我将采样周期设为30 * 24 * 60 * 60秒,因为每月仅记录一次数据!当我绘制FFT时,我得到的主频为3.28x10 ^ -8 Hz。现在我该怎么解释?怎么说这个信号多久出现一次?
datax=VarName1;
datay=VarName2;
datay_mean=datay-mean(datay);
class(datax)
dataxx=datetime(datax);
class(dataxx)
figure;
plot(dataxx,datay)
datetick('x', 'keepticks','keeplimits')
title('actual plot of temp in years')
Y = fft(datay_mean);
L = length(datay_mean);
T = 30*24*60*60
Fs = 1/(T);
f_adj1=(0:L-1)/L;
figure;
plot(f_adj1,abs(Y/L))
title('Single-Sided Amplitude Spectrum of X(t)')
xlabel('normalized (freq)')
ylabel('|P1(f)|')
f_adj2=(0:L-1)*Fs/L;
figure;
plot(f_adj2,abs(Y/L))
title('Single-Sided Amplitude Spectrum of X(t)')
xlabel('(freq)')
ylabel('|P1(f)|')