Command Synchronization Method and System for Marine Seismic Exploration

Abstract

The present invention discloses a command synchronization method and system for marine seismic exploration. The command issued by this method is a high-speed clock with a variable duty cycle. Transmitting the high-speed clock with a variable duty cycle to the sensors as a command can be received and executed by all sensors simultaneously, rather than a conventional frame of commands, and there is no need to adjust the command execution time of all command receiving devices through delay compensation parameters, thereby completely eliminating command phase deviation.

Description

Technical Field

[0001] The present invention relates to the field of exploration technology, and in particular, to a method and system for command synchronization 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 the seismic energy reflected from the interfaces between different layers in the subsurface formation.

[0003] In a marine seismic exploration system, an air gun array is usually used as the sound source, and a seismic streamer is used to collect seismic energy. The air gun array and the seismic streamer are generally towed behind a recording vessel, at a depth between six and nine meters in the water. The air gun array is about two hundred meters away from the recording vessel, while the streamer is six to fifteen kilometers long.

[0004] Usually, there are multiple sensors distributed along the seismic streamer inside the seismic streamer, which are used to detect the seismic signals reflected from the formation by the air gun array that excites the sound source, and to transmit the digitized seismic signals to an on-board indoor recording system.

[0005] Since multiple sensors are distributed in a six - to - fifteen - kilometer streamer, the number can reach 480 to 1200, and the sensors are connected by transmission lines. However, the command transmission between sensors is not broadcast, but is relayed step by step. Therefore, for commands that need to be synchronized in real time, such as the start of acquisition issued from the on - board console, as the number of sensors increases, the time deviation of the command reaching each sensor becomes larger and larger, that is, a command phase deviation occurs. This results in the degradation of the quality of seismic data because all sensors receive the start - acquisition and other commands asynchronously. Therefore, it is crucial to synchronize the commands of multiple sensors in the streamer. Summary of the Invention

[0006] In view of the above problems, the present invention is proposed to provide a method and system for command synchronization in marine seismic exploration that overcomes or at least partially solves the above problems.

[0007] According to one aspect of the present invention, there is provided a method for command synchronization in marine seismic exploration. An on - board console is connected to a streamer transmission line, and m - level sensors are distributed on the streamer transmission line. The method includes:

[0008] When the on - board console receives a command trigger signal, it adjusts the duty cycle of a high - speed clock within one cycle in real time according to the type of the command to be issued, and transmits the high - speed clock with the adjusted duty cycle as a command to the first - level sensor on the streamer transmission line through the streamer transmission line;

[0009] While transmitting the high-speed clock to the next-level sensor, the first-level sensor identifies the duty cycle of the received high-speed clock and responds to the command according to the duty cycle.

[0010] Starting from i = 2, the i-th level sensor receives the high-speed clock relayed without delay from the previous-level sensor. While transmitting the high-speed clock to the next-level sensor, it identifies the duty cycle of the received high-speed clock, responds to the command according to the duty cycle, assigns i as i + 1, and repeats this step until i = m - 1.

[0011] The m-th level sensor receives the high-speed clock relayed without delay from the previous-level sensor, simultaneously identifies the duty cycle of the received high-speed clock, responds to the command according to the duty cycle, and completes the command synchronization.

[0012] According to another aspect of the present invention, there is provided a command synchronization system for marine seismic exploration, including: a shipborne console, a tow cable transmission line connected to the shipborne console, and m levels of sensors distributed on the tow cable transmission line.

[0013] The shipborne console is configured to, when receiving a command trigger signal, adjust the duty cycle of the high-speed clock within one cycle in real time according to the type of the command to be issued, and transmit the high-speed clock with the adjusted duty cycle as a command to the first-level sensor on the tow cable transmission line through the tow cable transmission line.

[0014] The first-level sensor is configured to, while transmitting the high-speed clock to the next-level sensor, identify the duty cycle of the received high-speed clock and respond to the command according to the duty cycle.

