UWB time synchronization system, method and device based on one-way broadcast mode

Abstract

The invention relates to a UWB time synchronization system, method and device based on a one-way broadcast mode. The system comprises a reference node and a child node, wherein the reference node and the child node comprise a chip atomic clock, a frequency synthesizer, a UWB radio frequency chip and a main controller; the main controller of the reference node is used for controlling the UWB radio frequency chip to generate broadcast data with a reference timestamp according to a 1PPS signal output by the chip atomic clock, and the UWB radio frequency chip sends the broadcast data to the child node; uWB radio frequency chips of the child nodes receive broadcast data and send receiving timestamps and reference timestamps to main controllers of the child nodes, and the main controllers calculate frequency differences according to the accumulated receiving timestamps and the reference timestamps and conduct PID dynamic calibration on chip atomic clock frequencies of the child nodes according to the frequency differences. And calculating and calibrating the time difference according to the receiving timestamp and the sending timestamp. By adopting the system, the reliability and continuity of time synchronization can be improved.

Description

Technical Field

[0001] The present application relates to the field of wireless communication technology, and in particular to a UWB time synchronization system, method and device based on a unidirectional broadcast mode. Background Art

[0002] Time synchronization technology plays a key role in modern distributed systems and Internet of Things applications, and is widely used in wireless sensor networks, drone clusters, smart manufacturing, and smart transportation. Current time synchronization methods are mainly divided into methods based on wireless communication protocols (such as Bluetooth, Wi-Fi, Zigbee, etc.) and high-precision time synchronization technologies that rely on satellite navigation systems.

[0003] In the Bluetooth-based time synchronization scheme, the Bluetooth periodic two-way communication signal is usually used to achieve the transmission and alignment of the timestamp. This scheme can generally achieve a synchronization accuracy of 10 to 100 microseconds, but the accuracy may be affected by factors such as channel delay and transmission interval. Through protocol improvements or the addition of timestamp correction technology, the accuracy of Bluetooth synchronization can be up to 10 microseconds.

[0004] Wi-Fi time synchronization methods include time synchronization schemes based on the IEEE 802.11 protocol and timestamp mutual transmission mechanisms based on the MAC layer. Compared with Bluetooth, Wi-Fi time synchronization has higher accuracy, generally reaching an accuracy of 1 to 10 microseconds. In a local network, through precise timestamp recording and a high-frequency correction mechanism, the accuracy of Wi-Fi time synchronization can reach sub-microseconds.

[0005] High-precision time synchronization methods based on satellite navigation systems (such as GPS, GLONASS, BeiDou, etc.) are widely used in distributed systems with extremely high precision requirements. This method uses high-precision clocks on satellites to provide Universal Time Coordinated (UTC) signals. Ground devices achieve nanosecond-level time synchronization by receiving timestamp information from multiple satellites and eliminating signal propagation delays. Although atmospheric interference and multipath effects may affect the reception accuracy, reliable high-precision synchronization can still be ensured through time correction and anti-interference algorithms. It is suitable for scenarios that require strict synchronization, such as power systems, communication base stations, and financial systems. However, in denied environments such as indoors and underground, time synchronization and communication coordination between devices become extremely difficult due to the loss or interference of external signals. This is particularly critical for distributed systems, especially in application scenarios with strict requirements on time synchronization accuracy (such as drone cluster collaboration and intelligent transportation), which will lead to reduced efficiency and reliability of the collaborative system. Summary of the invention

[0006] Based on this, it is necessary to provide a UWB time synchronization system, method and device based on a unidirectional broadcast mode to address technical problems such as the inability to use in the above-mentioned denied environment, low time synchronization accuracy, and resource consumption of two-way communication.

