A long-endurance, high-precision timekeeping and time service terminal and method

Abstract

A long-endurance high-precision timekeeping and time dissemination terminal and method of the present invention relate to the field of time synchronization, and include: a low-power MCU chip, a high-precision 1PPS phase discrimination chip, and a voltage-controlled crystal oscillator; the MCU chip includes a 1PPS generation module, a 1PPS phase discrimination control module, a PID control module, a temperature compensation module, and a time conversion module; the 1PPS generation module obtains an external standard 1PPS+ToD signal, and generates a local 1PPS signal and a delayed 1PPS signal; the 1PPS phase discrimination control module controls the 1PPS phase discrimination chip to compare the external standard 1PPS signal and the delayed 1PPS signal; the PID control module adjusts the voltage control value of the voltage-controlled crystal oscillator; the temperature compensation module performs frequency compensation on the voltage-controlled crystal oscillator according to the ambient temperature detected in real time; the voltage-controlled crystal oscillator provides a reference clock for the MCU chip; the time conversion module converts the external standard ToD signal into Beidou time to disseminate time to Beidou user equipment. The present invention can achieve a long-endurance timekeeping days and high timekeeping accuracy, meeting the requirements for accurate time of Beidou user equipment.

Description

Technical Field

[0001] The present invention relates to the technical field of time synchronization, and particularly to a long-endurance high-precision timekeeping and time dissemination terminal and method. Background Art

[0002] In contemporary communication systems, time synchronization accuracy is a core technical indicator for ensuring data transmission, network collaboration, and service quality. With the rapid development of fields such as 5G / 6G communication, the Internet of Things, industrial Internet, and financial high-frequency trading, the dependence of distributed systems on time dissemination accuracy is even more critical, and precise time synchronization has become an important support for the development of the industry's technology.

[0003] The Beidou navigation signal reception requires precise time information. When the Beidou user equipment captures the long code, it needs to rely on the local precise time for chip synchronization. The time deviation between the Beidou user equipment and the satellite signal must be less than ±1 second to ensure the capture synchronization of the long code signal.

[0004] To meet the all-weather ±1 second time accuracy requirement of the Beidou user equipment, there are currently mainly two solutions.

[0005] (1) The RTC timekeeping solution inside the Beidou user equipment: When the Beidou user equipment powers on to capture the long code, it obtains the reference time from the local RTC chip. The disadvantage of this RTC timekeeping solution is the low timekeeping accuracy. After 5.8 days of timekeeping, the timekeeping accuracy exceeds ±1 second, and it cannot support the Beidou long code capture work.

[0006] (2) The time dissemination solution using an external time synchronization device: When the Beidou user equipment powers on to capture the long code, it first obtains the time information from the external time synchronization device through the serial port. The disadvantage of this solution is that the power-off timekeeping endurance time of the external time synchronization device is too short, only maintaining for 24 hours, and it cannot support the high-precision time service required for the Beidou user equipment to power on at any time. Summary of the Invention

[0007] The main purpose of the present invention is to overcome the above defects in the prior art, and propose a long-endurance high-precision timekeeping and time dissemination terminal and method. By using a low-power signal processing board and clock taming to achieve time acquisition, timekeeping, and time dissemination, it has the characteristics of long endurance time and high timekeeping accuracy, and effectively solves the problem that the Beidou user equipment cannot reliably perform long code direct capture due to poor internal timekeeping accuracy.

[0008] The present invention adopts the following technical solutions:

[0009] On the one hand, a long-endurance high-precision timekeeping and time dissemination terminal includes a signal processing board, and the signal processing board includes: a low-power MCU chip, a high-precision 1PPS phase discrimination chip, and a voltage-controlled crystal oscillator; the MCU chip includes a 1PPS generation module, a 1PPS phase discrimination control module, a PID control module, a temperature compensation module, and a time conversion module;

