A time service reliability evaluation mechanism is adopted in the time service device

Abstract

The application discloses a time service device adopting a time source reliability evaluation mechanism, and the device constructs a time source reliability evaluation mechanism, comprehensively evaluates operation states, signal validity and signal quality of multiple time sources, forms a time source reliability evaluation result, and constructs a time source reliability decision model according to the reliability evaluation result, so that dynamic selection and seamless switching of the multiple time sources are realized, and continuous and stable time service information is generated. The device comprises a GNSS navigation module, a constant temperature crystal oscillator module, an RTC crystal oscillator module, a time source reliability decision module and a main control module, wherein the GNSS navigation module and the constant temperature crystal oscillator module adopt independent isolated power supply, and output signals are sent into the main control module after being optically isolated. Compared with the prior art, the application introduces a time source reliability decision mechanism, realizes intelligent management of multiple time sources, and is helpful to improve the reliability, continuity and anti-interference capability of the time service system in a complex environment.

Description

Technical Field

[0001] This invention relates to the field of time information processing technology, and in particular to a time synchronization device employing a time source reliability evaluation mechanism. Background Technology

[0002] With the increasing demands for time synchronization accuracy and continuity in fields such as communication networks, power systems, rail transportation, industrial automation, data centers, financial transactions, and aerospace, highly reliable time synchronization devices have become an important component of time synchronization systems. Currently, time synchronization devices typically use the Global Navigation Satellite System (GNSS) as the standard time source, combined with local time sources such as oven-controlled crystal oscillators (OCXO) and real-time clocks (RTCs), to provide unified and accurate time information for various devices.

[0003] To improve the reliability of time synchronization systems, existing time synchronization devices generally adopt a multi-time source redundancy design. When the primary time source malfunctions or fails, the system switches to a backup time source to maintain the time synchronization function, thereby improving system availability. Currently, multi-time source time synchronization systems typically employ fixed priority switching, primary / backup switching, or switching methods based on single-state detection. For example, they determine the availability of a time source based on information such as GNSS lock status, second pulse output status, and time message validity, and then complete the time source switching accordingly.

[0004] However, the aforementioned time source management methods mainly rely on fixed priorities or single-state judgments, lacking the ability to comprehensively evaluate the operating status of multiple time sources, the validity of time signals, and signal quality. When multiple time sources simultaneously experience performance fluctuations, signal quality degradation, or varying degrees of anomalies, existing technologies struggle to fully reflect the actual reliability of each time source. This can easily lead to unreasonable time source selection, frequent switching, or continued use of less reliable time sources, thereby affecting the continuity, stability, and reliability of the time synchronization system.

[0005] Furthermore, as the application scenarios of time synchronization systems continue to expand, the types of time sources have gradually expanded from a single GNSS to various heterogeneous time sources such as GNSS, local high-stability crystal oscillators, RTC, and network time sources. Because different time sources differ in their operating modes, stability, accuracy, and failure modes, existing technologies lack a unified reliability evaluation mechanism for different types of time sources, and also lack a method for dynamically managing multiple time sources based on unified evaluation results, making it difficult to fully leverage the advantages of redundant multi-time-source configurations.

[0006] Therefore, existing technologies still require a time synchronization device that can perform unified reliability evaluation on multiple time sources and dynamically select and switch time sources based on the evaluation results, in order to improve the reliability, continuity and stability of the time synchronization system in complex application environments. Summary of the Invention

[0007] The purpose of this invention is to provide a timing device that employs a time source reliability evaluation mechanism to achieve dynamic selection and automatic switching of multiple time sources, thereby improving the reliability, continuity, and stability of the timing system.

[0008] To achieve the above objectives, the present invention provides the following solution: A time synchronization device employing a time source reliability evaluation mechanism includes: Multiple time source modules are used to provide time sources with different sources and precision; The time source reliability decision module includes a time source reliability evaluation module and a time source switching unit. It is used to establish and dynamically update a candidate time source ranking table from best to worst based on the reliability evaluation results output by the time source reliability evaluation module, use the candidate time source ranking table as the time source reliability decision model, and determine the current time source based on the time source reliability decision model. When the current time source does not meet the preset reliability conditions, it automatically selects the time source with the best ranking in the candidate time source ranking table. The time source reliability evaluation module is used to execute a unified time source reliability evaluation mechanism: comprehensively acquire the operating status, time signal validity and time signal quality parameters of each time source, and generate the corresponding reliability evaluation results for each time source. When the current time source does not meet the preset reliability conditions, the time source switching unit automatically selects the best-ranked time source from the candidate time source sorting table. The main control module, connected to the time source reliability decision module, is used to generate and output the time synchronization based on the current time synchronization source.

