.

[0010] In a second aspect, the embodiment of the present application further provides a high-stable crystal oscillator taming system, comprising the high-stable crystal oscillator taming device described in any one of the embodiments of the first aspect, and further comprising: a satellite module, a display module and a storage module. The satellite module is used to receive the time signal sent by the satellite and transmit it to the detection module. The display module is used to display the working status of the high-stable crystal oscillator taming device. The storage module is used to store temperature compensation data, high-stable crystal oscillator aging data, program code or configuration information.

[0011] Furthermore, the storage module includes a synchronous dynamic random access memory and a serial memory. The synchronous dynamic random access memory is used to store data for temperature compensation and aging compensation. The serial memory is used to store program code or configuration information.

[0012] In a third aspect, the embodiments of the present application further provide a high-stability crystal oscillator taming method, using the device or system described in any one of the embodiments of the first aspect or the second aspect, comprising the steps of: The phase detection module receives the satellite time signal and determines the validity of the satellite time signal; In response to the satellite time signal being valid, the second signal sent by the high-stability crystal oscillator to be tested is obtained and the time signal is subjected to phase difference detection to obtain a comparison signal; The comparison signal is subjected to aging compensation and temperature compensation, and then a voltage control voltage value is obtained through PID adjustment; The voltage-controlled voltage value is converted into an analog signal; The analog signal controls the output frequency of the high-stability crystal oscillator, so that the output frequency domain is synchronized with the satellite time signal.

[0013] In one of the embodiments, the method further comprises the steps of: setting a preset time length, and adjusting the output frequency of the high-stability crystal oscillator once every preset time length.

[0014] In one embodiment, the aging compensation specifically comprises the steps of: Modeling of aging processes; modeling parameters include nominal frequency, frequency accuracy, load capacitance, aging rate, drive level, equivalent series resistance, or package stress; Power on the high-stability crystal oscillator to be tested and sample data through the filter; Select the model of corresponding time according to the power-on time, and supplement the aging of the data curve of the high-stability crystal oscillator to be tested.

[0015] In one embodiment, the temperature compensation specifically comprises the steps of: Acquire a temperature compensation database; the temperature compensation database contains voltage data corresponding to the temperature near the high-stability crystal oscillator and the temperature compensation; Measure the temperature near the high-stability crystal oscillator and select the voltage data corresponding to the temperature compensation; The voltage data is added to the voltage end of the high-stability crystal oscillator to control the oscillation frequency of the high-stability crystal oscillator.

[0016] At least one of the above technical solutions adopted in the embodiments of the present application can achieve the following beneficial effects: This application effectively improves the frequency stability and accuracy of high-stability crystal oscillators by combining technologies such as Kalman filtering, aging compensation, temperature compensation, and PID regulation. At the same time, when 1PPS is invalid, reliable time maintenance can be achieved by using temperature compensation data and aging compensation data that are efficiently stored and quickly retrieved, ensuring that the system can still maintain good time accuracy under special circumstances. This system adds UPS and battery packs. When the power supply is abnormal, the UPS power supply and battery pack can be seamlessly switched immediately to provide continuous and stable power support for key equipment and systems, ensuring that the technology or products involved in the patent are not affected by power outages, and that long-term measurement data remain valid, thereby maintaining normal operation and reducing the risks of data loss, equipment damage, and business interruption caused by power outages.

[0017] This application effectively improves the frequency accuracy and long-term frequency stability of high-stability crystal oscillators by combining technologies such as Kalman filtering, aging compensation, temperature compensation, and PID regulation. At the same time, when 1PPS is invalid, the stored temperature compensation data and the evaluated aging data can be used to achieve time retention, ensuring that the system can still maintain a certain time accuracy under special circumstances. Through the host computer display module, it is convenient for users to monitor and manage the working status of the equipment in real time, which has good practicality and application prospects. BRIEF DESCRIPTION OF THE DRAWINGS The drawings described herein are used to provide a further understanding of the present application and constitute a part of the present application. The illustrative embodiments of the present application and their descriptions are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings: Figure 1 A structural diagram of a high-stability crystal oscillator taming device is provided for the embodiment of the present application; Figure 2 Provides a comparison diagram of output waveforms before and after Kalman filtering for the embodiment of the present application; Figure 3 A structural diagram of a high-stability crystal oscillator taming system is provided for the embodiment of the present application; Figure 4 A flow chart of a high-stability crystal oscillator taming method is provided for the embodiment of the present application; Figure 5 The comparison curve of the output frequency before and after compensation in the embodiment of the present application; Figure 6 This is a structural block diagram of the temperature compensation solution of the embodiment of the present application; Figure 7 This is a comparison chart of the measured data and the fitted data of the temperature curve of the embodiment of the present application. DETAILED DESCRIPTION