[0010] The 1PPS generation module obtains an external standard 1PPS+ToD signal, and after being processed by the timer circuit, generates a local 1PPS signal and a delayed 1PPS signal. The local 1PPS signal is output to the time conversion module, and the delayed 1PPS signal is output to the 1PPS phase discriminator chip; the 1PPS phase discrimination control module controls the 1PPS phase discriminator chip to compare the external standard 1PPS signal and the delayed 1PPS signal to obtain a phase difference value; the PID control module adjusts the voltage control value of the voltage-controlled crystal oscillator according to the phase difference value; the temperature compensation module performs frequency compensation on the voltage-controlled crystal oscillator according to the ambient temperature detected in real time; the voltage-controlled crystal oscillator provides a reference clock for the MCU chip; the time conversion module converts the external standard ToD signal into Beidou time to time the Beidou user equipment.

[0011] Preferably, the MCU chip further includes a time detection module; the time detection module obtains the current UTC time of the Beidou user equipment, and compares it with the UTC time after the external standard ToD signal is converted to judge the accuracy of the UTC time of the Beidou user equipment. When the accuracy does not reach the preset value, the Beidou user equipment is timed through the time conversion module.

[0012] Preferably, the MCU chip further includes: a filtering module; the filtering module filters the phase difference value output by the 1PPS phase discriminator chip and then outputs it to the PID control module.

[0013] Preferably, the long-endurance high-precision timekeeping and timing terminal further includes: a DAC chip; the DAC chip receives the voltage control value output by the PID control module, performs digital-to-analog conversion and then outputs it to the voltage-controlled crystal oscillator.

[0014] Preferably, the long-endurance high-precision timekeeping and timing terminal further includes: an LDO linear power supply; the LDO linear power supply supplies power to the MCU chip and the 1PPS phase discriminator chip.

[0015] Preferably, the long-endurance high-precision timekeeping and timing terminal further includes: a thermal insulation cavity; the thermal insulation cavity is composed of a nickel-plated material cavity and an aerogel material filler; the signal processing board is arranged inside the thermal insulation cavity to achieve temperature isolation and maintain a constant magnetic field.

[0016] Preferably, the timer circuit adopts a two-stage timer cascading method, including a first timer, a second timer and a third timer; the first timer is connected to the external standard 1PPS+ToD signal, generates a 1ms cycle timing, triggers the second timer to generate a local 1PPS signal, and triggers the third timer to generate a delayed 1PPS signal.

[0017] Preferably, the temperature compensation module performs frequency compensation on the voltage-controlled crystal oscillator according to the ambient temperature detected in real time, as shown below:

[0018] ;

[0019] wherein, is the temperature compensation coefficient, obtained by fitting, ; is the ambient temperature at which the voltage-controlled crystal oscillator operates; is the temperature at which the frequency value is; is the reference temperature; is the reference temperature at which the frequency value is.

[0020] On the other hand, a long-endurance high-precision timekeeping and time service method, based on the timekeeping and time service terminal described above, the method includes:

[0021] The timekeeping and time service terminal is powered on and runs, entering the time acquisition process. The time acquisition methods include automatic traceability and manual traceability. Specifically, it receives the 1PPS+ToD output of an external standard time source to automatically obtain the standard time; when there is no external standard time source, it uses the manual input method to obtain the reference time; through traceability, the 1PPS signal of the external standard time source is used to clock-tame the local voltage-controlled crystal oscillator to generate a high-precision frequency signal and a local 1PPS signal, which are subjected to UTC time conversion and leap second processing to generate the Beidou time signal;

[0022] After the time acquisition is completed, it enters the timekeeping process. The MCU chip uses the high-precision frequency signal to keep the local 1PPS signal and the "year", "month", "day", "hour", "minute", and "second" running continuously; when it detects that the power of the timekeeping and time service terminal is lower than the preset ratio, it prompts that the power is low, and when it detects that the timekeeping duration exceeds the preset number of days, it prompts that the accuracy is low;

[0023] During the timekeeping process, if a time service request from a Beidou user device is received, it enters the time service process to perform serial port time service on the Beidou user device.