[0015] Starting from i = 2, the i-th level sensor is configured to receive the high-speed clock relayed without delay from the previous-level sensor, identify the duty cycle of the received high-speed clock while transmitting the high-speed clock to the next-level sensor, respond to the command according to the duty cycle, assign i as i + 1, and repeat this step until i = m - 1.

[0016] The m-th level sensor is configured to receive the high-speed clock relayed without delay from the previous-level sensor, simultaneously identify the duty cycle of the received high-speed clock, respond to the command according to the duty cycle, and complete the command synchronization.

[0017] According to the solution provided by the present invention, the issued command is a high-speed clock with a changed duty cycle, rather than a conventional one-frame command. There is no need to adjust the command execution time of all command receiving devices through delay compensation parameters. At the same time, since all sensors have achieved clock synchronization, the high-speed clock with the changed duty cycle transmitted to the sensors can also be received and executed by all sensors simultaneously, thus completely eliminating the command phase deviation.

[0018] The above description is only an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention, it can be implemented according to the content of the specification. And in order to make the above and other objects, features and advantages of the present invention more obvious and understandable, the specific embodiments of the present invention are given below. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] 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 as limiting the present invention. Moreover, throughout the drawings, the same reference numerals are used to represent the same components. In the drawings:

[0020] Figure 1 A flowchart showing a command synchronization method for marine seismic exploration according to an embodiment of the present invention is shown;

[0021] Figure 2 A schematic structural diagram of a command synchronization system for marine seismic exploration according to an embodiment of the present invention is shown;

[0022] Figure 3 A schematic diagram of a sensor is shown. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0023] The exemplary embodiments of the present invention will be described in more detail below with reference to the 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 completely conveyed to those skilled in the art.

[0024] Figure 1 A flowchart showing a command synchronization method for marine seismic exploration according to an embodiment of the present invention is shown. The on-board console is connected to the tow cable transmission line, and m-level sensors are distributed on the tow cable transmission line, such as Figure 1 shown, the method includes the following steps:

[0025] Step S101, when the on-board console receives a command trigger signal, it adjusts the duty cycle of the high-speed clock in one cycle in real time according to the type of command to be issued, and transmits the high-speed clock after duty cycle adjustment as a command to the first-level sensor on the tow cable transmission line through the tow cable transmission line.

[0026] The shipborne console obtains a high-speed clock based on the GNSS signal and transmits the high-speed clock to each level of sensors on the tow cable transmission line in real time through the tow cable transmission line. Each level of sensors (except the last-level sensor) transmits the received high-speed clock to the next-level sensor and at the same time 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. After receiving the high-speed clock, the last-level sensor 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, thus achieving clock synchronization between the sensors.

[0027] When the shipborne console receives a command trigger signal, the shipborne console changes the duty cycle of the high-speed clock within one cycle on the high-speed clock it outputs according to the type of command to be issued. The high-speed clock after duty cycle adjustment will be transmitted as a command to the first-level sensor through the tow cable transmission line. Among them, the types of commands to be issued include: data acquisition command type, data marking command type, or stop data acquisition command type.

[0028] Step S102, while transmitting the high-speed clock to the next-level sensor, the first-level sensor identifies the duty cycle of the received high-speed clock and responds to the command according to the duty cycle.

[0029] Step S103, starting from i = 2, the i-th level sensor receives the high-speed clock relayed without delay from the previous-level sensor, identifies the duty cycle of the received high-speed clock while transmitting the high-speed clock to the next-level sensor, responds to the command according to the duty cycle, assigns i to i + 1, and repeats this step until i = m - 1.

[0030] Step S104, the m-th level sensor receives the high-speed clock relayed without delay from the previous-level sensor, simultaneously identifies the duty cycle of the received high-speed clock, responds to the command according to the duty cycle, and completes command synchronization.

[0031] Specifically, after receiving the high-speed clock with adjusted duty cycle transmitted by the tow cable transmission line, the first-level sensor directly relays the high-speed clock to the second-level sensor without delay. At the same time, the first-level sensor identifies the duty cycle of the received high-speed clock, that is, determines the specific value of the duty cycle of the high-speed clock, and determines what kind of command is received according to the duty cycle and immediately responds to the command.