[0018] In order to make the purpose, technical solution and advantages of the present application clearer, the technical solution of the present application will be clearly and completely described below in combination with the specific embodiments of the present application and the corresponding drawings. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present application.

[0019] The technical solutions provided by various embodiments of the present application are described in detail below in conjunction with the accompanying drawings.

[0020] Figure 1 A structure diagram of a high-stability crystal oscillator taming device is provided for an embodiment of the present application, including a judgment module 100 , a phase detection module 110 , an aging module 120 , a temperature module 130 and an adjustment module 140 .

[0021] The judgment module is used to receive the satellite time signal and make a validity judgment; For example, the judgment module receives a 1PPS (pulse per second) time signal from a satellite and judges the validity of the time signal. In response to the 1PPS being valid, the phase detection module processes and calculates the time signal.

[0022] For example, a single Beidou receiver receives the time signal from a Beidou satellite through a Beidou antenna and converts it into a 1PPS (pulse per second) signal and inputs it into the FPGA. The FPGA quickly compares it with the internal 1PPS signal to determine its validity.

[0023] If the difference between the two is within the effective range of the set threshold, 1PPS is valid. If the difference exceeds the set threshold, 1PPS is invalid.

[0024] The phase detection module is used to receive the second signal sent by the high-stability crystal oscillator to be tested and the time signal of the satellite to perform phase difference detection to obtain a comparison signal.

[0025] The processing and calculation are specifically that the phase detection module receives the second signal sent by the high-stability crystal oscillator and performs phase difference detection on the satellite time signal to obtain a comparison signal.

[0026] The aging module and the temperature module respectively perform aging compensation and temperature compensation on the comparison signal and then send the comparison signal to the adjustment module.

[0027] The frequency of the high-stability crystal oscillator is compensated through aging compensation and temperature compensation respectively.

[0028] Preferably, a Kalman filter module 150 is further included to filter the measurement noise of the comparison signal.

[0029] The phase difference between the second signal and the second signal generated by the frequency division of the high-stability crystal oscillator is detected, and the measurement noise is filtered through the Kalman filter module before aging compensation and temperature compensation.

[0030] The phase detection signal contains many error signals, most of which are random errors. If these errors are ignored, the stability of the crystal oscillator output frequency will be greatly affected.

[0031] In order to reduce the adverse effects of errors on the system, the measurement results of the phase difference must be processed.

[0032] Kalman filtering is very suitable for solving the filtering and estimation problems of optimal phenomena. It uses state equations and recursive methods to process, takes the minimum mean square error as the criterion, and estimates through the previous estimate and the most recent observation data. It is suitable for real-time processing.

[0033] Based on this, the system uses the Kalman filter algorithm to filter the measurement results to eliminate interference.

[0034] Equation of state: Formula 1 Observation equation: Formula 2 Covariance calculation: Formula 3 Optimization Estimate: Formula 4 Kalman gain calculation: Formula 5 Covariance update calculation: Formula 6 Estimated error covariance initial value: Formula 7 in, and They are Moment and System status at the moment; is a system parameter, yes The measured value at the moment, is a parameter of the measurement system. Random signal and represent process noise and observation noise respectively. is the estimated error covariance, is the covariance matrix of process noise, is the observation noise covariance matrix, is the Kalman gain. The average value of the first 200 observations is used as the initial state estimation vector , and based on the initial value of the estimated error covariance: Formula 8 Compute the initial value of the estimated error covariance.

[0035] The output waveform after Kalman filtering is compared with the waveform of the output signature, as shown in Figure 2 shown.

[0036] The adjustment module is used to convert the comparison signal into an adjustment signal and send it to the high-stability crystal oscillator to be tested, so as to adjust the output frequency of the high-stability crystal oscillator.