[0024] Preferably, before performing serial port time service on the Beidou user device, it further includes:

[0025] Receiving the serial port time information of the Beidou user device, detecting the UTC time output by the Beidou user device, and measuring whether the "year", "month", "day", "hour", "minute", and "second" are accurate. If not, perform serial port time service on the Beidou user device; otherwise, do not perform serial port time service.

[0026] As can be seen from the above description of the present invention, compared with the prior art, the present invention has the following beneficial effects:

[0027] (1) The present invention realizes time acquisition, timekeeping, and time dissemination through the low-power circuit and clock taming algorithm of the signal processing board. The MCU chip therein adopts an ultra-low-power chip, and the 1PPS phase discrimination chip adopts a high-precision time interval measurement chip. By adjusting the voltage-controlled voltage and frequency of the voltage-controlled crystal oscillator, it is ensured to provide a reference clock with high precision frequency for the MCU chip, making the timekeeping and time dissemination terminal of the present invention have the characteristics of long battery life and high timekeeping accuracy.

[0028] (2) The present invention includes a time detection function, which can judge the accuracy of UTC time before disseminating time to the Beidou user equipment, and only disseminate time to the Beidou user equipment when it is inaccurate, further improving the battery life.

[0029] (3) The thermal insulation cavity of the present invention is composed of a nickel-plated material cavity and an aerogel material filler. The thermal insulation cavity installs the signal processing board inside the cavity to achieve temperature isolation and constant magnetic field for the circuits in the signal processing board, reducing external environmental interference. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is the clock taming structure block diagram of the signal processing board of this embodiment of the present invention;

[0031] Figure 2 It is the structure block diagram of the long battery life and high-precision timekeeping and time dissemination terminal of this embodiment of the present invention;

[0032] Figure 3 It is the flow schematic diagram of the long battery life and high-precision timekeeping and time dissemination method of this embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0033] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the drawings in the embodiments of the present invention; obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0034] In the description of the present invention, it should be noted that the terms "include", "comprise" or any other variation thereof are intended to cover a non-exclusive inclusion, so that a process, method, article or device including a series of elements not only includes those elements but also includes other elements not expressly listed, or further includes elements inherent to such process, method, article or device. Without further limitations, the element defined by the statement "including one..." does not exclude the existence of additional identical elements in the process, method, article or device including the said element.

[0035] See Figure 1As shown in the figure, a long-endurance high-precision timekeeping and time dissemination terminal of the present invention includes a signal processing board, and the signal processing board includes: a low-power MCU chip 10, a high-precision 1PPS phase discrimination chip 20, a voltage-controlled crystal oscillator 30, and a DAC chip 40; the MCU chip 10 includes a 1PPS generation module 101, a 1PPS phase discrimination control module 102, a PID control module 103, a temperature compensation module 104, a time conversion module 105, a time detection module 106, and a filtering module 107;

[0036] The 1PPS generation module 101 obtains an external standard 1PPS+ToD signal (generated by an external standard time source device), generates a local 1PPS signal and a delayed 1PPS signal after being processed by a timer circuit, the local 1PPS signal is output to the time conversion module 105, and the delayed 1PPS signal is output to the 1PPS phase discrimination chip 20; the 1PPS phase discrimination control module 102 controls the 1PPS phase discrimination chip 20 to compare the external standard 1PPS signal and the delayed 1PPS signal to obtain a phase difference, which is input to the PID control module 103 after being filtered by the filtering module 107; the PID control module 103 adjusts the voltage control value of the voltage-controlled crystal oscillator 30 according to the phase difference, and inputs it to the voltage-controlled crystal oscillator 30 after being converted by the DAC chip 40; the temperature compensation module 104 performs frequency compensation on the voltage-controlled crystal oscillator 30 according to the detected ambient temperature in real time; the voltage-controlled crystal oscillator 30 provides a reference clock for the MCU chip 10; the time detection module 106 obtains the current UTC time of the Beidou user equipment, and compares it with the UTC time converted from the external standard ToD signal to judge the accuracy of the UTC time of the Beidou user equipment, and triggers the time conversion module 105 when the accuracy does not reach the preset value; the time conversion module 105 converts the external standard ToD signal into Beidou time to disseminate time to the Beidou user equipment.

