A design method of marine master-slave clock based on mixed signal system

Abstract

The application discloses a marine master-slave clock design method based on a mixed signal system, uses 220V alternating current to replace a traditional 24V power supply master-slave clock system, replaces a traditional serial port time service communication master-slave clock system by modulating a time service communication signal in a 220V marine lighting power grid, and realizes that a master clock distributes standard time information to each slave clock. Through the above design, the defect of insufficient load capacity of the traditional master clock is solved from the root, the demand for voltage and signal strength in the front end is avoided, meanwhile, a large number of serial port cables do not need to be additionally laid out, and the reliability and economy of the master-slave clock system are greatly improved. The technical scheme disclosed by the application can be used for distributing standard time information of satellite navigation, short wave and Loran-C and other devices received by a marine master-slave clock to positions needing time display on the whole ship, and providing continuous and unified time display services for personnel on the whole ship.

Description

Technical Field

[0001] This invention relates to a design method for a marine master-slave clock that simultaneously utilizes power line carrier timing technology and serial port timing technology, belonging to the field of marine navigation timekeeping equipment. Background Technology

[0002] Individual quartz crystal clocks typically accumulate errors due to variations in their operating environment and assembly processes. Consequently, time synchronization issues inevitably arise among individual clocks installed on the same ship, requiring regular calibration by the crew, which is extremely inconvenient. A ship has a high requirement for consistent time across all its compartments, and this timeframe needs to be quickly adjusted according to its time zone. Therefore, using only individual high-precision clocks and satellite navigation synchronization for each individual clock is impractical and inefficient. Thus, in the marine industry, a high-precision, highly reliable, and highly consistent master-slave clock system is typically deployed.

[0003] In the field of shipbuilding, a clock system consisting of a master clock and multiple slave clocks is called a master-slave clock system [1]. Its main advantage over a single clock is that the master clock can directly receive standard time and location information provided by satellite navigation equipment and other timing equipment, while multiple slave clocks receive the time information broadcast by the master clock through a serial port to provide continuous and unified time display for users on board. When the ship's latitude and longitude change, the master clock can adjust the time zone in a timely manner according to the location information provided by the satellite navigation equipment and uniformly distribute it to all slave clocks on board. At the same time, the master-slave clock system reduces the demand for the independent timekeeping capability of slave clocks by using the master clock to calibrate the slave clocks, which greatly improves the cost-effectiveness of the master-slave clock system.

[0004] Figure 1The traditional shipboard master-slave clock system architecture is presented, where the master clock and slave clocks are connected via serial cables to synchronously transmit 1pps+TOD timing signals and 24V DC power. This architecture suffers from three significant drawbacks: First, the number of serial ports on the master clock is limited, and each port is constrained by its drive capability, typically supporting no more than 20 slave clocks. For larger ships with numerous working compartments, the slave clock capacity of a single master clock is insufficient. Second, considering the impedance of long-distance cables leading to signal and power attenuation, slave clocks connected to the end of a single serial port are prone to insufficient voltage and signal loss. The current main solution is to increase the output voltage and signal strength of the serial port on the master clock to overcome signal and power attenuation at the end. However, this solution also results in excessively high input voltage for slave clocks connected to the front end, leading to a high failure rate over long-term use. Third, the current system uses serial cables for both timing and power supply, requiring significant cable consumption during shipboard installation. For larger ships, this presents particularly significant drawbacks in terms of economy and installation complexity.

[0005] Power line communication (PLC) technology has been extensively studied in the Internet of Things (IoT) field. With the development of signal processing technology, PLC is widely regarded as an important digital communication method to replace dedicated networks in fields such as building automation, smart homes, office automation, and remote meter reading [2]. Power line communication (PLC) [3] [5] is a special communication technology that uses power lines as a medium for data transmission. The basic idea of ​​this technology is: the input end modulates the original signal onto a high-frequency carrier wave, and then connects it to the power line for transmission through a coupling circuit; the output end decouples the corresponding high-frequency signal on the power line through a coupler, and then restores and separates it through a modem to obtain the original data information; finally, it is transmitted to various terminal devices in the system network for control. As an emerging communication technology, the biggest feature of PLC is its ability to utilize existing power lines for data signal transmission; theoretically, data signal transmission can be achieved using only a 220V AC power line.

