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1、2020/7/17,1,Digital Signal Processing,Department of Applied Physics , Physics College, Jilin University,卓仲畅 (Zhong chang Zhuo) Email:,2020/7/17,2,个人简介,卓仲畅，男，博士，教授。工作单位：吉林大学物理学院。 教育经历: 1981/091985/06,吉林大学,物理系, 磁学专业,学士 1990/09-1993/06,燕山大学,信息工程学院,电路与系统专业,硕士 2000/09-2005/06, 吉林大学电子科学与工程学院,微电子学与固体电子学专业,
2、博士 工作经历： 1985/07-1988/11, 山东科技大学, 助教 1988/12-1990/08 ,河北秦皇岛市技术监督局, 工程师1993/03-1999/05, 燕山大学信息工程学院 ,讲师 1999/06-2004/11, 吉林大学物理学院, 讲师 2004/12-2009/08, 吉林大学物理学院, 副教授 2007/10-2008/10, 韩国仁荷(Inha)大学, 研究教授2009/10-2009/11 韩国国立教育大学 访问教授2010/04-20106 西班牙马德里康普顿斯(Complutense)大学, 访问教授2009/09-至今, 吉林大学物理学院, 教授。 研究
3、方向：(1)光纤光学相关无源器件的设计与制作；(2)光纤光栅和光纤放大器及其在光纤通信和光纤传感中的应用；(3)光纤中基于动态光纤光栅的光速减慢和光存储及其应用；(4)光纤中光孤子的传输和控制及其应用；(5)光纤中光子信息处理等。 (6) 数字信号处理。 社会兼职：创新人才推进计划评审专家。国家科技部国际科技合作计划评审专家。 山东省自然科学基金评审专家。 学术杂志编委: Applied Physics Frontier。杂志的审稿人：Journal of the Optical Society of America B, Optical Engineering，Optics % Number
4、 of samples f1=1; % Frequency of the sinewave FS=200; % Sampling Frequency n=0:N-1; % Sample index numbers x=sin(2*pi*f1*n/FS); % Generate the signal, x(n) t=1:N*(1/FS); % Prepare a time axis subplot(2,1,1); % Prepare the figure plot(t,x); % Plot x(n) title(Sinwave of frequency 1000Hz FS=8000Hz); xl
5、abel(Time, s); ylabel(Amplitude); grid; Rxx=xcorr(x); % Estimate its autocorrelation subplot(2,1,2); % Prepare the figure plot(Rxx); % Plot the autocorrelation grid; title(Autocorrelation function of the sinewave); xlable(lags); ylabel(Autocorrelation);,2020/7/17,54,2020/7/17,55,A=ones(1,4),zeros(1,
6、8),ones(1,8); A2=filter(0,0,0,0,0,1,1,A); acor , lags= xcorr(A,A2); subplot(3,1,1) ,stem(A), title(Original signal A); subplot(3,1,2) ,stem(A2), title(Sample shifted signal A2); subplot(3,1,3), stem(lags,acor/length(A) title(Full cross-correlation of A and A2);,2020/7/17,56,2020/7/17,57,2020/7/17,58
7、,Digital Filtering,The equation for finite impulse response (FIR) filtering is,Where, xk and yk are the input and output of the filter respectively and hk for k = 0,1,2,N-1 are the filter coefficients,2020/7/17,59,Filter structure,A common filtering objective is to remove or reduce noise from a want
8、ed signal.,2020/7/17,60,(a) (b) (c),(d) (e) (f),Figure : Reconstructed bi-level text images for degradation caused by h1 and AWGN. (a) Original, (b) 2D Inverse, (c) 2D Wiener, (d)PIDD, (e) 2D VA-DF, (f) PEB-FCNRT,2020/7/17,61,Discrete Transformation离散变换,Discrete transforms allow the representation o
9、f discrete-time signals in the frequency domain or the conversion between time and frequency domain representations. Many discrete transformations exists but the discrete Fourier transform (DFT) is the most widely used one. DFT is defined as:,IDFT is defined as:,2020/7/17,62,MATLAB function for DFT,
10、function Xk = dft(xn) N=length(xn); n = 0:1:N-1; % row vector for n k = 0:1:N-1; % row vecor for k WN = exp(-1*j*2*pi/N); % Twiddle factor (w) nk = n*k; % creates a N by N matrix of nk values WNnk = WN . nk; % DFT matrix Xk = (WNnk*xn );,2020/7/17,63,Matlab Function for IDFT,function xn = idft(Xk) %
11、 Computes Inverse Discrete Transform % - % xn = idft(Xk) % xn = N-point sequence over 0 = n = N-1 % Xk = DFT coeff. array over 0 = k = N-1 % N = length of DFT % N = length(Xk); n = 0:1:N-1; % row vector for n k = 0:1:N-1; % row vecor for k WN = exp(-j*2*pi/N); % Wn factor nk = n*k; % creates a N by
12、N matrix of nk values WNnk = WN . (-nk); % IDFT matrix xn = abs(Xk * WNnk)/N; % row vector for IDFT values,2020/7/17,64,Example,Let xn be a 4-point sequence,x=1, 1, 1, 1; N = 4; X = dft(x,N); magX = abs(X) ; phaX = angle(X) * 180/pi; magX= 4.0000 0.0000 0.0000 0.0000 phaX= 0-134.981-90.00-44.997,202
13、0/7/17,65,Modulation调制,Discrete signals are rarely transmitted over long distances or stored in large quantities in their raw form. Signals are normally modulated to match their frequency characteristic to those of the transmission and/or storage media to minimize signal distortion, to utilize the a
14、vailable bandwidth efficiently, or to ensure that the signal have some desirable properties. Two application areas where the idea of modulation is extensively used are: 1. telecommunications 2. digital audio engineering High frequency signal is the carrier The signal we wish to transmit is the modul
15、ating signal,2020/7/17,66,Three most commonly used digital modulation schemes for transmitting Digital data over bandpass channels are: Amplitude shift keying (ASK) Phase shift keying (PSK) Frequency shift keying (FSK),When digital data is transmitted over an all digital network a scheme known As pulse code modulation (PCM) is used.,2020/7/17,67,Grading Policy,Homework 30% Final Exam - 40 % Seminar-30%,