[0037] In this embodiment, the low-power MCU chip 10 may be an ultra-low-power chip GD32L series MCU, and the high-precision 1PPS phase discrimination chip 20 may be a high-precision time interval measurement TDC chip MS1 series. It should be noted that the model is not specifically limited in this embodiment, as long as it can achieve ultra-low power consumption and high precision.

[0038] The MCU chip 10 is connected to the 1PPS phase discrimination chip 20, and the MCU chip 10 communicates with the 1PPS phase discrimination chip 20 through an SPI interface, controls the 1PPS phase discrimination chip 20 to perform 1PPS signal time delay measurement between two channels, and reads the delayed 1PPS signal output by the 1PPS generation module 101 through the 1PPS phase discrimination chip 20 SPI interface.

[0039] The voltage-controlled crystal oscillator 30 can be a low-power 10 MHz frequency, ±0.2 ppm stability voltage-controlled crystal oscillator 30; the MCU chip 10 is connected to the voltage-controlled crystal oscillator 30, and the voltage-controlled crystal oscillator 30 outputs a 10 MHz frequency signal to provide a reference clock for the MCU chip 10, which is used as the clock signal for the operation of the MCU chip 10 and the trigger of the timer.

[0040] The DAC chip 40 can adopt a 16-bit digital-to-analog chip. The MCU chip 10 is connected to the DAC chip 40, and the MCU chip 10 controls the DAC chip 40 through the SPI interface to achieve precise voltage output, which is used to control the voltage-controlled voltage of the voltage-controlled crystal oscillator 30.

[0041] Furthermore, the long-endurance high-precision timekeeping and time dissemination terminal further includes: an LDO linear power supply (not shown in Figure 1 , see Figure 2 the power supply in the signal processing board in

[0042] The LDO linear power supply can be a linear voltage regulator chip with low ripple and small static current. The linear power supply is respectively connected to the MCU chip 10 and the voltage-controlled crystal oscillator 30, and the LDO linear power supply provides a low-ripple voltage for the MCU chip 10 and the voltage-controlled crystal oscillator 30 to ensure the accuracy of the working voltage and the voltage-controlled voltage value of the voltage-controlled crystal oscillator 30.

[0042] Furthermore, the long-endurance high-precision timekeeping and time dissemination terminal further includes: a thermal insulation cavity, which is an external thermal insulation constant magnetic field cavity, and the cavity is composed of a nickel-plated material cavity and an aerogel material filler. The signal processing board circuit composed of the MCU chip 10, the 1PPS phase discrimination chip 20, the DAC chip 40, the voltage-controlled crystal oscillator 30, and the linear power supply is installed inside the thermal insulation cavity to achieve temperature isolation and constant magnetic field for the circuit.

[0043] Specifically, the 1PPS generation module 101 can be generated by the hardware timer circuit inside the MCU chip 10 and has the characteristic of accurate counting. To achieve the accurate generation of the 1PPS signal, it is completely implemented by the MCU hardware timer circuit. The general timer of the MCU chip 10 in this embodiment is 16 bits, the timer base frequency is 40 MHz, the resolution is 25 ns, and the maximum timing is up to 1.6 ms, and it cannot time up to 1 s. Therefore, a two-stage timer cascade method is adopted. The first timer TIMER1 is configured with a count of 40,000 to generate a 1 ms cycle timing, triggering the second timer TIMER2 and the third timer TIMER3. Both TIMER2 and TIMER3 are configured with a count of 1,000 to trigger the PWM to generate a 1 Hz signal, that is, to implement the local 1PPS output function, where TIMER2 generates the local 1PPS signal. TIMER3 is provided for the phase discriminator to output with a 1 ms delay according to the requirement of the phase discriminator for the lagging timing of the measurement signal, providing a 1PPS signal with a measured delay of 1 ms for the 1PPS phase discriminator chip 20.

