Timing method for subsea node instruments

Abstract

The present invention discloses a method for timing an underwater node instrument, comprising the following steps: (1) setting an underwater node Node and three (or more) node positioning timing units (PTUs) on the seabed, wherein the node positioning timing unit (PTU) includes an underwater communication unit and a surface transceiver controller; (2) the node positioning timing unit sends a positioning message to the underwater node and receives a positioning response from the underwater node; (3) the node positioning timing unit sends a timing message to the underwater node; (4) the underwater node corrects its own clock to obtain precise timing. The beneficial effects of the present invention are as follows: each node positioning timing unit (PTU) sends positioning timing information and the propagation delay of the underwater node to the underwater node (Node), and the underwater node corrects its own clock according to the information sent by the positioning timing unit (PTU), thereby obtaining precise timing. Precise timing can be obtained without the need for expensive and power-consuming atomic clocks, which can significantly reduce costs, extend standby time, and improve acquisition efficiency.

Description

Technical Field

[0001] The present invention relates to the technical field of seabed node instrument timing, and in particular to a seabed node instrument timing method. Background Art

[0002] Subsea node instruments are widely used in offshore oil, gas, and other mineral exploration due to their minimal impact on the surface environment, high-quality data collection, and efficient operation. Node instruments continuously collect and record data during field operations. After node recovery, the data is segmented using the shot firing time to generate the required shot data. Therefore, the node instrument's location information and clock accuracy are crucial technical specifications. Timing must achieve microsecond-level accuracy, and positioning accuracy must reach centimeter-level accuracy.

[0003] For example, a method for positioning an underwater seismic node with application number CN116165605A and announcement date 2023.5.26 includes: determining a first slant distance between a master ship and an underwater acoustic transponder and the position of the master ship, and determining a first predicted trajectory of the position of the underwater acoustic transponder based on the first slant distance and the position of the master ship; determining a second slant distance between a slave ship and the underwater acoustic transponder and the position of the slave ship, and determining a second predicted trajectory of the position of the underwater acoustic transponder based on the second slant distance and the position of the slave ship.

[0004] Because seafloor node seismometers are located on the seabed, they cannot receive radio signals normally and cannot use satellite positioning and timing like land-based ones. Therefore, almost all seafloor node seismometers currently use high-precision atomic clocks as their clocks. However, this will bring some problems to the large-scale promotion and application of seafloor node seismometers:

[0005] (1) High cost: The cost of an atomic clock used for timekeeping is about RMB 40,000, accounting for more than 60% of the node instruments; positioning uses a special secondary positioning system and positioning ship, which increases construction costs.

[0006] (2) High power consumption: affects the continuous working time of node instruments at the bottom of the water, reducing construction efficiency;

[0007] (3) If the instrument is restarted, the time and position information will be lost, making the collected data unusable. Therefore, it is urgent to design a timing method for seabed node instruments to solve the above problems. Summary of the Invention

[0008] The purpose of the present invention is to provide a timing method for seabed node instruments to solve the above-mentioned deficiencies in the prior art.

[0009] In order to achieve the above object, the present invention provides the following technical solutions:

[0010] The timing method of the submarine node instrument includes the following steps:

[0011] S1: Positioning

[0012] (1) Setting up a seabed node and three (or more) positioning and timing units (PTUs) on the seabed. The PTUs include an underwater communication unit and a surface transceiver controller.

[0013] (2) The underwater communication unit of the node positioning and timing unit (PTU) sends positioning messages to the seabed nodes respectively;

[0014] (3) The three positioning timing units (PTUs) receive the positioning response from the seabed node and calculate the round-trip delay time between each sending the positioning message and receiving the response message. Based on the round-trip delay time, the distance d between the seabed node and the three underwater communication units of the three positioning timing units (PTUs) is calculated. n ;

[0015] (4) The three node positioning timing units (PTUs) will be at a distance d n It is sent to the positioning and timing status monitoring host CCU through a high-speed wireless communication channel. The positioning and timing status monitoring host CCU integrates the d measured by the positioning and timing units PTU of the three nodes. n (n=1, 2, 3, ...) can calculate the position of the seabed node to be located;

[0016] S2. Timing

[0017] The surface transceiver controller of each node's positioning and timing unit (PTU) obtains accurate time information from the satellite or the positioning and timing status monitoring host CCU, and sends the accurate time information and the measured round-trip delay time of the seabed node to the seabed node;

[0018] In this process, the positioning timing unit (PTU) of each node needs to correct the timing delay t0 between the surface transceiver controller and the underwater communication unit;

[0019] S3. System calibration

[0020] (1) Correct the physical distance between the surface transceiver controller and the underwater communication unit, i.e., the distance Ln between the surface transceiver controller and the underwater communication unit;

[0021] (2) Correcting the signal transmission delay between the surface transceiver controller and the underwater communication unit is called the system delay t on ;

[0022] (3) According to the corrected Ln and t on, and obtain the precise time t0, so that the seabed node Node can obtain accurate timing information without error.

