Design And Implementation Of Moving-coil Geophone Tester Based On FPGA

Oil, as a source of energy substances, is hailed as the blood of modern industrial development. But its huge demand and limited storage capacity makes the oil explo-ration become very important. Seismic exploration, which is the most common mean of oil exploration, not only has a high resolution and accuracy, but also can meet the de-mand of the deep exploration depth, which is unmatched by other exploration methods. The transducer is a key feature of the seismic exploration, which can collect seismic signals and convert them into electrical signals and transmit them to the back-end for collection, preservation and analysis. It is undeniable that the traditional moving-coil geophone with its stability, reliability and low cost advantages, is widely used in the field of seismic exploration for more than40years. Only after confirmation of the geo-phones in the work can the smooth progress of the entire exploration and the reliability of the obtained results be ensured. If an error occurs, it will cause huge losses, so it is necessary that all the geophones should be checked before every exploration, which will ensure the overall quality of the collection. At present, in the foreign markets, the series of SMT geophone testers produced by the United States I/O company with higher precision are widely used, but their high cost and English operation interface make us uncomfortable and inconvenient. However, the geophone testers made by our country have a variety of types and the measuring accuracy varies. They always take the single-chip microcomputer as the core processor. Considering the strong capacity of logic control of the programmable logic device FPGA, this paper designed a moving-coil geophone tester with the FPGA as the core processor.This paper is divided into the following chapters:The first chapter is the introduction, mainly introduces the background of the project, including the development of moving-coil geophone testers. In addition, the research content and the arrangement of the overall structure are introduced.The second chapter introduces the measurement principle of existing methods of onshore seismic exploration, the parameters of the moving-coil geophone and their test principle. Through the comparison of different test principles, the DC excitation method can be the most suitable for the design of portable tester.The third chapter mainly introduces the hardware design and the logic design of the tester. The power supply module, front-end test circuit module, signal generator mod-ule, data acquisition module and data transmission module are introduced respectively. The data acquisition module, which uses the high-precision analog-to-digital conver-sion chip ADS1282, collects the32-bit data and transmits them to PC clients through the protocol processing chip W5300and the network port. Because the clocks of every module are not all the same, the clock distribution scheme with FPGA control is briefly described in the third section.The fourth chapter introduces the software design of data transmission and data processing. In the software design, based on Winsock network programming, this paper implements the data reception of PC client by using TCP socket interface functions such as "connect ()". The data processing software is realized by VC#programming in Windows environment.The fifth chapter introduces the actual measurement and analysis of geophone pa-rameter tester. The modules are debugged respectively by using SignalTap ii. After that, the moving-coil geophones No.1-7are measured and the results are compared with those tested by SMT-150. The comparison indicates that the tester in this paper gets a high accuracy in DC resistance, damping ratio and natural frequency parameter test. But the sensitivity test is insufficient, which need further improvement.The sixth chapter is the summary and outlook, summarizes the main work of this paper, and also points out the shortcomings and improvements.