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Demodulation System for Fiber Bragg Grating Sensors Using digital filtering Technique

Transactions of Tianjin University 2008年第1期14卷 27-30页

作者：吕辰刚胡志雄祖鹏葛春风武星 School of Electronic Information Engineering Tianjin University School of Precision Instrument and Opto-Electronics Engineering Tianjin University

A discrimination measurement method and demodulation technique for fiber Bragg grating (FBG) sensors were presented using digital filtering technique. The system can control a tunable fiber Fabry-Perot filter with sawtooth wave voltage generated by digital clock to interrogate FBG sensors. Using the analogue digital converter (ADC), the reflected FBG signals were sampled with synchronous digital clock. With the aid of digital matched filtering technique, the sampled FBG signals were processed to obtain the maximum signal-to-noise ratio (SNR) and the Bragg wavelength shift from the FBG signals was recovered. The results demonstrate that this system has a scanning range of 1 520 nm-1 575 nm,and the wavelength detection accuracy is less than 2 pm with 1.5 Hz scanning frequency.

关键词： fiber Bragg gratings demodulation sensor digital filtering

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digital Imaging Reconstruction from Multiple Angle Diversity Using digital filtering Technique

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Journal of Systems Engineering and Electronics 1991年第1期2卷 67-73页

作者： Wu Chuanjie and Li ShizhiDept. of Electronic Engineering, Beijing Institute of Technology P.O. Box 327, Beijing 100081, China Dept. of Electronic Engineering Beijing China of Technology P.O. Box 327 Beijing 100081 China

Microwave diffraction tomography is a process to infer the internal structure of an objectfrom multiple angle views of microwave diffraction shadow. Being sensitive to variations in refractive index of the object, the procedure can be used to measure permittivity distributions within dielectric objects and to image soft tissues for biomedical applications. The optimal resolution distance obtainable is half a wavelength, but this can rarely be achieved because of practical limitations. Some procedures, however, are available to improve the practical resolution. One, which is suitable for microwave tomography, is to use multiple angle views data and to combine the resulting images. The other, which is suitable for improving the image reconstruction resolution, is to use the digital filtering technique and the filtered backpropagation algorithm. A system operating over the X-band microwave frequency is described and some experimental results for objects in air are given.

关键词： digital filtering digital image reconstruction Microwave diffraction tomography.

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Tremor suppression in master-slave robot remote welding system

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China Welding 2011年第2期20卷 63-66页

作者：陈洪堂李海超高洪明吴林 State Key Laboratory of Advanced Welding Production Technology Harbin Institute of Technology Harbin 150001

Welding seam tracking precision was decreased due to human hand tremor during the master-slave welding teleoperation. To solve this problem, a master-slave robot remote welding system was built, the system consisted of a master manipulator with six degree of freedom （ DOF ） , an industrial computer control system and a slave Motoman HP3 J robot, and human hand tremor and digital filtering were discussed. An optimal digital filter was designed to clean human tremor signal for improving the welding seam tracking precision. The experimental results show that the digital filter suppresses the operator＇ s tremor signal.

关键词： remote welding master-slave teleoperation hand tremor digital filtering

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Research on a Pulse Interference Filter Used for the Fiber Bragg Grating Interrogation System

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Photonic Sensors 2018年第3期8卷 270-277页

作者： Weifang ZHANG Feifei REN Yingwu LI Bo JIN Wei DAI School of Reliability and Systems Engineering Beihang University Beijing 100191 China School of Energy and Power Engineering Beihang University Beijing 100191 China

In this paper, a novel pulse interference filter for fiber Bragg grating （FBG） interrogation based on the tunable Fabry-Perot （F-P） filtering principle is proposed and experimentally demonstrated. The self-developed FBG interrogation system is devised for the aircraft health management of key structures. Nevertheless, the pulse interference is detected in the reflection spectrum of FBG causing interrogation system unstable. To address the problem, the first-order lag pulse broadening filter is proposed in this paper. The first-order lag filter is applied to preprocess and smooth the original signal, meanwhile enhancing the signal-to-noise ratio （SNR）. Afterwards, peaks of reflection spectrum are distinguished with pulse interference by pulse broadening. Experimental results indicate that 634 peaks are detected before adopting the first-order lag pulse broadening filter. Comparatively, the number of peaks decreases to 203 after filtering the interference pulse, and the correct rate of peak detection is higher than 98.5%. Through the comparison with the finite impulse response （FIR） filter, the advantage of first-order lag filter is proved. The vibration monitoring experiment demonstrates that this system has high dynamic precision with a dynamic interrogation range of 0Hz-400Hz, and the maximum repetition rate of 800Hz.

