Study Of PGC Demodulation For Fiber Sensors

As a kind of optical sensor developing at high speed, fiber granting laser sensor is drawing more and more attention. Compared with traditional fiber sensor, its structure is much simpler. Its accuracy is much higher and its capability of building network is much greater. The ability of detecting the vibration and strain of fiber granting laser sensor is not only related to the performance of itself, but the performance of the demodulation counts a lot.This paper, in which the principle of sensing of the optical sensor, especially the fiber granting laser sensor is introduced, also illustrates the development status of phase-generated-carrier(PGC). But the significant part of it is to state the detecting system with GPS and the two improved demodulation methods. In all, three parts are included in this paper.In the first part the principle of sensing of fiber granting sensor is introduced and by analyzing the theory of PGC method, we build a fiber demodulating system based on CompactRIO which can demodulate the signals of 16 fiber granting sensors at the same time. Besides an experiment is conducted to test the dynamic range、 accuracy and the weakest signal which can be detected. Finally it turns out the performance of this system is satisfactory. In the second part, we propose a new demodulation method named PGC double-differential-and-cross-multiplying(PGC-DDCM). Not only theoretically the advantages of the improved algorithm are demonstrated. But experimental details show that the performances of PGC-DCM are much better than PGC-DDCM demodulation. In the third part we present another improved PGC demodulation method named PGC differential-self-integrating(PGC-DSMI) algorithm. Like the first improved method mentioned before, the advantages of the novel method are demonstrated theoretically and proved in the simulation. The results show that PGC-DSMI can overcome the impact of the modulation depth.