[0044] The 1PPS phase discrimination control module 102 can be the internal software program of the MCU chip 10, mainly to control the 1PPS phase discriminator chip 20. Specifically, it generates a control signal when obtaining the external standard 1PPS+ToD signal, completes the measurement of the time delay value of the two input 1PPS signals (the external standard 1PPS signal and the delayed 1PPS signal) by the 1PPS phase discriminator chip 20, and reads the test data through the SPI interface.

[0045] The phase discrimination of the 1PPS signal mainly compares the externally input standard 1PPS with the locally generated delayed 1PPS signal, and measures the deviation between the two input 1PPS signals through a high-precision TDC chip. Since the TDC chip can only measure two signals with a certain range of phase differences, the measurement range of this method is selected to be 500 ns to 4 ms. Therefore, the 1PPS signal output by the local third timer TIMER3 is delayed by 1 ms to ensure that the timing of the standard 1PPS and the locally generated 1PPS signal meets the measurement requirements. Connect the external standard 1PPS signal to the START pin of the TDC chip, connect the delayed 1PPS signal to the STOP1 pin of the chip, and control the enable signals EN_START, EN_STOP and the reset signal RSTN through the MCU to enable the chip to start signal measurement. Read the measurement result through the SPI interface between the MCU chip 10 and the TDC chip to obtain the measured phase difference.

[0046] When the externally input 1PPS signal comes from an external standard time source device such as a Beidou receiver, there is a certain amount of short-term jitter, and the jitter range is about 3 - 10 ns. Along with the phase discrimination process, this jitter error is brought into the phase discrimination result. Therefore, the filtering module 107 filters this error. Considering that this jitter characteristic is mostly an occasional outlier, the median recursive average filtering method is adopted to ensure the purity and accuracy of the phase difference. First, continuously collect N phase difference values, arrange them in a queue with a fixed length of N, and follow the first-in, first-out principle. When a new value is collected, put this value at the end of the queue and discard one value at the head of the queue. Secondly, arrange the N values in the queue from largest to smallest, remove the two values at the head and tail, that is, the maximum and minimum values in the values, and then calculate the arithmetic mean of the remaining values and output it as the current phase difference value.

[0047] The PID control module 103 can be implemented through the internal software program of the MCU chip 10. It mainly realizes calculating the 1PPS signal phase discrimination value (phase difference value) into a voltage adjustment value through the PID control algorithm, and operating the DAC chip 40 through the SPI interface of the MCU chip 10 to realize frequency adjustment of the voltage-controlled crystal oscillator 30.

[0048] The PID control algorithm is mainly used to achieve the purpose of frequency calibration by changing the voltage-controlled value of the crystal oscillator, and adjust the voltage-controlled value of the crystal oscillator according to the phase difference output by the phase discriminator. , to reach a dynamic equilibrium state. Since the calculation amount of the PID control algorithm is small and the algorithm complexity is relatively low, it is suitable for the software operation of the ultra-low power consumption MCU chip 10. The algorithm formula is as follows:

[0049] );

[0050] Among them, is the voltage control difference; is the voltage control value at the current moment; is the voltage control value at the previous moment; is the sampling period; is the phase difference at the current moment; is the average value of the phase differences in the previous time period; is the average value of the phase differences in the previous two time periods; is the proportional coefficient; is the differential coefficient; is the integral coefficient.

[0051] The sampling period of this embodiment is 5 seconds, and the voltage control value changes once every 5 seconds. Finally, the obtained is the difference between the current voltage-controlled oscillator (VCO) and the previous one. In the PID control algorithm, the role of proportional adjustment is to instantly respond to the deviation between the expected value and the current value. When the proportional coefficient is larger, the adjustment strength is greater, and the control parameters are more stable. Conversely, when the proportional coefficient is smaller, the control parameters are more prone to oscillation. Integral adjustment is used to accumulate and eliminate the residual error generated by the proportional adjustment link and usually works together with proportional adjustment. The differential part mainly regulates the change speed of the deviation to prevent the change of the deviation. In this embodiment, the PID coefficients are set in two stages. In the initial synchronization stage, the proportional coefficient is 3.8, the differential coefficient is 1.2, and the integral coefficient is 0.3. After synchronization and stabilization, the proportional coefficient is 3.5, the differential coefficient is 1.1, and the integral coefficient is 0.25, which can calibrate the frequency accuracy of the VCO 30 at the 5E-12 level.