[0009] Preferably, the time source reliability evaluation mechanism detects the validity of the time signal by performing arrival window detection on the second pulse signal, and by verifying the checksum, field validity, positioning validity flag, and number of visible satellites of the time message; The time source reliability evaluation mechanism detects the quality of time signals by measuring the deviation and dispersion of adjacent second pulse intervals based on a high-stability clock to assess jitter, and by comparing and counting multiple time sources to assess frequency deviation.

[0010] Preferably, the reliability evaluation results generated by the time source reliability evaluation module include one or more combinations of reliability level, reliability score and reliability priority.

[0011] Preferably, the multiple time source modules include at least: GNSS navigation module, used to provide a GNSS navigation time source with a standard time reference; Thermostatic crystal oscillator module is used to provide a thermostatic crystal oscillator time source with a high stability time reference; RTC crystal oscillator module, used to provide a low-power local time base RTC time source when an external time source is unavailable; The network time synchronization module obtains network time sources via NTP or PTP protocols; all time sources are input and participate in the time source reliability evaluation mechanism.

[0012] Preferably, the GNSS navigation time source and the temperature-controlled crystal oscillator time source are powered by independent isolated power supply units; The time signals output from the GNSS navigation time source and the isothermal crystal oscillator time source are transmitted to the main control module and the time source reliability evaluation module via an optical signal isolation module.

[0013] Preferably, the time source reliability decision module adopts a hysteresis interval strategy when switching time sources, that is, setting different degradation thresholds and recovery thresholds; when a high-priority time source recovers from a failed or degraded state, it maintains an effective state for a preset confirmation time before switching back to the high-priority time source. During the switching process, the main control module gradually pulls the local time at a limited rate to ensure that the output time is continuous and without abrupt changes.

[0014] Preferably, the main control module has a built-in mutual difference voting mechanism; when multiple time sources are in a valid state at the same time, the main control module compares the mutual deviation of the output times of each time source, removes abnormal time sources whose deviation exceeds a preset threshold from the candidate queue, and then selects based on the reliability evaluation results of the remaining time sources.

[0015] Preferably, the device further includes a crystal oscillator discipline unit, which is located within the main control module; the crystal oscillator discipline unit uses the standard time signal output by the GNSS navigation time source as a reference and performs frequency calibration on the isothermal crystal oscillator time source through a digital phase-locked loop; When the GNSS navigation time source is lost, the crystal oscillator discipline unit maintains the most recent voltage control value and extrapolates and corrects the voltage control value based on the pre-stored model of the isothermal crystal oscillator aging rate and temperature sensitivity coefficient, so as to maintain the timekeeping accuracy of the isothermal crystal oscillator time source.

[0016] According to specific embodiments provided by the present invention, the present invention discloses the following technical effects: (1) This invention proposes a time source reliability evaluation mechanism, which realizes the unified reliability evaluation of multiple heterogeneous time sources, provides a unified evaluation basis for time source management, and effectively overcomes the shortcomings of existing technologies that rely on fixed priority or single state detection for time source switching. Based on the time source reliability evaluation results, this invention constructs a time source reliability decision model to realize the dynamic selection and automatic switching of multiple time sources. When the performance of the time source deteriorates or an anomaly occurs, the time source switching can be completed quickly, thereby improving the continuity and reliability of the time synchronization system.