[0007] A UWB time synchronization system based on a unidirectional broadcast mode, the system comprising: A reference node and a subnode, wherein the reference node and the subnode include a chip atomic clock, a frequency synthesizer, a UWB radio frequency chip and a main controller; the main controller is connected to the chip atomic clock and the UWB radio frequency chip respectively; The UWB radio frequency chip is connected to the chip atomic clock; The frequency synthesizer is connected to the chip atomic clock and the UWB radio frequency chip respectively, and is used to convert the 10 MHz signal provided by the chip atomic clock into a standard time signal of the UWB radio frequency chip; On the reference node, the main controller of the reference node controls the UWB radio chip to generate broadcast data with a reference timestamp according to the 1PPS signal output by the chip atomic clock, and the UWB radio chip sends the broadcast data to the child node; On the child node, the UWB RF chip of the child node receives the broadcast data and sends the receiving timestamp and the reference timestamp to the main controller of the child node. It is triggered by the 1PPS signal output by the chip atomic clock, sends an empty data packet and sends the sending timestamp to the main controller of the child node. The main controller calculates the frequency difference based on the accumulated receiving timestamps and the reference timestamps, performs PID dynamic calibration on the chip atomic clock frequency of the child node based on the frequency difference, calculates and calibrates the time difference based on the receiving timestamp and the sending timestamp to achieve time synchronization.

[0008] A UWB time synchronization method based on a unidirectional broadcast mode, the method comprising: Generate broadcast data with reference timestamp through reference node and send it to child nodes; The sub-node receives the broadcast data and extracts the reference timestamp, sends an empty data packet, calculates the frequency difference based on the accumulated received timestamp and the reference timestamp, performs PID dynamic calibration on the chip atomic clock frequency of the sub-node based on the frequency difference, calculates and calibrates the time difference based on the received timestamp and the sent timestamp, and realizes time synchronization.

[0009] A UWB time synchronization device based on a unidirectional broadcast mode, the device comprising: Chip atomic clock, frequency synthesizer, UWB radio frequency chip and main controller; The chip atomic clock is used to provide a time reference signal to the frequency synthesizer and the main controller; the time reference signal includes a 10 MHz signal and a 1PPS signal; The frequency synthesizer is used to convert the 10 MHz signal into a standard time signal and send it to the UWB radio frequency chip; The UWB radio frequency chip uses the standard time signal as the working frequency source, is used to send broadcast data to the child node when the device is used as a reference node, and is used to receive broadcast data and send the receiving timestamp and the reference timestamp to the main controller when the device is used as a child node, and send an empty data packet and obtain the sending timestamp and send it to the main controller at the same time; The main controller is used to control the UWB radio frequency chip to generate broadcast data with a reference timestamp and transmit it to the child node according to the 1PPS signal when the device acts as a reference node, and is used to calculate the frequency difference according to the accumulated reception timestamp and the reference timestamp when the device acts as a child node, perform PID dynamic calibration on the chip atomic clock frequency of the child node according to the frequency difference, calculate and calibrate the time difference according to the reception timestamp and the transmission timestamp, and realize time synchronization.

[0010] The above-mentioned UWB time synchronization system, method and device based on the unidirectional broadcast mode provide a high-stability time reference signal through the chip atomic clock, and the frequency synthesizer ensures the reliability of UWB communication. The reference node sends the timestamp through unidirectional broadcast without the need for the child node to respond, thereby reducing communication conflicts. In addition, the high-frequency bandwidth characteristics of UWB are utilized to enhance the anti-interference capability, and efficient and conflict-free time synchronization is achieved in multi-node scenarios, adapting to the communication needs of complex environments, and having strong scalability. The UWB radio frequency chip of the child node receives the broadcast timestamp of the reference node, and records the received timestamp at the same time. Through the trigger signal output by its own chip atomic clock, an empty data packet is generated and sent, and the sent timestamp is recorded at the same time. The frequency difference is calculated based on the received timestamp and the reference timestamp, and the frequency of the chip atomic clock is dynamically adjusted through PID control to eliminate the accumulated error in real time. The time difference is calculated based on the received timestamp and the sent timestamp, and the precise clock reference after the frequency difference calibration is used to fine-tune the own time reference according to the phase calibration mechanism to eliminate the phase deviation, thereby achieving high-precision synchronization under long-term operation, avoiding inaccuracy caused by error accumulation, improving the reliability and sustainability of time synchronization, and ensuring efficient and stable system operation through rigorous system operation logic. The embodiments of the present invention can achieve nanosecond-level time synchronization, providing reliable protection for applications with strict time requirements (such as drone cluster collaboration and intelligent transportation). BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 is a structural block diagram of a UWB time synchronization system based on a unidirectional broadcast mode in one embodiment; Figure 2 A schematic diagram of the communication process between a reference node and a sub-node in one embodiment; Figure 3 A schematic diagram of the overall operation logic of the system in one embodiment; Figure 4 A schematic diagram of actual operation results of a UWB time synchronization system in an embodiment; Figure 5 FIG. 4 is a structural block diagram of a UWB time synchronization device based on a unidirectional broadcast mode in an embodiment. DETAILED DESCRIPTION

