| In this paper, the analyzing technique and specific steps for reducing the noise level of conditioning circuits used for the examining and measuring system of weak signal is pre sented by studying a conditioning circuits for use in the measurement of micro-displacement with an optieal fiber sensor. The theoretical foundation, the selecting principle of circuit parameters and the designing method of preamplifier are given and analyzed in detail for the phase modulation of low noise of weak signal and the demodulation procedure of telephone digits. The rasults indicate that the micro-displacement resolution of 0.005nm level can be achieved by our proposed conditioning circuits ecorperated with optical fiber sensor. |
