Method and System for Synchronizing Data Acquisition and Seismic Source Ignition Moment in Marine Seismic Exploration

Abstract

The present invention discloses a method and system for synchronizing data acquisition and source firing time in marine seismic exploration. The solution provided by the present invention utilizes the fixed time difference between a first pulse signal, i.e., the signal triggered at the source preparation time, and a second pulse signal, i.e., the signal triggered at the source firing time. When the first pulse signal is triggered, the high-speed clock is adjusted so that when the second pulse signal is triggered, the high-speed clock is also synchronized with the source firing time, thereby ensuring that the zero reference time of the output seismic data is synchronized with the source firing t R ime.

Description

Technical Field

[0001] The present invention relates to the field of exploration technology, and particularly to a method and system for synchronizing data acquisition and seismic source ignition time in marine seismic exploration. Background Art

[0002] The principle of a marine seismic exploration system is to obtain geophysical information data by applying acoustic energy from a sound source to the earth and detecting seismic energy reflected from interfaces between different layers in underground strata.

[0003] In the cabin of a marine seismic exploration ship, a real-time navigation system calculates the seismic source preparation time t0 and the ignition reference time t R according to the current coordinates, the current ship speed and the target shot coordinates, and then sends a trigger pulse signal (t0, usually -160 ms) to the seismic source system in advance. The seismic source ignites at time t R , and at the same time sends a trigger pulse signal (CTB) to the on-board console. After receiving this pulse signal, the on-board console synchronously converts it into a start command and sends it to the underwater sensors. After receiving the start command, all underwater sensors perform synchronous acquisition and upload seismic data, and it is required that the zero reference time (0 ms) of the uploaded seismic data be synchronized with the seismic source ignition time t R .

[0004] Since the analog-to-digital conversion chips applicable to marine seismic acquisition are usually 24-bit ultra-low-noise high-resolution Σ-Δ type analog-to-digital converters, whose structure includes a Σ-Δ modulator and a digital filter (FIR). This brings a problem that when the analog-to-digital conversion chip starts synchronous acquisition, the data in the digital filter is cleared, and a certain amount of data (group delay t D ) needs to be lost and participate in the filter calculation to output correct data. That is, if all sensors receive the synchronous acquisition command at time t R , the seismic data output corresponding to the time from t R to t R + t D is not correct data.

[0005] To avoid the above problem, the usual approach is to manually send the synchronous clock and the synchronous acquisition command (at time t0) in advance, so that the analog-to-digital converter performs acquisition and filtering in advance, and outputs seismic data x[n] (n = t0...) corresponding to the sampling interval of this synchronous clock. Then, after the acquisition system receives the seismic source ignition signal (at time t R ), and sends the ignition command to all sensors. The sensors can obtain the correct seismic data x[m] (m = t R ...) corresponding to time t R ... from the data stream of x[n] (n = t0...) according to the received command time and the group delay, so as to avoid the time period from t DErroneous data within a certain time.

[0006] However, the sampling interval of the seismic data x[n] (n = t0…) is synchronized with a manually started synchronous clock, while the source firing signal (at time t R instant) is not associated with this synchronous clock, which results in a time phase error d between the source firing time t R instant and the x[t R instant. At the same time, there is also a command phase error int(D) in the transmission of the issued synchronous acquisition command and the firing command to all sensors. Eventually, it will lead to the asynchronization between the zero reference time (0 ms) of the output seismic data and the source t R firing time. Summary of the Invention

[0007] In view of the above problems, the present invention is proposed to provide a method and system for synchronizing data acquisition and source firing time in marine seismic exploration that overcomes or at least partially solves the above problems.

[0008] According to one aspect of the present invention, there is provided a method for synchronizing data acquisition and source firing time in marine seismic exploration. The on - board console is connected to the tow - cable transmission line, and multiple - level sensors are distributed on the tow - cable transmission line. The method includes:

[0009] When the on - board console receives the first pulse signal triggered by the navigation system, it adjusts the duty cycle of the high - speed clock within one cycle to a first duty cycle, and transmits the high - speed clock with the first duty cycle as the first command in real - time to each sensor on the tow - cable transmission line through the tow - cable transmission line;

[0010] Each sensor performs data acquisition according to the high - speed clock with the first duty cycle, and uploads the acquired data to the on - board console;

[0011] When the on - board console receives the second pulse signal triggered by the source firing, it adjusts the duty cycle of the high - speed clock within one cycle to a second duty cycle, and transmits the high - speed clock with the second duty cycle as the second command in real - time to each sensor on the tow - cable transmission line through the tow - cable transmission line;

[0012] During the data acquisition process, if each sensor detects the high - speed clock with the second duty cycle, it marks the acquired data with the firing time, and uploads the marked data to the on - board console, thus completing the synchronization of data acquisition and source firing time.

