Seismic data synchronous sampling method and device, electronic equipment and storage medium

Abstract

The invention discloses a seismic data synchronous sampling method and device, electronic equipment and a storage medium, and relates to the technical field of data processing, and the method comprises the steps that a recording system transmits a synchronous calibration clock signal to a forwarding node; each forwarding node transmits the synchronous calibration clock signal to the acquisition node of the level and the forwarding node of the lower level; each acquisition node transmits the synchronous calibration clock signal to a subordinate acquisition node; any acquisition node determines the delay amount of receiving the synchronous calibration clock signal; each acquisition node performs corresponding delay compensation on the local clock signal according to the delay amount so as to synchronize the local clock signal of each acquisition node; and each acquisition node synchronously samples seismic data according to the synchronized local clock signal. For the transmission delay, the transmission delay of each acquisition node is compensated step by step according to the delay amount between any two acquisition nodes, so that the synchronization precision and the synchronous sampling precision of the local clock signal of each acquisition node are improved.

Description

Technical Field

[0001] The present application relates to the field of data processing technology, and in particular to a method, device, electronic equipment and storage medium for synchronous sampling of seismic data. Background Art

[0002] The marine three-dimensional seismic data acquisition system is usually a distributed data acquisition system. The marine three-dimensional seismic data acquisition system generally includes multiple acquisition channels. The synchronous sampling accuracy of all acquisition channels directly affects the three-dimensional high-resolution imaging results of the marine three-dimensional seismic data acquisition system.

[0003] The traditional synchronization method of distributed data acquisition system is not suitable for marine three-dimensional seismic data acquisition system because seawater has an attenuation effect on electromagnetic waves and the synchronization accuracy of related synchronization technology cannot meet the synchronization requirements. Summary of the invention

[0004] The main purpose of the embodiments of the present application is to provide a method, device, electronic device and storage medium for synchronous sampling of seismic data to improve the synchronous sampling accuracy of seismic data.

[0005] To achieve the above-mentioned purpose, an embodiment of the present application provides a method for synchronous sampling of seismic data in one aspect. The method is applied to a seismic data acquisition system, wherein the seismic data acquisition system includes a recording system and multiple working sections, each of the working sections includes a forwarding node and multiple acquisition nodes, each of the forwarding nodes is connected in sequence, and each of the acquisition nodes is connected in sequence after the forwarding node in the same working section; the method includes the following steps:

[0006] The recording system transmits the synchronous calibration clock signal to the forwarding node;

[0007] Each of the forwarding nodes transmits the synchronous calibration clock signal to the collection node at the same level and the forwarding node at the next level respectively;

[0008] Each of the acquisition nodes transmits the synchronous calibration clock signal to the acquisition node at the lower level;

[0009] Any one of the acquisition nodes determines a delay amount for receiving the synchronous calibration clock signal;

[0010] Each of the acquisition nodes performs corresponding delay compensation on the local clock signal according to the delay amount, so as to synchronize the local clock signals of each of the acquisition nodes;

[0011] Each of the acquisition nodes synchronously samples seismic data according to the synchronized local clock signal.

[0012] In some embodiments, any one of the acquisition nodes determines the delay amount of receiving the synchronous calibration clock signal, comprising the following steps:

[0013] Any one of the acquisition nodes generates the delay amount for the received synchronous calibration clock signal through a built-in delay compensation module.

[0014] In some embodiments, each of the acquisition nodes performs corresponding delay compensation on the local clock signal according to the delay amount to synchronize the local clock signal of each of the acquisition nodes, including the following steps:

[0015] Each of the collection nodes respectively calculates the transmission delay between itself and the other collection nodes;

[0016] The clock module in each of the acquisition nodes calibrates the corresponding local clock signal according to the delay amount, the corresponding transmission delay and the synchronous calibration clock signal.

[0017] In some embodiments, each of the collection nodes respectively calculates the transmission delay between itself and the other collection nodes, comprising the following steps:

[0018] Each of the collection nodes respectively calculates the transmission delay between itself and any other collection node;

[0019] The expression for calculating the transmission delay is:

[0020]

[0021] Among them, t ij,gh is the transmission delay between the jth collection node on the i-th working segment and the hth collection node on the g-th working segment; t d is the transmission delay time of the signal sending interface, t r is the transmission delay time of the signal receiving interface, t e is the transmission delay time per unit length of the transmission line; l b is the transmission line distance between the forwarding nodes, l c is the transmission line distance from the forwarding node to the collection node or the transmission line distance between the collection nodes; m is the total number of the working sections, and n is the total number of the collection nodes on one working section.

[0022] In some embodiments, each of the acquisition nodes synchronously samples seismic data according to the synchronized local clock signal, including the following steps:

[0023] The synchronization event module in each of the acquisition nodes generates a synchronization event according to the synchronization calibration clock signal and the synchronization command signal;

[0024] Each of the acquisition nodes responds to the synchronization event and synchronously samples the seismic data according to the synchronized local clock signal.

[0025] In some embodiments, before the recording system transmits the synchronous calibration clock signal to the forwarding node, the method further comprises the following steps:

[0026] The NTP server calibrates the first clock signal according to the satellite timing signal reference to obtain a second clock signal;

[0027] The NTP server inputs the second clock signal into the recording system;

[0028] The recording system divides the frequency of the second clock signal to obtain the synchronous calibration clock signal.

[0029] In some embodiments, the method further comprises the following steps:

[0030] Each of the acquisition nodes transmits the seismic data obtained by sampling to the corresponding forwarding node;

[0031] The forwarding node transmits the seismic data to the recording system.