[0032] Starting from the second-level sensor up to the (m - 1)-th level sensor, each level of sensor receives the high-speed clock after duty cycle adjustment relayed without delay from the previous level sensor. While transmitting the high-speed clock after duty cycle adjustment to the next level sensor, it identifies the duty cycle of the received high-speed clock (the clock after duty cycle adjustment) and responds to the command according to the duty cycle.

[0033] The last level of sensor, after receiving the high-speed clock after duty cycle adjustment, identifies the duty cycle of the received high-speed clock (the clock after duty cycle adjustment) and responds to the command according to the duty cycle.

[0034] In this embodiment, each level of sensor on the tow cable transmission line is the same. Inside each level of sensor, there is a receiving chip, a clock phase-locked loop PLL, and a transmitting chip. As Figure 3 shown, during the process of realizing command synchronization, after the receiving chip of each level of sensor (except the last level of sensor) receives the high-speed clock after duty cycle adjustment, it will process in two paths simultaneously. One path is to relay the received high-speed clock without delay to the next level of sensor and directly transmit it through the transmitting chip. This transmission is not processed, so the transmission time is negligible. The other path is to immediately respond to the command. Specifically, the sensor identifies the duty cycle of the received high-speed clock, determines what kind of command is received according to the duty cycle, and then responds to the command.

[0035] In this embodiment, the clock transmitted to the next level of sensor is the clock that has not been processed by the current level of sensor. Since it is not processed first and then transmitted as in the prior art, the transmission of the high-speed clock between sensors is a relay transmission without delay. Thus, it can be determined that each sensor responds to the command synchronously.

[0036] In an alternative embodiment of the present invention, after the high-speed clock is transmitted through multiple levels of sensors, the duty cycle of the high-speed clock changes continuously, which may cause subsequent sensors to be unable to accurately identify the command. To enable the sensors to accurately respond to the command, the method further includes: inserting a controller every n levels of sensors on the tow cable transmission line, transmitting the high-speed clock output by the n-th level of sensor to the next-level controller connected to the n-th level of sensor, and the next-level controller performs duty cycle restoration processing on the received high-speed clock and transmits the high-speed clock after duty cycle restoration processing to the sensor connected to the next-level controller.

[0037] Specifically, after passing through n - level sensors, the high - speed clock transmitted by the n - th level sensor is input to the next - level controller of the n - th level sensor. After receiving the high - speed clock, the next - level controller performs duty - cycle recovery processing on the high - speed clock. It should be noted that although the duty - cycle of the high - speed clock changes continuously after passing through n - level sensors, the duty - cycle of the high - speed clock transmitted to the next - level controller is still within the corresponding duty - cycle range of the corresponding command. Therefore, the next - level controller can identify which command the high - speed clock corresponds to through the duty - cycle of the high - speed clock, and then restore the duty - cycle of the high - speed clock to the corresponding preset duty - cycle threshold. Here, the preset duty - cycle threshold corresponds to the maximum value of the duty - cycle range corresponding to the command. Specifically, the next - level controller determines the command type according to the duty - cycle of the received high - speed clock, and then performs duty - cycle recovery processing on the high - speed clock according to the command type, restoring it to the initially adjusted duty - cycle. Then, the high - speed clock after duty - cycle recovery processing is output to the next - level sensor behind it without delay, thereby ensuring that all sensors on the towed cable transmission line can identify the command and synchronously respond to the command, thus eliminating the phase error of the sensor's response to the command. Among them, the empirical value of n can be 24. When it is greater than 24, it is very likely that the duty - cycle of the high - speed clock transmitted by the n - th level sensor is less than the minimum value of the duty - cycle range corresponding to the command, resulting in the next - level controller misidentifying the high - speed clock as other commands and causing subsequent sensors to respond to the command incorrectly. In this embodiment, m is much larger than n.