[0006] References

[0007] [1] Huang Guoxiong, Zhuang Qianbo, Yin Wentao. Design and implementation of network time synchronization system based on ship clock signal. [2] Zhang Baohui, Liu Haitao, Chen Changde. Concept and key technologies of "four-network integration" of telephone, computer, television and power grid [J]. Proceedings of the Chinese Society for Electrical Engineering, 2001, 21(2): 60-65. [3] Peng Zhichao. Simulation study on network security situational awareness of power line carrier communication based on improved Markov algorithm [J]. Electrical Automation, 2024, 46(2): 80 82. [4] Yang Ting, He Ziyang, Sun Zhaoshuai, et al. Research on cross-layer resource allocation algorithm for broadband power line carrier communication for concurrent multi-service [J]. Power System Technology, 2021, 45(8): 3257 3267. [5] Shen Hongtao, Li Fei, Shi Lun, et al. Data fusion algorithm for power line carrier communication based on minimum spanning tree routing [J]. Journal of Terahertz Science and Electronic Information, 2023, 21(8): 1002 1006. Summary of the Invention The technical problem this invention aims to solve is as follows: Existing marine master-slave clocks generally consist of a master clock and several slave clocks. The master clock receives standard time information provided by satellite navigation equipment and other timing devices, while the slave clocks receive the time information broadcast by the master clock via serial ports, providing continuous and unified time display for users on board. In traditional marine master-slave clock arrangements, the master clock and slave clocks are connected via serial lines to synchronously transmit 1pps+TOD timing signals and 24V DC power. The load capacity of a single serial line is limited, and the number of slave clocks typically does not exceed 20. On board, the impedance of long-distance cables will cause attenuation of power supply and timing signals. Slave clocks mounted at the end of a single serial port are prone to insufficient voltage and signal loss. Existing solutions increase the output voltage and signal strength of the serial port at the master clock end to offset the signal attenuation caused by transmission distance. However, this technology has the disadvantage of increasing the input voltage of the slave clocks mounted at the front end, leading to a high failure rate of some slave clocks mounted at the front end after long-term use.

[0008] To address the aforementioned technical problems, the present invention discloses a design method for a marine master-slave clock based on a hybrid signal system. The method is characterized by using 220V AC power instead of the traditional 24V power supply for the master-slave clock system, and replacing the traditional serial port time synchronization master-slave clock system with a time synchronization communication signal modulated in the 220V marine lighting power grid. The slave clocks are functionally divided into general-purpose slave clocks and relay slave clocks. The master clock communicates directly with the relay slave clocks via standard serial communication. After receiving the time synchronization information from the master clock, the relay slave clock converts it through a power communication module and modulates the master clock time synchronization information into the 220V marine lighting power grid. Each general-purpose slave clock connected to the same 220V marine lighting power grid obtains the master clock time information by receiving the power carrier time synchronization signal in the current power grid. Meanwhile, the general-purpose sub-clock modulates parameter information, including its own operating status, into the 220V marine lighting grid and reports it to the relay sub-clock using power line carrier communication. The relay sub-clock then aggregates the parameter information of each general-purpose sub-clock and reports it, along with its own operating status information, to the master clock via a serial port, enabling the master clock to monitor the operating status of each sub-clock.

[0009] Preferably, the master clock communicates and synchronizes with the relay-type slave clock via a direct serial port connection.

[0010] Preferably, the relay-type sub-clock is connected to the general-purpose sub-clock via a power line carrier communication link to form a cascaded loop for communication and time synchronization.

[0011] Preferably, the master clock functional module includes, but is not limited to, a display and control module, a motherboard module, a clock control module, and a slave clock communication module.

[0012] Preferably, the functions of the display and control module include, but are not limited to: responding to user operations and realizing human-machine interface control; having module working status detection, judgment and reporting functions; and having sub-clock working status integrated display function; The functions of the motherboard module include, but are not limited to: performing human-computer interaction functions; displaying the human-computer interaction interface; and summarizing the working status of other modules inside the device. The functions of the clock control module include, but are not limited to: parsing, storing and synchronizing time code information, sending time codes; judging the validity status of the second pulse, synchronizing, judging the synchronization result, and outputting; querying and reporting the lock status and working status of the disciplined crystal oscillator; realizing the function of sending time information and autonomous timekeeping; and detecting, judging and reporting the working status. The functions of the sub-clock communication module include, but are not limited to: parsing and sending time code information; monitoring and managing the working status of the working cabin sub-clock; and having the functions of module working status detection, judgment and reporting.

[0013] Preferably, the slave clock functional module includes, but is not limited to, a time code receiving module, a serial communication module, a power communication module, and a display and control module.

