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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，, K: i) j" `% r- e$ ^5 |; n
%%模拟创建需要观察的信号7 o5 v5 p* ?* N1 g x1 i8 \1 \8 }# k* X
Fs = 1000; % Sampling frequency! I( Z2 B1 G) ?" h! U
T = 1/Fs; % Sample time
q) i8 J8 C* Y* v8 [9 @! Q. `) u! s& \L = 1000; % Length of signal3 u% O! j! ^0 k- `* y5 A
t = (0P-1)*T; % Time vector& m- E! f( g6 o3 K. K& s+ w; N5 h
% Sum of a 50 Hz sinusoid and a 120 Hz sinusoid5 c- g6 }$ O0 x2 l1 Q
x = 0.7*sin(2*pi*50*t) + sin(2*pi*120*t);" e& `9 J$ U) R( I
%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6 u5 `) h% Y1 S; h6 |
y = x + 2*randn(size(t)); % Sinusoids plus noise, }; v: B4 @: i8 w, ^) s
plot(Fs*t(1:50),y(1:50))
1 T1 f4 p. ?8 ktitle('Signal Corrupted with Zero-Mean Random Noise')4 ~0 H1 u& q+ p1 }. S M
xlabel('time (milliseconds)')
# `& n" `6 N1 C# }%%fft观察信号的频谱图
3 s, p5 l( [5 \, \! P- G) iNFFT = 2^nextpow2(L); % Next power of 2 from length of y
4 ~$ a- L- h" B+ j- NY = fft(y,NFFT)/L;# ^/ a' h u" b5 S& G
f = Fs/2*linspace(0,1,NFFT/2+1);9 x- D" \7 ^8 u* i6 A1 | I
% Plot single-sided amplitude spectrum.
l' t7 q1 L9 j* W: o: ^6 gplot(f,2*abs(Y(1:NFFT/2+1)))6 k9 `6 g0 {5 g( y& P
title('Single-Sided Amplitude Spectrum of y(t)')
; L: p3 ^1 t E+ O5 pxlabel('Frequency (Hz)')9 Z2 \6 [+ C3 |3 t! n+ R" l
ylabel('|Y(f)|')
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发表于 2022-8-30 11:20
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