[0038] In an alternative embodiment of the present invention, due to various reasons such as the transmission medium, some sensors in the m - level sensors may not successfully receive the high - speed clock as a command, or due to severe jitter generated when the high - speed clock is transmitted between sensors, the controller performs incorrect duty - cycle recovery, resulting in a change in the high - speed clock received by subsequent sensors. Therefore, the method further includes: each level of sensor controls the counter inside the sensor to perform command cumulative reception count processing according to the duty - cycle of the received high - speed clock. Specifically, it can be determined whether the duty - cycle of the received high - speed clock transmitted by each level of sensor matches the duty - cycle condition corresponding to any of the to - be - issued command types. Among them, each to - be - issued command type corresponds to a duty - cycle condition, and the duty - cycle conditions corresponding to different to - be - issued command types are different; if so, control the counter inside the sensor to increment the command cumulative reception count corresponding to the to - be - issued command type by 1. If it does not match the duty - cycle condition corresponding to any of the to - be - issued command types, no processing may be performed. After the command trigger signal ends, the command cumulative reception count is uploaded to the on - board console for the on - board console to determine whether the sensor normally responds to the corresponding command according to the command cumulative reception counts uploaded by each level of sensor.

[0039] In an alternative embodiment of the present invention, the method further includes: if the controller receives that the duty cycle of the transmitted high-speed clock matches the duty cycle condition corresponding to the command type to be issued, the controller controls the counter inside it to increment the received count corresponding to the command type to be issued by 1. After the command trigger signal ends, the cumulative received count corresponding to the command type to be issued is uploaded to the on-board console for the on-board console to determine whether the controller performs duty cycle recovery processing based on the cumulative received count corresponding to the command type uploaded by the controller. This is mainly to determine whether the controller normally performs duty cycle recovery processing, so that when it is determined that some sensors do not respond to commands normally, it can be accurately analyzed whether it is caused by the controller not performing duty cycle recovery or other reasons.

[0040] In an alternative embodiment of the present invention, the response to the command according to the duty cycle further includes:

[0041] If the duty cycle of the high-speed clock meets the first duty cycle condition, data acquisition is performed in response to the command;

[0042] If the duty cycle of the high-speed clock meets the second duty cycle condition, data marking processing is performed in response to the command;

[0043] If the duty cycle of the high-speed clock meets the third duty cycle condition, data marking is exited in response to the command.

[0044] In this embodiment, the commands to be issued during the marine seismic exploration process are mainly divided into three categories, including: data acquisition commands, data marking commands, or stop data acquisition commands. The above commands are all implemented by sending a high-speed clock. Therefore, in order to enable the sensor to accurately respond to the commands, three different duty cycle conditions are set for the three different types of commands respectively. For example, the data acquisition command corresponds to the first duty cycle condition, the data marking command corresponds to the second duty cycle condition, and the stop data acquisition command corresponds to the third duty cycle condition. The first duty cycle condition, the second duty cycle condition, and the third duty cycle condition respectively correspond to a duty cycle range value. After the sensor receives the high-speed clock with the duty cycle adjusted, the duty cycle of the high-speed clock is compared with the first duty cycle condition, the second duty cycle condition, and the third duty cycle condition respectively. If the duty cycle of the high-speed clock meets the first duty cycle condition, it can be determined that the command is a data acquisition command, and the sensor responds to the command to perform data acquisition; if the duty cycle of the high-speed clock meets the second duty cycle condition, it can be determined that the command is a data marking command, and the sensor responds to the command to perform data marking processing; if the duty cycle of the high-speed clock meets the third duty cycle condition, it can be determined that the command is a stop data acquisition command, and the sensor responds to the command to exit data acquisition.

[0045] Optionally, when the on-board console adjusts the duty cycle of the high-speed clock within one cycle, it adjusts the duty cycle of the high-speed clock to the corresponding preset duty cycle threshold according to the command type. The preset duty cycle threshold is the maximum value of the duty cycle range corresponding to the command. For example, if the command to be sent is a first-type command, the duty cycle of the high-speed clock is adjusted to the first preset duty cycle threshold; if the command to be sent is a second-type command, the duty cycle of the high-speed clock is adjusted to the second preset duty cycle threshold; if the command to be sent is a third-type command, the duty cycle of the high-speed clock is adjusted to the third preset duty cycle threshold. The first preset duty cycle threshold, the second preset duty cycle threshold, and the third preset duty cycle threshold are three different values and do not fall within the duty cycle ranges corresponding to other commands.

