《武汉大学数字信号实验.docVIP

姓名:全权 学号：2013302530120 班级：信安四班 日期：5月8日 实验2离散时间系统-时域分析 实验内容： 2.1 SIMULATION OF DISCRETE-TIME SYSTEMS Project 2.1 The Moving Average System (移动平均值系统) A copy of Program P2_1 is given below: % Program P2_1 % Simulation of an M-point Moving Average Filter % Generate the input signal n = 0:100; s1 = cos(2*pi*0.05*n); % A low-frequency sinusoid s2 = cos(2*pi*0.47*n); % A high frequency sinusoid x = s1+s2; % Implementation of the moving average filter M = input(Input Desired length of the filter = ); num = ones(1,M); y = filter(num,1,x)/M; %注：上式用滤波函数实现移动平均 % 当 M=2时，y=(x(n)+x(n-1))/M % 当 M=3时，y=(x(n)+x(n-1)+x(n-2))/M % Display the input and output signals clf; subplot(2,2,1); plot(n, s1); axis([0, 100, -2, 2]); xlabel(Time index n); ylabel(Amplitude); title(Signal #1); subplot(2,2,2); plot(n, s2); axis([0, 100, -2, 2]); xlabel(Time index n); ylabel(Amplitude); title(Signal #2); subplot(2,2,3); plot(n, x); axis([0, 100, -2, 2]); xlabel(Time index n); ylabel(Amplitude); title(Input Signal); subplot(2,2,4); plot(n, y); axis([0, 100, -2, 2]); xlabel(Time index n); ylabel(Amplitude); title(Output Signal); axis; Insert program code here. Copy from m-file(s) and paste. Answers: Q2.1 The output sequence generated by running the above program for M = 2 with x[n] = s1[n]+s2[n] as the input is shown below. s2 = cos(2*pi*0.47*n); % A high frequency sinusoid Insert MATLAB figure(s) here. Copy from figure window(s) and paste. The component of the input x[n] suppressed（抑制） by the discrete-time system simulated by this program is - s2 = cos(2*pi*0.47*n); % A high frequency sinusoid Q2.2 Program P2_1 is modified to simulate the LTI system y[n] = 0.5(x[n]–x[n–1]) and process the input x[n] = s1[n]+s2[n] resulting in the output sequence shown below: % Program P2_1 % Simulation of an M-point Moving Average Filter % Generate the input signal n = 0:100; s1 = cos(2*pi*0.05*n); % A low-frequency sinusoid s2 = cos(2*pi*0.47*n); % A high frequency sinusoid x