Development Of Portable Current Waveform Recorder

Electrical prospecting transmitter current waveform recorder is an important device for monitoring operating state of transmitter and recording its output current when performing active source electrical prospecting. In the inversion of this kind of electrical method, the source current data at the transmitter side is usually operated together with the earth response data at the receiver side to obtain accurate subsurface information. Therefore, the validity of data recorded by current waveform recorder directly affects the results of inversion. The validity of data is mainly reflected in the synchronization of the acquisition time and the accuracy of data amplitude and frequency. To obtain rich and valid transmitter current data, this paper designs and realizes one portable current waveform recorder for recording transmitter current,based on high-speed ADC, NAND Flash, ARM, FPGA as well as GPS synchronization module and Bluetooth communication module.The development of portable current waveform recorder includes hardware and software in two parts. In hardware,first determines the core and auxiliary functions of the recorder, and then analyzes and demonstrates the concrete realization of each function. Finally the paper designs the main scheme, in which, high-speed ADC is responsible for collecting data, NAND Flash, SD card with Data Flash is responsible for storing data, and ARM with FPGA is responsible for system control, the Bluetooth module is responsible for human-computer interaction and GPS module is responsible for time synchronization, and realizes the concrete circuits. In software, mainly implements the program of collection control synchronized with PPS signal in terms of FPGA programs. In the terms of ARM programs, first transplants ?C/OS-?operating system on the chip, and then on the basis of ?C/OS-?, the paper mainly realizes the massive data real-time storage program, which includes NAND Flash storage management program based on physical block state table and Data Flash storage management program based FTL. On the basis of FTL, the paper transplants FAT file system on Data Flash. In the terms of upper computer programs, implements current file reading and waveform plotting program based on Qt. Finally, tests the sub-modules and overall performance of the instrument.The portable current waveform recorder developed in this paper has linearity of ±2.3% in the range of ± 10A. The sampling rate ranges from 10KSPS to 2MSPS. The real-time storing speed is up to 8.3Mbytes/s, which can meets the requirement of data storage under 2MSPS sampling rate. The storage management effect for both NAND Flash and Data Flash is good, and the difference between the maximum and minimum wear value of physical blocks in NAND Flash is only one.