这个例子显示一个理想采样信号及其幅度谱和相位谱，并可以修改参数。 此外还包括几个其他的信号。

主文件spy102.m

%初始化根窗体

clf reset;

set(gcf,'Units','pixels','position' ,[185 50 860 655],'name', '信号谱线分析',...

'numbertitle', 'off', 'Tag', 'dsp');

set(gcf, 'defaultuicontrolfontsize' ,12);

set(gcf, 'defaultuicontrolfontname' , ' 宋体 ' );

%添加组件

%三个axes，用来显示图像

labelTitle1 = uicontrol(gcf,'Style', 'text', 'String', '理想采样信号序列',...

'Position',[60 610 660 20], 'BackgroundColor', [.8 .8 .8]);

axesH1 = axes('Units','pixels','Position', [50 450 660 160]);

labelTitle2 = uicontrol(gcf,'Style', 'text', 'String', '理想采样信号的幅度谱',...

'Position', [60 405 660 20], 'BackgroundColor', [.8 .8 .8]);

axesH2 = axes('Units','pixels','Position', [50 240 660 160]);

labelTitle3 = uicontrol(gcf,'Style', 'text', 'String', '理想采样信号的相位谱',...

'Position', [60 195 660 20], 'BackgroundColor', [.8 .8 .8]);

axesH3 = axes('Units','pixels','Position', [50 30 660 160]);

%右侧编辑区域,包含几个用于画图的参数A、α、ω、T

labelTT = uicontrol(gcf,'Style', 'text', 'String', '理想采样信号','Position', [750 575 80 30],...

'BackgroundColor', [.8 .8 .8], 'FontSize', 10);

labelA = uicontrol(gcf,'Style', 'text', 'String', 'A','Position', [760 545 60 20],...

'BackgroundColor', [.8 .8 .8], 'FontSize', 10);

dataA = uicontrol(gcf,'Style', 'edit', 'String', '1','Position', [760 525 60 20], 'FontSize', 10);

labelAlpha = uicontrol('Style', 'text', 'String', 'α','Position', [760 470 60 20],...

'BackgroundColor', [.8 .8 .8], 'FontSize', 10);

dataAlpha = uicontrol(gcf,'Style', 'edit', 'String', '0.4','Position', [760 450 60 20], 'FontSize', 10);

labelW = uicontrol(gcf,'Style', 'text', 'String', 'ω','Position', [760 395 60 20],...

'BackgroundColor', [.8 .8 .8], 'FontSize', 10);

dataW = uicontrol(gcf,'Style', 'edit', 'String', '2.0734','Position', [760 375 60 20], 'FontSize', 10);

labelT = uicontrol(gcf,'Style', 'text', 'String', 'T','Position', [760 320 60 20],...

'BackgroundColor', [.8 .8 .8], 'FontSize', 10);

dataT = uicontrol(gcf,'Style', 'edit', 'String', '1','Position', [760 300 60 20], 'FontSize', 10);

%用于更改图像的按钮

btnH = uicontrol(gcf,'Style', 'pushbutton', 'String', 'Plot',...

'Position', [755 240 70 25], 'FontSize', 10);

%列表框，用于显示其他几种图形

labelOt = uicontrol(gcf,'Style', 'text', 'String', '其他','Position', [743 180 100 20],...

'BackgroundColor', [.8 .8 .8], 'FontSize', 10);

listboxH = uicontrol(gcf,'Style', 'listbox', 'String', {'单位脉冲序列';'矩形序列';'特定冲击串';'卷机计算';'卷积定律验证'},...