[0052] The temperature compensation module 104 can be implemented through the internal software program of the MCU chip 10, mainly to establish the curve relationship between the temperature value and the frequency value within the working temperature range and perform real-time temperature measurement and frequency compensation during the operation of the terminal. For the crystal oscillator frequency accuracy index, temperature is the main influencing factor, and the repeatability of the influence of temperature on the crystal oscillator frequency is good. During the entire service life cycle of the crystal oscillator, the temperature characteristics are basically constant. Therefore, the present invention tests the variation characteristics of the frequency index of the VCO 30 with temperature, establishes a temperature compensation model based on the test data, and writes a compensation algorithm to compensate for the temperature drift. The temperature compensation formula is:

[0053] ;

[0054] where, is the temperature compensation coefficient, obtained by fitting, ; is the ambient temperature at which the VCO 30 operates; is the temperature at which the frequency value is measured; is the reference temperature; is the frequency value at the reference temperature at which the frequency value is measured.

[0055] During specific implementation, temperature compensation parameter sampling can be performed before the product leaves the factory. Use a temperature change test chamber to perform temperature rise and fall tests on the crystal oscillator circuit. By controlling the temperature change, measure the output frequency of the crystal oscillator to obtain the corresponding data of frequency and temperature and the sampling time. Use this data to build a model to obtain the temperature compensation model curve of the crystal oscillator, which is used as the key data for the timekeeping algorithm processing, so as to realize frequency deviation compensation of the crystal oscillator when the ambient temperature changes, and improve the timekeeping accuracy index of the crystal oscillator.

[0056] The time conversion module 105 and the time detection module 106 can be implemented through the internal software program of the MCU chip 10. It mainly realizes the conversion of the UTC time (obtained through the ToD signal) received from the external standard time source device into Beidou time, and packs and outputs it to the Beidou user device according to the Beidou CCTIM statement format. At the same time, it can compare the deviation between the UTC time of the received Beidou user device and the local time, and output the comparison result from the serial port to the integrated control board of the terminal.

[0057] Furthermore, the long-endurance high-precision timekeeping and time service terminal of this embodiment further includes: a circular connector assembly. The signal processing board is connected to the circular connector assembly through an interface driver chip. The time acquisition port circular connector assembly is connected to the external standard time source device, and the time service port circular connector assembly is connected to the Beidou user device.

[0058] See Figure 2 As shown, a long-endurance high-precision timekeeping and time service terminal, in addition to including a signal processing board, also includes an integrated control board, an interface board, an OLED liquid crystal screen, a lithium-ion battery, etc. Among them, the signal processing board is connected to the integrated control board to realize core time signal and information processing for the entire terminal. The integrated control board provides power voltage, keys and external connection functions for the entire terminal. The lithium-ion battery, liquid crystal screen and interface board are auxiliary units to complete the function realization of the entire terminal. Communication between each board or component adopts a micro-connector and FPC line design to enable reliable communication between each functional unit.

[0059] See Figure 3 As shown, this embodiment also discloses a long-endurance high-precision timekeeping and time service method, based on the timekeeping and time service terminal described above. The method includes:

[0060] The timekeeping and time service terminal is powered on and runs, and enters the time acquisition process. The time acquisition methods include automatic traceability and manual traceability. Specifically, it is to receive the 1PPS+ToD output of the external standard time source to automatically obtain the standard time; when there is no external standard time source, use the manual input method to obtain the reference time; through traceability, the 1PPS signal of the external standard time source is used to perform clock taming on the local voltage-controlled crystal oscillator (the principle of clock taming is shown in Figure 1), generate a high-precision frequency signal and a local 1PPS signal, and generate a Beidou time signal after UTC time conversion and leap second processing;

[0061] After the time acquisition is completed, the timekeeping process is entered. The MCU chip uses a high-precision frequency signal to keep the local 1PPS signal and the "year", "month", "day", "hour", "minute", and "second" running continuously. When it is detected that the power of the timekeeping and timing terminal is lower than the preset ratio, a low power prompt is given. When it is detected that the timekeeping duration exceeds the preset number of days, a low precision prompt is given.

