Research On Synchronization Technology Of Distributed Seismic Data Acquisition

Seismic exploration is one of the effective methods in petroleum exploration,Three component,high density,multi channel number is the development direction of distributed seismic data acquisition system.The synchronization of seismic data acquisition is directly related to the accuracy of the subsequent processing and interpretation of seismic data,which is an important and critical factor in the distributed seismic data acquisition system.Due to the increase of the number of nodes in the distributed seismic acquisition system and the independence of each other,it also brings some difficulties to the data acquisition and synchronization.In the distributed system,synchronization is usually used to add time stamp to the data.The basic requirement is to keep the clock of each node.Because of the increase of the number of nodes,the traditional network timing method increases the complexity and difficulty of the network time service method.In view of the above problems,this paper is supported by the National Natural Science Foundation of China(the development of the seismic data acquisition system in the complex mountainous area).In this paper,the problem of single node data acquisition synchronization and clock synchronization in distributed acquisition system is studied and designed.In the research and design of single node data acquisition synchronization,this paper realizes the design of 32 bit high precision seismic data acquisition node based on STM32F429ZET6 low power and high performance microprocessor.In the single sampling interval,the parallel acquisition and synchronization of three component data of the acquisition node is realized by the hardware SPI communication protocol.Design of 32 bit A/D chip ADS1282 conversion circuit,acquisition circuit,power supply circuit and driver development.After testing,the synchronization accuracy of single node and 3 channel signal is less than 2ns,and the linear correlation of the signal is 99.99%,which has a good synchronization leve.In the research and design of the clock synchronization of the acquisition node,this paper combines the characteristics of the GPS time without accumulated error and the short-term stability of the local clock.Design is completed based on the GPS clock as the center of the clock acquisition node for timing,at the same time using the high precision 1PPS second pulse measurement and calibration of the local clock frequency,reduce the error of the local clock drift of the clock.Design the software and hardware design of the local time service system based on GPS.The design and implementation of local clock frequency measurement,adjustment and timestamp generation.After testing,the synchronization error between nodes in the GPS timing 1PPS is less than 30ns.Single node timestamp error is less than 0.1 us.The inter node clock error is less than lOus.Through the study of this paper,the problem of single node data acquisition synchronization and multi node clock synchronization in seismic data acquisition is studied.An effective method is studied and designed,which provides an effective solution to the synchronization problem of seismic data acquisition.