关键词： Fiber Bragg grating tunable F-P filtering principle pulse interference digital filtering

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A three-dimensional transient electromagnetic data inversion method based on a time–frequency transformation

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Applied Geophysics 2020年第3期17卷 361-376页

作者： Yang Yun-Jian Wang Xu-Ben Liu Xue-Jun Mi Xiao-Li Mao Lifeng College of Geophysics Chengdu University of TechnologyChengduSichuan 610059China BGP Inc. Zhuozhou 072750China

Herein,a three-dimensional(3D)inversion method in the frequency domain based on a time–frequency transformation was developed to improve the efficiency of the 3D inversion of transient electromagnetic(TEM)*** Fourier transform related to the electromagnetic response in the frequency and time domains becomes a sine or cosine transform under the excitation of downward-step *** established a transformation matrix based on the digital fi ltering calculation for the sine transform,and then the frequency domain projection of the TEM data was determined from the linear transformation system using the smoothing constrained least squares inversion method,in which only the imaginary part was used to maintain the TEM data transformation equivalence in the bidirectional ***,the time-domain TEM inversion problem was indirectly and effectively solved in the frequency *** the 3D inversion of the transformed frequency-domain data,the limited-memory Broyden–Fletcher–Goldfarb–Shannoquasi–Newton(L-BFGS)method was used and modifi ed with a restart strategy to adjust the regularization parameter when the algorithm tended to a local *** data tests showed that our domain transformation method can stably project the TEM data into the frequency domain with very high accuracy;furthe rmore,the 3D inversion of the transformed frequency-domain data is stable,can be used to recover the real resistivity model with an acceptable effi ciency.

关键词： Transient electromagnetic method TEM digital filtering time-frequency transformation 3D EM forward 3D EM inversion

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Application of Wavelet Threshold Method to DTG Signal Processing

Application of Wavelet Threshold Method to DTG Signal Proces...

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2010 Chinese Control and Decision Conference

作者： Tao Cai~1,Minggang Gan~1,Ting Yu~1 1.School of Automation,Beijing Institute of Technology,Beijng 100081,China

＜正＞In the process of azimuth measuring,the output signal of a gyro always contains noises caused by gyro drifting and ambient environmental *** order to reduce the noises and recover the original signal,conventional digital filtering methods such asⅡR and FIR could be *** the outputs of these filters would be distorted or in lack of smoothness under some special *** analysis is suitable to this circumstance for its characteristic of multi-resolution of time and frequency and localization in ***,a wavelet threshold filter is designed,and the simulating result is given.A comparison was made on the results of wavelet threshold,IIR and FIR filtering *** analysis demonstrates that wavelet threshold filtering performance is the best.

关键词： Gyro digital filtering FIR IIR Wavelet threshold filtering

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A Distinguishing Method of the Ultrasonic Signal Waveform Starting Point

A Distinguishing Method of the Ultrasonic Signal Waveform St...

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2012年计算机应用与系统建模国际会议

作者： Jiao Bing Chen Xiaoying Ye Song Wen Yating Institute of Meteorology PLA Univ. of Sci. & Tech.

According to the application of ultrasonic in wind speed, flow and liquid level measurement, a method about distinguishing ultrasonic signal waveform starting point was introduced. The high-powered DSP chip was chosen as the system’s processor. The IIR band-pass digital filter was designed to eliminate disturbance. Marked change in fluctuation of ultrasonic signal sample was checked using the hypothesis testing to find the jumping off point of signal waveform.

关键词： ultrasonic digital filtering hypothesis testing DSP microprocessor

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High-Precision Orbit Prediction for COMPASS Navigation Satellite Based On ANN Model

High-Precision Orbit Prediction for COMPASS Navigation Satel...

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第五届中国卫星导航学术年会

As to the problem of rapid attenuation of predictive orbit precision got by dynamics model, a new method of satellite orbit prediction based on Artificial Neural Network （ANN） model was proposed. we attemped to make use of ANN as the tool of constituting orbit prediction model, search the rule of orbit prediction, then utilize ANN model to compensate the orbit prediction error. The short-term, middle-term and long-term forcast project were established. The experiment results showed that, the rates of improvement of predicting 4、8 days were respectively 40.14%～64.67%、56.13%～73.02%. The orbit prediction error control technique was brought forward, because the probability of success was not 100%. The ANN model was effective to improve orbit prediction for satellites in COMPASS navigation system.

关键词： COMPASS Navigation satellite Artificial Neural Network orbit prediction digital filtering smoothing

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