Study On Key Techniques Of Ultra-Low Frequency Standard Vibration System For Seismometer Calibration

In this dissertation, several key technical problems were discussed and some resolutions were made on them in order to develop the calibration system of ultra-low frequency standard vibration, which was associating with National Scientific Infrastructure Platform for building special conditions "Building of national ultra-low frequency standard vibration device" and China Earthquake Administration "Research on ultra-low frequency standard vibration system for calibration of seismometer".In chapter 1, the aims and significance of the dissertation were presented. Firstly, the seismometer and its calibration technique were given. Seismometer is a special kind of vibration transducer, which follows conventional calibration methods for vibration transducer. Secondly, the present research status on standard vibration metrology at home and abroad was reviewed and its developing trend was pointed out. In the end, the main research content and aim of the dissertation was addressed.In chapter 2, the key technical problems of ultra-low frequency vibration table were researched. Firstly, a kind of double magnetic circuit was verified to improve the evenness and intensity of magnetic field in large-distance horizontal vibration table, which was researched in theory and simulation analysis. Secondly, some factors influencing the waveform distortion of the ultra-low frequency vibration table were researched and their resolutions were made. In the end, the other technical problems of vibration of vibration table were researched.In chapter 3, the special technical problems of ultra-low frequency standard vibration system were researched. Firstly, the proper foundation and vibration isolation of vibration and laser interferometer were designed based on dynamic and static principles. Secondly, how to choose different motion parameters to feed back based on different frequency band was given, the mechanism of velocity feedback and displacement feedback were researched as two key points. In the end, the related techniques of ultra-low frequency power amplifier were researched.In chapter 4, the designing problems of ultra-low frequency full automatic calibration system were researched. Firstly, the executive structure of the system was determined. Secondly, a full automatic measure and control software which was developed with virtual instrument programming language - LabVIEW was designed to realize highly automation in calibrating seismometer.In chapter 5, the achievements of the dissertation were summarized and the further research work that needs to be done was put forward.