[0032] To achieve the above-mentioned purpose, another aspect of the embodiment of the present application provides a seismic data synchronous sampling device, which is used to implement the seismic data synchronous sampling method as described above, and the device includes:

[0033] A clock signal sending unit, used for the recording system to transmit the synchronous calibration clock signal to the forwarding node;

[0034] A clock signal forwarding unit, used for each of the forwarding nodes to transmit the synchronous calibration clock signal to the collection node at the same level and the forwarding node at the next level;

[0035] A clock signal transmission unit, used for each of the acquisition nodes to transmit the synchronous calibration clock signal to the acquisition node at the lower level;

[0036] A delay amount determination unit, used for any one of the acquisition nodes to determine the delay amount of receiving the synchronous calibration clock signal;

[0037] A clock synchronization unit, used for each of the acquisition nodes to perform corresponding delay compensation on the local clock signal according to the delay amount, so as to synchronize the local clock signal of each of the acquisition nodes;

[0038] The synchronous sampling unit is used for each of the acquisition nodes to synchronously sample seismic data according to the synchronized local clock signal.

[0039] To achieve the above-mentioned purpose, another aspect of an embodiment of the present application proposes an electronic device, which includes a memory and a processor, wherein the memory stores a computer program, and the processor implements the above-mentioned method for synchronous sampling of seismic data when executing the computer program.

[0040] To achieve the above-mentioned purpose, another aspect of an embodiment of the present application provides a computer-readable storage medium, wherein the computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the above-mentioned method for synchronous sampling of seismic data is implemented.

[0041] The embodiments of the present application include at least the following beneficial effects:

[0042] The present application can transmit the synchronous calibration clock signal to the forwarding node through the recording system; each forwarding node transmits the synchronous calibration clock signal to the current level acquisition node and the lower level forwarding node respectively; each acquisition node transmits the synchronous calibration clock signal to the lower level acquisition node; any acquisition node determines the delay amount of receiving the synchronous calibration clock signal; each acquisition node performs corresponding delay compensation on the local clock signal according to the delay amount, so as to synchronize the local clock signal of each acquisition node; each acquisition node synchronously samples seismic data according to the synchronized local clock signal. In view of the objective transmission delay, the present application compensates the transmission delay of each acquisition node step by step according to the delay amount between any two acquisition nodes, thereby improving the synchronization accuracy of the local clock signal of each acquisition node, and can further improve the accuracy of synchronous sampling. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0044] Figure 1 An example structural diagram of a seismic data acquisition system provided in an embodiment of the present application;

[0045] Figure 2 A schematic diagram of a flow chart of a method for synchronous sampling of seismic data provided in an embodiment of the present application;

[0046] Figure 3 An example flow chart of step S240 provided in an embodiment of the present application;

[0047] Figure 4 An example flow chart of step S250 provided in an embodiment of the present application;

[0048] Figure 5 An example flow chart of obtaining a synchronous calibration clock signal provided in an embodiment of the present application;

[0049] Figure 6 An example flow chart of transmitting seismic data provided in an embodiment of the present application;

[0050] Figure 7 A high synchronization precision sampling model diagram of a non-phase-locked loop local clock asynchronously driven by an embodiment of the present application;

[0051] Figure 8 An example structural diagram of a synchronization processing module provided in an embodiment of the present application;

[0052] Fig. 9 A schematic diagram of the generation principle of the ADC working clock provided in the embodiment of the present application;

[0053] Fig.10 A schematic diagram of the structure of a seismic data synchronous sampling device provided in an embodiment of the present application;

[0054] Fig.11 A schematic diagram of the hardware structure of an electronic device provided in an embodiment of the present application. DETAILED DESCRIPTION

[0055] In order to make the purpose, technical solutions and advantages of the present application clearer, the present application is further described in detail below in conjunction with the accompanying drawings and examples. It should be understood that the specific embodiments described herein are only used to explain the present application and are not intended to limit the present application. When the following description refers to the drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the embodiments of the present application. They are only examples of devices and methods consistent with some aspects of the embodiments of the present application as detailed in the attached claims.

[0056] It is understood that the terms "first", "second", etc. used in this application can be used to describe various concepts in this article, but unless otherwise specified, these concepts are not limited by these terms. These terms are only used to distinguish one concept from another concept. For example, without departing from the scope of the embodiment of the present application, the first information may also be referred to as the second information, and similarly, the second information may also be referred to as the first information. Depending on the context, the words "if" and "if" as used herein can be interpreted as "at the time of" or "when" or "in response to determination".

[0057] The terms "at least one", "multiple", "each", "any", etc. used in this application, at least one includes one, two or more, multiple includes two or more, each refers to each of the corresponding multiple, and any refers to any one of the multiple.

[0058] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application belongs. The terms used herein are only for the purpose of describing the embodiments of this application and are not intended to limit this application.

[0059] Before describing the embodiments of the present application in detail, some related technologies involved in the embodiments of the present application are first described as follows:

[0060] Marine 3D seismic data acquisition is usually completed by a ship towing a seismic source and multiple seismic streamers (buoyant cables equipped with hydrophones). Each streamer is connected by a leader section and towed by a corresponding cable winch. During the seismic data acquisition process, the ship travels in the waters above the seabed target according to a predetermined route, dragging the streamer in the direction of the survey line while exciting seismic waves through the seismic source, and the hydrophones placed in the floater in a specific arrangement record the signals transmitted from the seismic waves downward to the underground reflective layer and returned.

