Design Of Data Acquisition Software Of Broadband Seismic Recorder

Seismology is an embranchment of geophysics. By the application of physics theories and methods, it researches scientific problems about spread of seismic waves in the Earth's interior, Earth's internal structure and physical properties, cause of earthquake, gestation and development process of earthquake and prediction of earthquake, etc. Observation is the primary means to investigate earthquake and internal structure of earth, and seismic data received by seismic recorder is the basic data for seismologists'work of research. In the improving process of seismic instrument, the introduction of electronic technology has played an important role. Importing electronic feekback technology and digital technology into seismic records, widens the band width of seismic records, which means both sick and strong seismic signals can be recorded. The progress of observing has brought a series of important progress to seismology, and the most important of which is that the resolution of the earthquake and the internal structure of the Earth has been greatly improved.Broadband seismic recorder is a three-component seismic signal acquisition system with high-precision, wide-band and low consumption. Wide dynamic range, small size, light weight, mobile convenience and a strong ability to adapt to the environment, it can both be used for natural seismic data acquisition and large-volume blast of seismic data acquisition. In recent years the use of natural seismic data to study the Earth's interior structure and the earthquake epicenter develops very fast. The near-field earthquake records received by the digital observation system with broadband and dynamic range carry on rich information about source and media, and it provides an effective means for the further understanding of the earthquake epicenter process of the internal structure of the Earth.Combined with the special application environment and based on the former research, in this paper, a software design method of broadband seismograph is proposed, the software design work is completed and the primary test results are presented at last. The paper mainly discusses the design method and process of data acquisition software of broadband seismic recorder. The main contents are in the following: Taking the 24bitΔ-Σconversion set (CS5372 and CS5376) as the acquisition hardware, FPGA for the logic control core of the A/D interface circuit, after finishing the FPGA driver design and the configuration of CS5376 and AD9850, seismic data acquisition software system with large dynamic range is designed and realized; the large storage problem is solved by CF card technology and SEG-2 document storage format; the test function switch is realized through the software design of ARM and FPGA, which makes the field self-diagnosis and more convenient field application of the instrument possible.The data acquisition module is the basis of seismograph, and then the design of data acquisition software is the main content of this paper. The realize of data acquisition software are as following: The data acquisition system consists of low-pass filter, preamplifier, 24 bitΔ-ΣA/D, and logic control circuit, etc. First, configure with the working parameters of CS5376 in theΔ-ΣA/D conversion set. Then, after finishing the FPGA driver design under Embedded Linux, AT91RM9200 sends orders to FPGA, and FPGA realizes its logic control function to the data acquisition system. At last, the data acquisition function of seismograph is completed.Mass data storage uses CF card as memory medium and standard SEG-2 file format for data storage format. On the basis of completed CF card driver under Embedded Linux, the data transfers from FIFO of FPGA to the memory of AT91RM9200, and is stored in the CF card with SEG-2 format at last. The written data is operates by standard file format FAT32, and then data file writing in CF card can dump and process in PC machine conveniently.As the seismograph can record the signal both excited by artificial hypocenter and nature hypocenter, the online test function for higher reliability is much more important in the long field record. The system test function in broad-band seismograph includes: the detector, short circuit, sine wave, and impulse test. The switch of corresponding test functions is completed through the software design of AT91RM9200 and logic control unit.Finally, the main work and results are concluded, and the further improvements and suggestions are proposed.