[0012] In order to make the purpose, technical solution and advantages of the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0013] In one embodiment, Figure 1 As shown, a UWB time synchronization system based on a unidirectional broadcast mode is provided, comprising: A reference node and a subnode, wherein the reference node and the subnode include a chip atomic clock, a frequency synthesizer, a UWB radio frequency chip and a main controller; the main controller is respectively connected to the chip atomic clock and the UWB radio frequency chip; the UWB radio frequency chip is connected to the chip atomic clock; The frequency synthesizer is connected to the chip atomic clock and the UWB radio frequency chip respectively, and is used to convert the 10 MHz signal provided by the chip atomic clock into a standard time signal of the UWB radio frequency chip; On the reference node, the main controller of the reference node controls the UWB radio chip to generate broadcast data with a reference timestamp according to the 1PPS signal output by the chip atomic clock, and the UWB radio chip sends the broadcast data to the child node; On the child node, the UWB RF chip of the child node receives the broadcast data and sends the receiving timestamp and the reference timestamp to the main controller of the child node. It is triggered by the 1PPS signal output by the chip atomic clock, sends an empty data packet and sends the sending timestamp to the main controller of the child node. The main controller calculates the frequency difference based on the accumulated receiving timestamps and the reference timestamps, performs PID dynamic calibration on the chip atomic clock frequency of the child node based on the frequency difference, calculates and calibrates the time difference based on the receiving timestamp and the sending timestamp to achieve time synchronization.

[0014] In this embodiment, the chip atomic clock is responsible for providing stable time reference signals, including 10 MHz and 1 PPS (pulse per second) signals. Among them, the 1 PPS signal provides a tick signal per second for the main controller to ensure the basic time scale of the system. The 10 MHz signal is converted to 38.4 MHz via a frequency synthesizer as the operating frequency source of the UWB RF chip to meet the frequency requirements of the UWB chip.

[0015] During system operation, the UWB radio chip will generate an interrupt when sending or receiving a broadcast signal, and transmit the corresponding sending timestamp or receiving timestamp to the main controller via SPI (serial peripheral interface). The main controller performs operations based on the received timestamp to calculate the system's time offset to adjust the device's time synchronization accuracy in real time. The main controller then feeds back the calculation results to the chip atomic clock via the RS232 interface to calibrate its frequency, thus achieving closed-loop control of the hardware solution.