[0023] Furthermore, in step (3) of S1, the algorithm for round-trip delay time is:

[0024] The round-trip delay times obtained by the three underwater communication units are t1, t2, and t3 respectively, and the distance between the seabed node Node1 to be located and the three underwater communication units is

[0025]

[0026] Where V is the propagation speed of the signal in water, n = 1, 2, 3;

[0027] The three node positioning timing units PTU will calculate the distance d n The data is sent to the positioning timing status monitoring host CCU through a high-speed wireless communication channel. The positioning timing status monitoring host CCU integrates the d measured by the positioning timing units PTU of the three nodes. n (n=1, 2, 3, ...) can calculate the position of the seabed node to be located; positioning usually adopts three-point positioning, with three underwater communication units as the center, d n Draw a circle with the radius of 1, and the three circles intersect at one point. The position of this intersection is the position of the seabed node to be located.

[0028] Furthermore, in S2, assuming that the three node positioning timing units PTU all send signals at time t0, the timing signal sent by each node positioning timing unit PTU carries the round-trip propagation delay t of the seabed node Node measured by itself. n (n=1,2,3,…), then the timing signals sent by the three node positioning timing units PTU received by the seabed node Node are t r1 =t0+t1 / 2, t r2 =t0+t2 / 2, t r3 =t0+t3 / 2, ..., where n = 1, 2, 3, ...; the submarine node parses t1, t2 and t3 from the received timing signal, and can infer the precise time t0 = t r1 -t1 / 2=t r2 -t2 / 2=t r3 -t3 / 2, because t0 comes from satellite timing, its accuracy is equivalent to that of an atomic clock, which can fully meet the timing accuracy of the seabed node.

[0029] Furthermore, in step (1) of S3, the surface transceiver controller and the underwater communication unit are connected by a hard link or a hinge, wherein the hinge needs to be straightened by a counterweight to ensure that Ln is accurate and stable. The correction measurement of Ln is performed when the equipment is deployed, and the Ln measurement result is saved in the positioning and timing status monitoring host (CCU) as a system parameter for correcting the positioning of the seabed node Node.

[0030] Furthermore, in step (2) of S3, the delay t between the surface transceiver controller and the underwater communication unit is corrected. on The specific method is as follows: the surface transceiver controller of each node positioning and timing unit (PTU) sends a delay test signal to its own underwater communication unit. After receiving the delay test signal, the underwater communication unit returns a response signal to the surface transceiver controller. The surface transceiver control unit measures the round-trip delay from the transmission of the delay test signal to the return of the response by the underwater communication unit. Half of this round-trip delay is the delay t between the second pulse from the surface transceiver controller to the underwater communication unit. on (n=1, 2, 3, ...).

[0031] Furthermore, in step (3) of S3, the specific calibration method is:

[0032] Because the timing signal sent by the actual node positioning timing unit PTU carries the two-way propagation delay t of the seabed node Node measured by itself. n In addition to the PTU, the PTU also carries a node positioning timing unit (n=1, 2, 3, ...). It calculates the precise pulse per second (PPS) time t0 from the satellite signal or the positioning timing status monitoring host CCU. The transmission delay between the PTU surface transceiver controller and the underwater communication unit is t0n (n=1, 2, 3, ...), and then the transmission delay between the underwater communication unit and the seabed node Node is t0n (n=1, 2, 3, ...). n / 2 (n=1, 2, 3, ...), the actual timing signal received by the submarine node is t r1 =t0+t 01 +t1 / 2,t r2 =t0+t 02 +t2 / 2,t r3 =t0+t 03 +t3 / 2, ..., where (n=1, 2, 3, ...), the submarine node parses t from the received timing signal. 01 , t1, t 02 , t2 and t 03 , t3 can be inferred from the exact time t0 = t r1 -t 01 -t1 / 2=t r2 -t 02 -t2 / 2=tr3 -t 03 -t3 / 2, so that the seabed nodes can obtain accurate timing information without error.

