Application Of FPGA In3D-SIP System

3D exploration which can overcome the volume effect is the trend of the electromagnetic exploration. Spectrum Induced Polarization (SIP) is a promising exploration method due to its ability to suppress even eliminate the electromagnetic coupling and to evaluate the nature of anomaly sources. Therefor it’s of great importance to carry out research on portable, low power, able-to-updated instruments for3D SIP method. Field programmable gate array (FPGA), which has abundant logic resources and can be programmable, is suitable for complex digital systems, of which the functions can be updated without changing the hardware. It is low power and flexible. Thus there are broad application prospects in electromagnetic instruments for FPGA.For abrove reasons, a FPGA-based circuit to generate waveform control signals synchronized to PPS was designed and realized, and a circuit based on FPGA to realize multi-channel expansion for data acquisition system was designed. They will be applied in3D SIP instruments. In the design of control signal generating circuit of synchronizing waveform, ROM was generated based on the internal RAM of FPGA to store waveform data. Thus the density of integration was improved and the circuit is convenient for waveform expansion. The clock from GPS module was used as the internal system clock of FPGA, which makes the frequencies generated more accurate and stable. Synchronization module was designed to make the output of waveform control signals synchronized to the rising edge of1PPS. Thus absolute phase can be measured in3D SIP exploration. Dead time generating module was designed to avoid the turn-off time of inverter, making the transmitter more reliable. In the design of multi-channel expansion circuit for data acquisition system, a scheme is presented and the internal circuit of FPGA was designed. A module for high serial data transmission was designed, which can transfer1-6group data one time. Therefor the number of channels can be dynamically expanded.In this paper,3D SIP technology, and the status and the problems of the transmitters at home and abroad, the development and application status of FPGA, and the application status of FPGA in electromagnetic instrument are described first. Then the scheme of FPGA-based transmitter is presented, and the details of the signal generating circuit of the synchronizing waveform control is introduced. The FPGA-based multi-channel expansion data acquisition system is designed next, and then the design of multi-channel expansion circuit in FPGA is introduced. At the end of the paper the summary and suggestions of the work are given.