[0016] In the above-mentioned UWB time synchronization method based on the unidirectional broadcast mode, a high-stability time reference signal is provided by the chip atomic clock, and the frequency synthesizer ensures the reliability of UWB communication. The reference node sends the timestamp through unidirectional broadcasting without the need for the child node to respond, thereby reducing communication conflicts. In addition, the high-frequency bandwidth characteristics of UWB are utilized to enhance the anti-interference capability, and efficient and conflict-free time synchronization is achieved in multi-node scenarios, adapting to the communication needs of complex environments, and having strong scalability. The UWB radio frequency chip of the child node receives the broadcast timestamp of the reference node, and records the receiving timestamp at the same time. Through the trigger signal output by its own chip atomic clock, an empty data packet is generated and sent, and the sending timestamp is recorded at the same time. The frequency difference is calculated based on the receiving timestamp and the reference timestamp, and the frequency of the chip atomic clock is dynamically adjusted through PID control to eliminate the accumulated error in real time. The time difference is calculated based on the receiving timestamp and the sending timestamp, and the precise clock reference after the frequency difference calibration is used. The own time reference is fine-tuned according to the phase calibration mechanism to eliminate the phase deviation, thereby achieving high-precision synchronization under long-term operation, avoiding inaccuracy caused by error accumulation, improving the reliability and sustainability of time synchronization, and ensuring efficient and stable system operation through rigorous system operation logic. The embodiments of the present invention can achieve nanosecond-level time synchronization, providing reliable protection for applications with strict time requirements (such as drone cluster collaboration and intelligent transportation).

[0017] In one embodiment, a frequency difference is calculated based on the accumulated receiving timestamps and the reference timestamps, and a PID dynamic calibration is performed on the chip atomic clock frequency of the child node based on the frequency difference, including: calculating the receiving time interval between two broadcasts based on the receiving timestamp of the received broadcast data, calculating the reference time interval of the corresponding two reference timestamps, and obtaining the frequency error ratio based on the receiving time interval and the reference time interval; calculating the frequency difference based on the frequency error ratio, and performing the PID dynamic calibration on the chip atomic clock frequency of the child node based on the frequency difference; calculating and calibrating the time difference based on the receiving timestamp and the sending timestamp, including: calculating the time difference between nodes based on the receiving timestamp of the received broadcast data and the sending timestamp of the sent empty data packet; extracting the phase offset of the child node based on the time difference, and performing phase calibration by adjusting the phase offset.

[0018] Specifically, the node communication process is as follows: Figure 2The child node calculates the frequency ratio of the two reference node broadcast data and estimates the error of its local clock frequency relative to the reference node clock frequency, as shown in formula (1).

[0019] (1) in represents the reference node frequency, Indicates the frequency of this node, Indicates The timestamp of the node broadcast packet is referenced at all times. Indicates The sub-node receives the timestamp of the reference node broadcast time. From this, we can also get the time difference between nodes. The calculation formula is shown in formula (2).

[0020] (2) in, Indicates When the sub-node sends the timestamp of the empty data packet, after obtaining the clock time difference and frequency difference data, the chip atomic clock can be dynamically calibrated through PID. The calibration formula is shown in formula (3).

[0021] (3) in Indicates the clock parameters that need to be adjusted. is the proportional gain, is the current time difference Produces a correction quantity, The integral gain integrates the accumulated error of the past time to eliminate the continuous deviation in long-term operation. is the differential gain, which is adjusted according to the rate of change of the time error (i.e. the derivative of the error). The differential term can predict the trend of the error change, allowing the system to make adjustments in advance when the error changes rapidly to avoid large offsets.

[0022] In one embodiment, the chip atomic clock is used to provide a time reference signal to a frequency synthesizer and a main controller; the time reference signal includes a 10 MHz signal and a 1 PPS signal.

[0023] In one embodiment, the standard time signal of the UWB radio frequency chip is a 38.4 MHz signal.

[0024] In one embodiment, the system further comprises: after power-on, initializing the chip atomic clock, frequency synthesizer and UWB radio frequency chip of the reference node and the sub-node in sequence.

[0025] The overall operation logic of the system is as follows Figure 3As shown. After the device is started, the initialization process is first performed. To ensure the accurate start of the time signal, the initialization activates the chip atomic clock, frequency synthesizer and UWB radio frequency chip in sequence to ensure the unity of the time base between each module. After the initialization is completed, the device will detect whether it is a reference node. The main function of the reference node is to periodically send broadcast data with precise timestamps for other sub-nodes to synchronize. After receiving the timestamp of the reference node, the sub-node calculates the deviation between its own time and the reference time by sending an empty data packet triggered by PPS, and compensates and calibrates accordingly, thereby achieving accurate time synchronization.

