pinpufenxi.m

本程序仿真了信号与系统中的频谱混叠

function varargout = pinpufenxi(varargin)
% PINPUFENXI M-file for pinpufenxi.fig
%      PINPUFENXI, by itself, creates a new PINPUFENXI or raises the existing
%      singleton*.
%
%      H = PINPUFENXI returns the handle to a new PINPUFENXI or the handle to
%      the existing singleton*.
%
%      PINPUFENXI('CALLBACK',hObject,eventData,handles,...) calls the local
%      function named CALLBACK in PINPUFENXI.M with the given input arguments.
%
%      PINPUFENXI('Property','Value',...) creates a new PINPUFENXI or raises the
%      existing singleton*.  Starting from the left, property value pairs are
%      applied to the GUI before pinpufenxi_OpeningFunction gets called.  An
%      unrecognized property name or invalid value makes property application
%      stop.  All inputs are passed to pinpufenxi_OpeningFcn via varargin.
%
%      *See GUI Options on GUIDE's Tools menu.  Choose "GUI allows only one
%      instance to run (singleton)".
%
% See also: GUIDE, GUIDATA, GUIHANDLES

% Edit the above text to modify the response to help pinpufenxi

% Last Modified by GUIDE v2.5 28-Apr-2006 22:33:45

% Begin initialization code - DO NOT EDIT
gui_Singleton = 1;
gui_State = struct('gui_Name',       mfilename, ...
                   'gui_Singleton',  gui_Singleton, ...
                   'gui_OpeningFcn', @pinpufenxi_OpeningFcn, ...
                   'gui_OutputFcn',  @pinpufenxi_OutputFcn, ...
                   'gui_LayoutFcn',  [] , ...
                   'gui_Callback',   []);
if nargin && ischar(varargin{1})
    gui_State.gui_Callback = str2func(varargin{1});
end

if nargout
    [varargout{1:nargout}] = gui_mainfcn(gui_State, varargin{:});
else
    gui_mainfcn(gui_State, varargin{:});
end
% End initialization code - DO NOT EDIT


% --- Executes just before pinpufenxi is made visible.
function pinpufenxi_OpeningFcn(hObject, eventdata, handles, varargin)
% This function has no output args, see OutputFcn.
% hObject    handle to figure
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    structure with handles and user data (see GUIDATA)
% varargin   command line arguments to pinpufenxi (see VARARGIN)

% Choose default command line output for pinpufenxi
handles.output = hObject;

% Update handles structure
guidata(hObject, handles);

% UIWAIT makes pinpufenxi wait for user response (see UIRESUME)
% uiwait(handles.figure1);


% --- Outputs from this function are returned to the command line.
function varargout = pinpufenxi_OutputFcn(hObject, eventdata, handles) 
% varargout  cell array for returning output args (see VARARGOUT);
% hObject    handle to figure
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    structure with handles and user data (see GUIDATA)

% Get default command line output from handles structure
varargout{1} = handles.output;


% --- Executes on button press in 频谱混叠.
function pinpuhundie_Callback(hObject, eventdata, handles)
% hObject    handle to 频谱混叠 (see GCBO)
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    structure with handles and user data (see GUIDATA)
n=[0:1:9];
x=cos(0.48*pi*n)+cos(0.52*pi*n); %原始序列 
w=[0:1:500]*2*pi/500;    %0-2*pi区域分为501点
subplot(4,1,1);
stem(n,x); 
title('x(n) (0<=n<=9)'); 
xlabel('n'); 
axis([0,10,-2.5,2.5]);
line([0,10],[0,0]);
x1=fft(x);       %fft变换
magx1=abs(x1(1:1:10)); 
k1=0:1:9;
w1=2*pi/10*k1;
subplot(4,1,2); 
stem(w1/pi,magx1); %两个门函数
title('X(K) 有混叠');
axis([0,1,0,10]); 

n=[0:1:99];
x=cos(0.48*pi*n)+cos(0.52*pi*n);
subplot(4,1,3);
stem(n,x);
title('改善后 x(n) (0<=n<=99)'); 
xlabel('n'); 
axis([0,100,-2.5,2.5]);
line([0,100],[0,0]); 
x1=fft(x); 
magx1=abs(x1(1:1:50));  
k1=0:1:49; 
w1=2*pi/100*k1;
subplot(4,1,4); 
stem(w1/pi,magx1);
title('X(K)'); 
axis([0,1,0,55]);