[0013] According to another aspect of the present invention, there is provided a system for synchronizing data acquisition and source firing time in marine seismic exploration, including: an on - board console, a tow - cable transmission line connected to the on - board console, and multiple - level sensors distributed on the tow - cable transmission line;

[0014] A shipborne console, which is configured to adjust the duty cycle of a high-speed clock within one period to a first duty cycle when receiving a first pulse signal triggered by a navigation system, and transmit the high-speed clock with the first duty cycle as a first command to each sensor on a tow cable transmission line in real time through the tow cable transmission line; and, when receiving a second pulse signal triggered by a seismic source ignition, adjust the duty cycle of the high-speed clock within one period to a second duty cycle, and transmit the high-speed clock with the second duty cycle as a second command to each sensor on the tow cable transmission line in real time through the tow cable transmission line;

[0015] Each sensor is configured to collect data according to the high-speed clock with the first duty cycle, and upload the collected data to the shipborne console; and, during the data collection process, if a high-speed clock with the second duty cycle is detected, mark the ignition time of the collected data, and upload the marked data to the shipborne console to complete the synchronization of data collection and seismic source ignition time.

[0016] The solution provided by the present invention utilizes the fixed time difference between the first pulse signal and the second pulse signal, adjusts the high-speed clock when triggering the first pulse signal, so that when triggering the second pulse signal, the high-speed clock is also synchronized with the seismic source ignition time, thereby ensuring that the zero reference time (0ms) of the output seismic data is synchronized with the seismic source ignition t R ime.

[0017] The above description is only an overview of the technical solution of the present invention. In order to be able to understand the technical means of the present invention more clearly, it can be implemented according to the content of the specification. And in order to make the above and other purposes, features and advantages of the present invention more obvious and understandable, the following specifically describes the embodiments of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] By reading the following detailed description of the preferred embodiments, various other advantages and benefits will become clear to those of ordinary skill in the art. The drawings are only for the purpose of showing the preferred embodiments and are not considered to be a limitation of the present invention. And throughout the drawings, the same reference numerals are used to represent the same components. In the drawings:

[0019] Figure 1 A schematic flow chart of a method for synchronizing data collection and seismic source ignition time in marine seismic exploration according to an embodiment of the present invention is shown;

[0020] Figure 2 A schematic structural diagram of a system for synchronizing data collection and seismic source ignition time in marine seismic exploration according to an embodiment of the present invention is shown. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0021] Exemplary embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. Although the exemplary embodiments of the present invention are shown in the drawings, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided so that the present invention can be more thoroughly understood and the scope of the present invention can be fully conveyed to those skilled in the art.

[0022] Figure 1 The flowchart of a method for synchronizing data acquisition and source firing time in marine seismic exploration according to an embodiment of the present invention is shown. The on-board console is connected to the towed cable transmission line, and multiple levels of sensors are distributed on the towed cable transmission line, such as Figure 1 As shown, the method includes the following steps:

[0023] Step S101, when the on-board console receives the first pulse signal triggered by the navigation system, it adjusts the duty cycle of the high-speed clock within one period to the first duty cycle, and transmits the high-speed clock with the first duty cycle as the first command to each sensor on the towed cable transmission line in real time through the towed cable transmission line.

[0024] Specifically, the on-board console continuously outputs a high-speed clock to the underwater sensor. In the cabin of the marine seismic exploration ship, the real-time navigation system calculates the source preparation time t0 based on the current coordinates, the current ship speed, and the target shot coordinates, and at the source preparation time t0, sends the first pulse signal to the on-board console. Among them, the first pulse signal is a start pulse signal (start pulse signal). In order to synchronize data acquisition and source firing time, when the on-board console receives the first pulse signal triggered by the navigation system, it starts to adjust the high-speed clock it outputs. Specifically, the on-board console adjusts the duty cycle of the high-speed clock within one period to the first duty cycle, thereby realizing that the time when the on-board console issues the first command is aligned with the first pulse signal.

