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标题: 两个序列的卷积和运算的MATLAB实现（1） [打印本页]
作者: mytomorrow    时间: 2020-6-1 14:09
标题: 两个序列的卷积和运算的MATLAB实现（1）
设矩形脉冲 是脉冲响应 的LTI系统的输入，求输出 y(n).
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下面的脚本中用到了一个自定义的函数，也就是两个信号相加的函数：
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9 O! G, \! d7 K5 p4 p' T7 ?function [y,n] = sigadd(x1,n1,x2,n2)
  b/ I  [' _- H( W& d% p5 ?3 r1 V$ k% implements y(n) = x1(n) + x2(n)
4 X# s% h& `+ H; A. w% [y,n] = sigadd(x1,n1,x2,n2)
" T& H; J7 U0 a9 P+ M# u5 s- T7 }" `$ P5 a$ d%——————————————————————————————
* s0 g" \) Q+ ~0 n4 _% k, F% y = sum sequence over n, which includes n1 and n2
/ u$ \' o+ l4 @% P3 X% x1 = first sequence over n1
" G7 a1 q6 q2 C7 ^$ |5 d' I% x2 = second sequence over n2( n2 can be different from n1)
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2 A2 ?$ O0 \$ h1 y1 g  fn = min( min(n1), min(n2) ):max( max(n1), max(n2) ); %duration of y(n)
% f6 D' }8 ~- u7 _y1 = zeros(1,length(n)); y2 = y1; %initialization
) }" H1 j* m) s0 s: z, t$ x% [y1( find( ( n >= min(n1) )&( n <= max(n1) ) == 1  )  ) = x1; %x1 with duration of y1
2 U) L9 E# P. y- J" N, u$ b; f/ ~y2( find( ( n >= min(n2) )&( n <= max(n2) ) == 1  )  ) = x1; %x2 with duration of y2# A7 I( E; Z0 u& O! j5 m! B) b, Y
y = y1 + y2;
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. O1 o& L" |; r直接给出MATLAB脚本：
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clc
' `" ~) j; ?6 V* {1 [0 K9 kclear
5 I: c; U$ v5 B# l" Y$ jclose all
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1 b* l9 [1 H! m% help stepseq: J+ K% b3 c6 s
%   generate x(n) = u(n - n0); n1 <= n <= n2
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%  [x,n] = stepseq(n0, n1, n2);& n& E( `  K" `) [2 l9 ]- a7 @
[u1,n1] = stepseq(0,-5,45);2 D4 F% ]! d6 P
[u2,n2] = stepseq(10,-5,45);
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( v) Q3 R" F; X0 h3 `! Z% generate signal x(n)+ z% u' T2 V+ N9 S* x; X' {" X- d
[x,n] = sigadd(u1,n1,-u2,n2);
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9 N6 N2 I/ z' M% f% generate signal h(n); n7 W  K" J- D  n
m = -5:45;
; e: K0 l: R2 Y/ {h = ( (0.9).^m ).* u1;
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% the convolution of x(h) and h(n)" t, }, x4 o/ F
y = conv(x,h);
/ `* f: s) z! B% ensure the index' N0 Z$ F& p5 x3 l- G
nyb = n(1)+ m(1);
, ]) y6 W0 d! G8 C! H- _1 Mnye = n(length(x)) +n(length(h));
: r- u% O+ e2 E& J2 a- Qny = nyb:nye;; X/ b6 i1 K0 J
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subplot(3,1,1);- l3 T) ^$ [7 T5 J( u2 i0 p' ?  Z
stem(n,x);
- x5 ~7 d' L6 j% T; ^! @# Z" Y+ s% htitle('x(n)');
5 d: T! I- u" i: H" Q6 o% Sxlabel('n')
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subplot(3,1,2);+ o8 V$ M0 R7 M4 Z
stem(m,h);
; w& _/ E) _* ?1 P" }4 U5 Z$ Ftitle('h(n)');! ?* I/ j' z" R' j. E2 J6 R, j
xlabel('n')
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0 ?" T8 Z- z. Y4 q- msubplot(3,1,3);* n8 `  `% U/ D2 Q/ I% k+ C
stem(ny,y);
/ P  L% ^$ l- S1 Ytitle('the conv of x(n) and h(n)');
+ h5 _+ ?* c* I. N/ j- x( A; Xxlabel('n')6 e1 i$ }$ S5 f5 L$ ?' M& ?
xlim([-5,45]);9 ]. b+ @! Z- L  X8 b$ ^
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作者: Heaven_1    时间: 2020-6-1 15:08
subplot这个函数经常使用
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