Method and device for synchronizing conversion clocks in distributed seismic signal acquisition nodes

Abstract

The invention relates to the field of geophysical exploration, and provides a model and method for utilizing signal lines to transmit. Phases of low-frequency signals output by frequency dividers in different nodes can be uniform, and automatic estimation and real-time correction can be simply and efficiently conducted on transmission delay errors of conversion clocks. According to the technical scheme, a device for synchronizing the conversion clocks in the distributed seismic signal acquisition nodes comprises an upper computer, a hydrophone and the nodes. The upper computer comprises a computer, a command module, a main clock module and a signal driver, wherein the command module, the main clock module and the signal driver are arranged inside the computer. The computer sends various commands to the command module and receives detected data sent by the nodes. The command module transfers the commands from the computer to the nodes and can transmit estimated transmission delay parameters to the nodes. The signal driver is used for conducting drive amplification on the sent signals. The method and device are mainly applied to geophysical exploration.

Description

technical field [0001] The present invention relates to the field of geophysical exploration, and specifically relates to a synchronization method and device for converting clocks in distributed seismic signal acquisition nodes. technical background [0002] When the seismic detection system is used to collect seismic signals, it is necessary to provide a synchronous conversion clock for all analog-to-digital converters to ensure that all analog-to-digital converters can simultaneously convert analog signals into digital signals. Typically, the frequency of this conversion clock f o and signal sampling rate f s same, and it is a low-frequency signal; for example, the highest sampling rate of mainstream seismic detection systems is generally f s =4KHz; so the frequency of the conversion clock is also f o =f s =4KHz. In order to distribute a synchronous conversion clock to the distributed seismic signal acquisition nodes (hereinafter referred to as nodes) in the seismic d...

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Problems solved by technology

However, the commonly used method proposed in literature [1-3] has the following three disadvantages: (1) It is necessary to set up a separate downlink transmission channel for the transmission of the conversion clock, which also means that there must be a dedicated Signal drivers and equalizers and signal transmission lines are used to transmit the converted clock; however, on the one hand, the inner diameter of the streamer in the underwater part of the seismic detection system is small and cannot accommodate a large number of transmission lines. Therefore, the transmission lines in the actual seismic detection system should be The less the better; on the other hand, the more the number of downlink channels, the more unstable factors will be brought to the entire seismic detection system, and the reliability of the seismic detection system will be worse. If there is a fault, the entire seismic detection system will not work normally. Therefore, the less the number of downlinks in the actual seismic detection system, the more reliable the seismic detection system will be; The signal delay time of the signal equalizer is uncertain and unknown, which brings inconvenience to the correction of the transmission delay error of the conversion clock; (3) During the transmission process of the conversion clock, the transmission of the signal generated by the signal driver, the equalizer and the transmission line The delay cannot be accurately estimated in real time, and the transmission delay is compensated in real time according to the estimated value; on the one hand, this has an adverse effect on the synchronization accuracy of the conversion clock; on the other hand, the correction of the synchronization error has brought Inconvenience

[0003] In addition, if a frequency f is set in the main node of the seismic detection system m If the high-frequency main clock is set in each node to divide the frequency of the high-frequency main clock to generate the conversion clock, then the conversion clock generated in each node must be asynchronous, because after The multi-valued phase of the signal after the frequency divider determines that the generated conversion clock will have different initial phases, that is, the converted clock after frequency division will not be synchronous, and it will not satisfy the conversion mentioned above. The clock should have frequency and phase consistency requirements

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