'Position', [743 80 100 80], 'FontSize', 10);

%设置回叫函数和初始化图像显示

set(btnH,'Callback', 'btnCall(axesH1,axesH2,axesH3,dataA,dataAlpha,dataW,dataT,labelTitle1,labelTitle2,labelTitle3)');

set(listboxH,'Callback', 'listboxCall(listboxH,axesH1,axesH2,axesH3,labelTitle1,labelTitle2,labelTitle3)');

btnCall(axesH1,axesH2,axesH3,dataA,dataAlpha,dataW,dataT,labelTitle1,labelTitle2,labelTitle3);

btnCall.m

function varargout = btnCall(axesH1,axesH2,axesH3,dataA,dataAlpha,dataW,dataT,labelTitle1,labelTitle2,labelTitle3)

%BTNH_CALLBACK Summary of this function goes here

% Detailed explanation goes here

A = str2double(get(dataA,'String'));

a = str2double(get(dataAlpha,'String'));

w0 = str2double(get(dataW,'String'));

T = str2double(get(dataT,'String'));

%信号曲线

n=0:50;

x=A*exp(-a*n*T).*sin(w0*n*T);

stem(axesH1,n,x);

set(axesH1,'XGrid','on','YGrid','on');

set(labelTitle1,'String','理想采样信号序列');

%幅度谱

k=-25:25;

W=(pi/12.5)*k;

X=x*(exp(-j*pi/12.5)).^(n'*k);

magX=abs(X);

stem(axesH2,magX);

set(axesH2,'XGrid','on','YGrid','on');

set(labelTitle2,'String','理想采样信号的幅度谱');

%相位谱

angX=angle(X);

stem(axesH3,angX);

set(axesH3,'XGrid','on','YGrid','on');

set(labelTitle3,'String','理想采样信号的相位谱');

function varargout = listboxCall(listboxH,axesH1,axesH2,axesH3,labelTitle1,labelTitle2,labelTitle3)

value = get(listboxH,'Value');

%判断选中的值，显示相应的图形

if value==1

uis(axesH1,axesH2,axesH3,labelTitle1,labelTitle2,labelTitle3);

elseif value==2

recs(axesH1,axesH2,axesH3,labelTitle1,labelTitle2,labelTitle3);

elseif value==3

maic(axesH1,axesH2,axesH3,labelTitle1,labelTitle2,labelTitle3);

elseif value==4

convo(axesH1,axesH2,axesH3,labelTitle1,labelTitle2,labelTitle3);

elseif value==5

conlc(axesH1,axesH2,axesH3,labelTitle1,labelTitle2,labelTitle3);

end

%单位脉冲序列

function uis(axesH1,axesH2,axesH3,labelTitle1,labelTitle2,labelTitle3)

n=1:50;

x=zeros(1,50);

x(1)=1;

%信号曲线

stem(axesH1,n,x);

set(axesH1,'XGrid','on','YGrid','on');

set(labelTitle1,'String','单位脉冲序列');

%幅度谱

k=-25:25;

X=x*(exp(-j*pi/12.5)).^(n'*k);

magX=abs(X);

stem(axesH2,magX);

set(axesH2,'XGrid','on','YGrid','on');

set(labelTitle2,'String','单位冲击信号的幅度谱');

%相位谱

angX=angle(X);

stem(axesH3,angX);

set(axesH3,'XGrid','on','YGrid','on');

set(labelTitle3,'String','单位冲击信号的相位谱');

%矩形序列

function recs(axesH1,axesH2,axesH3,labelTitle1,labelTitle2,labelTitle3)

n=1:5;

x=sign(sign(10-n)+1);

%信号曲线

stem(axesH1,n,x);

set(axesH1,'XGrid','on','YGrid','on');

set(labelTitle1,'String','矩形序列');

%幅度谱

k=-25:25;

X=x*(exp(-j*pi/25)).^(n'*k);

magX=abs(X);

stem(axesH2,magX);

set(axesH2,'XGrid','on','YGrid','on');

set(labelTitle2,'String','矩形序列的幅度谱');

%相位谱

angX=angle(X);

stem(axesH3,angX);

set(axesH3,'XGrid','on','YGrid','on');

set(labelTitle3,'String','矩形序列的相位谱');

%特定冲击串序列

function maic(axesH1,axesH2,axesH3,labelTitle1,labelTitle2,labelTitle3)

n=1:50; % 义序列的长度是50

x=zeros(1,50); %注意：MATLAB 中数组下标从1 始

x(1)=1;

x(2)=2.5;

x(3)=2.5;

x(4)=1;