[0033] Furthermore, the node positioning and timing unit (PTU) and the seabed node (Node) each have a unique ID number, and the ID number is written into the device before the system is deployed.

[0034] Furthermore, the node positioning and timing unit (PTU) is connected to the positioning and timing status monitoring host (CCU) through high-speed general wireless communication technology, and the node positioning and timing unit (PTU) is connected to the seabed node Node through dedicated underwater acoustic wireless communication technology.

[0035] Furthermore, the surface transceiver controller and the underwater communication unit of the node positioning and timing unit (PTU) are connected by a hard rod and a soft cable with adjustable length, wherein the hard rod ensures the physical distance between the surface transceiver controller and the underwater communication unit, and the soft cable realizes power supply and communication between the surface transceiver controller and the underwater communication unit.

[0036] Furthermore, the surface transceiver controller of the node positioning and timing unit (PTU) has its own positioning and timing device, which can receive satellite signals, such as GPS, Beidou or GRONASS, and output pulse per second (PPS: Pulse Per Second) to achieve accurate positioning and timing.

[0037] In the above technical solution, the timing method of the submarine node instrument provided by the present invention is:

[0038] 1. Under the control of the positioning and timing status monitoring host (CCU), the seabed node Node responds to the positioning command of the node positioning and timing unit (PTU). After receiving the positioning response of the seabed node Node, the node positioning and timing unit (PTU) calculates the propagation delay between the node positioning and timing unit (PTU) and the seabed node. Each node positioning and timing unit (PTU) reports its own positioning position and the measured seabed node delay to the positioning and timing status monitoring host (CCU). The positioning and timing status monitoring host (CCU) calculates the position of the seabed node Node; three ( or more) node positioning timing units (PTUs) send timing messages to the seabed node Node, and the seabed node Node receives the timing messages sent by the three (or more) surrounding node positioning timing units (PTUs), calculates the precise time information, and corrects its own clock to obtain precise timing. This timing method can obtain precise timing without using an atomic clock, thereby solving the problems of high cost and high power consumption brought about by the large-scale promotion of existing seabed node seismometers that use high-precision atomic clocks as their own clocks, and the loss of time and position information when the instrument is restarted, resulting in the unavailability of collected data. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments described in the present invention. For ordinary technicians in this field, other drawings can also be obtained based on these drawings.

[0040] Figure 1 A schematic structural diagram of a node positioning and timing method diagram provided for an embodiment of the submarine node instrument timing method of the present invention.

[0041] Figure 2 Schematic diagram of three-point positioning principle provided for the embodiment of the timing method of the submarine node instrument of the present invention

[0042] Structural diagram.

[0043] Figure 3 A schematic diagram of the connection structure between the underwater communication unit and the surface transceiver controller provided in an embodiment of the seabed node instrument timing method of the present invention. DETAILED DESCRIPTION

[0044] In order to enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings.

[0045] like Figure 1-3 As shown, the timing method for submarine node instruments provided by the embodiment of the present invention includes the following steps:

[0046] S1: Positioning, e.g. Figure 1 shown

[0047] (1) Set up a seabed node Node1 and three (or more) positioning and timing units (PTUs) on the seabed. The PTUs include an underwater communication unit and a surface transceiver controller.

[0048] (2) The underwater communication unit of the node positioning timing unit (PTU) sends a positioning message to the seabed node Node. The seabed node (Node) replies with a positioning response to the positioning timing unit (PTU). The positioning timing unit (PTU) measures the delay between the positioning response and the positioning request message of the seabed node;

[0049] (3) The surface transceiver controller of the node positioning and timing unit (PTU) obtains its own precise position and timing information through satellite or timing monitoring host (CCU), and then sends timing messages to the seabed node Node through the underwater communication unit. The three (or more) node positioning and timing units (PTU) receive the positioning response from the seabed node Node, calculate the round-trip delay time between each of them from sending the positioning message to receiving the response message, and calculate the distance d between the seabed node Node and the three underwater communication units of the three (or more) node positioning and timing units (PTU) based on the round-trip delay time. n ;

[0050] The algorithm for the round-trip delay time is:

[0051] The round-trip delay times obtained by the three underwater communication units are t1, t2, and t3 respectively, and the distance between the seabed node Node1 to be located and the three underwater communication units is

[0052]

[0053] Where V is the propagation speed of the signal in water, n = 1, 2, 3;

