A new fire alarm system based on FBG sensor has been investigated to determine its potential in fire alarm applications
for highway tunnel. The system has been experimentally tested and some of its application are reported. The results show
that the new fire alarm system is capable of fixed temperature alarm and rate-of-rise alarm promptly; the fire place can
easily determined according to the location of maximum temperature; the temperature distribution and the rule of
temperature development in the tunnel can be obtained at the same time.
A method for calculating the optical-signal-to-noise ratio (OSNR) of an optical performance monitor (OPM) is discussed. OSNR is one of the most import parameters determining DWDM system performance because of its dominance in determining the bit-error-rate (BER). However for the optical and electric components’ limitations, most OPMs are less accurate and dynamic range in measuring OSNR. In order to improve OSNR, heightening measuring accuracy of the signal power and the noise power are both required. The method for improving accuracy of measuring the signal power, namely Gauss Fitting, can heighten the signal power in the selected bandwidth by 1-2 dB. For improving accuracy of measuring the noise power, a kind of algorithm about deconvolution and signal recovery is discussed, which is used to sharpen the signal figure and eliminate effect of signal power to noise power (named cross talk). After deconvolution, the power of the pits of a 100 GHz channel signal can be depressed by 6-8 dB. In conclusion, a research on how to calculate OSNR in the OPM is discussed. By Gauss Fitting and deconvolution, the signal can be recovery efficiently and the result of OSNR can be heightened by 7-10 dB.