[0046] For example, the duty cycle of the high-speed clock transmitted by the on-board console before receiving the command trigger signal is 50%. When it is determined that a collection command needs to be sent, the duty cycle of the high-speed clock can be adjusted to 25%. This is only an example and has no restrictive effect.

[0047] In this embodiment, the on-board console can drag multiple tow cable transmission lines, and multiple sensors are distributed on each tow cable transmission line. The on-board console can send the high-speed clock to the first-level sensors on the tow cable transmission line in real time through each tow cable transmission line.

[0048] In an optional implementation manner of the present invention, before the on-board console obtains the high-speed clock according to the GNSS signal and sends the high-speed clock to the sensors at all levels on the tow cable transmission line in real time through the tow cable transmission line, before the on-board console transmits the high-speed clock through the tow cable transmission line, it sends a clock notification instruction to the sensors at all levels through the tow cable transmission line. Each level of sensor prepares to receive the high-speed clock according to this clock notification instruction and does not delay and relay the received high-speed clock. Specifically, after each level of sensor receives the clock notification instruction, it parses the clock notification instruction and transmits it to the next level of sensor until it is transmitted to the last level of sensor. When the clock is not sent, the link between the receiving chip and the sending chip inside the sensor is disconnected. Each level of sensor knows that the on-board console is about to transmit the high-speed clock by parsing the instruction. Therefore, the link between the receiving chip and the sending chip inside the sensor is connected.

[0049] The solution provided by the present invention is that the sent command is a high-speed clock with a changed duty cycle, rather than a conventional one-frame command, and there is no need to adjust the command execution time of all command receiving devices through delay compensation parameters. At the same time, since all sensors have achieved clock synchronization, the high-speed clock with the changed duty cycle transmitted to the sensors can also be received and executed by all sensors at the same time, thus completely eliminating the command phase deviation.

[0050] Figure 2FIG. 2 shows a schematic diagram of a command synchronization system for marine seismic exploration according to an embodiment of the present invention. Figure 2 As shown, the system includes: a shipborne control console 201, a streamer transmission line 202 connected to the shipborne control console, and m-level sensors 203 are distributed on the streamer transmission line.

[0051] The shipborne control console is used to adjust the duty cycle of the high-speed clock in one cycle in real time according to the type of command to be issued when receiving the command trigger signal, and transmit the high-speed clock with the duty cycle adjusted as a command to the first-level sensor on the towed cable transmission line in real time through the towed cable transmission line;

[0052] The first-level sensor is used to identify the duty cycle of the received high-speed clock while transmitting the high-speed clock to the next-level sensor, and respond to the command according to the duty cycle;

[0053] Starting from i=2, the i-th level sensor is used to receive the high-speed clock transmitted by the previous level sensor without delay, identify the duty cycle of the received high-speed clock while transmitting the high-speed clock to the next level sensor, respond to the command according to the duty cycle, assign i to i+1, and repeat this step until i=m-1;

[0054] The m-th level sensor is used to receive the high-speed clock transmitted by the upper level sensor without delay, and at the same time identify the duty cycle of the received high-speed clock, respond to the command according to the duty cycle, and complete command synchronization.

[0055] Specifically, after receiving the high-speed clock with adjusted duty cycle transmitted by the tow cable transmission line, the first-level sensor directly relays the high-speed clock to the second-level sensor without delay. At the same time, the first-level sensor identifies the duty cycle of the received high-speed clock, that is, determines the specific value of the duty cycle of the high-speed clock, and determines what kind of command is received according to the duty cycle and responds to the command immediately.

[0056] Starting from the 2nd level sensor to the m-1th level sensor, the sensor at this level receives the high-speed clock with duty cycle adjustment transmitted by the previous level sensor without delay, and while transmitting the high-speed clock with duty cycle adjustment to the next level sensor, it identifies the duty cycle of the received high-speed clock (clock with duty cycle adjustment), and responds to the command according to the duty cycle.