[0054] The three node positioning timing units PTU will calculate the distance d n The data is sent to the positioning timing status monitoring host CCU through a high-speed wireless communication channel. The positioning timing status monitoring host CCU integrates the d measured by the positioning timing units PTU of the three nodes. n (n=1, 2, 3, ...) can calculate the position of the seabed node to be located; positioning usually adopts three-point positioning, with three underwater communication units as the center, d n Draw a circle with a radius of 1, and the three circles intersect at one point. The position of this intersection is the position of the seabed node to be located, such as Figure 2 As shown;

[0055] (4) The submarine node parses the received timing information and then corrects its own clock to obtain the precise timing required by the node instrument. The three node positioning timing units (PTUs) will be at a distance of d n It is sent to the positioning and timing status monitoring host CCU through a high-speed wireless communication channel. The positioning and timing status monitoring host CCU integrates the d measured by the positioning and timing units PTU of the three nodes. n (n=1, 2, 3, ...) can calculate the position of the seabed node to be located;

[0056] S2. Timing

[0057] The surface transceiver controller of each node's positioning and timing unit (PTU) obtains accurate time information from the satellite or the positioning and timing status monitoring host CCU, and sends the accurate time information and the measured round-trip delay time of the seabed node to the seabed node;

[0058] In this process, the positioning timing unit (PTU) of each node needs to correct the timing delay t0 between the surface transceiver controller and the underwater communication unit;

[0059] Assuming that the three node positioning timing units PTU all send signals at time t0, the timing signal sent by each node positioning timing unit PTU carries the round-trip propagation delay t of the seabed node Node measured by itself. n (n=1,2,3,…), then the timing signals sent by the three node positioning timing units PTU received by the seabed node Node are t r1 =t0+t1 / 2, t r2 =t0+t2 / 2, t r3 =t0+t3 / 2, ..., where n = 1, 2, 3, ...; the submarine node parses t1, t2 and t3 from the received timing signal, and can infer the exact time t0 = t r1 -t1 / 2=t r2 -t2 / 2=t r3 -t3 / 2, because t0 comes from satellite timing, its accuracy is equivalent to that of an atomic clock, which can fully meet the timing accuracy of the seabed node.

[0060] S3. System calibration

[0061] (1) Correct the physical distance between the surface transceiver controller and the underwater communication unit, i.e., the distance Ln between the surface transceiver controller and the underwater communication unit.

[0062] The surface transceiver controller and the underwater communication unit are connected by a hard link or hinge. The hinge needs to be straightened with a counterweight to ensure that Ln is accurate and stable. The Ln calibration measurement is performed when the equipment is deployed. The Ln measurement results are saved in the positioning and timing status monitoring host (CCU) as system parameters and used to correct the positioning of the seabed node.

[0063] (2) Correct the signal transmission delay (called system delay) between the surface transceiver controller and the underwater communication unit t on ,

[0064] Correct the delay t between the surface transceiver controller and the underwater communication unit on The specific method is as follows: the surface transceiver controller of each node positioning and timing unit (PTU) sends a delay test signal to its own underwater communication unit. After receiving the delay test signal, the underwater communication unit returns a response signal to the surface transceiver controller. The surface transceiver control unit measures the round-trip delay from the transmission of the delay test signal to the return of the response by the underwater communication unit. Half of this round-trip delay is the delay t between the second pulse from the surface transceiver controller to the underwater communication unit. on (n=1, 2, 3, ...);

[0065] (3) According to the corrected Ln and t on , and obtain the precise time t0, so that the seabed node Node can obtain accurate timing information without error.

[0066] The specific calibration method is: the timing signal sent by the actual node positioning timing unit PTU carries the two-way propagation delay t of the seabed node Node measured by itself. n In addition to the PTU, the PTU also carries a node positioning timing unit (n=1, 2, 3, ...). It calculates the precise pulse per second (PPS) time from the satellite signal. The transmission delay between the PTU surface transceiver controller and the underwater communication unit is t0n (n=1, 2, 3, ...), and then the transmission delay between the underwater communication unit and the seabed node is t n / 2 (n=1, 2, 3, ...), the actual timing signal received by the submarine node is t r1 =t0+t 01 +t1 / 2,t r2 =t0+t 02 +t2 / 2,t r3 =t0+t 03 +t3 / 2, ..., where (n=1, 2, 3, ...), the submarine node parses t from the received timing signal. 01 , t1, t 02 , t2 and t 03, t3 can be inferred from the exact time t0 = t r1 -t 01 -t1 / 2=t r2 -t 02 -t2 / 2=t r3 -t 03 -t3 / 2, so that the seabed nodes can obtain accurate timing information without error.

