| Geophone is the special sensor that could convert signal of mechanical vibration into signal of electricity and could be used in seism prospecting or measure of project-field. It is also a special precision machining combined with electric instrument. Its capability directly affects recording quality of seismic wave and explaining of seismic data. It is the most important part during collecting seismic wave data.This paper mainly introduces a kind of means about subdivision of grating moire fringe and its device used on grating geophone system. Based on principle of subdivision, this device could realize 200 part-subdivision depended on common effects of differential amplifier, filer, comparator, trigger, analog-to-digital converter and DSP. This device has six main advantages described as follows:1. Differential amplifier circuit and filer circuit improve the quality of original moire fringe and ultra-fast comparators improve the quality of pulse.2. The set adapts the high speed 12 bits A/D. It has eight - channel track/hold circuits. So the parts of the apparatus are reduced and the system stability is improved. The least variety which analog-to-digital converter could distinguish is 2.441mV.3. The DSP completes software-subdivision of grating moire fringe, the data process time is less 12 y S and responding-frequency of the system is improved.4. The resolution of grating geophone reach to 50nm and its performance is enhanced highly. 200 part-subdivision is carried out by software. The capability of grating geophone is improved.5. The number of subdivision could be changed flexibly. The maximal number of subdivision could reach to 2048.6. The system acquires A/D value of shift- point by means of combined effect of software and hardware, which is innovational compared with traditional discriminating-direction circuitry.Combined hardware and software, the application of subdivision to grating geophone, will be developed toward the nice prospect.
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