[0014] Preferably, the serial communication module is configured only in the relay-type sub-clock.

[0015] Preferably, the functions of the time code receiving module include, but are not limited to: receiving and processing time synchronization information; The functions of the serial communication module include, but are not limited to: receiving messages from the master clock and sending messages to the master clock; The functions of the power communication module include, but are not limited to: modulation and demodulation of the time signal; and relay enhancement of the power time signal as a relay node. The functions of the display and control module include, but are not limited to: displaying sub-clock time information; responding to user operations and controlling the sub-clock; detecting, judging, and reporting the working status of the sub-clock module; and integrating the display of the working status of the sub-clock.

[0016] Preferably, the marine master-slave clock signal transmission process between the master clock and the slave clock includes the following steps: Step 1: The ship's master clock equipment receives the time signal broadcast by the time synchronization equipment; Step 2: After the master clock receives the time signal, it performs the validity detection, judgment and switching of the time source. After confirming that the time signal is normal, it performs processing work including the discipline, synchronization and maintenance of the temperature compensated crystal oscillator. Step 3: The master clock transmits time information and control commands from the master clock to the relay-type slave clock for synchronization. The relay-type slave clock reports the working status messages of all its subordinate general-purpose slave clocks and itself to the master clock via the serial port. Step 4: After receiving the time signal, the relay-type sub-clock performs the validity detection, judgment and switching of the time source. After confirming that the time signal is normal, it performs processing work including the discipline, synchronization and maintenance of the temperature-compensated crystal oscillator. Step 5: The relay-type slave clock uses the power communication module to modulate the received time information and the control commands from the master clock to the slave clock into the lighting circuit. The general-purpose slave clock uses the power communication module to obtain the time information and control commands from the lighting circuit. After the time delay is compensated by bidirectional communication, it performs processing work including disciplining, synchronizing and maintaining the slave clock crystal oscillator, and synchronously reports its own working status information to the lighting circuit. Step 6: The master clock display and control module interacts with the ship's information system via the network port; Step 7: When the ship is used for cross-time zone navigation, set up dual time zone time and year / month / day display function for all ship relay and general-purpose slave clocks through the master clock display and control interface.

[0017] Preferably, in step 1, the master clock has an autonomous timekeeping function, which allows a time information to be manually input without receiving external time signals, so that the master clock can operate in autonomous timekeeping mode.

[0018] This invention replaces the traditional 24V power supply master-slave clock system with 220V AC power. It replaces the traditional serial port time communication master-slave clock system by modulating a time synchronization communication signal within the 220V marine lighting grid, enabling the master clock to distribute standard time information to each slave clock. This design fundamentally solves the problem of insufficient load capacity in traditional master clocks, avoids increasing voltage and signal strength requirements at the front end, and eliminates the need for extensive additional serial port cabling, significantly improving the reliability and economy of the master-slave clock system. The technical solution disclosed in this invention can be used to distribute standard time information received by the marine master-slave clocks from satellite navigation, shortwave, and Roland-C equipment to all locations on the ship requiring time display, providing continuous and unified time display services for all personnel.

[0019] Compared with existing technical solutions, the present invention has the following beneficial effects: (i) It solves the problem of high failure rate of existing marine master-slave clocks. By using 220V power line carrier timing technology, the original serial communication and 24V DC power supply system are replaced. This avoids the problem of signal attenuation and voltage drop in long-distance transmission that traditional master-slave clocks have to compensate for by increasing the input voltage and signal strength of the slave clock at the front end. This can significantly reduce the failure rate of marine master-slave clocks in the long term.

[0020] (ii) Significantly improves the economic efficiency of marine master-slave clocks. By modulating the communication and timing signals through the marine 220V lighting circuit, the power supply and timing of the master-slave clocks are realized without the need for additional radial serial port cables. For ships with large tonnage and many compartments, this greatly reduces the amount of cable laying, and its economic efficiency is particularly significant.

[0021] (iii) The installation and commissioning procedures for marine master-slave clocks are simplified. Existing marine master-slave clocks require separate connections to a 24V power supply line and a serial time synchronization line during cabin installation. Their installation location is limited by the reserved space for cable laying in the cabin, making the installation and commissioning process complex. In contrast, the marine master-slave clock based on a hybrid signal system proposed in this application only requires plugging the plug into a 220V lighting grid socket in the cabin, making it plug-and-play and greatly simplifying the installation and commissioning process.

