High-speed Data Acquisition And Processing Of Broadband Spectral Interferometric Fiber Fabry-perot Sensor

Broadband spectral interferometric Fabry-Perot sensor not only has the advantage of strong anti-electromagnetic interference ability,good stability and small size,but also has the characteristics of high measurement accuracy and large scale operation.Therefore,it has a great application prospect in the fields of large scale structural health monitoring and aviation aircraft performance testing.However,Fabry-Perot sensor system is often used in static measurement occasions,and rarely used in dynamic monitoring field.This is because the conventional Fabry-Perot measurement system needs to obtain thousands of complete interference spectrum data to ensure the accuracy of signal demodulation.The intensive spectral data acquisition and algorithm processing are extremely timeconsuming,which makes the broadband spectral interferometric Fabry-Perot measurement system difficult to meet the needs of high-speed dynamic measurement.In order to break through the speed limit,and under the premise of high precision,it is necessary to achieve breakthroughs in both data acquisition and demodulation processing of broadband spectral interferometric signals.In the process of demodulation,the maximum likelihood parameter estimation demodulation algorithm is applied,which can reduce the amount of spectral sample data by two orders of magnitude,and still guarantee the original accuracy.This algorithm lays a theoretical foundation for greatly reducing the amount of spectral data acquisition.Therefore,a breakthrough is made in data acquisition of broadband spectral interferometric signal,and a sparse spectrum highspeed acquisition and demodulation system is developed.This paper mainly completes the following research contents:(1)According to the broadband spectral interferometric signal of Fabry-Perot sensor,the minimum sampling points of broadband spectral interferometric signal under different Fabry-Perot cavity lengths are deduced from the perspective of Nyquist sampling theorem.The demodulation errors of the maximum likelihood estimation algorithm for different spectral data samples are simulated and analyzed.(2)According to the sampling points,the number of channels for sparse spectral acquisition is determined.Analyzing and choosing the key devices by combining the multi-channel data acquisition mode and the situation of data acquisition module in the market.(3)According to the overall design scheme of sparse spectrum high-speed acquisition and demodulation system,the hardware module system of data acquisition is built.The control program of data acquisition and data communication of the lower computer is designed,and each part of the hardware module is tested.According to the algorithm principle,the real-time demodulation program of cavity length for broadband spectrum interferometric Fiber-Fabry sensor is developed.(4)The sparse spectrum high-speed acquisition and demodulation experimental system is built.The experimental programs is designed to verify the overall performance of the system.Static experiments verify the feasibility of the hardware system for sparse spectral sampling and the accuracy of the maximum likelihood demodulation algorithm.Through dynamic experiments,it is verified that the sparse spectrum sampling and demodulation system can collect data at 200 KSPS sampling rate.But in order to ensure the demodulation accuracy,the real-time measurement speed of the whole experimental system is 600 Hz when demodulating with the maximum likelihood estimation algorithm.