Based on distributed fiber Bragg grating (FBG) techniques, this paper proposes the framework of a building structure health monitoring system, then introduces its operational principle, and studies a few critical prob- lems such as system capacity limit, strain/temperature cross-sensitivity and signal demodulation, etc.

The temperature-pressure cross sensitivity is decreas.

Because there was the cross sensitivity of two sensors to CO and methane gas in mine,a gas sensor array system based on BP neural network and the method of signal processing on BP neural network for increasing precision of detection CO were researched in this paper.

Then a novel plan to increase the sensitivity was proposed in view of the wavelength difference among various region,thus both the sensitivity is doubled and the cross sensitivity is solved.

On the basis of the equation of Bragg gratings,the physical mechanics of the cross sensitivity from simultaneous measurement of strain and temperature with optical fiber Bragg grating are studied.