Studies Of Fidelity Capability Of Grating Geophone Based On DSP

In seismic prospecting, geological information is obtained by the acquisition system through grating geophone. However, the design of real time signal analysis and reproduce system is still a difficult problem. Grating geophone is very important and will directly work on the recording and explaining of seismic wave data. The direction distinguishing and subdivision of grating geophone signal are the most important part of the signal processing. As a result,how to deal with the problems of traditional direction discriminating technique to get the seismic wave signal, and convert it into analog signal which can be received by seismograph, have become the main tasks.Through the deeply research on characteristic of vibration signal, the quality of current grating vibration signal processing methods is compared. Combined with the special advantages of AVR MCU and DSP in control and arithmetic function. Respectively, the deeply studied on the real-time system of grating vibration signal processing based on the coprocessor AVR MCU and the processor DSP has been made. The main achievements in scientific research of this paper are as follows:1. The current theory of the grating geophone are analyzed, the research on theory of vibration signal and signal direction distinguishing, subdivision technique is mastered.2. AVR MCU controls an A/D converter which has four sampling holders. It converts three synchronous signals. The limitation of traditional data acquisition method which use single sampling holder resulted in the asynchronism of data acquisition is eliminated.3. The vibration signal high expansion subdivision and filter algorithm based on amplitude subdivision principle and digital filter technology by DSP is designed.4. A new method to get the amplitude information of the vibration is put forward in this paper. According to the working principle of the grating digital measuring device, the subdivision value of the non-full moire fringe wave is acquired and added to the full moire fringe number. Then the function which reflects the relationship of the amplitude of seismic wave and time will be acquired. The point where movement direction changed can be ignored in this method and direction discerning signal is only used to control the up-down counter. In this way, the error result from the delay direction discerning signal by hardware can be highly reduced.5. The grating geophone system based on DSP can successfully collect the data from the grating geophone which can work by an artifical percussion and platform vibrator stimulation. Experience shows that the general trend of these data is consi stent with the simulation result which research group did. We can find signal d irection distinguishting points clearly from these data.6. I am using the LabWindows/CVI design a host computer interface which ca n always display the size and time of the amplitude in order to observe and analys e the experimental data.