[0067] In one embodiment provided by the present invention, each of the node positioning and timing unit (PTU) and the seabed node (Node) has a unique ID number, and the ID number is written into the device before the system is deployed.

[0068] In another embodiment provided by the present invention, the node positioning and timing unit (PTU) is connected to the positioning and timing status monitoring host (CCU) through high-speed general wireless communication technology, and the node positioning and timing unit (PTU) is connected to the seabed node Node through dedicated underwater acoustic wireless communication technology.

[0069] In another embodiment provided by the present invention, Figure 3 As shown, the surface transceiver controller and the underwater communication unit of the node positioning and timing unit (PTU) are connected by a hard rod and a soft cable with adjustable length. The hard rod ensures the physical distance between the surface transceiver controller and the underwater communication unit, and the soft cable realizes power supply and communication between the surface transceiver controller and the underwater communication unit.

[0070] In one embodiment provided by the present invention, the surface transceiver controller of the node positioning and timing unit (PTU) has its own positioning and timing device, which can receive satellite signals, such as GPS, Beidou or GRONASS, and output pulse per second (PPS: Pulse Per Second) to achieve accurate positioning and timing.

[0071] The above description is merely illustrative of certain exemplary embodiments of the present invention. It goes without saying that those skilled in the art will be able to modify the described embodiments in various ways without departing from the spirit and scope of the present invention. Therefore, the above drawings and description are illustrative in nature and should not be construed as limiting the scope of protection of the claims.

Claims

1. A method for timing a submarine node instrument, characterized in that: The following steps are involved: S1: Positioning (1) Set up a seabed node Node1 and three or more positioning and timing units (PTUs) on the seabed. The PTUs include an underwater communication unit and a surface transceiver controller. (2) The underwater communication unit of the node positioning timing unit (PTU) sends a positioning message to the seabed node Node. The seabed node (Node) replies with a positioning response to the positioning timing unit (PTU). The positioning timing unit (PTU) measures the delay between the positioning response and the positioning request message of the seabed node; (3) The surface transceiver controller of the node positioning and timing unit (PTU) obtains its own precise position and timing information through satellite or timing monitoring host (CCU), and then sends timing messages to the seabed node Node through the underwater communication unit. Three or more node positioning and timing units (PTU) receive the positioning response from the seabed node Node, calculate the round-trip delay time between each sending the positioning message and receiving the response message, and calculate the distance d between the seabed node Node and the three underwater communication units of the three or more node positioning and timing units (PTU) based on the round-trip delay time. n ; The algorithm for the round-trip delay time is: The round-trip delay times obtained by the three underwater communication units are t1, t2, and t3 respectively, and the distance between the seabed node Node1 to be located and the three underwater communication units is Where V is the propagation speed of the signal in water, n = 1, 2, 3; The three node positioning timing units PTU will calculate the distance d n The data is sent to the positioning timing status monitoring host CCU through a high-speed wireless communication channel. The positioning timing status monitoring host CCU integrates the d measured by the positioning timing units PTU of the three nodes. n (n=1, 2, 3, ...) can calculate the position of the seabed node to be located; positioning usually adopts three-point positioning, with three underwater communication units as the center, d n Draw a circle with the radius of 1, and the three circles intersect at one point. The position of this intersection is the position of the seabed node to be located; (4) The submarine node parses the received timing information and then corrects its own clock to obtain the precise timing required by the node instrument. The three node positioning timing units (PTUs) will be at a distance of d n It is sent to the positioning and timing status monitoring host CCU through a high-speed wireless communication channel. The positioning and timing status monitoring host CCU integrates the d measured by the positioning and timing units PTU of the three nodes. n (n=1, 2, 3, ...) can calculate the position of the seabed node to be located; S2. Timing The surface transceiver controller of each node's positioning and timing unit (PTU) obtains accurate time information from the satellite or the positioning and timing status monitoring host CCU, and sends the accurate time information and the measured round-trip delay time of the seabed node to the seabed node; In this process, the positioning timing unit (PTU) of each node needs to correct the timing delay t0 between the surface transceiver controller and the underwater communication unit; S3. System calibration (1) Correct the physical distance between the surface transceiver controller and the underwater communication unit, that is, the distance Ln between the surface transceiver controller and the underwater communication unit; (2) Correcting the signal transmission delay between the surface transceiver controller and the underwater communication unit is called the system delay t on ; (3) According to the corrected Ln and t on , and obtain the precise time t0, so that the seabed node Node can obtain accurate timing information without error.