[0022] (iv) It provides a new means of time acquisition for other time users on board, which helps to promote the intelligent upgrade of the ship's electronic equipment. By installing the master-slave clock device proposed in this application, the time signal can be modulated in the ship's 220V lighting grid. Other time-using electronic equipment can be upgraded to provide intelligent time distribution services for the entire ship by adding power communication modules. Attached Figure Description

[0023] Figure 1 This illustrates the architecture of a traditional shipboard master-slave clock system; Figure 2 This illustrates a marine master-slave clock system architecture based on a hybrid signal system. Figure 3 This is a flowchart of a marine master-slave clock signal transmission system based on a hybrid signal architecture. Detailed Implementation

[0024] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

[0025] The present invention aims to propose a design method for a shipboard master-slave clock system that integrates serial port and low-voltage power distribution network carrier communication technologies, so as to solve the drawbacks of traditional shipboard master-slave clock systems.

[0026] The marine master-slave clock based on a hybrid signal system proposed in this invention consists of a master clock and slave clocks. The master clock can be designed as a wall-mounted or standard rack-mounted socket structure according to installation space requirements, and the slave clocks can also be designed as circular or square slave clocks according to installation space requirements. Slave clocks are functionally divided into general-purpose slave clocks and relay slave clocks. The main difference between general-purpose and relay slave clocks is that relay slave clocks have both serial communication and power line carrier communication modules, while general-purpose slave clocks only have a power line carrier communication module.

[0027] The master clock communicates directly with the relay-type slave clocks via standard serial communication, enabling distributed time distribution services. After receiving time information from the master clock, the relay-type slave clocks convert it via a power communication module and modulate it into the ship's lighting distribution network. Each general-purpose slave clock connected to the same lighting distribution network receives the master clock's time information by receiving power line carrier timing signals from that network. Furthermore, the general-purpose slave clocks can also modulate their own operating status and other parameters into the lighting distribution network and report them to the relay-type slave clocks using power line carrier communication. The relay-type slave clocks then aggregate the operating status and other parameter information from all the general-purpose slave clocks and report it, along with their own operating status information, to the master clock via serial port, enabling the master clock to monitor the operating status of each slave clock. In summary, the master clock and slave clocks achieve distributed time distribution services through cascading, and the master clock enables centralized display and status control of both the master and slave clocks. The master clock communicates with the relay-type slave clocks via a direct serial connection; the relay-type slave clocks communicate with the general-purpose slave clocks in a cascaded loop via a power line carrier communication link. The overall architecture is as follows: Figure 2 As shown.

[0028] The master clock functional module includes, but is not limited to, a display and control module, a motherboard module, a clock control module, and a slave clock communication module, among which: (1) The display and control module functions generally include, but are not limited to, responding to user operations and realizing human-machine interface control; having module working status detection, judgment and reporting functions; and having sub-clock working status integrated display function; (2) The functions of the motherboard module generally include, but are not limited to, performing human-machine interaction functions; displaying the human-machine interaction interface; and summarizing the working status of other modules inside the device. (3) The functions of the clock control module generally include, but are not limited to, parsing, storing and synchronizing time code information, sending time code; judging the validity status of the second pulse, synchronizing, judging the synchronization result, and outputting the results; querying and reporting the lock status and working status of the disciplined crystal oscillator; realizing the function of sending time information and autonomous timekeeping; and detecting, judging and reporting the working status. (4) The functions of the sub-clock communication module generally include, but are not limited to, parsing and sending time code information; monitoring and managing the working status of the sub-clock in the working compartment; and having the functions of module working status detection, judgment and reporting.

[0029] The slave clock functional module includes, but is not limited to, a time code receiving module, a serial communication module, a power communication module, and a display and control module, wherein: (1) The functions of the time code receiving module generally include, but are not limited to, receiving and processing time information; (2) The serial communication module is only configured in the relay type sub-clock, and its functions generally include, but are not limited to, receiving messages from the master clock and sending messages to the master clock; (3) The functions of the power communication module generally include, but are not limited to, modulation and demodulation of the timing signal; and relay enhancement of the power timing signal as a relay node; (4) The display and control module functions generally include, but are not limited to, displaying sub-clock time information; responding to user operations and realizing control of the sub-clock; having sub-clock module working status detection, judgment and reporting functions; and having sub-clock working status integrated display function.