[0017] (2) This invention constructs a multi-source redundant timing system by employing multiple time sources, including GNSS navigation time sources, temperature-controlled crystal oscillator time sources, RTC time sources, and network time sources, thereby improving the fault tolerance and availability of the timing system in complex application environments. Through independent power supply and optical isolation design, the impact of power supply noise and electromagnetic interference on the time signal quality is effectively reduced, improving the accuracy of time source reliability evaluation results and the stability of the timing system. This invention can be widely applied in power systems, communication networks, rail transit, industrial control, data centers, financial transactions, aerospace, BeiDou high-precision timing, and other application scenarios with high requirements for time synchronization reliability, possessing good engineering application value and promising prospects for promotion. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a schematic diagram of the structure of a timing device with time source reliability decision-making provided in an embodiment of the present invention; Figure 2 This is a schematic diagram of another timing device (including an isolated power supply module and an optical signal isolation module) provided in an embodiment of the present invention; Figure 3 This is a schematic diagram of another time synchronization device (complete embodiment) provided in an embodiment of the present invention; Figure 4 This is a schematic diagram of the structure of a desktop time synchronization device provided in an embodiment of the present invention; Figure 5 This is a schematic diagram of the structure of a rack-mounted time synchronization device provided in an embodiment of the present invention; Figure label explanations: 100-Main control module, 110-Crystal oscillator discipline unit, 200-GNSS navigation module, 210-GNSS navigation unit, 220-Signal conversion unit, 300-Crystal oscillator module, 310-Crystal oscillator, 400-RTC crystal oscillator module, 410-RTC crystal oscillator, 460-Temperature compensated crystal oscillator, 500-Network time synchronization module, 510-Ethernet PHY chip, 520-RJ45 network interface, 540-Network time receiving unit, 60 0-Power supply module, 610-Input power supply, 620-Voltage regulator, 700-Time source reliability decision module, 710-Time source reliability evaluation module, 720-Time source switching unit, 800-Isolation power supply module, 810-First isolation power supply unit, 820-Second isolation power supply unit, 900-Optical signal isolation module, 910-Electro-optical conversion unit, 920-Optical transmission medium, 930-Photoelectric conversion unit, 1000-Display module, 1100-Configuration interface module. Detailed Implementation

[0020] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0022] like Figure 1 As shown, Figure 1 A timing device according to an embodiment of the present invention is shown. The device includes a main control module 100, a GNSS navigation module 200, a temperature-controlled crystal oscillator module 300, an RTC crystal oscillator module 400, and a time source reliability decision module 700. The time source reliability decision module 700 includes a time source reliability evaluation module 710 and a time source switching unit 720. The output terminals of the GNSS navigation module 200, the temperature-controlled crystal oscillator module 300, and the RTC crystal oscillator module 400 are respectively connected to the corresponding signal input terminals of the time source reliability decision module 700. The control terminal of the time source switching unit 720 is connected to the output terminal of the time source reliability evaluation module 710, and the output terminal of the time source switching unit 720 is connected to the signal input terminal of the main control module 100.

[0023] In this embodiment, the GNSS navigation module 200 outputs a pulse-per-second (1PPS) signal and a serial time message carrying year, month, day, hour, minute, and second information (e.g., the RMC statement in the NMEA-0183 protocol); the temperature-controlled crystal oscillator module 300 outputs a frequency signal with high short-term stability as a calibration clock pulse; the RTC crystal oscillator module 400 outputs a low-frequency clock pulse with power consumption in the microampere range, which can be powered by a button battery or supercapacitor and continue timing during a power outage of the entire device. The time source reliability evaluation module 710 tests each time source from two dimensions: effectiveness and quality.

[0024] Regarding validity: Arrival window detection is used for the second pulse signal, that is, a tolerance window is set before and after the expected arrival time. Only when the rising edge falls within the window is it judged as a valid pulse. If there are several consecutive missing or out-of-window pulses, the source is judged as invalid. The checksum, field value validity, and whether the location validity flag and the number of visible satellites meet the threshold are checked for the time message. The time and second pulse sequence number in the message are cross-checked. If the two are inconsistent, it is judged as unreliable.

[0025] In terms of quality: the interval between adjacent second pulses is measured using the clock of the temperature-controlled crystal oscillator as the counting time base, and the deviation and dispersion of the interval are statistically analyzed within the sliding window as a jitter index; the frequency deviation between each oscillator is estimated by mutual counting and comparison.

[0026] Based on this, the time source reliability evaluation module 710 generates a three-level reliability status word of "effective, deteriorated, or failed" for each time source.

[0027] The time source switching unit 720 selects the reliable status word as the highest priority time source based on a preset priority table (in this embodiment, the GNSS navigation module 200 takes precedence over the oven-controlled crystal oscillator module 300, and the oven-controlled crystal oscillator module 300 takes precedence over the RTC crystal oscillator module 400). To avoid repeated switching in critical states, the inferior threshold and the recovery threshold use different values ​​to form a hysteresis interval, and after the higher priority time source recovers to validity, it must be stably maintained for a preset confirmation duration before the switchback is executed. During the switching execution, no step correction is made to the output time; instead, the main control module 100 gradually pulls the local time at a limited rate, so that the output time always remains monotonous and continuous without any jumps.

