For a long time

a spectrograph is used to inspect the reflective wavelength of a fiber Bragg grating sensor. But with the wide application of the fiber Bragg grating sensor

the spectrograph gradually brings more and more limitation. The text introduces regulating the cavity length according to the principle of Fabry-Perot cavity multiple light beam transmission. When Fabry-Perot cavity meets given conditions

its transmitted light will become the strongest or weakest

thus the model of cavity demodulation system is established. And relevant variables can be obtained by checking F-P parameters. According to the characters of a fiber Bragg grating

a matching filter demodulation model is established

in which another fiber Bragg grating is used to follow the change of the measured fiber Bragg grating and then the measured parameters are obtained. The paper points out the key issues to be solved when the demodulation projects are used. To improve the accuracy and real time capability of the demodulation system

a single clip processor is used to deal with related data information of the system. Its applications in the demodulation system and related interfaces are expatiated

and the design of hardware and software are presented in detail.