[0062] During the timekeeping process, if a timing request from a Beidou user device is received, the timing process is entered to perform serial port timing for the Beidou user device.

[0063] Preferably, before performing serial port timing for the Beidou user device, it further includes:

[0064] Receiving the serial port time information of the Beidou user device, detecting the UTC time output by the Beidou user device, and measuring whether the "year", "month", "day", "hour", "minute", and "second" are accurate. If not, perform serial port timing for the Beidou user device (for example, one-time timing lasts for 10 seconds to complete the serial port timing for the Beidou user device); otherwise, do not perform serial port timing.

[0065] Figure 3 In this case, the reference source status refers to the valid identification of the timing information of the external standard time source device. If the identification is valid, time acquisition is performed; otherwise, continue to wait for time acquisition.

[0066] When it is detected that the power of the timekeeping and timing terminal is lower than the preset ratio, a low power prompt is given. When it is detected that the timekeeping duration exceeds the preset number of days, a low precision prompt is given. Specifically, when the internal power of the terminal is detected to be lower than the preset ratio, such as 20%, the liquid crystal screen interface prompts "Low power, please charge". When the terminal detects that the timekeeping duration exceeds 60 days, the liquid crystal screen interface prompts "Low precision, please perform time acquisition".

[0067] As described above, the present invention realizes time acquisition, timekeeping, timing, and time detection through the low-power circuit and clock taming algorithm of the signal processing board. By adjusting the voltage control voltage and frequency of the voltage-controlled crystal oscillator, it is ensured that a high-precision frequency reference clock is provided for the MCU chip, making the timekeeping and timing terminal of the present invention have the characteristics of long battery life and high timekeeping accuracy. The lithium-ion battery can be used for 30 days with a time deviation of ±300 milliseconds after being fully charged once. Compared with the RTC timekeeping of the Beidou user device with a time deviation of ±1 second in 5.8 days, the battery life is increased by 5 times and the timekeeping accuracy is increased by 15 times, effectively solving the problem that the Beidou user device cannot reliably perform long code direct capture due to poor internal timekeeping accuracy.

[0068] The above are only the preferred specific embodiments of the present invention; however, the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention, according to the technical solution of the present invention and its improved concept, making equivalent substitutions or changes, shall be covered by the protection scope of the present invention.

Claims

1. A long-endurance high-precision timekeeping and time dissemination terminal, including a signal processing board, characterized in that, The signal processing board includes: a low-power MCU chip, a high-precision 1PPS phase discrimination chip, and a voltage-controlled crystal oscillator; the MCU chip includes a 1PPS generation module, a 1PPS phase discrimination control module, a PID control module, a temperature compensation module, and a time conversion module; The 1PPS generation module obtains an external standard 1PPS+ToD signal, and after being processed by a timer circuit, generates a local 1PPS signal and a delayed 1PPS signal. The local 1PPS signal is output to the time conversion module, and the delayed 1PPS signal is output to the 1PPS phase discrimination chip; the 1PPS phase discrimination control module controls the 1PPS phase discrimination chip to compare the external standard 1PPS signal and the delayed 1PPS signal to obtain a phase difference; the PID control module adjusts the voltage control value of the voltage-controlled crystal oscillator according to the phase difference; the temperature compensation module performs frequency compensation on the voltage-controlled crystal oscillator according to the real-time detected ambient temperature; the voltage-controlled crystal oscillator provides a reference clock for the MCU chip; the time conversion module converts the external standard ToD signal into Beidou time to time the Beidou user equipment.