[0057] The last level sensor, after receiving the high-speed clock after the duty cycle is adjusted, identifies the duty cycle of the received high-speed clock (the clock after the duty cycle is adjusted), and responds to the command according to the duty cycle.

[0058] In this embodiment, each level of sensors on the towed cable transmission line is the same. Inside each level of sensor, there is a receiving chip, a clock phase-locked loop (PLL), and a transmitting chip. As Figure 3 shown, during the process of realizing command synchronization, the receiving chip of each level of sensor (except the last level of sensor) will process the received high-speed clock with adjusted duty cycle in two paths simultaneously after receiving it. One path is to relay the received high-speed clock to the next level of sensor without delay and directly transmit it through the transmitting chip. Since this transmission is not processed, the transmission time is negligible. The other path is to immediately respond to the command. Specifically, the sensor identifies the duty cycle of the received high-speed clock and determines what kind of command is received according to the duty cycle, and then responds to the command.

[0059] In this embodiment, the clock transmitted to the next level of sensor is the clock that has not been processed by the current level of sensor. Since it is not processed first and then transmitted as in the prior art, the transmission of the high-speed clock between sensors is a non-delay relay transmission. Therefore, it can be determined that each sensor responds to the command synchronously.

[0060] Optionally, a controller is inserted every n levels of sensors on the towed cable transmission line. The high-speed clock output by the nth level of sensor is transmitted to the next-level controller connected to the nth level of sensor. The next-level controller performs duty cycle restoration processing on the received high-speed clock and transmits the high-speed clock after duty cycle restoration processing to the sensor connected to this next-level controller.

[0061] Specifically, after every n levels of sensors, the high-speed clock transmitted by the nth level of sensor is input to the next-level controller of the nth level of sensor. After receiving the high-speed clock, the next-level controller performs duty cycle restoration processing on the received high-speed clock. The duty cycle of the high-speed clock transmitted to the next-level controller is still within the corresponding duty cycle range of the corresponding command. Therefore, the next-level controller can identify what kind of command the high-speed clock corresponds to through the duty cycle of the high-speed clock. Then, the duty cycle of the high-speed clock is restored to the corresponding preset duty cycle threshold, where the preset duty cycle threshold corresponds to the maximum value of the duty cycle range corresponding to the command. Then, the high-speed clock after restoration processing is output to the next-level sensor behind it, thereby ensuring that all sensors on the towed cable transmission line can identify the command and respond to the command synchronously, thus eliminating the phase error of the sensors responding to the command. Among them, the empirical value of n can be 24. When it is greater than 24, it is very likely that the duty cycle of the high-speed clock transmitted by the nth level of sensor is less than the minimum value of the duty cycle range corresponding to the command, resulting in the next-level controller misidentifying the high-speed clock as other commands and causing subsequent sensors to respond to the command incorrectly. In this embodiment, m is much larger than n.

[0062] Optionally, each level of sensors is further adapted to: control a counter inside the sensor to perform command cumulative reception count processing according to the duty cycle of the received high-speed clock, and after the command trigger signal ends, upload the command cumulative reception count to the on-board console for the on-board console to determine whether the sensor normally responds to the corresponding command according to the command cumulative reception counts uploaded by each level of sensors.

[0063] Optionally, each level of sensors is further adapted to: determine whether the duty cycle of the received high-speed clock transmitted by each level of sensors matches the duty cycle condition corresponding to any of the to-be-issued command types;

[0064] If so, control the counter inside the sensor to increment the command cumulative reception count corresponding to the to-be-issued command type by 1.

[0065] Optionally, the controller is further adapted to: if the duty cycle of the received high-speed clock transmitted matches the duty cycle condition corresponding to the to-be-issued command type, control the counter inside the controller to increment the reception count corresponding to the to-be-issued command type by 1, and after the command trigger signal ends, upload the cumulative reception count corresponding to the to-be-issued command type to the on-board console for the on-board console to determine whether the controller performs duty cycle recovery processing according to the cumulative reception count corresponding to the to-be-issued command type uploaded by the controller.