[0026] Specifically, the process on the left describes the initialization of the hardware module to ensure that the system has working conditions. The system detects whether the device has completed power-on startup. After power-on, the chip atomic clock is initialized. If the initialization fails, the system needs to try again. After the chip atomic clock is successfully initialized, the frequency synthesizer and UWB radio frequency chip are initialized in turn. After successful initialization, the system enters the running state. The system's 1PPS (pulse per second signal) is used to trigger the UWB radio frequency chip clock reset to ensure that the module's time synchronization benchmark is consistent. The process on the right details how the reference node and the sub-node complete broadcasting, monitoring, time calibration and frequency calibration during operation, forming a complete time synchronization closed-loop system. The reference node broadcasts the timestamp according to the PPS signal triggered every second, and ensures the reliability of the broadcast through anti-collision calculation; the sub-node monitors the broadcast information, and after receiving the timestamp of the reference node, it confirms the validity of the data by sending a receipt message. Subsequently, the sub-node is triggered by the PPS signal, actively sends an empty data packet, and uses the received timestamp and its own sending timestamp to dynamically calibrate the frequency error of the chip atomic clock through the PID controller, and finally performs phase difference calibration to ensure high-precision time synchronization with the reference node. The entire process runs in a cycle to achieve continuous synchronization and dynamic adjustment of the system.

[0027] In a specific embodiment, a UWB time synchronization system is built according to the time synchronization system architecture of the present invention. The clock crystal oscillator adopts SA.45s, outputs 10 MHz signal and 1 PPS signal, and the short-term stability is 2.5 within the 1 s average period. 10 -10 , long-term aging is less than 9 per month 10 -10 , the maximum frequency change is 5 within the temperature range of -10 to 35 degrees Celsius 10 -10. It can be digitally servo-adjusted via a serial interface. The frequency synthesizer uses the low-jitter LMX2571, which converts the 10 MHz clock signal into the 38.4 MHz signal required by the UWB module. The UWB module uses the DW1000 chip, which is an integrated ultra-wideband, low-power, and low-cost UWB signal transceiver chip with high-precision ranging and data transmission capabilities. It can extract the timestamp of the arrival time of the data packet at a resolution of 15.6 ps, and the measurement accuracy is better than 10 cm. The main processor uses the Kinetis K22F, which is a high-performance, low-power microcontroller based on the ARM Cortex-M4 core, running at a frequency of 120 MHz, with 512 KB Flash and 128 KB SRAM, supporting a variety of peripheral interfaces such as USB, UART, SPI, I2C, and built-in hardware encryption and analog signal processing functions.

[0028] The present invention conducted experiments on the UWB time synchronization system built by using 5 nodes to build the UWB time synchronization system. Each node informed the adjacent node of its current timestamp through broadcasting. The node compensated according to the acquired time difference. The node time slot was 1 s, the parameter sampling period was 1 s, and 300 samples were taken. The experiment checked the clock synchronization effect by measuring the 1PPS output signal of the atomic clock of each node. Figure 4 is the time difference between each node and node 1. From the results, it can be seen that after about 100 synchronizations, each node achieves time synchronization, the time difference tends to be stable relative to the reference node 1, and the time difference range is less than 8 ns, which can meet the requirements of nanosecond time synchronization.