[0030] The signal transmission process of a marine master-slave clock based on a hybrid signal system is as follows: Figure 3 As shown, the specific steps include: The first step involves the ship's master clock system receiving timing signals from satellite navigation, Loran-C, shortwave, and other timing equipment. These signals typically include pulse signals and time code signals, and are usually transmitted via RS-422 or RS-485 serial ports. It should be noted that the master clock also has an autonomous timekeeping function; a time can be manually input even without external timing signals, enabling the master clock to operate in autonomous timekeeping mode.

[0031] The second step is that after the master clock receives the time signal, it performs the validity detection, judgment and switching of the time source. After confirming that the time signal is normal, it performs the discipline, synchronization and holding processing of the temperature-controlled crystal oscillator.

[0032] The third step involves the master clock transmitting time information and control commands to the slave clocks via a 422 or 485 serial port to the relay slave clocks for synchronization. The relay slave clocks then report the working status messages of all their subordinate general-purpose slave clocks and themselves to the master clock via the serial port.

[0033] The fourth step is that after the relay-type sub-clock receives the time signal, it also needs to carry out the validity detection, judgment and switching of the time source. After confirming that the time signal is normal, it needs to carry out the discipline, synchronization and maintenance of the temperature-compensated crystal oscillator.

[0034] The fifth step involves the relay-type slave clock using a power communication module to modulate the received time information and the master clock's control commands to the slave clock onto the lighting circuit. The general-purpose slave clock uses a power communication module to obtain the time information and control commands from the lighting circuit. After two-way communication to compensate for the time delay, it performs the discipline, synchronization, and holding processes of the slave clock crystal oscillator, and simultaneously reports its own working status information to the lighting circuit.

[0035] The sixth step involves the master clock display and control module interacting with the ship's information system via the network port. The interaction mainly includes, but is not limited to, the working status of the master and slave clocks, and the control commands and parameters of the ship's superior system to the master and slave clocks.

[0036] The seventh step is to enable dual time zone time and date display functions for all ship relay and general-purpose slave clocks through the master clock display interface when the ship is in a cross-time zone navigation scenario.

[0037] The technical solution disclosed in this invention is based on power line carrier communication (PLC) technology, which innovates the signal transmission and power supply mechanism of existing marine master-slave clocks. It replaces the original 24V DC power supply with AC power from the 220V marine lighting grid, solving the problem of voltage drop caused by long-distance transmission. On the other hand, by modulating the timing communication signal in the power line, the slave clock power communication module mounted in the power line can also act as a relay node to relay and enhance the signal while demodulating the timing signal. This solves the problem of signal attenuation in long-distance serial communication on ships inherent in existing slave clocks, and greatly improves the load capacity of the master clock's single-channel serial port output line.

[0038] Those skilled in the art will understand that the features described in the various embodiments and / or claims of this invention can be combined or combined in various ways, even if such combinations or combinations are not explicitly described in this disclosure. In particular, the features described in the various embodiments and / or claims of this invention can be combined or combined in various ways without departing from the spirit and teachings of this disclosure. All such combinations and / or combinations fall within the scope of this disclosure.

[0039] The embodiments of the present invention have been described above. However, these embodiments are for illustrative purposes only and are not intended to limit the scope of this disclosure. Although various embodiments have been described above, this does not mean that the measures in the various embodiments cannot be used advantageously in combination. The scope of the present invention is defined by the appended claims and their equivalents. Various substitutions and modifications can be made by those skilled in the art without departing from the scope of the present invention, and all such substitutions and modifications should fall within the scope of this disclosure.

Claims

1. A design method for a marine master-slave clock based on a hybrid signal system, characterized in that, The traditional 24V power supply master-slave clock system is replaced by 220V AC power. The traditional serial port time communication master-slave clock system is replaced by modulating the time communication signal in the 220V marine lighting power grid. The slave clocks are divided into general-purpose slave clocks and relay slave clocks according to their functions. The master clock communicates directly with the relay slave clocks through standard serial communication. After receiving the time information from the master clock, the relay slave clock converts it through the power communication module and modulates the master clock time information into the 220V marine lighting power grid. Each general-purpose slave clock connected to the same 220V marine lighting power grid obtains the master clock time information by receiving the power carrier time signal in the current power grid. Meanwhile, the general-purpose sub-clock modulates parameter information, including its own operating status, into the 220V marine lighting grid and reports it to the relay sub-clock using power line carrier communication. The relay sub-clock then aggregates the parameter information of each general-purpose sub-clock and reports it, along with its own operating status information, to the master clock via a serial port, enabling the master clock to monitor the operating status of each sub-clock.