[0025] The on-board console takes the high-speed clock with the first duty cycle as the first command, where the first command is the source preparation time command, that is, the t0 time command, and transmits the first command to each sensor on the towed cable transmission line in real time through the towed cable transmission line.

[0026] Step S102, each sensor performs data acquisition according to the high-speed clock with the first duty cycle, and uploads the acquired data to the on-board console.

[0027] After each sensor receives a high-speed clock with a first duty cycle, it performs data acquisition according to the high-speed clock with the first duty cycle, obtains a series of data x[n] (n = t0…) aligned with the first pulse signal, and uploads the acquired data to the on-board console. Specifically, after each sensor receives the high-speed clock, it first identifies and determines the value of the duty cycle of the high-speed clock. When it determines that the value is the first duty cycle, it starts data acquisition.

[0028] Among them, the high-speed clock with the first duty cycle is transmitted from the first-stage sensor to the last-stage sensor level by level. During this process, each stage of the sensor does not perform parsing but directly transmits the high-speed clock with the first duty cycle to the next-stage sensor. Therefore, the synchronization of the first command is achieved, that is, each sensor receives the first command at the same moment, and each sensor immediately performs data acquisition when receiving the first command, thus ensuring that each sensor responds to the first command to perform data acquisition at the same moment.

[0029] After passing through multiple stages of sensors and the tow cable transmission line, the duty cycle of the high-speed clock with the first duty cycle will change, which will cause subsequent sensors to be unable to accurately identify. To ensure that each sensor can correctly identify the first command and respond to the command to perform data acquisition, a controller is inserted every n stages of sensors on the tow cable transmission line. After passing through n stages of sensors, the high-speed clock transmitted by the nth-stage sensor is input to the next-stage controller of the nth-stage sensor. After receiving the high-speed clock, the next-stage controller performs duty cycle restoration processing on the high-speed clock, and then outputs the high-speed clock with the first duty cycle restored to the next-stage sensor behind it, thereby ensuring that all sensors on the tow cable transmission line can identify the first command and synchronously execute data acquisition. Among them, the empirical value of n can be 24.

[0030] Step S103, when the on-board console receives the second pulse signal triggered by the seismic source ignition, it adjusts the duty cycle of the high-speed clock within one cycle to the second duty cycle, and transmits the high-speed clock with the second duty cycle as the second command to each sensor on the tow cable transmission line in real time through the tow cable transmission line. Among them, the trigger interval between the first pulse signal and the second pulse signal is a fixed time difference.

[0031] When the seismic source ignites, it will send a second pulse signal to the on-board console. When the on-board console receives the second pulse signal triggered by the seismic source ignition, it starts to adjust the high-speed clock it outputs. Specifically, the on-board console adjusts the duty cycle of the high-speed clock within one cycle to the second duty cycle. The on-board console uses the high-speed clock with the second duty cycle as the second command. Among them, the second command is the seismic source ignition moment command, that is, t RThe moment command is to transmit the second command to each sensor on the towed cable transmission line in real time through the towed cable transmission line. Among them, the second pulse signal is a CTB pulse signal, and the second command is a seismic source ignition reference moment command.

[0032] The triggering interval between the first pulse signal and the second pulse signal is a fixed time difference, and the fixed time difference is an integer multiple of the data sampling period. For example, the duration of the fixed time difference is 160 ms. Of course, it can also be other durations, which are not specifically limited here.

[0033] The moment when the on-board console issues the first command is aligned with the first pulse signal. Using the fixed time difference between the first pulse signal and the second pulse signal, the high-speed periodic clock is adjusted in advance when the first pulse signal is triggered, so that when the second pulse signal is triggered at the seismic source ignition moment, the high-speed clock is also synchronized with the seismic source ignition moment, and thus ensuring that the zero reference time (0 ms) of the output seismic data is synchronized with the seismic source t R ignition moment, eliminating the command phase difference between the first command and the second command.

[0034] Step S104, during the data acquisition process of each sensor, if a high-speed clock with a second duty cycle is detected, the data collected is marked with the ignition moment, and the marked data is uploaded to the on-board console to complete the synchronization of data acquisition and seismic source ignition moment.

