11 November 2014 Research of AGC technology in a digital optical fiber sensing system with PGC modulation and demodulation
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Abstract
The magnitude of light intensity on the photo-to-electric detector fluctuates all the time in an optic fiber sensing system, because of the influence of various factors in the fiber optic sensing system and from the external environment. As a result of the excessive intensity, the electric signal will be overload after the amplifier circuit with constant enlargement factor, and when the light intensity becames too small, it will reduce the signal-to-noise ratio of the electric signal. Therefore, it is necessary to introduce an automatic gain control (AGC) module into the system, which can insure the electric signal in a reasonable magnitude. In order to solve the problem of optic intensity fluctuating in the optical fiber sensing system with PGC modulation and demodulation, in this paper, firstly, it is analyzed that the impact of different magnitudes of interferential intensity to the PGC demodulation in theory. Secondly, a reasonable control method is put forward and an AGC module based on the AD602 chip is designed and produced. Finally, it is proved that the optic fiber sensor system with an AGC module has strong ability to resist fluctuation of light intensity within 40dB.
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Jianfeng Tang, Shuidong Xiong, Yan Zhang, "Research of AGC technology in a digital optical fiber sensing system with PGC modulation and demodulation", Proc. SPIE 9274, Advanced Sensor Systems and Applications VI, 92740M (11 November 2014); doi: 10.1117/12.2071334; https://doi.org/10.1117/12.2071334
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