[0028] The main control module 100 can be a microcontroller unit (MCU), utilizing its input capture and timing counting peripherals to achieve pulse measurement; or it can be a field-programmable gate array (FPGA), implemented with internal counting and selection logic. The time source reliability evaluation module 710 and the time source switching unit 720 can be implemented by the on-chip peripherals and multiplexing logic of the main control module 100, or they can be independent logic circuits. When the selected time source is the GNSS navigation module 200, the main control module 100 obtains the absolute time based on the second pulse and time message; when the selected time source is an oscillator-type time source, the main control module 100 uses the most recent valid absolute time as the starting point and counts backwards according to the clock pulse of the oscillator to achieve timekeeping.

[0029] In a cost-sensitive simplified embodiment, the temperature-controlled crystal oscillator module 300 can be omitted or replaced by a temperature-compensated crystal oscillator module. In this case, the device consists of a GNSS navigation module 200, an RTC crystal oscillator module 400, a time source reliability decision module 700, and a main control module 100, forming the simplest implementation.

[0030] Figure 2 A timing device according to another embodiment of the present invention is shown, which adds an isolated power supply module 800 and an optical signal isolation module 900 to the device according to Embodiment 1. The isolated power supply module 800 includes a first isolated power supply unit 810 and a second isolated power supply unit 820, the output terminals of which are respectively connected to the power input terminals of the GNSS navigation module 200 and the temperature-controlled crystal oscillator module 300.

[0031] In this embodiment, both the first isolated power supply unit 810 and the second isolated power supply unit 820 employ transformer-isolated DC-DC converter circuits (e.g., flyback or push-pull topologies), with an isolation withstand voltage of 1500V DC or higher. The output of the second isolated power supply unit 820 is then supplied to the cryogenic crystal oscillator module 300 after passing through a filter network and a low-noise linear regulator. The output frequency of the cryogenic crystal oscillator is highly sensitive to power supply ripple, which is converted into frequency modulation noise through its voltage control terminal and internal circuitry. Therefore, secondary purification of its power supply can directly improve the phase noise of the output clock. The first isolated power supply unit 810 provides independent power to the RF front-end of the GNSS navigation module 200, preventing harmonics from digital switching noise from falling into the satellite navigation frequency band and reducing receiver sensitivity. Each isolated power domain does not share a return path with the main control digital power domain, cutting off the noise circulation channel at the source.

[0032] The optical signal isolation module 900 includes an electro-optical conversion unit 910, an optical transmission medium 920, and a photoelectric conversion unit 930. The input of the electro-optical conversion unit 910 is connected to the second pulse output of the GNSS navigation module 200 and the clock output of the oven-controlled crystal oscillator module 300. A driving circuit drives a light-emitting diode or laser diode to modulate the electrical pulse into an optical pulse. The optical transmission medium 920 is a multimode or single-mode optical fiber. The photoelectric conversion unit 930 consists of a photodiode, a transimpedance amplifier, and a shaping comparator. It restores the optical pulse to a steeply edged electrical pulse and sends it to the time source reliability decision module 700. Because optical fiber is an electrically insulating medium, there is no conductive path between the circuits on both sides of the isolation boundary, and common-mode transients and ground loop currents are completely blocked. When the GNSS antenna and receiving unit are installed outdoors or far from the host, the optical fiber link also provides lightning protection and supports transmission distances of tens of meters or more. The propagation delay introduced by the optical link is a fixed constant that can be measured during device factory calibration and compensated for by the main control module 100 as a fixed offset, thus not affecting timing accuracy. In a simplified embodiment where size and cost are more critical, the optical signal isolation module 900 can also be implemented using a high-speed digital optical coupler, whose light-emitting device, isolation medium, and light-receiving device are integrated into a single package, suitable for desktop use.