[0037] In one embodiment, the regulation module comprises: a PID control unit and a DAC data conversion unit. The PID control unit is used to receive the compensated comparison signal and convert it into a voltage-controlled voltage value. The DAC data conversion unit is used to convert the voltage-controlled voltage value into a regulation signal.

[0038] The compensated signal is adjusted by PID to obtain a voltage-controlled voltage value, which is converted into an analog signal by the DAC digital-to-analog conversion module. It is used to control the output frequency of the high-stability crystal oscillator to keep it synchronized with the time signal of the Beidou satellite, thereby achieving the complementary advantages of the good long-term stability of the satellite timing and the high short-term stability of the local crystal oscillator.

[0039] In one embodiment, a temperature sensor 160 is also included (at Figure 3 The temperature sensor is used to detect the internal and external temperatures of the high-stability crystal oscillator and transmit the temperature data to the temperature module.

[0040] The temperature sensor is used to monitor the internal and external temperatures of the high-stability crystal oscillator in real time and transmit the temperature data to the temperature module.

[0041] Figure 3 A structural diagram of a high-stability crystal oscillator taming system is also provided for an embodiment of the present application, including the high-stability crystal oscillator taming device described in any one of the embodiments of the first aspect, and also including: a satellite module 210, a display module 220 and a storage module 230.

[0042] The satellite module is used to receive the time signal sent by the satellite and transmit it to the detection module.

[0043] For example, the satellite module uses a single Beidou receiver to receive the time signal of the Beidou satellite through the Beidou line 210 - 1 , and converts it into a 1PPS (pulse per second) signal and inputs it into the FPGA 200 .

[0044] For example, the FPGA is a field programmable gate array, and the FPGA completes the functions of phase detection and frequency divider.

[0045] STM32 is a processing chip. STM32 completes the functions of Kalman filtering, aging compensation, temperature compensation and PID control.

[0046] The FPGA and the STM32 serve as the core control system, receiving the 1PPS signal from the single Beidou receiver, the temperature data of the temperature sensor, and the output frequency signal of the high-stable crystal oscillator. The system receives satellite signals through the Beidou antenna, and the single Beidou receiver is used to receive the time signal of the Beidou satellite and convert it into a 1PPS (pulse per second) signal and input it into the FPGA. The FPGA makes a validity judgment on the 1PPS. When the 1PPS is valid, the measurement noise is filtered through the Kalman filter module, the signal is adjusted through the PID regulation, and then converted into an analog signal through the DAC digital-to-analog conversion module, which is used to control the output frequency of the high-stable crystal oscillator to keep it synchronized with the time signal of the Beidou satellite. While taming, the temperature and the voltage control voltage adjustment are measured respectively, and the aging slope is estimated. After the 1PPS signal disappears, the measurement data is used for temperature and aging compensation.

[0047] The display module 220 is used to display the working status of the high-stability crystal oscillator taming device.

[0048] The display module may be a display screen, which is connected to the FPGA via the serial port module 240 and the host computer 250, and is used to display information such as the working status, compensation parameters, and time synchronization accuracy of the high-stability crystal oscillator, so as to facilitate user monitoring and management. The storage module is used to store temperature compensation data, high-stability crystal oscillator aging data, program code or configuration information.

[0049] Furthermore, the storage module includes a synchronous dynamic random access memory 230 - 1 and a serial memory 230 - 2 .

[0050] The synchronous dynamic random access memory has a large memory capacity and is used to store a large amount of temperature compensation and aging compensation data. When 1PPS is invalid, FPGA retrieves the temperature compensation data in the synchronous dynamic random access memory SDRAM to achieve the time keeping function. The serial memory has limited storage capacity and is mainly used for storing program codes or configuration information so that the system can quickly enter a locked state.

[0051] Furthermore, it also includes a power supply system 260 for supplying power to the high-stability crystal oscillator taming device described in the present application, and connecting a UPS power supply 270 and a battery pack 280 .

[0052] The UPS power supply provides power to the power supply system, for example, through a 220V mains supply.

[0053] The battery pack is used to prevent power outages.

