Adaptive Multichannel Control for Anti-Aliasing in Fiber-Optic Fabry-Perot Vibration Systems

In order to extend the frequency measurement bandwidth of Fabry-Perot (F-P) sensors, solve the frequency aliasing, and improve the real-time demodulation system, a multichannel adaptive sampling anti-aliasing system was proposed, which addresses the issues of frequency demodulation error resulting from frequency aliasing, multichannel fusion noise, and the elevated computational time, resulting from the high sampling rate. This method uses an adaptive control system based on phase error to automatically adjust the sampling density and enhance the precision of local computation through interpolation so that to mitigate the occurrence of the aliasing. Through experiment and simulation, the control system has been implemented in an FPGA, and the vibration test of the F-P vibration sensor was conducted over the range of 2k-20k. In comparison to the conventional demodulation, this method doubles effective bandwidth, and the maximum relative error was less than 0.1%, the linear regression was calculated, resulting in an {R}^{{2}} value of 0.999964. This methodology described herein will be employed for the development of a broadband F-P vibration sensor with a high real-time in situ frequency demodulation system.