[0061] The synchronous sampling accuracy of all acquisition channels directly affects the three-dimensional high-resolution imaging results of the marine seismic exploration system. This application aims at the demand for high-synchronous precision sampling of a large number of distributed signal acquisition channels in the marine high-precision small three-dimensional seismic acquisition system. Based on the system structure characteristics of the right-angle comb shape, a high-precision synchronous sampling method combining the short-term stability of the node local asynchronous drive clock and the master-slave synchronous calibration of the local sampling clock is proposed. According to the improved model of high-synchronous precision sampling driven by the asynchronous drive of the non-phase-locked loop local clock of master-slave synchronization, the influence of factors such as clock stability, transmission delay and phase jitter on the synchronous sampling error is analyzed. As the improved model of high-synchronous precision sampling cannot eliminate the synchronous sampling error caused by transmission delay, a high-precision calibration method for synchronous sampling error with step-by-step compensation of transmission delay is designed.

[0062] Disadvantages of existing technology:

[0063] For distributed data acquisition systems, there are some mature system synchronization methods, such as satellite timing, Network Time Protocol NTP (Network Time Protocol) and high-precision time synchronization protocol PTP (Precision Time Protocol).

[0064] Satellite timing synchronization technology is a synchronization technology that uses the GPS global satellite system / Beidou navigation satellite system to synchronize the timing of distributed nodes. The satellites of the GPS / Beidou system have high-precision atomic clocks inside. By sending satellite signals, real-time and high-precision timing can be performed uninterruptedly around the world. The distributed data acquisition system can use the GPS receiving unit to receive the relevant timing information of the satellite, analyze the spatial coordinates and standard time, and complete the satellite timing. The advantage of satellite timing synchronization technology is that it can achieve a synchronization accuracy of 10ns, and at the same time, it uses satellite wireless signals for transmission, which is not restricted by the geographical environment. However, the cost of using satellite timing synchronization technology is high, and the electromagnetic wave signal will also attenuate when propagating in water.

[0065] NTP synchronization technology uses the network time protocol to synchronize the clocks of multiple devices. NTP has three working modes: client-server mode, broadcast mode, and symmetric mode. The client-server mode is often used for clock synchronization. The synchronization topology adopted is a layered structure, and each layer has several time servers. Devices with higher clock accuracy are used as servers, and other devices are used as clients. The server is synchronized with the standard time through broadcasting, satellite, etc., and the client is indirectly synchronized with the standard time by synchronizing with the server. The client sends a timestamp information message with the current time of the client to the server. After receiving the message, the server will reply with a timestamp information message with the current time of the server. The client calculates the time difference between the two timestamp information based on the two timestamp information to complete the clock synchronization. The synchronization accuracy of NTP synchronization technology is low, generally only reaching the millisecond level, and it is easily affected by network messages, and is gradually replaced by PTP synchronization technology.

[0066] PTP synchronization technology is developed on the basis of NTP synchronization technology, and uses the precision clock synchronization protocol to complete the clock synchronization of distributed systems. Compared with satellite timing synchronization technology, PTP synchronization technology has the advantage of low cost and higher synchronization accuracy than NTP synchronization technology. The synchronization principle of PTP synchronization technology is similar to that of NTP synchronization technology, both of which adopt the master-slave synchronization mode, but PTP synchronization technology obtains the time difference through messages.

[0067] The traditional synchronization method of the distributed data acquisition system is not suitable for the marine high-precision small 3D seismic acquisition system. Seawater has an attenuation effect on electromagnetic waves, and the synchronization accuracy of the NTP synchronization technology cannot meet the system requirements. The synchronization sampling accuracy of the traditional marine seismic exploration system's synchronization sampling technology needs to be improved, and it is not suitable for the right-angle comb structure of the small 3D seismic exploration system.

[0068] This application aims at the "single leading segment-multiple working segments" right-angle comb system structure of small three-dimensional seismic exploration system, and constructs a high-synchronization precision sampling improvement model based on the master-slave synchronization model and the asynchronous drive of the non-phase-locked loop local clock. Based on the influence of clock stability, transmission delay, and phase jitter on the synchronous sampling error, a synchronous sampling error calibration method with step-by-step transmission delay compensation is proposed, which effectively reduces the synchronous sampling error caused by signal transmission delay.

[0069] Before describing the synchronous sampling method of seismic data in the embodiment of the present application, the seismic data acquisition system of the present application is described. The seismic data acquisition system may include a recording system and multiple working sections, each of which includes a forwarding node and multiple acquisition nodes. Each forwarding node is connected in sequence, and each acquisition node is connected in sequence after the forwarding node in the same working section. For example, Figure 1 An example structural diagram of a seismic data acquisition system.

[0070] Specifically, the seismic data acquisition system of this embodiment can adopt a high-precision small three-dimensional high-resolution marine seismic exploration system, which is a distributed seismic data acquisition system with a right-angle comb structure. For example, there are 192 hydrophone channels, such as Figure 1 As shown. It is very important to achieve synchronous sampling of all hydrophone channels. The subsequent signal processing and seismic data inversion of the system are based on high-synchronous precision sampling between different channels. According to the principle of marine seismic exploration, synchronous sampling errors will cause errors in the calculation of the seabed stratum depth, which will further cause errors in the stratum inversion analysis and will not achieve the goal of high-resolution exploration of small three-dimensional high-resolution marine seismic exploration systems. This embodiment designs a matching high-synchronous precision sampling method for the "single leading segment-multiple working segments" right-angle comb system structure, and realizes the synchronous sampling of the acquisition channels of all acquisition nodes in the system. The synchronous sampling accuracy is better than 20ns.

[0071] Next, the synchronous sampling method of seismic data of this embodiment is described. Figure 2 The present application embodiment provides a method for synchronous sampling of seismic data, which may include but is not limited to S100 to S140, as follows:

[0072] S200: The recording system transmits a synchronous calibration clock signal to the forwarding node.