[0054] Figure 4 This is a flow chart of a high-stability crystal oscillator taming method according to an embodiment of the present application, using the device or system described in any one of the first aspect or the second aspect, comprising the steps of: Step 310: The phase detection module receives the satellite time signal and determines the validity of the satellite time signal; Step 320: In response to the satellite time signal being valid, the second signal sent by the high-stability crystal oscillator to be tested is obtained, and a phase difference detection is performed between the second signal and the time signal to obtain a comparison signal; Step 330: The comparison signal is subjected to aging compensation and temperature compensation, and then a voltage control voltage value is obtained through PID regulation; In one embodiment, the aging compensation specifically comprises the steps of: modeling the aging process; the modeling parameters include parameters such as nominal frequency, frequency accuracy, load capacitance, aging rate, drive level, equivalent series resistance or package stress; Power on the high-stability crystal oscillator to be tested and sample data through the filter; Select the model of corresponding time according to the power-on time, and supplement the aging of the data curve of the high-stability crystal oscillator to be tested.

[0055] Due to many factors such as the structural process of crystal manufacturing, crystal electrode oxidation, temperature gradient effect and pressure release effect, the crystal resonant frequency changes slowly and monotonously with working time. This phenomenon is called the aging effect of the crystal oscillator.

[0056] This frequency change of the crystal oscillator gradually stabilizes after it is powered on and runs for a period of time. Since the short-term unstable factors in the measured data will affect the output frequency of the crystal oscillator and generate noise, thus affecting the aging trend of the crystal oscillator, the data obtained in the experiment are pre-processed and then modeled.

[0057] For example, this application uses a Savitzky-Golay filter to implement filtering of sampled data, and the smooth function in MATLAB can be used to set the window function size of the filter to implement data filtering. The early aging speeds of different crystal oscillators vary greatly, but the differences in the later aging are not obvious. After the crystal oscillator is powered on for 10 hours, it gradually enters the approximate linear region. If the early aging is obvious, the segmented method can be used to model the aging process. During subsequent program processing, the model can be selected according to the power-on time to achieve aging supplementation for each segment. The least squares method can be used to achieve fitting modeling of the aging curve. The least squares method achieves the optimal coefficient matching of the function by minimizing the sum of squares of the errors, that is, the sum of squares of the measured value and the theoretical value is minimized. Figure 5 This is a comparison curve of the high-stable crystal oscillator output frequency before and after compensation.

[0058] In one embodiment, the temperature compensation specifically comprises the steps of: Acquire a temperature compensation database; the temperature compensation database contains voltage data corresponding to the temperature near the high-stability crystal oscillator and the temperature compensation; Measure the temperature near the high-stability crystal oscillator and select the voltage data corresponding to the temperature compensation; The voltage data is added to the voltage control terminal of the high-stability crystal oscillator to control the oscillation frequency of the high-stability crystal oscillator.

[0059] The temperature compensation solution consists of a temperature sensor, STM32 processor 410 (A / D410-1, EEPROM410-2), DAC digital-to-analog conversion module, reference power supply and high-stability crystal oscillator. The structural block diagram is as follows Figure 6 As shown. The temperature sensor measures the temperature T near the high-stable crystal oscillator and transmits it to the FPGA. The FPGA converts it into a digital value NT representing the temperature through A / D acquisition and conversion. Using NT as the address, the temperature compensation control voltage data stored at the address is read from the EEPROM, and after FPGA processing and correction, it is sent to the DAC digital-to-analog conversion module to become the corresponding analog temperature compensation control voltage and added to the voltage control end of the high-stable crystal oscillator to control the oscillation frequency of the high-stable crystal oscillator.

[0060] The Figure 7 It can be seen that the crystal oscillator output frequency accuracy curve changes under different ambient temperatures. From this figure, we can see the influence of temperature on the accuracy of the crystal oscillator output frequency. The goal of this application is to eliminate the influence of temperature on the output frequency accuracy as much as possible by compensation.

[0061] The correction includes: temperature hysteresis correction, dynamic temperature coefficient correction, and judgment and elimination of sudden interference.

[0062] Step 340, converting the voltage control voltage value into an analog signal; Step 350: The analog signal controls the output frequency of the high-stability crystal oscillator so that the output frequency is synchronized with the satellite time signal.

[0063] In one embodiment, the method further comprises the steps of: Step 360: Set a preset time length, and adjust the output frequency of the high-stability crystal oscillator once every preset time length.