2. The long-endurance high-precision timekeeping and time dissemination terminal according to claim 1, wherein The MCU chip also includes a time detection module; the time detection module obtains the current UTC time of the Beidou user equipment, and compares it with the UTC time after the external standard ToD signal is converted to judge the accuracy of the UTC time of the Beidou user equipment. When the accuracy does not reach the preset value, the Beidou user equipment is timed through the time conversion module.

3. The long-endurance high-precision timekeeping and time dissemination terminal according to claim 1, wherein The MCU chip also includes a filtering module; the filtering module filters the phase difference output by the 1PPS phase discrimination chip and then outputs it to the PID control module.

4. The long-endurance high-precision timekeeping and time service terminal according to claim 1, characterized in that, It also includes: A DAC chip; the DAC chip receives the voltage control value output by the PID control module, performs digital-to-analog conversion, and then outputs it to the voltage-controlled crystal oscillator.

5. The long-endurance high-precision timekeeping and time dissemination terminal according to claim 1, wherein, It also includes: An LDO linear power supply; the LDO linear power supply supplies power to the MCU chip and the 1PPS phase discrimination chip.

6. The long-endurance high-precision timekeeping and time-transfer terminal according to claim 1, characterized in that, It also includes: An insulation cavity; the insulation cavity is composed of a nickel-plated material cavity and an aerogel material filler; the signal processing board is arranged inside the insulation cavity to achieve temperature isolation and maintain a constant magnetic field.

7. The long-endurance high-precision timekeeping and time-transferring terminal according to claim 1, characterized in that, The timer circuit adopts a two-stage timer cascade method, including a first timer, a second timer, and a third timer; the first timer is connected to the external standard 1PPS+ToD signal, generates a 1ms cycle timing, triggers the second timer to generate a local 1PPS signal, and triggers the third timer to generate a delayed 1PPS signal.

8. The long-endurance high-precision timekeeping and time service terminal according to claim 1, wherein The temperature compensation module performs frequency compensation on the voltage-controlled crystal oscillator according to the real-time detected ambient temperature, as follows: ； Among them, is the temperature compensation coefficient, obtained by fitting, ; is the ambient temperature at which the voltage-controlled crystal oscillator operates; is the temperature at which the frequency value is measured; is the reference temperature; is the reference temperature at which the frequency value is measured.

9. A long-endurance high-precision timekeeping and time dissemination method, characterized in that, Based on the timekeeping and timing terminal according to any one of claims 1 to 8, the method includes: The time-keeping and time-service terminal powers on and runs, entering the time acquisition process. The time acquisition methods include automatic traceability and manual traceability. Specifically, it receives the 1PPS+ToD output of an external standard time source to automatically obtain the standard time; when there is no external standard time source, it uses the manual input method to obtain the reference time; through traceability, the 1PPS signal of the external standard time source is used to clock-tame the local voltage-controlled crystal oscillator to generate a high-precision frequency signal and a local 1PPS signal, which are subjected to UTC time conversion and leap second processing to generate the Beidou time signal. After the time acquisition is completed, it enters the time-keeping process. The MCU chip uses the high-precision frequency signal to keep the local 1PPS signal and the "year", "month", "day", "hour", "minute", and "second" running continuously; when it detects that the power of the time-keeping and time-service terminal is lower than the preset ratio, it prompts that the power is low, and when it detects that the time-keeping duration exceeds the preset number of days, it prompts that the accuracy is low. During the time-keeping process, if a time-service request from a Beidou user equipment is received, it enters the time-service process to perform serial port time service for the Beidou user equipment.

10. The long-endurance high-precision timekeeping and time dissemination method according to claim 9, characterized in that, Before performing serial port time service for the Beidou user equipment, it also includes: Receiving the serial port time information of the Beidou user equipment, detecting the UTC time output by the Beidou user equipment, and measuring whether the "year", "month", "day", "hour", "minute", and "second" are accurate. If they are not accurate, perform serial port time service for the Beidou user equipment; otherwise, do not perform serial port time service.

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