[0066] Optionally, the to-be-issued command types include: data acquisition command type, data marking command type, or stop data acquisition command type.

[0067] In this embodiment, the commands to be issued during marine seismic exploration are mainly divided into three categories, including: data acquisition commands, data marking commands, and stop data acquisition commands. The above commands are all implemented by sending a high-speed clock. Therefore, in order to enable the sensor to accurately respond to the commands, three different duty cycle conditions are respectively set for the three different types of commands. For example, the data acquisition command corresponds to the first duty cycle condition, the data marking command corresponds to the second duty cycle condition, and the stop data acquisition command corresponds to the third duty cycle condition. The first duty cycle condition, the second duty cycle condition, and the third duty cycle condition respectively correspond to a duty cycle range value. After the sensor receives the high-speed clock with the duty cycle adjusted, it compares the duty cycle of the high-speed clock with the first duty cycle condition, the second duty cycle condition, and the third duty cycle condition respectively. If the duty cycle of the high-speed clock meets the first duty cycle condition, it can be determined that the command is a data acquisition command, and the sensor responds to the command to perform data acquisition; if the duty cycle of the high-speed clock meets the second duty cycle condition, it can be determined that the command is a data marking command, and the sensor responds to the command to perform data marking processing; if the duty cycle of the high-speed clock meets the third duty cycle condition, it can be determined that the command is a stop data acquisition command, and the sensor responds to the command to exit data acquisition.

[0068] The solution provided by the present invention issues a high-speed clock with a changed duty cycle as the command, rather than a conventional one-frame command, and does not require adjusting the command execution time of all command receiving devices through delay compensation parameters. At the same time, since all sensors have achieved clock synchronization, the high-speed clock with the changed duty cycle transmitted to the sensors can also be received and executed by all sensors simultaneously, thus completely eliminating the command phase deviation.

[0069] The algorithms or displays provided herein are not inherently related to any particular computer, virtual system, or other device. Various general-purpose systems can also be used in conjunction with the teachings based herein. The structure required to construct such a system 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 descriptions of specific languages above are for disclosing the best mode of the present invention.

[0070] 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 can 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.

[0071] 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 foregoing description of the exemplary embodiments of the present invention, the various features of the embodiments of the present invention are sometimes grouped together in a single embodiment, figure, or description thereof. However, the disclosed method should not be construed as reflecting an 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 of 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.

[0072] 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 used 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 expressly 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.

[0073] 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.

[0074] The various component embodiments 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 device program for executing part or all of the methods described herein (for example, a computer program and a computer program product). Such a program for 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.

[0075] It should be noted that the above embodiments illustrate the present invention rather than limit the present invention, 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 a unit claim 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 command synchronization method for marine seismic exploration, where an on-board console is connected to a towed cable transmission line, and m-level sensors are distributed on the towed cable transmission line. The method includes: When the on-board console receives a command trigger signal, it adjusts the duty cycle of the high-speed clock within one cycle in real time according to the type of command to be issued, and transmits the high-speed clock with the adjusted duty cycle as a command to the first-level sensor on the towed cable transmission line through the towed cable transmission line; While transmitting the high-speed clock to the next-level sensor, the first-level sensor identifies the duty cycle of the received high-speed clock and responds to the command according to the duty cycle; Starting from i = 2, the i-th level sensor receives the high-speed clock relayed without delay from the previous-level sensor. While transmitting the high-speed clock to the next-level sensor, it identifies the duty cycle of the received high-speed clock, responds to the command according to the duty cycle, assigns i to i + 1, and repeats this step until i = m - 1; The m-th level sensor receives the high-speed clock relayed without delay from the previous-level sensor, simultaneously identifies the duty cycle of the received high-speed clock, responds to the command according to the duty cycle, and completes command synchronization; Each level of sensor 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.

