THE DESIGN AND REALIZATION OF THE SIGNAL GENERATOR FOR THE CALIBRATION OF MT INSTRUMENT BASED ON FPGA AND GPS SYNCHRONIZATION
SHEN Rui-jie1,2, Qiu Kai-lin2, YAO Hong-chun1,2, HE Zhan-xiang2, LU Xiang-hong1, CHEN Ru-jun1,3,4
1. School of Geosciences and Info-physics, Central South University, Changsha 410083, China;
2. Non-seismic Survey, BGP, CNPC, Zhuozhou 072751, China;
3. Postdoctoral Research Station of BGP, CNPC, Zhuozhou 072751, China;
4. Postdoctoral Station of Computer Science and Technology, Central South University, Changsha 410083, China
In this paper, a FPGA-based GPS synchronous signal generator for the calibration of MT instrument is presented. Under the control of AT91RM9200 processor, five square wave signals with specific frequencies of 0.09375, 0.2344, 2.5, 20 Hz and 24 Hz for calibration can be generated, and are synced with GPS's PPS. Multiple frequencies calibration is all done at the same time due to the nature of square wave composed of extensive odd harmonics. We designed a SPI interface to realize the communication between FPGA and AT91RM9200. The soft IP processor PicoBlaze, as the control center inside FPGA, is employed to analyze and process the control parameters, and to control the synthesis of frequencies and their synchronization to the rising edge of PPS. The synthesized square signal is transmitted to the analog channel board through photon-coupled isolator. As the test result proves, the signal generator works well, and calibration signals have a lag of less than 1.5μs to the rising edge of PPS, more-than-10 MHz bandwidth and stable amplitude, which meets the calibration requirement.
申瑞杰, 邱开林, 姚红春, 何展翔, 卢祥弘, 陈儒军. 基于GPS同步的大地电磁采集站标定信号发生器设计与实现[J]. 物探与化探, 2013, 37(1): 82-87.
SHEN Rui-jie, Qiu Kai-lin, YAO Hong-chun, HE Zhan-xiang, LU Xiang-hong, CHEN Ru-jun. THE DESIGN AND REALIZATION OF THE SIGNAL GENERATOR FOR THE CALIBRATION OF MT INSTRUMENT BASED ON FPGA AND GPS SYNCHRONIZATION. Geophysical and Geochemical Exploration, 2013, 37(1): 82-87.
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