[0073] Specifically, the recording system may send a synchronization calibration clock signal to one of the forwarding nodes via a cable between the recording system and the forwarding nodes.

[0074] S210: Each of the forwarding nodes transmits the synchronous calibration clock signal to the collection node at the same level and the forwarding node at the next level respectively.

[0075] Specifically, a forwarding node receives a synchronous calibration clock signal from a recording system, and then transmits the synchronous calibration clock signal to a lower-level forwarding node. Each forwarding node can also transmit the synchronous calibration clock signal to a collection node of a working segment at this level.

[0076] S220: Each of the acquisition nodes transmits the synchronous calibration clock signal to the lower-level acquisition node.

[0077] Specifically, each collection node receives a synchronous calibration clock signal from a forwarding node or an upper collection node of the current working segment, and then transmits it to a lower collection node. It is understandable that if the current collection node is the last level collection node, the synchronous calibration clock signal may not be transmitted downward.

[0078] S230: Any one of the acquisition nodes determines a delay amount for receiving the synchronous calibration clock signal.

[0079] Specifically, each acquisition node can receive the synchronous calibration clock signal, and then can determine the delay amount of receiving the synchronous calibration clock signal. It can be understood that the delay amounts corresponding to different acquisition nodes may be different. Therefore, this embodiment can use any acquisition node to determine its corresponding delay amount.

[0080] Further, step S230 may include S231:

[0081] S231: Any one of the acquisition nodes generates the delay amount for the received synchronous calibration clock signal through a built-in delay compensation module.

[0082] Specifically, each acquisition node may be provided with a delay compensation module, and the delay compensation module generates a corresponding delay amount for the synchronous calibration clock signal received in the acquisition node.

[0083] S240: Each of the acquisition nodes performs corresponding delay compensation on the local clock signal according to the delay amount, so as to synchronize the local clock signal of each of the acquisition nodes.

[0084] Specifically, all the collection nodes perform corresponding delay compensation according to the delay amount determined by any one of the collection nodes, so that the local clock signals of all the collection nodes are synchronized.

[0085] Reference Figure 3 , step S240 may include S241-S242:

[0086] S241: Each of the collection nodes calculates the transmission delay between itself and the other collection nodes.

[0087] It is understandable that, since the time at which the synchronous calibration clock signal is transmitted to each acquisition node is different, there is a delay in the time at which each acquisition node receives the synchronous calibration clock signal.

[0088] Furthermore, step S241 may include:

[0089] Each of the collection nodes respectively calculates the transmission delay between itself and any other collection node;

[0090] The expression for calculating the transmission delay is:

[0091]

[0092] Among them, t ij,gh is the transmission delay between the jth collection node on the i-th working segment and the hth collection node on the g-th working segment; t d is the transmission delay time of the signal sending interface, t r is the transmission delay time of the signal receiving interface, t e is the transmission delay time per unit length of the transmission line; l b is the transmission line distance between the forwarding nodes, l c is the transmission line distance from the forwarding node to the collection node or the transmission line distance between the collection nodes; m is the total number of the working sections, and n is the total number of the collection nodes on one working section.

[0093] Specifically, each collection node calculates the transmission delay between itself and other collection nodes.

[0094] S242: The clock module in each of the acquisition nodes calibrates the corresponding local clock signal according to the delay amount, the corresponding transmission delay and the synchronous calibration clock signal.

[0095] Specifically, the clock module can generate a local clock signal, and the corresponding transmission delay and synchronization calibration clock signal are input into the clock module to calibrate the local clock signal.

[0096] S250: Each of the acquisition nodes synchronously samples seismic data according to the synchronized local clock signal.

[0097] Specifically, each acquisition node can adopt seismic data at the same timestamp according to the synchronized local clock signal, thereby achieving synchronous sampling.

[0098] Reference Figure 4 , step S250 may further include S251-S252:

[0099] S251: The synchronization event module in each of the acquisition nodes generates a synchronization event according to the synchronization calibration clock signal and the synchronization command signal.

[0100] Specifically, each acquisition node may be provided with a synchronization event module, and the synchronization calibration clock signal and the synchronization command signal are input into the synchronization event module together, thereby generating a synchronization event.

[0101] S252: Each of the acquisition nodes responds to the synchronization event and synchronously samples the seismic data according to the synchronized local clock signal.

[0102] Exemplarily, the triggering mode of the synchronization event may be timely triggering or delayed triggering, etc. After each acquisition node responds to the synchronization time, it synchronously samples the seismic data according to the synchronized local clock signal.

[0103] Reference Figure 5 Before step S200, the embodiment of the present application may further include steps S101 to S103:

[0104] S101: The NTP server calibrates the first clock signal according to the satellite timing signal reference to obtain a second clock signal;

[0105] S102: the NTP server inputs the second clock signal into the recording system;

[0106] S103: The recording system divides the frequency of the second clock signal to obtain the synchronous calibration clock signal.

[0107] It is understandable that this embodiment can use the satellite timing signal reference to generate an accurate synchronous calibration clock signal.

[0108] Reference Figure 6 In a further implementation manner, the embodiment of the present application may further include steps S261 to S262:

[0109] S261: Each of the acquisition nodes transmits the sampled seismic data to the corresponding forwarding node.

[0110] Specifically, each acquisition node transmits the seismic data to the forwarding node of the current working section in turn.

[0111] S262: The forwarding node transmits the seismic data to the recording system.

[0112] Each forwarding node transmits the seismic data of the current working section to the forwarding node connected to the recording system, and then the forwarding node connected to the recording system transmits the seismic data to the recording system.

[0113] Next, the solution of the embodiment of the present application will be introduced and explained in detail with reference to specific application examples.