2. The design method for a marine master-slave clock based on a hybrid signal system as described in claim 1, characterized in that, The master clock communicates and synchronizes with the relay-type slave clock via a direct serial port connection.

3. The design method for a marine master-slave clock based on a hybrid signal system as described in claim 2, characterized in that, The relay-type sub-clock forms a cascaded loop with the general-purpose sub-clock via a power line carrier communication link for communication and time synchronization.

4. The design method for a marine master-slave clock based on a hybrid signal system as described in claim 1, characterized in that, The master clock functional module includes, but is not limited to, a display and control module, a motherboard module, a clock control module, and a slave clock communication module.

5. The design method for a marine master-slave clock based on a hybrid signal system as described in claim 4, characterized in that, The functions of the display and control module include, but are not limited to: responding to user operations and realizing human-machine interface control; having module working status detection, judgment and reporting functions; and having sub-clock working status integrated display function; The functions of the motherboard module include, but are not limited to: performing human-computer interaction functions; displaying the human-computer interaction interface; and summarizing the working status of other modules inside the device. The functions of the clock control module include, but are not limited to: parsing, storing and synchronizing time code information, sending time codes; determining the validity status of the second pulse, synchronizing, determining and outputting the synchronization result; querying and reporting the lock status and working status of the disciplined crystal oscillator. It enables functions such as sending time information and autonomously keeping to schedule; and functions for detecting, judging, and reporting work status. The functions of the sub-clock communication module include, but are not limited to: parsing and sending time code information; monitoring and managing the working status of the working cabin sub-clock; and having the functions of module working status detection, judgment and reporting.

6. The design method for a marine master-slave clock based on a hybrid signal system as described in claim 1, characterized in that, The slave clock functional modules include, but are not limited to, a time code receiving module, a serial communication module, a power communication module, and a display and control module.

7. The design method for a marine master-slave clock based on a hybrid signal system as described in claim 6, characterized in that, The serial communication module is only configured in the relay-type sub-clock.

8. The design method for a marine master-slave clock based on a hybrid signal system as described in claim 6, characterized in that, The functions of the time code receiving module include, but are not limited to: receiving and processing time synchronization information; The functions of the serial communication module include, but are not limited to: receiving messages from the master clock and sending messages to the master clock; The functions of the power communication module include, but are not limited to: modulation and demodulation of the time signal; and relay enhancement of the power time signal as a relay node. The functions of the display and control module include, but are not limited to: displaying sub-clock time information; responding to user operations and controlling the sub-clock; detecting, judging, and reporting the working status of the sub-clock module; and integrating the display of the working status of the sub-clock.

9. The design method for a marine master-slave clock based on a hybrid signal system as described in claim 1, characterized in that, The marine master-slave clock signal transmission process between the master clock and the slave clock includes the following steps: Step 1: The ship's master clock equipment receives the time signal broadcast by the time synchronization equipment; Step 2: After the master clock receives the time signal, it performs the validity detection, judgment and switching of the time source. After confirming that the time signal is normal, it performs processing work including the discipline, synchronization and maintenance of the temperature compensated crystal oscillator. Step 3: The master clock transmits time information and control commands from the master clock to the relay-type slave clock for synchronization. The relay-type slave clock reports the working status messages of all its subordinate general-purpose slave clocks and itself to the master clock via the serial port. Step 4: After receiving the time signal, the relay-type sub-clock performs the validity detection, judgment and switching of the time source. After confirming that the time signal is normal, it performs processing work including the discipline, synchronization and maintenance of the temperature-compensated crystal oscillator. Step 5: The relay-type slave clock uses the power communication module to modulate the received time information and the control commands from the master clock to the slave clock into the lighting circuit. The general-purpose slave clock uses the power communication module to obtain the time information and control commands from the lighting circuit. After the time delay is compensated by bidirectional communication, it performs processing work including disciplining, synchronizing and maintaining the slave clock crystal oscillator, and synchronously reports its own working status information to the lighting circuit. Step 6: The master clock display and control module interacts with the ship's information system via the network port; Step 7: When the ship is used for cross-time zone navigation, set up dual time zone time and year / month / day display function for all ship relay and general-purpose slave clocks through the master clock display and control interface.

10. The design method for a marine master-slave clock based on a hybrid signal system as described in claim 9, characterized in that, In step 1, the master clock has an autonomous timekeeping function, which allows a time information to be manually input without receiving external time signals, so that the master clock can operate in autonomous timekeeping mode.

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