2. The method according to claim 1, wherein The method further includes: Insert a controller every n levels of sensors on the towed cable transmission line, transmit the high-speed clock output by the n-th level sensor to the next-level controller connected to the n-th level sensor, and the next-level controller performs duty cycle restoration processing on the received high-speed clock and transmits the high-speed clock after duty cycle restoration processing to the sensor connected to this next-level controller.

3. The method according to claim 1 or 2, wherein The method further includes: Each level of sensor controls the counter inside the sensor to perform statistics processing on the cumulative number of received commands according to the duty cycle of the received high-speed clock. After the command trigger signal ends, upload the cumulative number of received commands to the on-board console for the on-board console to judge whether the sensor normally responds to the corresponding command according to the cumulative number of received commands uploaded by each level of sensor.

4. The method according to claim 3, wherein That each level of sensor controls the counter inside the sensor to perform statistics processing on the cumulative number of received commands according to the duty cycle of the received high-speed clock further includes: Judge whether the duty cycle of the received high-speed clock transmitted by each level of sensor matches the duty cycle condition corresponding to any type of command to be issued; If so, control the counter inside the sensor to increment the cumulative number of received commands corresponding to the type of command to be issued by 1.

5. The method according to claim 1 or 2, wherein The method further includes: if the controller receives that the duty cycle of the transmitted high-speed clock matches the duty cycle condition corresponding to the type of command to be issued, the counter inside the controller is controlled to increment the received times corresponding to the type of command to be issued by 1. After the command trigger signal ends, the cumulative received times corresponding to the type of command to be issued are uploaded to the on-board console for the on-board console to determine whether the controller performs duty cycle recovery processing according to the cumulative received times corresponding to the type of command uploaded by the controller.

6. The method according to claim 1 or 2, wherein, The types of commands to be issued include: data acquisition command type, data marking command type, or stop data acquisition command type.

7. An order synchronization system for marine seismic exploration, comprising: An on-board console, a tow cable transmission line connected to the on-board console, and m-level sensors are distributed on the tow cable transmission line; The on-board console is configured to, when receiving a command trigger signal, adjust the duty cycle of the high-speed clock within one cycle in real time according to the type of command to be issued, and transmit the high-speed clock with the adjusted duty cycle as a command to the first-level sensor on the tow cable transmission line through the tow cable transmission line; The first-level sensor is configured to, while transmitting the high-speed clock to the next-level sensor, identify the duty cycle of the received high-speed clock, and respond to the command according to the duty cycle; Starting from i = 2, the i-th level sensor is configured to receive the high-speed clock relayed without delay by the previous-level sensor, identify the duty cycle of the received high-speed clock while transmitting the high-speed clock to the next-level sensor, respond to the command according to the duty cycle, assign i to i + 1, and repeat this step until i = m - 1; The m-th level sensor is configured to receive the high-speed clock relayed without delay by the previous-level sensor, identify the duty cycle of the received high-speed clock at the same time, respond to the command according to the duty cycle, and complete command synchronization; Each level of sensor 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.

8. The system according to claim 7, wherein A controller is inserted every n levels of sensors on the tow cable transmission line, and the high-speed clock output by the n-th level sensor is transmitted to the next-level controller connected to the n-th level sensor. The next-level controller performs duty cycle recovery processing on the received high-speed clock, and transmits the high-speed clock after the duty cycle recovery processing to the sensor connected to the next-level controller.

9. The system according to claim 7 or 8, wherein Each level of sensor is further adapted to: each level of sensor controls the counter inside the sensor to perform statistics processing on the cumulative received times of the command according to the duty cycle of the received high-speed clock. After the command trigger signal ends, the cumulative received times of the command are uploaded to the on-board console for the on-board console to determine whether the sensor normally responds to the corresponding command according to the cumulative received times of the command uploaded by each level of sensor.

10. The system according to claim 9, wherein, Each level of sensor is further adapted to: determine whether the duty cycle of the transmitted high-speed clock received by each level of sensor matches the duty cycle condition corresponding to any type of command to be issued; If so, control the counter inside the sensor to increment the cumulative received times of the command corresponding to the type of command to be issued by 1.

Images