[0114] Specifically, this embodiment includes the following technical solutions:

[0115] 1. Improved master-slave synchronous sampling method driven by non-phase-locked loop local clock asynchronously.

[0116] This embodiment adopts a high-precision synchronous sampling method that combines the short-term stability of the node local asynchronous drive clock with the master-slave synchronization calibration of the local sampling clock. Its model is as follows: Figure 7 As shown. This synchronous sampling method improves the traditional master-slave synchronous sampling method. The traditional synchronization method uses clock data recovery and phase-locked loop technology to recover the master clock in the acquisition node to generate the ADC working clock, and synchronizes the ADC working clock with the master clock through the phase-locked loop technology. This embodiment uses the local clock of the acquisition node to drive the Σ-Δ ADC sampling, and the sent master clock is used as a periodic calibration signal to synchronize and calibrate the local clock to achieve synchronous sampling. The master clock is named the synchronous calibration clock SCC (Synchronous Calibration Clock).

[0117] SCC is sent from the recording system to each acquisition node. The NTP server of the recording system outputs a 10MHz synchronization clock signal. The 10MHz clock signal is input into the synchronization calibration module and divided to generate SCC, which is used to synchronize the working clock of the ADC of each acquisition node. At the same time, the recording system sends a synchronization command to control the synchronization of all ADCs in the acquisition node.

[0118] SCC and synchronization command information are transmitted via the wired downlink medium l a The distance is first sent to forwarding node 1, and then the distance l traveled by forwarding node 1 b Forwarded to the next-stage forwarding node, and at the same time passed through l c The distance is forwarded to the collection node 1 of this working section, and then each collection node of this working section receives it in turn, and the subsequent forwarding node repeats the above process. Finally, all collection nodes receive SCC and synchronization command information. There are equalizers and drivers in the forwarding nodes and collection nodes to receive and send commands and synchronization information.

[0119] Each acquisition node has a local clock with high short-term stability to control the operation of the acquisition node. A synchronization processing module is set inside the acquisition node to receive SCC and synchronization command information. The synchronization processing module generates the ADC working clock inside, performs synchronization calibration processing on the ADC working clock according to the SCC received by the information receiving interface module, and sends synchronization events to the ADC according to the synchronization command to further synchronize the conversion process of all ADCs. Compared with the synchronization method of the traditional marine seismic exploration system, this method does not use a phase-locked loop to align the phase of the master and slave clocks, but uses the master clock to periodically calibrate the ADC working clock. After the sampling rate changes, there is no need to go through a long locking time, nor is there a need to reconfigure the phase-locked loop and ADC. Resynchronization is achieved in the next SCC cycle after the sampling rate is changed.

[0120] 2. Design of SCC generation, sending and synchronization processing modules.

[0121] 2.1 Generation and Transmission of SCC

[0122] The NTP server on board will output a 10MHz synchronous clock signal, which will be input into the recording system. The 10MHz signal will be divided internally to generate SCC. The satellite timing signal reference will be introduced externally to the NTP server to calibrate the 10MHz synchronous clock signal. The recording system will send the SCC to the lower-level forwarding node and collection node through the signal driver chip, and the signal equalization chip on the collection node will receive the SCC.

[0123] 2.2 Design of synchronization processing module.

[0124] The example structure of the synchronization processing module is as follows Figure 8 The synchronization processing module mainly includes an ADC working clock generation module and a synchronization event sending module. The synchronization processing module receives SCC and synchronization command information. On the one hand, SCC is input into the ADC working clock generation module for calibrating the ADC working clock, and on the other hand, it is input into the synchronization event sending module to generate ADC synchronization events in conjunction with the synchronization command signal.

[0125] Fig. 9 This is the principle diagram of the ADC working clock generation. First, the local

[0126] 3. Error analysis and correction method of synchronous sampling model.

[0127] Although an improved master-slave synchronous sampling model is proposed, there are factors affecting the synchronous sampling error in the improved synchronous sampling model. In the following content, a detailed analysis of the factors affecting the synchronous sampling error is made and a high-precision calibration method for synchronous sampling error with step-by-step compensation of transmission delay is proposed.

[0128] 3.1 Error analysis of synchronous sampling model.

[0129] The main factors affecting synchronous sampling errors are clock stability, transmission delay and phase jitter.

[0130] (1) Clock stability. The local clock of the acquisition node is generated by a crystal oscillator with an output frequency of f 0 The clock of the NTP server is a temperature-compensated crystal oscillator (OCXO). The OCXO is controlled and tamed by the satellite timing signal reference to provide a 10MHz clock synchronization signal. The frequency stability of the 10MHz synchronization clock signal output by the OCXO of the NTP server is ±2ppb, and the frequency stability of the TCXO of the acquisition node is ±2ppm. Although the clock frequency stability of the OCXO and TCXO outputs is relatively high, there is still a certain clock accumulation error.

[0131] (2) Transmission delay. The NTP server of the recording system outputs a 1PPS second pulse signal and a 10MHz clock signal. The SCC is generated by dividing the 10MHz clock signal. The SCC is sent to each collection node via a Category 6 twisted pair transmission line. Since the distance from the recording system to different collection nodes is different, there is a delay when each collection node receives the SCC.

[0132] (3) Phase jitter. The traditional synchronization method sends the detected data to the upload at the falling edge of the synchronization reference clock. Due to the phase jitter between the DRDY signal and the synchronization reference clock, the relationship between the two signals is uncertain. When the falling edge of the DRDY signal precedes the falling edge of the synchronization reference signal (Δt i,j ≤Δt s ), the data sent at the falling edge of the synchronous reference clock is the conversion data at the current moment; when the falling edge of the DRDY signal is later than the falling edge of the synchronous reference signal (Δt i,j ≥Δt s ), the data sent at the falling edge of the synchronous reference clock is the conversion data of the next sampling moment. Therefore, the phase jitter of the signal may cause a synchronous sampling error of 1 sampling cycle.