[0035] Each sensor continuously performs data acquisition according to the high-speed clock with the first duty cycle. During the data acquisition process, each sensor receives a high-speed clock with a second duty cycle, and can identify that the received high-speed clock is a kind of marking command according to the second duty cycle, so as to mark the data collected with the ignition moment. For example, a t R timestamp can be added. For example, mark the data at and after the t R moment as x[m] (m = t R …). By marking the ignition moment, it is convenient to distinguish which data is collected at the seismic source t R ignition moment. The data acquisition and marking are carried out at the seismic source ignition moment, eliminating the moment phase error between the seismic source ignition t R moment and the x[t R moment.

[0036] The data with the ignition moment mark is the first data collected at the seismic source ignition moment, thus ensuring that the zero reference time (0 ms) of the output seismic data is synchronized with the seismic source t R ignition moment, providing a guarantee for subsequent analysis based on the data after the seismic source ignition moment.

[0037] Among them, the high-speed clock with the second duty cycle is transmitted from the first-stage sensor to the last-stage sensor level by level. During this process, each stage of the sensor does not perform parsing but directly transmits the high-speed clock with the second duty cycle to the next-stage sensor. Therefore, the synchronization of the second command is achieved, that is, each sensor receives the second command at the same moment. Each sensor immediately performs data acquisition and ignition time marking when receiving the second command, thereby ensuring that each sensor responds to the second command at the same moment for data acquisition and ignition time marking.

[0038] After passing through multiple stages of sensors and tow cable transmission lines, the duty cycle of the high-speed clock with the second duty cycle will change, which will cause subsequent sensors to be unable to accurately identify it. To ensure that each sensor can correctly identify the second command and respond to the command for data acquisition, a controller is inserted every n stages of sensors on the tow cable transmission line. After passing through n stages of sensors, the high-speed clock transmitted by the nth-stage sensor is input to the next-stage controller of the nth-stage sensor. After receiving the high-speed clock, the next-stage controller performs duty cycle restoration processing on the high-speed clock, and then outputs the high-speed clock with the second duty cycle restored to the next-stage sensor behind it, thereby ensuring that all sensors on the tow cable transmission line can identify the second command and synchronously execute data acquisition and ignition time marking. Among them, the empirical value of n can be 24, or it can be other values.

[0039] This embodiment uses a one-cycle high-speed clock with a changed duty cycle as a command, eliminating the command phase error of the seismic source ignition signal sent to each sensor.

[0040] In an alternative embodiment of the present invention, it is usually required that data acquisition be synchronized with the source firing moment each time the source is fired. Therefore, when the source is fired next time, before adjusting the duty cycle of the high-speed clock within one cycle to the first duty cycle, the method further includes: adjusting the duty cycle of the high-speed clock within one cycle to the third duty cycle, and transmitting the high-speed clock with the third duty cycle as the third command to each sensor on the towed cable transmission line in real time through the towed cable transmission line; each sensor stops data acquisition according to the high-speed clock with the third duty cycle. Specifically, after each sensor receives the high-speed clock with the third duty cycle, it can identify that the received high-speed clock is a stop acquisition command according to the third duty cycle, and thus stops data acquisition according to the high-speed clock with the third duty cycle. Here, it is to make each sensor stop the previous data acquisition first; after a preset duration of transmitting the high-speed clock with the third duty cycle as the third command to each sensor on the towed cable transmission line in real time through the towed cable transmission line, adjust the duty cycle of the high-speed clock within one cycle to the first duty cycle, where the preset duration is an integer multiple of the data sampling period, and the preset time period is less than the fixed time difference, so as to ensure that the high-speed clock is also synchronized with the source firing moment.

[0041] In order to ensure the synchronization of data acquisition of each sensor, it is necessary to first synchronize the acquisition clocks of each sensor. Specifically, the synchronization of the acquisition clocks of each sensor can be achieved by the following method:

[0042] The on-board console obtains the high-speed clock according to the GNSS signal, and transmits the high-speed clock to each level of sensor on the towed cable transmission line in real time through the towed cable transmission line. Each level of sensor (except the last-level sensor) transmits the received high-speed clock to the next-level sensor and locks the received high-speed clock as the internal clock of the sensor through the clock phase-locked loop inside the sensor at the same time, and uses the internal clock as the sampling clock of the analog-to-digital converter inside the sensor. After the last-level sensor receives the high-speed clock, it immediately locks the received high-speed clock as the internal clock of the sensor through the clock phase-locked loop inside the sensor, and uses the internal clock as the sampling clock of the analog-to-digital converter inside the sensor, thereby realizing the clock synchronization between each sensor. The transmission of the high-speed clock between different sensors is without delay, so that each sensor can collect data at the same moment.

