PGC(phase generated carrier) demodulation scheme is used widely in fiber-optic sensors. In this paper, we analyzed what factors affect the demodulation effect of PGC scheme. We studied and simulated the relationship between the upper limit and the frequency of the carrier. We studied how signal's amplitude and frequency affect the demodulation effect. At last, we drew a conclusion that we must increase the frequency of the carrier to get better demodulation effect and ability.
Keywords-PGC demodulation scheme; dynamic range; carrier's frequency; demodulation effectI.
Aiming at the problem of most electric vehicles (EV) sounding false alarms due to touches, an EV alarm regionalization management control system based on multi-information fusion and the BSP model is designed in the present study. The proposed system uses multiple sensors to detect the state of the EV, and realizes multi-sensor information fusion by the Lagrange interpolation method. The ZigBee networking technology is used to carry out the regional management of EV alarms, establish a BSP model, realize the synchronous transmission of system status detection signals, and finally complete the alarm function. The experimental results show that the false alarm rate of traditional EV alarm systems is about 85.5%, that of alarm systems that perform state monitoring without information fusion is about 11.3%, and that of the proposed alarm system that performs multi-information fusion simultaneously is greatly reduced to about 0.5%.
We demonstrated a Kerr-lens mode-locked polycrystalline Cr:ZnS laser pumped by a narrow-linewidth linearpolarised monolithic Er:YAG nonplanar ring oscillator operated at 1645 nm. With a 5-mm-thick sapphire plate for intracavity dispersion compensation, a compact and stable Kerr-lens mode-locking operation was realised. The oscillator delivered 125-fs pulses at 2347 nm with an average power of 80 mW. Owing to the special polycrystalline structure of the Cr:ZnS crystal, the second to fourth harmonic generation was observed by random quasi-phase-matching.
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