Questions: A. What is the overall purpose of these code? B. Function "Close All" , "Clear” mean what? C. Key codes fft(y,NFET)/L; means what?
Please read codes which are wrote by
Matlab.
clear;
close all;
Fs = 4000; % sampling frequency
T = 1/Fs; %
L = 1000; %frequency length
t = (0:L-1)*T;
y = 0.7*cos(2*pi*25+t) + 2*cos(2*pi*24*t) + cos(2*pi*120*t);
NEFT = 2^nextpow2(L); %, The term circle is rounded to the nth
power of 2
Y = fft(y,NFFT)/L;
f = Fs/2*linspace(0.1, NFFT/2+1);
plot(f,2*abs(Y(1:NFFT/2+1)))
title('Unilateral amplitude spectrum)
xlabel('Freq (Hz)')
ylabel('|Y(f)|')
Questions:
A. What is the overall purpose of these code?
B. Function "Close All" , "Clear” mean what?
C. Key codes
fft(y,NFET)/L; means what?
D. Spectrum analysis is an important part of signal and system. Please
briefly describe the difference and relationship between FS and ft
of periodic signal.
E. In the above code, by what sampling frequency conditions, it can
draw two or three frequency components? Please analyze the reason
and show it in MATLAB.
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