[0033] Figure 3 Another embodiment of the present invention provides a timing device, which includes a main control module 100 (containing a crystal oscillator discipline unit 110), a GNSS navigation module 200 (containing a GNSS navigation unit 210 and a signal conversion unit 220), a temperature-controlled crystal oscillator module 300 (containing a temperature-controlled crystal oscillator 310), an RTC crystal oscillator module 400 (containing an RTC crystal oscillator 410), a temperature-compensated crystal oscillator module 450 (containing a temperature-compensated crystal oscillator 460), a network timing module 500 (containing an Ethernet PHY chip 510, an RJ45 network interface 520, and a network time receiving unit 540), a power supply module 600 (containing an input power supply 610 and a voltage regulator 620), a time source reliability decision module 700, an isolated power supply module 800, an optical signal isolation module 900, a display module 1000, and a configuration interface module 1100.

[0034] The GNSS navigation unit 210 is a multi-system satellite receiver that can simultaneously receive GPS and BeiDou signals to improve availability. Its first output terminal outputs a second pulse signal, and its second output terminal outputs a serial time message. The signal conversion unit 220 adapts the level and format of the message signal to a form that the main control module 100 can directly receive. Its specific implementation can be a level converter, an isolated transceiver, or a serial-to-parallel conversion circuit. This invention does not limit this.

[0035] The Oven-Operated Crystal 310, Temperature-Compensated Crystal 460, and RTC Crystal 410 form a three-tiered backup clock system with decreasing accuracy, power consumption, and cost: Oven-Operated Crystal 310: Maintains the quartz crystal at a constant temperature near the inflection point of its frequency-temperature characteristic curve through a temperature-controlled bath, resulting in significantly better short-term stability (seconds) and daily aging rate than other types of oscillators; Temperature-Compensated Crystal 460: Relies on an internal compensation network to maintain frequency accuracy on the order of one part per million throughout the entire operating temperature range, with power consumption and cost far lower than Oven-Operated Crystals; RTC Crystal 410: A 32.768kHz tuning fork crystal, specifically designed for low-power timekeeping.

[0036] The crystal oscillator discipline unit 110 forms a digital phase-locked loop: using the output clock of the oven-controlled crystal oscillator 310 as the counting time base, it captures the rising edge of the second pulse to obtain the phase difference sequence between the two; after the phase difference is filtered by the proportional-integral loop, the digital-to-analog converter generates a voltage-controlled voltage, which is fed back to the voltage-controlled input terminal of the oven-controlled crystal oscillator 310, locking its output frequency to the satellite reference for a long period of time. The loop time constant is set to several hundred seconds or more, on the one hand filtering out the short-term jitter of the satellite signal itself, and on the other hand fully preserving the excellent short-term stability of the oven-controlled crystal oscillator, thus compensating for each other's shortcomings.

[0037] When the satellite signal is lost, the crystal oscillator discipline unit 110 maintains the most recent voltage control value, and the thermostatic crystal oscillator 310 enters a timekeeping state. Furthermore, during the discipline process, the main control module 100 continuously identifies and stores the aging rate and temperature sensitivity coefficient of the thermostatic crystal oscillator 310; during the timekeeping period, the voltage control value is extrapolated and corrected according to the stored model, so that the accumulation of timekeeping error over time is significantly reduced, thereby extending the timekeeping duration for which the device meets the accuracy index under satellite-free conditions.

[0038] In this embodiment, the time source reliability evaluation module 710 generates reliable status words for five types of time sources: GNSS, external network time, temperature-controlled crystal oscillator, temperature-compensated crystal oscillator, and RTC. For multiple time sources that are simultaneously valid, the main control module 100 further compares the mutual deviations of the times they provide, and judges and removes time sources that significantly deviate from the majority of consistent results as abnormal. Through this mutual difference voting mechanism, the output of the device will not be contaminated by any single time source, including spoofed satellite signals or malfunctioning upstream servers, providing incorrect times.

[0039] In the network time synchronization module 500, the Ethernet PHY chip 510 and the RJ45 network interface 520 form a physical transmission channel. The main control module 100 runs the NTP server protocol and acts as a primary time server to respond to time synchronization requests from clients within the local area network. The timestamps of the request and response messages are inserted as close as possible to the physical layer to reduce the uncertainty caused by protocol stack processing delays. For applications requiring higher accuracy, it can also simultaneously support the Precision Time Protocol (PTP). The network time receiving unit 540 obtains the network time from the external upper-level NTP server through the same network interface and sends it to the time source reliability evaluation module 710 as a candidate time source for decision-making.