[0043] The solution provided by the present invention utilizes the fixed time difference between the first pulse signal and the second pulse signal to adjust the high-speed clock when the first pulse signal is triggered, so that when the second pulse signal is triggered, the high-speed clock is also synchronized with the source firing moment, thereby ensuring that the zero reference time (0 ms) of the output seismic data is synchronized with the source firing R moment.

[0044] Figure 2The figure shows a schematic structural diagram of a data acquisition and seismic source ignition time synchronization system according to an embodiment of the present invention. As Figure 2 shown, the system includes: a shipborne console 201, a tow cable transmission line 202 connected to the shipborne console, and a plurality of levels of sensors 203 distributed on the tow cable transmission line.

[0045] The shipborne console is configured to, when receiving a first pulse signal triggered by a navigation system, adjust the duty cycle of a high-speed clock within one cycle to a first duty cycle, and transmit the high-speed clock with the first duty cycle as a first command to each sensor on the tow cable transmission line in real time through the tow cable transmission line; and, when receiving a second pulse signal triggered by seismic source ignition, adjust the duty cycle of the high-speed clock within one cycle to a second duty cycle, and transmit the high-speed clock with the second duty cycle as a second command to each sensor on the tow cable transmission line in real time through the tow cable transmission line, wherein the triggering interval between the first pulse signal and the second pulse signal is a fixed time difference;

[0046] Each sensor is configured to perform data acquisition according to the high-speed clock with the first duty cycle, and upload the acquired data to the shipborne console; and, during the data acquisition process, if a high-speed clock with the second duty cycle is detected, mark the ignition time of the acquired data, and upload the marked data to the shipborne console to complete the synchronization of data acquisition and seismic source ignition time.

[0047] Optionally, the shipborne console is further configured to: before adjusting the duty cycle of the high-speed clock within one cycle to the first duty cycle, adjust the duty cycle of the high-speed clock within one cycle to a third duty cycle, and transmit the high-speed clock with the third duty cycle as a third command to each sensor on the tow cable transmission line in real time through the tow cable transmission line; and, after a preset duration of transmitting the high-speed clock with the third duty cycle as a third command to each sensor on the tow cable transmission line in real time through the tow cable transmission line, adjust the duty cycle of the high-speed clock within one cycle to the first duty cycle, wherein the preset duration is an integer multiple of the data sampling period, and the preset time period is less than the fixed time difference;

[0048] Each sensor is further configured to: stop data acquisition according to the high-speed clock with the third duty cycle.

[0049] Optionally, the fixed time difference is an integer multiple of the data sampling period.

[0050] Optionally, the first command is a seismic source preparation time command; the second command is a seismic source ignition reference time command.

[0051] Optionally, the first pulse signal is a start pulse signal; the second pulse signal is a CTB pulse signal.

[0052] The solution provided by the present invention utilizes the fixed time difference between the first pulse signal and the second pulse signal to adjust the high-speed clock in advance when the first pulse signal is triggered, so that when the second pulse signal is triggered, the high-speed clock is also synchronized with the source ignition moment, thereby ensuring that the zero reference time (0 ms) of the output seismic data is synchronized with the source ignition t R moment.

[0053] The algorithms or displays provided herein are not inherently related to any particular computer, virtual system, or other device. A variety of general-purpose systems can also be used in conjunction with the teachings provided herein. The structure required to construct such systems will be apparent from the above description. In addition, the embodiments of the present invention are not directed to any particular programming language. It should be understood that the content of the present invention described herein can be implemented using various programming languages, and the above description of specific languages is to disclose the best mode of the present invention.

[0054] In the specification provided herein, a large number of specific details are set forth. However, it can be understood that the embodiments of the present invention may be practiced without these specific details. In some instances, well-known methods, structures, and technologies have not been shown in detail so as not to obscure the understanding of this specification.