%信号曲线

stem(axesH1,n,x);

set(axesH1,'XGrid','on','YGrid','on');

set(labelTitle1,'String','特定冲击串序列n(x)=δ(n)+2.5δ(n-1)+2.5δ(n-2)+δ(n-3)');

%特定冲击串序列的幅度谱

k=-25:25;

X=x*(exp(-j*pi/12.5)).^(n'*k);

magX=abs(X); %绘制x(n) 的幅度谱

stem(axesH2,magX);

set(axesH2,'XGrid','on','YGrid','on');

set(labelTitle2,'String','特定冲击串序列的幅度谱');

%特定冲击串序列的相位谱

angX=angle(X); %绘制x(n) 的相位谱

stem(axesH3,angX);

set(axesH3,'XGrid','on','YGrid','on');

set(labelTitle3,'String','特定冲击串序列的相位谱');

%卷机计算

function convo(axesH1,axesH2,axesH3,labelTitle1,labelTitle2,labelTitle3)

n=1:50; % 义序列的长度是50

hb=zeros(1,50); %注意：MATLAB 中数组下标从1 始

hb(1)=1; hb(2)=2.5; hb(3)=2.5; hb(4)=1;

%系统h[n]

stem(axesH1,hb);

set(axesH1,'XGrid','on','YGrid','on');

set(labelTitle1,'String','系统hb[n]');

%输入信号x[n]

m=1:50; T=0.001; % 义序列的长度是和采样率

A=444.128; a=50*sqrt(2.0)*pi; %设置信号有关的参数

w0=50*sqrt(2.0)*pi;

x=A*exp(-a*m*T).*sin(w0*m*T); %pi 是MATLAB 义的π，信号乘可采用“.*”

stem(axesH2,magX);

set(axesH2,'XGrid','on','YGrid','on');

set(labelTitle2,'String','输入信号x[n]');

%输出信号y[n]

y=conv(x,hb);

stem(axesH3,angX);

set(axesH3,'XGrid','on','YGrid','on');

set(labelTitle3,'String','输出信号y[n]');

%卷积定律验证

function conlc(axesH1,axesH2,axesH3,labelTitle1,labelTitle2,labelTitle3)

figure(2);

n=1:50; % 义序列的长度是50

hb=zeros(1,50); %注意：MATLAB 中数组下标从1 始

hb(1)=1; hb(2)=2.5; hb(3)=2.5; hb(4)=1;

subplot(3,1,1);stem(hb);

title( '系统hb[n]');

m=1:50; T=0.001; % 义序列的长度是和采样率

A=444.128; a=50*sqrt(2.0)*pi; %设置信号有关的参数

w0=50*sqrt(2.0)*pi;

x=A*exp(-a*m*T).*sin(w0*m*T);

k=-25:25; X=x*(exp(-j*pi/12.5)).^(n'*k);

magX=abs(X); %绘制x(n) 的幅度谱

subplot(3,2,1);stem(magX);title('输入信号的幅度谱');

angX=angle(X); %绘制x(n) 的相位谱

subplot(3,2,2);stem(angX) ; title ('输入信号的相位谱')

Hb=hb*(exp(-j*pi/12.5)).^(n'*k);

magHb=abs(Hb); %绘制hb(n) 的幅度谱

subplot(3,2,3);stem(magHb);title( '系统响应的幅度谱');

angHb=angle(Hb); %绘制hb(n) 的相位谱

subplot(3,2,4);stem(angHb) ; title ( '系统响应的相位谱')

n=1:99; k=1:99;

y=conv(x,hb);

Y=y*(exp(-j*pi/12.5)).^(n'*k);

magY=abs(Y); %绘制y(n) 的幅度谱

subplot(3,2,5);stem(magY);title('输出信号的幅度谱');

angY=angle(Y); %绘制y(n) 的相位谱

subplot(3,2,6);stem(angY) ; title ('输出信号的相位谱')

%以下将验证的结果显示

figure(3);

XHb=X.*Hb;

subplot(2,1,1);stem(abs(XHb));title( 'x(n) 的幅度谱与hb(n)幅度谱相乘');

subplot(2,1,2);stem(abs(Y));title( 'y(n) 的幅度谱');

axis([0,60,0,8000])