The Implementation Of Distributed Wireless Data Acquisition

In recent years, seismic data acquisition system for seismic exploration for petroleum began to gradually introduce wireless sensor network technology. But now wireless sensor network used for the oil seismic exploration is not yet mature, and there are kinds of problems. Large full digital seismograph system which is researched and developed by the laboratory where the writer works has begun to join the wireless sensor network to meet the oil seismic exploration in the seismic data acquisition needs.Based on investigation on the wireless sensor networks and the study of the devices used in the realization of the distributed wireless sensor networks, this paper realizes initially the prototype of the distributed wireless data acquisition system, and has a number of tests on the data collection station and analyses the test results. The specific content of the work and testing is described as below.Design and complete distributed wireless data acquisition platform for controlling system, Include the hardware configuration of microprocessor, programmable clock synthesizer, power module and the driven configuration of the microprocessor. By adding the platform data acquisition module and the wireless communication module, and the software configuration of the two modules, the initial prototype of the distributed wireless data acquisition system is realized.Based on integration of data acquisition module of the distributed wireless data acquisition station, the test on the data acquisition module is realized. The ADC used in the data acquisition module of acquisition station is ADS1282. The software configuration of ADC, data acquisition of the tested signal, and the test software for ADC performance are all completed. Through the AD test, the RMS value of the ADC channel noise is 1.59 uV, harmonic distortion is 109.1 dB, dynamic range is 120.8 dB. The test results show that the performances of the ADC meet the demand for seismic data acquisition.Through the integration of wireless communication module of he distributed wireless data acquisition station, the wireless communication is realized between the stations. The core of the module is CC1101. By writing the driver configuration of CC1101 and test codes, the wireless communication is realized between the stations and the test for wireless communication is done. The total time for wireless communication test is about 2000 minutes, and the wireless communication error rate is less than 9.5×10^-10. This is shown that the wireless communication is stable and reliable.Based on the initial completion of the prototype of distributed wireless data acquisition system, a method used for clock synchronization between distributed wireless data acquisition units is realized. Through wireless communication the timers of CPU record the time of sending and receiving data packets between the stations to achieve clock synchronization. Through wireless communication the DAC of CPU adjusts the voltage of VCXO to improve the accuracy of clock synchronization further. In the two cases that the clock of the master and slave is synchronized or not, the distributed data acquisition, analysis and comparison are done. In this test of clock synchronization, the accuracy of clock synchronization of signal in master and salve station when clock is synchronized is 0.061 ms, which is better than 1.27ms when clock is not synchronized. The results show that the clock synchronization is very important for improving the synchronization of distributed data acquisition.In summary, the prototype of distributed wireless data acquisition system for oil seismic exploration is initially realized in this paper. And all of these have done a certain amount of preparation work for adding a distributed wireless data acquisition network to large full digital seismograph system development project of the laboratory.