[0055] Similarly, it should be understood that, in order to streamline the present invention and assist in understanding one or more of the various inventive aspects, in the above description of the exemplary embodiments of the present invention, the various features of the embodiments of the present invention are sometimes grouped together into a single embodiment, figure, or description thereof. However, the disclosed method should not be construed as reflecting the intention that the claimed invention requires more features than are expressly recited in each claim. Rather, as reflected in the following claims, the inventive aspects lie in less than all the features of the single foregoing disclosed embodiment. Thus, the claims following the detailed description are hereby expressly incorporated into the detailed description, with each claim standing on its own as a separate embodiment of the present invention.

[0056] Those skilled in the art can understand that the modules in the devices in the embodiments can be adaptively changed and disposed in one or more devices different from the embodiments. The modules or units or components in the embodiments can be combined into one module or unit or component, and in addition, they can be divided into multiple sub-modules or sub-units or sub-components. Except that at least some of such features and / or processes or units are mutually exclusive, any combination can be adopted to combine all the features disclosed in this specification (including the accompanying claims, abstract and drawings) and all the processes or units of any method or device so disclosed. Unless otherwise explicitly stated, each feature disclosed in this specification (including the accompanying claims, abstract and drawings) can be replaced by an alternative feature that provides the same, equivalent or similar purpose.

[0057] In addition, those skilled in the art can understand that although some of the embodiments herein include certain features included in other embodiments rather than other features, the combination of the features of different embodiments means that it is within the scope of the present invention and forms different embodiments. For example, in the following claims, any one of the claimed embodiments can be used in any combination.

[0058] Each component embodiment of the present invention can be implemented in hardware, or in software modules running on one or more processors, or in a combination thereof. Those skilled in the art should understand that a microprocessor or a digital signal processor (DSP) can be used in practice to implement some or all of the functions of some or all of the components according to the embodiments of the present invention. The present invention can also be implemented as a device or apparatus program (for example, a computer program and a computer program product) for executing part or all of the methods described herein. Such a program implementing the present invention can be stored on a computer-readable medium, or can be in the form of one or more signals. Such signals can be downloaded from an Internet website, or provided on a carrier signal, or provided in any other form.

[0059] It should be noted that the above embodiments are illustrative of the present invention rather than restrictive thereof, and those skilled in the art can design alternative embodiments without departing from the scope of the appended claims. In the claims, any reference signs placed between parentheses shall not be construed as limiting the claim. The word "comprising" does not exclude the presence of elements or steps not listed in the claim. The word "a" or "an" preceding an element does not exclude the presence of a plurality of such elements. The present invention can be implemented by means of hardware including several different elements and by means of a suitably programmed computer. In the unit claims listing several devices, several of these devices can be embodied by the same item of hardware. The use of the words first, second, and third, etc. does not denote any order. These words can be interpreted as names. The steps in the above embodiments, unless otherwise specified, should not be construed as limiting the order of execution.

Claims

1. A method for synchronizing data acquisition and seismic source ignition time in marine seismic exploration. The shipborne console is connected to the towed cable transmission line, and multiple levels of sensors are distributed on the towed cable transmission line. The method includes: When the shipborne console receives the first pulse signal triggered by the navigation system, it adjusts the duty cycle of the high-speed clock within one cycle to the first duty cycle, and transmits the high-speed clock with the first duty cycle as the first command to each sensor on the towed cable transmission line in real time through the towed cable transmission line. Among them, a controller is inserted every n levels of sensors on the towed cable transmission line. After passing through n levels of sensors, the high-speed clock transmitted by the nth-level sensor is input to the next-level controller of the nth-level sensor. After receiving the high-speed clock, the next-level controller performs duty cycle restoration processing on the high-speed clock, and outputs the high-speed clock with the first duty cycle restored again to the next-level sensor after the controller. Each sensor performs data acquisition according to the high-speed clock with the first duty cycle, and uploads the acquired data to the shipborne console. When the shipborne console receives the second pulse signal triggered by the seismic source ignition, it adjusts the duty cycle of the high-speed clock within one cycle to the second duty cycle, and transmits the high-speed clock with the second duty cycle as the second command to each sensor on the towed cable transmission line in real time through the towed cable transmission line. Among them, after passing through n levels of sensors, the high-speed clock transmitted by the nth-level sensor is input to the next-level controller of the nth-level sensor. After receiving the high-speed clock, the next-level controller performs duty cycle restoration processing on the high-speed clock, and outputs the high-speed clock with the second duty cycle restored again to the next-level sensor after it. The trigger interval between the first pulse signal and the second pulse signal is a fixed time difference, and the fixed time difference is an integer multiple of the data sampling period. During the data acquisition process of each sensor, if a high-speed clock with the second duty cycle is detected, the acquired data is marked with the ignition time, and the marked data is uploaded to the shipborne console to complete the synchronization of data acquisition and seismic source ignition time.