[0133] 3.2 Synchronous sampling model error correction method.

[0134] In order to correct the synchronous sampling error of signal transmission delay, a high-precision calibration method of synchronous sampling error with step-by-step compensation of transmission delay is proposed. The idea of ​​the calibration algorithm mainly includes two steps: transmission delay calculation and transmission delay compensation.

[0135] First, the signal transmission delay is estimated. Since the small 3D marine seismic exploration system has 8 acquisition nodes, the transmission delay measurement between each acquisition node is very complicated. Analysis shows that the main reasons for the delay in the signal transmission process include the transmission delay generated by the signal passing through the acquisition node and the transmission delay generated by the signal passing through the transmission line. Therefore, the total delay in the signal transmission process can be estimated as:

[0136]

[0137] In formula (1), Δt i,j is the delay time between the jth collection node in the i-th working section and the collection node on board, t d is the transmission delay of the signal sending interface, t r is the transmission delay of the signal receiving interface, t e is the transmission delay per unit length of the transmission line, l a To record the distance of the transmission line between the system and the forwarding module, l b is the distance of the transmission line between forwarding modules, l c is the distance from the forwarding module to the collection node and the transmission line between the collection nodes. At the same time, we can get:

[0138]

[0139] In formula (2), t ij,gh is the transmission delay between the jth acquisition node on the i-th working segment and the hth acquisition node on the g-th working segment.

[0140] From formula (2), we can find that t ij,gh with i, j, g, h, t d ,t r ,t e , l b and l c Related, among which i, j, g, h, l b and l c is a variable, t d ,t r and t e The signal transmission and reception interface chip used in this embodiment has a precisely fixed transmission delay, t d ,tr It is known that t e It can be obtained through actual measurement, b and l c In a specific system, it is a definite value, so the estimated value of the transmission delay between the jth collection node on the ith working segment and the hth collection node on the gth working segment can be calculated by formula (2).

[0141] Then, the signal transmission delay is compensated. A transmission delay compensation module is set in the jth acquisition node in the i-th working section. The delay compensation module generates a delay of size t for the SCC received in the acquisition node. ij,mn After the corresponding delay compensation is performed on all acquisition nodes, the synchronization error caused by the transmission delay is corrected, and the rising edge of the SCC of all acquisition nodes is at the same time t n,m , the rising edges of the working clocks of all ADCs are at the same moment, realizing synchronous sampling of all acquisition nodes.

[0142] The beneficial effects of this embodiment include:

[0143] 1. The synchronous sampling model of this embodiment improves the traditional master-slave synchronous sampling model. The traditional synchronization method uses clock data recovery and phase-locked loop technology to recover the master clock in the acquisition node to generate the ADC working clock, and synchronizes the ADC working clock with the master clock through the phase-locked loop technology. This method uses the local clock of the acquisition node to drive the Σ-Δ ADC sampling, and the sent master clock is used as a periodic calibration signal to synchronize and calibrate the local clock to achieve synchronous sampling. The master clock is named the synchronous calibration clock SCC (Synchronous Calibration Clock).

[0144] 2. The SCC of this embodiment is sent from the recording system to each acquisition node. The NTP server of the recording system outputs a 10MHz synchronization clock signal. The 10MHz clock signal is input into the synchronization calibration module for frequency division to generate the SCC, which is used to synchronize the working clock of the ADC of each acquisition node. At the same time, the recording system sends a synchronization command to control the synchronization of all ADCs in the acquisition node.

[0145] 3. The synchronization processing module of this embodiment mainly includes an ADC working clock generating module and a synchronization event sending module. The synchronization processing module receives SCC and synchronization command information. On the one hand, SCC is input into the ADC working clock generating module for calibrating the ADC working clock, and on the other hand, it is input into the synchronization event sending module to generate ADC synchronization events in cooperation with the synchronization command signal.

[0146] 4. In this embodiment, the local clock f is first multiplied by the frequency multiplier inside the acquisition node. 0 Frequency multiplication, with a frequency multiplication factor of N, generates a high-frequency clock signal fh , and then use the frequency divider to adjust f h The frequency division factor is M, which generates the ADC working clock f w , f w With the local clock f 0 The relationship is

[0147] This embodiment improves the traditional master-slave synchronous sampling model. Compared with the traditional synchronization method using clock data recovery and phase-locked loop technology, this embodiment recovers the master clock in the acquisition node to generate the ADC working clock, and synchronizes the ADC working clock with the master clock through the phase-locked loop technology. This embodiment uses the local clock of the acquisition node to drive the Σ-Δ ADC sampling, and the sent master clock is used as a periodic calibration signal to synchronize and calibrate the local clock to achieve synchronous sampling.

[0148] Reference Fig.10 The embodiment of the present application further provides a seismic data synchronous sampling device, which can implement the above-mentioned seismic data synchronous sampling method, and the device includes:

[0149] A clock signal sending unit, used for the recording system to transmit the synchronous calibration clock signal to the forwarding node;

[0150] A clock signal forwarding unit, used for each of the forwarding nodes to transmit the synchronous calibration clock signal to the collection node at the same level and the forwarding node at the next level;

[0151] A clock signal transmission unit, used for each of the acquisition nodes to transmit the synchronous calibration clock signal to the acquisition node at the lower level;

[0152] A delay amount determination unit, used for any one of the acquisition nodes to determine the delay amount of receiving the synchronous calibration clock signal;

[0153] A clock synchronization unit, used for each of the acquisition nodes to perform corresponding delay compensation on the local clock signal according to the delay amount, so as to synchronize the local clock signal of each of the acquisition nodes;

[0154] The synchronous sampling unit is used for each of the acquisition nodes to synchronously sample seismic data according to the synchronized local clock signal.