[0029] The present invention realizes high-precision time synchronization at the nanosecond level through the combination of hardware and software algorithms, and is suitable for distributed systems in denied environments such as indoors. Compared with the problem of limited accuracy of traditional time synchronization methods in environments such as indoors where signals are blocked or interfered with seriously, the present invention can achieve stable time synchronization in these environments. At the same time, compared with other synchronization methods in denied environments, the present invention can achieve high-precision nanosecond synchronization. The precise time base signal provided by the chip atomic clock, combined with the characteristics of UWB high-frequency bandwidth and PID dynamic calibration algorithm, enables the system to achieve nanosecond time synchronization. This high precision provides reliable protection for applications with strict time requirements. In addition, using the PID control algorithm, the system can dynamically adjust the chip atomic clock according to the current time deviation and historical deviation. This mechanism ensures that the system can compensate for time offset and frequency drift at any time and maintain long-term synchronization accuracy. Compared with other two-way communication time synchronization systems, the present invention reduces the consumption of communication resources, and obtains synchronization performance consistent with the two-way communication system through rigorous transceiver logic.

[0030] In one embodiment, a UWB time synchronization method based on a unidirectional broadcast mode is provided, and the specific steps include: Generate broadcast data with reference timestamp through reference node and send it to child nodes; The sub-node receives the broadcast data and extracts the reference timestamp, sends an empty data packet, calculates the frequency difference based on the accumulated received timestamp and the reference timestamp, performs PID dynamic calibration on the chip atomic clock frequency of the sub-node based on the frequency difference, calculates and calibrates the time difference based on the received timestamp and the sent timestamp, and realizes time synchronization.

[0031] In one embodiment, Figure 5 As shown, a UWB time synchronization device based on a one-way broadcast mode is provided, including: a chip atomic clock, a frequency synthesizer, a UWB radio frequency chip and a main controller; The chip atomic clock is used to provide time reference signals to the frequency synthesizer and the main controller; the time reference signals include 10 MHz signals and 1PPS signals; The frequency synthesizer is used to convert the 10 MHz signal into a standard time signal and send it to the UWB radio chip; The UWB radio frequency chip uses the standard time signal as the working frequency source, and is used to send broadcast data to the sub-node when the device is used as a reference node, and is used to receive broadcast data and send the receiving timestamp and the reference timestamp to the main controller when the device is used as a sub-node, and send an empty data packet and obtain the sending timestamp and send it to the main controller; The main controller is used to control the UWB radio frequency chip to generate broadcast data with a reference timestamp and transmit it to the child node according to the 1PPS signal when the device acts as a reference node, and is used to calculate the frequency difference according to the accumulated reception timestamp and the reference timestamp when the device acts as a child node, perform PID dynamic calibration on the chip atomic clock frequency of the child node according to the frequency difference, calculate and calibrate the time difference according to the reception timestamp and the transmission timestamp, and realize time synchronization.

[0032] For the specific definition of the UWB time synchronization device based on the unidirectional broadcast mode, please refer to the definition of the UWB time synchronization system based on the unidirectional broadcast mode above, which will not be repeated here. Each module in the above-mentioned UWB time synchronization device based on the unidirectional broadcast mode can be implemented in whole or in part by software, hardware and a combination thereof. The above-mentioned modules can be embedded in or independent of the processor in the computer device in the form of hardware, or can be stored in the memory of the computer device in the form of software, so that the processor can call and execute the operations corresponding to the above modules.

[0033] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0034] The above-described embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention. It should be pointed out that, for a person of ordinary skill in the art, several modifications and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the attached claims.

Claims

1. A UWB time synchronization system based on a one-way broadcast mode, characterized in that: The system includes a reference node and a subnode, wherein the reference node and the subnode include a chip atomic clock, a frequency synthesizer, a UWB radio frequency chip and a main controller; the main controller is respectively connected to the chip atomic clock and the UWB radio frequency chip; the UWB radio frequency chip is connected to the chip atomic clock; The frequency synthesizer is connected to the chip atomic clock and the UWB radio frequency chip respectively, and is used to convert the 10 MHz signal provided by the chip atomic clock into a standard time signal of the UWB radio frequency chip; On the reference node, the main controller of the reference node controls the UWB radio chip to generate broadcast data with a reference timestamp according to the 1PPS signal output by the chip atomic clock, and the UWB radio chip sends the broadcast data to the child node; On the child node, the UWB RF chip of the child node receives the broadcast data and sends the receiving timestamp and the reference timestamp to the main controller of the child node. It is triggered by the 1PPS signal output by the chip atomic clock, sends an empty data packet and sends the sending timestamp to the main controller of the child node. The main controller calculates the frequency difference based on the accumulated receiving timestamps and the reference timestamps, performs PID dynamic calibration on the chip atomic clock frequency of the child node based on the frequency difference, calculates and calibrates the time difference based on the receiving timestamp and the sending timestamp to achieve time synchronization.