[0064] For example, the comparison signal obtained by the phase difference detection between the satellite's time signal and the second signal of the high-stable crystal oscillator is used to adjust the output frequency of the high-stable crystal oscillator after aging compensation and temperature compensation. This process is carried out with a preset duration of 1S as a cycle.

[0065] The above is only an embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various changes and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included in the scope of the claims of the present application.

Claims

1. A high-stability crystal oscillator taming device, characterized in that: It includes a judgment module, a phase detection module, an aging module, a temperature module and an adjustment module; The judgment module is used to receive the satellite time signal and make a validity judgment; The phase detection module is used to receive the second signal sent by the high-stability crystal oscillator to be tested and the time signal of the satellite determined to be valid to perform phase difference detection to obtain a comparison signal; The aging module and the temperature module respectively perform aging compensation and temperature compensation on the comparison signal and then send the comparison signal to the adjustment module; The adjustment module is used to convert the comparison signal into an adjustment signal and send it to the high-stability crystal oscillator to be tested, so as to adjust the output frequency of the high-stability crystal oscillator.

2. The high stability crystal oscillator taming device according to claim 1, characterized in that: A Kalman filter module is also included to filter the measurement noise of the comparison signal.

3. The high stability crystal oscillator taming device according to claim 1, characterized in that: A temperature sensor is also included; The temperature sensor is used to detect the internal and external temperatures of the high-stability crystal oscillator and transmit the temperature data to the temperature module.

4. The high stability crystal oscillator taming device according to claim 1, characterized in that: The regulating module comprises: a PID control unit and a DAC data conversion unit; The PID control unit is used to receive the compensated comparison signal and convert it into a voltage control voltage value; The DAC data conversion unit is used to convert the voltage control voltage value into an adjustment signal.

5. A high-stability crystal oscillator taming system, characterized in that: The high-stability crystal oscillator taming device comprises any one of claims 1 to 4, and further comprises: a satellite module, a display module and a storage module; The satellite module is used to receive the time signal sent by the satellite and transmit it to the detection module; The display module is used to display the working status of the high-stability crystal oscillator taming device; The storage module is used to store temperature compensation data, high-stability crystal oscillator aging data, program code or configuration information.

6. The high stability crystal oscillator taming system according to claim 5, characterized in that: The storage module includes a synchronous dynamic random access memory and a serial memory; The synchronous dynamic random access memory is used to store data of temperature compensation and aging compensation; The serial memory is used to store program code or configuration information.

7. A high-stability crystal oscillator taming method, characterized in that: Using the device or system according to any one of claims 1 to 6, comprising the steps of: The phase detection module receives the satellite time signal and determines the validity of the satellite time signal; In response to the satellite time signal being valid, the second signal sent by the high-stability crystal oscillator to be tested is obtained and the time signal is subjected to phase difference detection to obtain a comparison signal; The comparison signal is subjected to aging compensation and temperature compensation, and then a voltage control voltage value is obtained through PID adjustment; The voltage-controlled voltage value is converted into an analog signal; The analog signal controls the output frequency of the high-stability crystal oscillator so that the output frequency is synchronized with the satellite time signal.

8. The high stability crystal oscillator taming method according to claim 7, characterized in that: Also includes the steps: Set a preset time length, and adjust the output frequency of the high-stability crystal oscillator once every preset time length.

9. The high stability crystal oscillator taming method according to claim 7, characterized in that: The aging compensation specifically comprises the following steps: Modeling of aging processes; modeling parameters include nominal frequency, frequency accuracy, load capacitance, aging rate, drive level, equivalent series resistance, or package stress; Power on the high-stability crystal oscillator to be tested and sample data through the filter; Select the model of corresponding time according to the power-on time, and supplement the aging of the data curve of the high-stability crystal oscillator to be tested.

10. The high stability crystal oscillator taming method according to claim 7, characterized in that: The temperature compensation specifically comprises the steps of: Acquire a temperature compensation database; the temperature compensation database contains voltage data corresponding to the temperature near the high-stability crystal oscillator and the temperature compensation; Measure the temperature near the high-stability crystal oscillator and select the voltage data corresponding to the temperature compensation; The voltage data is added to the voltage control terminal of the high-stability crystal oscillator to control the oscillation frequency of the high-stability crystal oscillator.

Images