[0155] It can be understood that the contents of the above method embodiments are all applicable to the present device embodiments, the functions specifically implemented by the present device embodiments are the same as those of the above method embodiments, and the beneficial effects achieved are also the same as those achieved by the above method embodiments.

[0156] The embodiment of the present application also provides an electronic device, the electronic device includes a memory and a processor, the memory stores a computer program, and the processor implements the above-mentioned method for synchronous sampling of seismic data when executing the computer program. The electronic device can be any intelligent terminal including a tablet computer, a car computer, etc.

[0157] It can be understood that the contents of the above method embodiments are all applicable to the present device embodiments, the functions specifically implemented by the present device embodiments are the same as those of the above method embodiments, and the beneficial effects achieved are also the same as those achieved by the above method embodiments.

[0158] See also Fig.11 , Fig.11 The hardware structure of an electronic device of another embodiment is illustrated, and the electronic device includes:

[0159] The processor 1101 may be implemented by a general-purpose CPU (Central Processing Unit), a microprocessor, an application-specific integrated circuit (ASIC), or one or more integrated circuits, and is used to execute relevant programs to implement the technical solutions provided in the embodiments of the present application;

[0160] The memory 1102 can be implemented in the form of a read-only memory (ROM), a static storage device, a dynamic storage device or a random access memory (RAM). The memory 1102 can store an operating system and other application programs. When the technical solution provided in the embodiment of this specification is implemented by software or firmware, the relevant program code is stored in the memory 1102, and the processor 1101 calls and executes a method for synchronous sampling of seismic data in the embodiment of this application;

[0161] Input / output interface 1103, used to implement information input and output;

[0162] The communication interface 1104 is used to realize the communication interaction between the device and other devices. The communication can be realized through a wired manner (such as USB, network cable, etc.) or a wireless manner (such as mobile network, WIFI, Bluetooth, etc.);

[0163] A bus 1105 that transmits information between various components of the device (e.g., the processor 1101, the memory 1102, the input / output interface 1103, and the communication interface 1104);

[0164] The processor 1101 , the memory 1102 , the input / output interface 1103 and the communication interface 1104 are connected to each other in communication within the device via the bus 1105 .

[0165] An embodiment of the present application also provides a computer-readable storage medium, which stores a computer program. When the computer program is executed by a processor, the above-mentioned method for synchronous sampling of seismic data is implemented.

[0166] It can be understood that the contents of the above method embodiments are all applicable to the present storage medium embodiments, the functions specifically implemented by the present storage medium embodiments are the same as those of the above method embodiments, and the beneficial effects achieved are also the same as those achieved by the above method embodiments.

[0167] The memory, as a non-transient computer-readable storage medium, can be used to store non-transient software programs and non-transient computer executable programs. In addition, the memory may include a high-speed random access memory, and may also include a non-transient memory, such as at least one disk storage device, a flash memory device, or other non-transient solid-state storage device. In some embodiments, the memory may optionally include a memory remotely disposed relative to the processor, and these remote memories may be connected to the processor via a network. Examples of the above-mentioned network include, but are not limited to, the Internet, an intranet, a local area network, a mobile communication network, and combinations thereof.

[0168] The embodiments described in the embodiments of the present application are intended to more clearly illustrate the technical solutions of the embodiments of the present application and do not constitute a limitation on the technical solutions provided in the embodiments of the present application. Those skilled in the art will appreciate that with the evolution of technology and the emergence of new application scenarios, the technical solutions provided in the embodiments of the present application are also applicable to similar technical problems.

[0169] Those skilled in the art will appreciate that the technical solutions shown in the figures do not constitute a limitation on the embodiments of the present application, and may include more or fewer steps than shown in the figures, or a combination of certain steps, or different steps.

[0170] The device embodiments described above are merely illustrative, and the units described as separate components may or may not be physically separated, that is, they may be located in one place or distributed on multiple network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0171] Those skilled in the art will appreciate that all or some of the steps in the methods disclosed above, and the functional modules / units in the systems and devices may be implemented as software, firmware, hardware, or a suitable combination thereof.

[0172] The terms "first", "second", "third", "fourth", etc. (if any) in the specification of the present application and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchangeable where appropriate, so that the embodiments of the present application described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any of their variations are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device comprising a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0173] It should be understood that in the present application, "at least one (item)" means one or more, and "plurality" means two or more. "And / or" is used to describe the association relationship of associated objects, indicating that three relationships may exist. For example, "A and / or B" can mean: only A exists, only B exists, and A and B exist at the same time, where A and B can be singular or plural. The character " / " generally indicates that the objects associated before and after are in an "or" relationship. "At least one of the following" or similar expressions refers to any combination of these items, including any combination of single or plural items. For example, at least one of a, b or c can mean: a, b, c, "a and b", "a and c", "b and c", or "a and b and c", where a, b, c can be single or multiple.

[0174] In the several embodiments provided in the present application, it should be understood that the disclosed devices and methods can be implemented in other ways. For example, the device embodiments described above are only schematic. For example, the division of the above units is only a logical function division. There may be other division methods in actual implementation, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, indirect coupling or communication connection of devices or units, which can be electrical, mechanical or other forms.

[0175] The units described above as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0176] In addition, each functional unit in each embodiment of the present application may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit. The above-mentioned integrated unit may be implemented in the form of hardware or in the form of software functional units.