2. The system according to claim 1, characterized in that The frequency difference is calculated based on the accumulated receiving timestamp and the reference timestamp, and the PID dynamic calibration of the chip atomic clock frequency of the child node is performed based on the frequency difference, including: Calculate the receiving time interval between two broadcasts according to the receiving timestamp of the received broadcast data, calculate the reference time interval between the two corresponding reference timestamps, and calculate the frequency error ratio according to the receiving time interval and the reference time interval; The frequency difference is calculated according to the frequency error ratio, and the PID dynamic calibration of the chip atomic clock frequency of the sub-node is performed according to the frequency difference.

3. The system according to claim 1, characterized in that Calculate the time difference and calibrate based on the receiving timestamp and sending timestamp, including: The time difference between nodes is calculated based on the receiving timestamp of the received broadcast data and the sending timestamp of the sent empty data packet; The phase offset of the subnode is extracted according to the time difference, and the phase calibration is performed by adjusting the phase offset.

4. The system according to claim 1, characterized in that The system further comprises: After power-on, the chip atomic clock, frequency synthesizer and UWB radio frequency chip of the reference node and sub-node are initialized in turn.

5. The system according to claim 1, characterized in that The chip atomic clock is used to provide a time reference signal to a frequency synthesizer and a main controller; the time reference signal includes a 10 MHz signal and a 1 PPS signal.

6. The system according to claim 1, characterized in that The standard time signal of the UWB radio frequency chip is a 38.4 MHz signal.

7. A UWB time synchronization method implemented in a UWB time synchronization system based on a unidirectional broadcast mode as claimed in any one of claims 1 to 6, characterized in that: The method comprises: Generate broadcast data with reference timestamp through reference node and send it to child nodes; The sub-node receives the broadcast data and extracts the reference timestamp, sends an empty data packet, calculates the frequency difference based on the accumulated received timestamp and the reference timestamp, performs PID dynamic calibration on the chip atomic clock frequency of the sub-node based on the frequency difference, calculates and calibrates the time difference based on the received timestamp and the sent timestamp, and realizes time synchronization.

8. A UWB time synchronization device of a UWB time synchronization system based on a unidirectional broadcast mode, characterized in that: The device includes a chip atomic clock, a frequency synthesizer, a UWB radio frequency chip and a main controller; The chip atomic clock is used to provide a time reference signal to the frequency synthesizer and the main controller; the time reference signal includes a 10 MHz signal and a 1PPS signal; The frequency synthesizer is used to convert the 10 MHz signal into a standard time signal and send it to the UWB radio frequency chip; The UWB radio frequency chip uses the standard time signal as the working frequency source, is used to send broadcast data to the child node when the device is used as a reference node, and is used to receive broadcast data and send the receiving timestamp and the reference timestamp to the main controller when the device is used as a child node, and send an empty data packet and obtain the sending timestamp and send it to the main controller at the same time; The main controller is used to control the UWB radio frequency chip to generate broadcast data with a reference timestamp and transmit it to the child node according to the 1PPS signal when the device acts as a reference node, and is used to calculate the frequency difference according to the accumulated reception timestamp and the reference timestamp when the device acts as a child node, perform PID dynamic calibration on the chip atomic clock frequency of the child node according to the frequency difference, calculate and calibrate the time difference according to the reception timestamp and the transmission timestamp, and realize time synchronization.

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