2. The method for timing a submarine node instrument according to claim 1, wherein: In S2, assuming that the three node positioning timing units PTU all send signals at time t0, the timing signal sent by each node positioning timing unit PTU carries the round-trip propagation delay t of the seabed node Node measured by itself. n (n=1,2,3,…), then the timing signals sent by the three node positioning timing units PTU received by the seabed node Node are t r1 =t0+t1 / 2, t r2 =t0+t2 / 2, t r3 =t0+t3 / 2, ..., where n = 1, 2, 3, ...; the submarine node parses t1, t2 and t3 from the received timing signal, and can infer the precise time t0 = t r1 -t1 / 2=t r2 -t2 / 2=t r3 -t3 / 2, because t0 comes from satellite timing or positioning timing status monitoring host CCU, its accuracy is equivalent to that of atomic clock, which can fully meet the timing accuracy of submarine nodes.

3. The method for timing a submarine node instrument according to claim 1, wherein: In step (1) of S3, the surface transceiver controller and the underwater communication unit are connected by a hard link or a hinge, wherein the hinge needs to be straightened by a counterweight to ensure that Ln is accurate and stable. The calibration measurement of Ln is performed when the equipment is deployed, and the Ln measurement result is saved in the positioning and timing status monitoring host (CCU) as a system parameter for correcting the positioning of the seabed node.

4. The method for timing a submarine node instrument according to claim 1, wherein: In step (2) of S3, the delay t between the surface transceiver controller and the underwater communication unit is corrected. on The specific method is as follows: the surface transceiver controller of each node positioning and timing unit (PTU) sends a delay test signal to its own underwater communication unit. After receiving the delay test signal, the underwater communication unit returns a response signal to the surface transceiver controller. The surface transceiver control unit measures the round-trip delay from the transmission of the delay test signal to the return of the response by the underwater communication unit. Half of this round-trip delay is the delay t between the second pulse from the surface transceiver controller to the underwater communication unit. on (n=1, 2, 3, ...).

5. The method for timing a submarine node instrument according to claim 1, wherein: In step (3) of S3, the specific calibration method is: Because the timing signal sent by the actual node positioning timing unit PTU carries the two-way propagation delay t of the seabed node Node measured by itself. n In addition to the PTU, the PTU also carries a node positioning timing unit (n=1, 2, 3, ...). It calculates the precise pulse per second (PPS) time t0 from the satellite signal or the positioning timing status monitoring host CCU. The transmission delay between the PTU surface transceiver controller and the underwater communication unit is t0n (n=1, 2, 3, ...), and then the transmission delay between the underwater communication unit and the seabed node Node is t0n (n=1, 2, 3, ...). n / 2 (n=1, 2, 3, ...), the actual timing signal received by the submarine node is t r1 =t0+t 01 +t1 / 2,t r2 =t0+t 02 +t2 / 2,t r3 =t0+t 03 +t3 / 2, ..., where (n=1, 2, 3, ...), the submarine node parses t from the received timing signal. 01 , t1, t 02 , t2 and t 03 , t3 can be inferred from the exact time t0 = t r1 -t 01 -t1 / 2=t r2 -t 02 -t2 / 2=t r3 -t 03 -t3 / 2, so that the seabed nodes can obtain accurate timing information without error.

6. The method for timing a submarine node instrument according to claim 1, wherein: The node positioning and timing unit (PTU) and the seabed node (Node) each have a unique ID number, and the ID number is written into the device before the system is deployed.

7. The method for timing a submarine node instrument according to claim 1, wherein: The node positioning timing unit (PTU) is connected to the positioning timing status monitoring host (CCU) through high-speed general wireless communication technology, and the node positioning timing unit (PTU) is connected to the seabed node Node through dedicated underwater acoustic wireless communication technology.

8. The method for timing a submarine node instrument according to claim 1, wherein: The surface transceiver controller and underwater communication unit of the node positioning and timing unit (PTU) are connected by a hard rod and a soft cable with adjustable length, wherein the hard rod ensures the physical distance between the surface transceiver controller and the underwater communication unit, and the soft cable realizes power supply and communication between the surface transceiver controller and the underwater communication unit.

9. The method for timing a submarine node instrument according to claim 1, wherein: The surface transceiver controller of the node positioning and timing unit (PTU) has its own positioning and timing device, which can receive satellite signals such as GPS, Beidou or GRONASS, and output pulse per second (PPS: Pulse Per Second) to achieve accurate positioning and timing.

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