[0177] If the integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present application, or the part that contributes to the prior art, or all or part of the technical solution can be embodied in the form of a software product, and the computer software product is stored in a storage medium, including multiple instructions to enable a computer device (which can be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods of various embodiments of the present application. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (Read-Only Memory, referred to as ROM), random access memory (Random Access Memory, referred to as RAM), disk or optical disk and other media that can store programs.

[0178] The preferred embodiments of the present invention are described above with reference to the accompanying drawings, but the scope of the rights of the present invention is not limited thereto. Any modification, equivalent substitution and improvement made by a person skilled in the art without departing from the scope and essence of the present invention should be within the scope of the rights of the present invention.

Claims

1. A method for synchronous sampling of seismic data, characterized in that: The method is applied to a seismic data acquisition system, which includes a recording system and multiple working sections, each of which includes a forwarding node and multiple acquisition nodes, each of which is connected in sequence, and each of which is connected in sequence after the forwarding node in the same working section; The method comprises the following steps: The recording system transmits the synchronous calibration clock signal to the forwarding node; Each of the forwarding nodes transmits the synchronous calibration clock signal to the collection node at the same level and the forwarding node at the next level respectively; Each of the acquisition nodes transmits the synchronous calibration clock signal to the acquisition node at the lower level; Any one of the acquisition nodes determines a delay amount for receiving the synchronous calibration clock signal; Each of the acquisition nodes performs corresponding delay compensation on the local clock signal according to the delay amount, so as to synchronize the local clock signals of each of the acquisition nodes; Each of the acquisition nodes synchronously samples seismic data according to the synchronized local clock signal.

2. A method for synchronous sampling of seismic data according to claim 1, characterized in that: Any one of the acquisition nodes determines the delay amount of receiving the synchronous calibration clock signal, comprising the following steps: Any one of the acquisition nodes generates the delay amount for the received synchronous calibration clock signal through a built-in delay compensation module.

3. A method for synchronous sampling of seismic data according to claim 1, characterized in that: Each of the acquisition nodes performs corresponding delay compensation on the local clock signal according to the delay amount, so as to synchronize the local clock signal of each of the acquisition nodes, including the following steps: Each of the collection nodes respectively calculates the transmission delay between itself and the other collection nodes; The clock module in each of the acquisition nodes calibrates the corresponding local clock signal according to the delay amount, the corresponding transmission delay and the synchronous calibration clock signal.

4. A method for synchronous sampling of seismic data according to claim 3, characterized in that: Each of the collection nodes calculates the transmission delay between itself and the other collection nodes, including the following steps: Each of the collection nodes respectively calculates the transmission delay between itself and any other collection node; The expression for calculating the transmission delay is: Among them, t ij,gh is the transmission delay between the jth collection node on the i-th working segment and the hth collection node on the g-th working segment; t d is the transmission delay time of the signal sending interface, t r is the transmission delay time of the signal receiving interface, t e is the transmission delay time per unit length of the transmission line; l b is the transmission line distance between the forwarding nodes, l c is the transmission line distance from the forwarding node to the collection node or the transmission line distance between the collection nodes; m is the total number of the working sections, and n is the total number of the collection nodes on one working section.

5. A method for synchronous sampling of seismic data according to claim 1, characterized in that: Each of the acquisition nodes synchronously samples seismic data according to the synchronized local clock signal, including the following steps: The synchronization event module in each of the acquisition nodes generates a synchronization event according to the synchronization calibration clock signal and the synchronization command signal; Each of the acquisition nodes responds to the synchronization event and synchronously samples the seismic data according to the synchronized local clock signal.

6. A method for synchronous sampling of seismic data according to claim 1, characterized in that: Before the recording system transmits the synchronous calibration clock signal to the forwarding node, the method further comprises the following steps: The NTP server calibrates the first clock signal according to the satellite timing signal reference to obtain a second clock signal; The NTP server inputs the second clock signal into the recording system; The recording system divides the frequency of the second clock signal to obtain the synchronous calibration clock signal.

7. A method for synchronous sampling of seismic data according to any one of claims 1 to 6, characterized in that: The method further comprises the following steps: Each of the acquisition nodes transmits the seismic data obtained by sampling to the corresponding forwarding node; The forwarding node transmits the seismic data to the recording system.

8. A seismic data synchronous sampling device, characterized in that: For implementing a method for synchronous sampling of seismic data according to claim 1, the device comprises: A clock signal sending unit, used for the recording system to transmit the synchronous calibration clock signal to the forwarding node; A clock signal forwarding unit, used for each of the forwarding nodes to transmit the synchronous calibration clock signal to the collection node at the same level and the forwarding node at the next level; A clock signal transmission unit, used for each of the acquisition nodes to transmit the synchronous calibration clock signal to the acquisition node at the lower level; A delay amount determination unit, used for any one of the acquisition nodes to determine the delay amount of receiving the synchronous calibration clock signal; A clock synchronization unit, used for each of the acquisition nodes to perform corresponding delay compensation on the local clock signal according to the delay amount, so as to synchronize the local clock signal of each of the acquisition nodes; The synchronous sampling unit is used for each of the acquisition nodes to synchronously sample seismic data according to the synchronized local clock signal.

9. An electronic device, characterized in that: The electronic device includes a memory and a processor, the memory stores a computer program, and the processor implements a method for synchronous sampling of seismic data as described in any one of claims 1 to 7 when executing the computer program.

10. A computer-readable storage medium storing a computer program, characterized in that: When the computer program is executed by a processor, a method for synchronous sampling of seismic data as claimed in any one of claims 1 to 7 is implemented.

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