% --- Executes on button press in 频谱泄漏.
function pinpuxielou_Callback(hObject, eventdata, handles)
% hObject    handle to 频谱泄漏 (see GCBO)
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    structure with handles and user data (see GUIDATA)
n=[0:1:127];
x=cos(0.48*pi*n)+cos(0.52*pi*n); 
subplot(4,1,1);
stem(n,x); 
title('x(n) (0<=n<=127)');
xlabel('n');
axis([0,127,-2.5,2.5]);
line([0,100],[0,0]);
w=[0:1:500]*2*pi/500;%0-2*pi区域分为501点 
x1=fft(x); 
magx1=abs(x1(1:1:64)); %窗口太短，会产生频谱泄漏
k1=0:1:63; 
w1=2*pi/128*k1; 
subplot(4,1,2); 
stem(w1/pi,magx1); 
title('X(K) 频谱泄漏'); 
axis([0,1,0,70]); 

n=[0:1:99];
x=cos(0.48*pi*n)+cos(0.52*pi*n);
subplot(4,1,3);
stem(n,x);
title('改善后 x(n) (0<=n<=99)'); 
xlabel('n'); 
axis([0,100,-2.5,2.5]);
line([0,100],[0,0]); 
x1=fft(x); 
magx1=abs(x1(1:1:50));  
k1=0:1:49; 
w1=2*pi/100*k1;
subplot(4,1,4); 
stem(w1/pi,magx1);
title('X(K)'); 
axis([0,1,0,55]);

% --- Executes on button press in 栅栏现象.
function zhalanxianxiang_Callback(hObject, eventdata, handles)
% hObject    handle to 栅栏现象 (see GCBO)
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    structure with handles and user data (see GUIDATA)
n=[0:1:9];
x=cos(0.48*pi*n)+cos(0.52*pi*n); 
w=[0:1:500]*2*pi/500;%0-2*pi区域分为501点
subplot(4,1,1);
stem(n,x); %虽达到奈奎斯特抽样间隔，但会遗漏高频成分
title('x(n) (0<=n<=9)'); 
xlabel('n'); 
axis([0,10,-2.5,2.5]);
line([0,10],[0,0]);
x1=fft(x); %fft变换
magx1=abs(x1(1:1:10)); 
k1=0:1:9;
w1=2*pi/10*k1;
subplot(4,1,2); 
stem(w1/pi,magx1); %抽样频率很高，高频成分没有遗漏
title('X(K)');
axis([0,1,0,10]); 


n=[0:1:9]; 
y=cos(0.48*pi*n)+cos(0.52*pi*n); 
n1=[0:1:99];
x=[y(1:1:10),zeros(1,90)]; 
subplot(4,1,3); 
stem(n1,x); 
title('x(n) (0<=n<=9+90zeros）');
xlabel('n'); 
axis([0,100,-2.5,2.5]);
line([0,100],[0,0]);
w=[0:1:500]*2*pi/500;%0-2*pi区域分为501点 
x1=fft(x);
magx1=abs(x1(1:1:51));  
k1=[0:1:50]; 
w1=2*pi/100*k1; 
subplot(4,1,4);
stem(w1/pi,magx1); 
title('改善后 X(K)');
axis([0,1,0,10]); 

% --- Executes on button press in 退出演示.
function quit_Callback(hObject, eventdata, handles)
% hObject    handle to 退出演示 (see GCBO)
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    structure with handles and user data (see GUIDATA)
selection = questdlg(['Close ' get(handles.figure1,'Name') '?'],...
                     ['Close ' get(handles.figure1,'Name') '...'],...
                     'Yes','No','Yes');
if strcmp(selection,'No')
    return;
end

delete(handles.figure1)