2. The method according to claim 1, wherein Before adjusting the duty cycle of the high-speed clock within one cycle to the first duty cycle, the method further includes: Adjusting the duty cycle of the high-speed clock within one cycle to the third duty cycle, and transmitting the high-speed clock with the third duty cycle as the third command to each sensor on the towed cable transmission line in real time through the towed cable transmission line. Each sensor stops data acquisition according to the high-speed clock with the third duty cycle. Adjusting the duty cycle of the high-speed clock within one cycle to the first duty cycle further includes: After a preset duration of transmitting the high-speed clock with the third duty cycle as the third command to each sensor on the towed cable transmission line in real time through the towed cable transmission line, adjusting the duty cycle of the high-speed clock within one cycle to the first duty cycle, where the preset duration is an integer multiple of the data sampling period, and the preset time period is less than the fixed time difference.

3. The method according to claim 1 or 2, wherein The first command is the seismic source preparation time command; the second command is the seismic source ignition reference time command.

4. The method according to claim 1 or 2, wherein The first pulse signal is the start pulse signal; the second pulse signal is the CTB pulse signal.

5. A data acquisition and seismic source ignition time synchronization system for marine seismic exploration, comprising: A shipborne console, a tow cable transmission line connected to the shipborne console, and multiple levels of sensors are distributed on the tow cable transmission line; The shipborne console is configured to, when receiving a first pulse signal triggered by a navigation system, adjust the duty cycle of a high-speed clock within one period to a first duty cycle, and transmit the high-speed clock with the first duty cycle as a first command to each sensor on the tow cable transmission line in real time through the tow cable transmission line; And, when receiving a second pulse signal triggered by a seismic source ignition, adjust the duty cycle of the high-speed clock within one period to a second duty cycle, and transmit the high-speed clock with the second duty cycle as a second command to each sensor on the tow cable transmission line in real time through the tow cable transmission line, wherein the trigger interval between the first pulse signal and the second pulse signal is a fixed time difference, and the fixed time difference is an integer multiple of the data sampling period; Each sensor is configured to perform data acquisition according to the high-speed clock with the first duty cycle and upload the acquired data to the shipborne console; and, during the data acquisition process, if a high-speed clock with the second duty cycle is detected, mark the acquired data with the ignition time, and upload the marked data to the shipborne console to complete the synchronization of data acquisition and the seismic source ignition time; Wherein, a controller is inserted every n levels of sensors on the tow cable transmission line. After passing through n levels of sensors, the high-speed clock transmitted by the nth-level sensor is input to the next-level controller of the nth-level sensor. After receiving the high-speed clock, the next-level controller performs duty cycle restoration processing on the high-speed clock, outputs the high-speed clock with the first duty cycle restored again to the next-level sensor after the controller, and outputs the high-speed clock with the second duty cycle restored again to the next-level sensor after it.

6. The system according to claim 5, wherein, The shipborne console is further configured to: before adjusting the duty cycle of the high-speed clock within one period to the first duty cycle, adjust the duty cycle of the high-speed clock within one period to a third duty cycle, and transmit the high-speed clock with the third duty cycle as a third command to each sensor on the tow cable transmission line in real time through the tow cable transmission line; And, after a preset duration of transmitting the high-speed clock with the third duty cycle as a third command to each sensor on the tow cable transmission line in real time through the tow cable transmission line, adjust the duty cycle of the high-speed clock within one period to the first duty cycle, wherein the preset duration is an integer multiple of the data sampling period, and the preset time period is less than the fixed time difference; Each sensor is further configured to: stop data acquisition according to the high-speed clock with the third duty cycle.

7. The system according to claim 5 or 6, wherein, The first command is a seismic source preparation time command; the second command is a seismic source ignition reference time command.

8. The system according to claim 5 or 6, wherein, The first pulse signal is a start pulse signal; the second pulse signal is a CTB pulse signal.

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