Help me sketch the sprectrum of this signal.
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Hi there,
I am really stuggling with two things:
First I would like to sketch the spectrum of this signal:
y(t) = cos(760*pi*t)*(4+3*cos(20*pi*t))
I would like the magnitude plot and the phase plot. I have been trying the following to no avail....
%%Time specifications:
Fs = 1000; % samples per second
dt = 1/Fs; % seconds per sample
StopTime = 1; % seconds
t = (0:dt:StopTime-dt)';
N = size(t,1);
%%Sine wave:
x = (cos(760*pi*t)).*(4+3*cos(20*pi*t));
%%Fourier Transform:
X = fftshift(fft(x));
%%Frequency specifications:
dF = Fs/N; % hertz
f = -Fs/2:dF:Fs/2-dF; % hertz
%%Plot the spectrum:
figure;
plot(f,abs(X)/N);
xlabel('Frequency (in hertz)');
title('Magnitude Response');
My second issue is very similar: Sketch the spectrum ( BOTH REAL AND IMAGINERY PARTS ) for:
x(t)=(10*cos(1000*pi*t+pi/6)) + (7*cos(500*pi*t-pi/3)) - (4cos(1500*pi*t))
I appreciate everyone's help. Best regards Paul
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Answers (2)
Nishitha Ayyalapu
on 17 Oct 2013
doc angle
doc real
doc imag
1.) For Phase Respone
plot(f,angle(X));
2.) To plot real and imaginary parts
plot(f,real(X))
plot(f,imag(X))
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