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2023-6-2 15:15 |
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签到天数: 1 天 [LV.1]初来乍到
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建议在帮助中搜fft，其范例example就是很好的例子，直接看英文原文更详细。程序如下，
' _* g2 J0 s" j8 \( c%%模拟创建需要观察的信号
9 X3 {* N# L. q. L" @1 s {Fs = 1000; % Sampling frequency& R. ~, S6 A5 a- L. O; r- L
T = 1/Fs; % Sample time7 ?' w: m7 W* |' L2 U( {' d
L = 1000; % Length of signal5 S% h. p/ l& f! m) S/ i
t = (0P-1)*T; % Time vector, g Q: p! V4 u( o, k
% Sum of a 50 Hz sinusoid and a 120 Hz sinusoid h+ }$ \3 R% ]% |: K4 j$ E1 Y
x = 0.7*sin(2*pi*50*t) + sin(2*pi*120*t);
( L2 G, Y |. u( E. H0 ]%这里改成加个cos的就是你想要的了 幅度相位平率组合自己设置吧/ q. r) g" ?, D$ n9 X* f( F
y = x + 2*randn(size(t)); % Sinusoids plus noise* a7 ^- G9 T% w2 v
plot(Fs*t(1:50),y(1:50))
! s1 N' D& l6 x4 Wtitle('Signal Corrupted with Zero-Mean Random Noise')
) z4 I5 O3 _- @3 n& n1 T% A3 ^* Bxlabel('time (milliseconds)')/ S, H, U) S% w) V* c
%%fft观察信号的频谱图9 R& D; ?2 l' K: A1 z
NFFT = 2^nextpow2(L); % Next power of 2 from length of y: r; ~9 A7 J, c; q
Y = fft(y,NFFT)/L;8 k0 a" D8 d1 _6 ]' q
f = Fs/2*linspace(0,1,NFFT/2+1);. k( Q/ g1 l+ H
% Plot single-sided amplitude spectrum.
$ e9 z$ Y3 n$ Jplot(f,2*abs(Y(1:NFFT/2+1)))
, J6 m Z! Q( @, r& I2 Z& htitle('Single-Sided Amplitude Spectrum of y(t)')' _: o! i' T/ e0 J- `8 w' n) t
xlabel('Frequency (Hz)')7 `! e' _& W1 J
ylabel('|Y(f)|')
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发表于 2022-8-30 11:20
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