Application Of Digital Filtering Technique In Telemetric Digital Seismic Data Acquisition Station

According to the National Development and Reform Commission recently released data show that China has become the world's second largest energy consuming countries. Therefore, the oil and gas resources for our national security, economic construction and social development have its significance. At present, the price of oil exploration equipment, mostly imported foreign equipment, is high and we are constrained by their monopoly of technology. It is the most important thing for geophysical instrument engineers to solve the above problems existing in China. At the same time, due to the rapid development of FPGA technology, it is gradually applied to digital signal processing unit. Compared with traditional DSP technology, it is greater flexibility.Currently, the most mature design of seismic acquisition stations provided by Cirrus Logic is that, CS3301, CS5373 and CS5378 are used together in the seismic data acquisition hardware. However the biggest flaw of the program is its cost. The purpose of the paper is to design FPGA-based hardware digital filter, and applied to seismic acquisition stations, and then replace the CS5378 chip, reducing the cost of seismic acquisition stations. The main work of the paper includes three parts: (a) design seismic acquisition station hardware; (b) design filtering program of seismic acquisition station; (c) measure the performance of seismic acquisition station programming (MATLAB).The hardware of the seismic acquisition station includes±2.5V power supply circuit, CS5373 reference voltage circuit, common mode filter circuit, differential mode filter circuit, system self-test circuit and so on.The software of the seismic acquisition station includes CIC, FIR, IIR filters, DA and gain control program, sampling rate control program, mode control program and so on. CIC, FIR, IIR filters are developed by MATLAB & Quartus II. CIC is the first section after the AD conversion. They decimate 1-bitΔΣdata into lower frequency (8KHz or 4KHz) 24-bit data suitable for the FIR and IIR filters. FIR as the second section consists of two cascaded stages (FIR1, FIR2). FIR1 compensates for CIC filter droop, and decimate by 2. FIR2 creates a low-pass corner to block aliased components of the input signal, decimate by 2. IIR creates a high-pass corner to block very low-frequency and DC components of the input signal.After completing the hardware and software of the seismic acquisition station, designing the program in MATLAB to measure the Noize, THD, CMRR and other major performance parameters.