[0040] In the power supply module 600, the input power supply 610 receives input from an external DC power supply or power adapter, and the voltage regulator 620 converts it into one or more sets of working voltages required by the main control module 100 and peripheral circuits; in the isolation power supply module 800, the input terminals of the two isolation power supply units are connected in parallel to the output terminal of the input power supply 610, and the output side of each unit constitutes an independent isolation power supply domain.

[0041] The display module 1000 is an OLED or LCD screen, connected to the main control module 100 via a serial bus and a pluggable connection via a socket. The main control module 100 detects the presence of the display module and drives it as needed. The displayed content includes real-time time, the currently selected time source identifier, the number of visible satellites, and the discipline / timekeeping status. In applications without on-site display requirements, the display module 1000 can be omitted without affecting other functions of the device, thus enabling optional configuration of the display function.

[0042] The configuration interface module 1100 can be a USB virtual serial port circuit, an RS232 interface circuit, or a network configuration channel multiplexed via an RJ45 network interface 520. Users can configure parameters such as time source priority tables, various detection thresholds, hysteresis intervals and retracement confirmation durations, NTP service parameters, and display options in the desktop software of the host computer. After attaching a checksum to the parameters, they are written to the non-volatile memory of the main control module 100 via the configuration interface module 1100 and take effect upon device power-on. The main control module 100 can also transmit the real-time status of each time source back to the host computer software via this interface for monitoring, thereby realizing desktop-based programmable configuration and management of the device.

[0043] The timing device of this invention adopts a modular architecture, with each module interconnected via a unified pulse signal interface, message signal interface, and power interface. Therefore, the same architecture can be tailored or expanded into different device forms according to the application scale. Based on this, this application also provides a timing device.

[0044] Figure 4A desktop timing device is shown. This device includes a desktop housing 30 and a timing device 10 as described in Embodiment 1 or Embodiment 2. The modules of the timing device 10 are integrated onto a single circuit board and housed within the housing 30. Its RJ45 network interface, configuration interface, and pluggable display module interface are led out to the surface of the housing 30. In this configuration, the temperature-controlled crystal oscillator module can be omitted or replaced by a temperature-compensated crystal oscillator module, and the optical signal isolation module can be implemented using a high-speed optocoupler, thereby compressing the device into a small desktop timing box suitable for laboratory, small local area network, and other similar applications.

[0045] Figure 5 A rack-mounted timing device is shown. This device includes a standard rack-mount housing 40 (e.g., a 19-inch 1U or 2U chassis), within which a backplane 41 is installed. The modules of the timing device 10 are distributed across multiple function boards and plugged into the backplane 41. Timing board 42: includes GNSS navigation module 200, first isolation power supply unit 810 and corresponding optical signal isolation module 900; Clock board 43: Includes a constant temperature crystal oscillator module 300, a temperature-compensated crystal oscillator module 450, an RTC crystal oscillator module 400, and a second isolated power supply unit 820; Main control decision board 44: Includes a main control module 100 and a time source reliability decision module 700; Time synchronization output board 45: Includes a network time synchronization module 500 and provides multiple RJ45 network interfaces; Power supply board 46: Includes a power supply module 600.

[0046] The pulse signals, message signals and power supplies of each functional board are interconnected via the backplane 41.

[0047] Furthermore, in rack-mount configuration, multiple time source cards 42 and multiple clock cards 43 can be plugged into the backplane 41. The time source on each card is connected to the time source reliability evaluation module 710 to participate in reliability decision-making, thereby achieving redundancy of multiple GNSS antennas and multiple oscillators. The power supply card 46 can be configured as two parallel redundant power supply cards. Multiple timing output cards 45 can be plugged into to expand the number of timing ports, enabling the device to be expanded into a rack-mounted timing server for computer room and data center applications. When any functional card fails, the time source reliability decision module 700 marks the time source on that card as failed and automatically switches to other valid time sources, ensuring that the overall timing output of the device is not interrupted.

[0048] Through the above description of the embodiments, those skilled in the art can clearly understand that each embodiment can be implemented by means of software plus necessary general-purpose hardware platforms, and of course, it can also be implemented by hardware. Based on this understanding, the above technical solutions, in essence or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, magnetic disk, optical disk, etc., and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute the methods described in the various embodiments or some parts of the embodiments.

