|
|
EDA365欢迎您登录！
您需要 登录 才可以下载或查看，没有帐号？注册
x
5 o; d8 b9 g2 {& H周期方波的表达式我就不提炼了，既然你来看文章了，我就不信你周期方波都不知道。
# L% o0 a' g1 K5 w/ x) {4 b$ w2 o K$ U C+ E0 d; O, W" |
占空比定义为：L/N，N为周期，下面我们对 L = 5，N = 20； L = 5，N = 40；L = 5，N = 60；L = 7，N = 60分别画出它们的DFS图作比较。" T- W3 |$ h& o8 j4 e
0 t1 ~( o, @; T% X: T" b
我觉得有必要先把对应的周期方波给出来（每幅图都只给出一个周期）：* ], {5 H( s7 X% u+ C
- y. f( y# A( }
- clc;clear;close all;
- % Periodic square wave parameters L = 5,N = 20
- L = 5;
- N = 20;
- n = 0:N-1;
- xn = [ones(1,L),zeros(1,N-L)];
- subplot(2,2,1)
- stem(n,xn);
- title('L = 5,N = 20');
- xlabel('n');ylabel('xtilde(n)');
- % Periodic square wave parameters L = 5,N = 40
- L = 5;
- N = 40;
- n = 0:N-1;
- xn = [ones(1,L),zeros(1,N-L)];
- subplot(2,2,2)
- stem(n,xn);
- title('L = 5,N = 20');
- xlabel('n');ylabel('xtilde(n)');
- % Periodic square wave parameters L = 5,N = 60
- L = 5;
- N = 60;
- n = 0:N-1;
- xn = [ones(1,L),zeros(1,N-L)];
- subplot(2,2,3)
- stem(n,xn);
- title('L = 5,N = 20');
- xlabel('n');ylabel('xtilde(n)');
- % Periodic square wave parameters L = 7,N = 60
- L = 7;
- N = 60;
- n = 0:N-1;
- xn = [ones(1,L),zeros(1,N-L)];
- subplot(2,2,4)
- stem(n,xn);
- title('L = 5,N = 20');
- xlabel('n');ylabel('xtilde(n)');
- , i* T) H+ \& |! @# m& y& w7 s/ ^; n
_ Y. r* h3 a$ y4 }, B: z; v ^9 t
, a+ \) Q' A9 v上面程序中的DFS函数定义在另一篇博文中：【 MATLAB 】离散傅里叶级数（DFS）及 IDFS 的 MATLAB 实现
) [& p1 m$ b! k# \, G
; d- x3 ^5 T2 |: t
! H8 |- Y `8 ^8 S" f* I
( U, P3 x, d) J7 L6 ]$ S% Z% p4 k
+ Q* v2 r2 e9 z) E8 i! t* g: K0 ~ o直接给出MATLAB脚本：
$ Z @/ G5 @# @2 X7 X; f0 {1 f6 w' E v, p; Z/ M
- clc;clear;close all;
- % Periodic square wave parameters L = 5,N = 20
- L = 5;
- N = 20;
- k = [-N/2:N/2];
- xn = [ones(1,L),zeros(1,N-L)];
- Xk = dfs(xn,N);
- magXk = abs( [ Xk(N/2+1:N),Xk(1:N/2+1) ] );
- subplot(2,2,1)
- stem(k,magXk);
- title('DFS of Square: L = 5,N = 20');
- xlabel('k');ylabel('Xtilde(k)');
- % Periodic square wave parameters L = 5,N = 40
- L = 5;
- N = 40;
- k = [-N/2:N/2];
- xn = [ones(1,L),zeros(1,N-L)];
- Xk = dfs(xn,N);
- magXk = abs( [ Xk(N/2+1:N),Xk(1:N/2+1) ] );
- subplot(2,2,2)
- stem(k,magXk);
- title('DFS of Square: L = 5,N = 40');
- xlabel('k');ylabel('Xtilde(k)');
- % Periodic square wave parameters L = 5,N = 60
- L = 5;
- N = 60;
- k = [-N/2:N/2];
- xn = [ones(1,L),zeros(1,N-L)];
- Xk = dfs(xn,N);
- magXk = abs( [ Xk(N/2+1:N),Xk(1:N/2+1) ] );
- subplot(2,2,3)
- stem(k,magXk);
- title('DFS of Square: L = 5,N = 60');
- xlabel('k');ylabel('Xtilde(k)');
- % Periodic square wave parameters L = 7,N = 60
- L = 7;
- N = 60;
- k = [-N/2:N/2];
- xn = [ones(1,L),zeros(1,N-L)];
- Xk = dfs(xn,N);
- magXk = abs( [ Xk(N/2+1:N),Xk(1:N/2+1) ] );
- subplot(2,2,4)
- stem(k,magXk);
- title('DFS of Square: L = 7,N = 60');
- xlabel('k');ylabel('Xtilde(k)');
7 j+ X! A6 f; H% F5 C" p
7 M, C3 O$ _1 g+ R" d
* [7 x2 |. S1 K8 D$ o& r( n
8 c/ W( w8 _; n0 E% v8 Q+ d& q9 m6 H
& N+ d9 B' c) n3 z7 S' N8 S# F$ e m, b' S
" i+ ]5 q* g9 r1 p |
|
/1 
发表于 2019-10-30 11:22
收藏
淘帖
支持！
反对！