Contents

1
2 谿瑚 蠏碁
3 谿瑚襭

1 #

碁Μ 覲 f(x)襯 螳 覃語 譯狩 覃語朱 蠍磯蟇磯. 覘 企 覲螳 る 讌..

ク 蟆 10朱 覦覓誤 螻 20朱 覦覓誤 り . [http]豢豌(http://www.abstractnew.com/2014/04/the-fast-fourier-transform-fft-without.html)
#set the sampling frequency 
samplingFrequency = 1000;

#create the indexes to sample at
timeInterval = 1/samplingFrequency;
signalIndex = seq(0, 1, by=timeInterval);

#amplitude of signal 1 
a1 = 2;  

#amplitude of signal 2 
a2 = 3;  

#frequency of signal 1 
f1 = 10; 

#frequency of signal 2
f2 = 20; 

#10 Hz Sine wave with peak amplitude 2
signal1 = a1 * sin(2 * pi * f1 * signalIndex);

#20 Hz Sine wave with peak amplitude 3
signal2 = a2 * sin(2 * pi * f2 * signalIndex);

#input signal is the sum of two signals in this case with frequencies 10 and 20 Hz
inputSignal = signal1 + signal2;
fft02_1.png

譯手鍵 蠏碁襯 豺覃 れ螻 螳蟇磯.
fft01.png

蠍磯郁 企. 一危一 譯手鍵 焔 豢豢 覲伎蟆 碁Μ 覲企. R 蠍磯蓋朱 fft(螻 碁Μ 覲) 襯 螻牛.
fourierComponents = fft(inputSignal);
plot(abs(fourierComponents[1:50]))
fft02.png
x豢 10螻 20 蟇郁碓 覲伎手碓. 襾語 ′企. y豢 瑚鍵.
碁Μ 覲 蠍蟆 覲 豬渚. 企 蟆曙 企襴 覲.

2 谿瑚 蠏碁 #

fourier_trans.gif
--source: https://isaacscienceblog.com/2017/08/13/fourier-transform/

3 谿瑚襭 #