[0049] This document uses specific examples to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of the present invention. Furthermore, those skilled in the art will recognize that, based on the ideas of the present invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A time synchronization device employing a time source reliability evaluation mechanism, characterized in that, include: Multiple time source modules are used to provide time sources with different sources and precision; The time source reliability decision module includes a time source reliability evaluation module and a time source switching unit; This is used to establish and dynamically update a candidate time source ranking table from best to worst based on the reliability evaluation results output by the time source reliability evaluation module. The candidate time source ranking table is used as a time source reliability decision model, and the current time source is determined based on the time source reliability decision model. When the current time source does not meet the preset reliability conditions, the time source with the best ranking in the candidate time source ranking table is automatically selected. The time source reliability evaluation module is used to execute a unified time source reliability evaluation mechanism: comprehensively acquire the operating status, time signal validity and time signal quality parameters of each time source, and generate the corresponding reliability evaluation results for each time source; When the current time source does not meet the preset reliability conditions, the time source switching unit automatically selects the optimal time source from the candidate time source sorting table. The main control module is connected to the time source reliability decision module and is used to generate and output the time synchronization based on the current time synchronization source.

2. The timing device employing a time source reliability evaluation mechanism according to claim 1, characterized in that, The time source reliability evaluation mechanism detects the validity of the time signal by performing arrival window detection on the second pulse signal, and by verifying the checksum, field validity, positioning validity flag, and number of visible satellites of the time message. The time source reliability evaluation mechanism detects time signal quality by measuring the deviation and dispersion of adjacent second pulse intervals based on a high-stability clock to assess jitter, and by comparing and counting multiple time sources to assess frequency deviation.

3. A timing device employing a time source reliability evaluation mechanism according to claim 1, characterized in that, The reliability evaluation results generated by the time source reliability evaluation module include one or more combinations of reliability level, reliability score and reliability priority.

4. A timing device employing a time source reliability evaluation mechanism according to claim 1, characterized in that, The plurality of time source modules include at least: GNSS navigation module, used to provide a GNSS navigation time source with a standard time reference; Thermostatic crystal oscillator module is used to provide a thermostatic crystal oscillator time source with a high stability time reference; RTC crystal oscillator module, used to provide a low-power local time base RTC time source when an external time source is unavailable; The network time synchronization module obtains network time sources via NTP or PTP protocols; all time sources are input and participate in the time source reliability evaluation mechanism.

5. A timing device employing a time source reliability evaluation mechanism according to claim 4, characterized in that, The GNSS navigation time source and the temperature-controlled crystal oscillator time source are powered by independent isolated power supply units. The time signals output by the GNSS navigation time source and the isothermal crystal oscillator time source are transmitted to the main control module and the time source reliability evaluation module via an optical signal isolation module.

6. A timing device employing a time source reliability evaluation mechanism according to claim 1, characterized in that, The time source reliability decision module adopts a hysteresis interval strategy when switching time sources, that is, setting different deterioration thresholds and recovery thresholds; when a high-priority time source recovers from a failed or deteriorated state, it maintains the effective state for a preset confirmation time before switching back to the high-priority time source. During the switching process, the main control module gradually pulls the local time at a limited rate to ensure that the output time is continuous and without abrupt changes.

7. A timing device employing a time source reliability evaluation mechanism according to claim 1, characterized in that, The main control module has a built-in mutual difference voting mechanism. When multiple time sources are in a valid state at the same time, the main control module compares the mutual deviation of the output times of each time source, removes abnormal time sources whose deviation exceeds a preset threshold from the candidate queue, and then selects based on the reliability evaluation results of the remaining time sources.

8. A timing device employing a time source reliability evaluation mechanism according to claim 1, characterized in that, The device also includes a crystal oscillator discipline unit, which is located within the main control module; the crystal oscillator discipline unit uses the standard time signal output by the GNSS navigation time source as a reference and performs frequency calibration on the isothermal crystal oscillator time source through a digital phase-locked loop; When the GNSS navigation time source is lost, the crystal oscillator discipline unit maintains the most recent voltage control value and extrapolates and corrects the voltage control value based on the pre-stored model of the isothermal crystal oscillator aging rate and temperature sensitivity coefficient, so as to maintain the timekeeping accuracy of the isothermal crystal oscillator time source.

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