MATLAB Answers

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To compute magnitude and phase spectrum

Asked by Sri Srujan Gollapudi on 3 Oct 2019
Latest activity Edited by Deepak Kumar on 11 Oct 2019
Hello,
I have a function, for that I need to find the magnitude and phase spectrum on matlab. Can someone please help me with the code, please?
The parameters are A=2 a=4 -20<=F<=20.
44.JPG
This is the function.

  2 Comments

Where is 'F' being used in the function? Also, what do you mean by 'magnitude of the function'?
Even I'm not sure of that. But if we leave out the limits of F, how can I find the magnitude and phase sepctra with given values of A and a for the above fucntion?

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1 Answer

Answer by Deepak Kumar on 7 Oct 2019
Edited by Deepak Kumar on 11 Oct 2019
 Accepted Answer

I'm not sure what F is referring here.
However, we can find the Magnitude and Phase spectrum of a function using FFT function in matlab. I have wrirren the below code to evalute the magnitude and phase spectrum of the given function and also plotted them.
clc
clear
close all
A=2;
a=4;
fs=1000; % Sampling frequency
t=0:1/fs:1; %Time
x=A*exp(-a.*t); %Signal
plot(t,x) %Plotting the time domain signal
xlabel('t');
ylabel('x(t)');
title('Time domain Signal')
N=length(x);
N1=2^nextpow2(N);
X=fft(x,N1);
X=X(1:N1/2);%Discard Half of Points
X_mag=abs(X); %Magnitude Spectrum
X_phase=phase(X); %Phase Spectrum
f=fs*(0:N1/2-1)/N1; %Frequency axis
figure
plot(f,(X_mag/N1)); %Plotting the Magnitude Spectrum after Normalization
xlabel('Frequency (Hz)');
ylabel('Magnitude Spectrum');
title('Magnitude Spectrum vs f')
figure
plot(f,X_phase); %Plotting the frequency domain
xlabel('Frequency (Hz)');
ylabel('Phase Spectrum');
title('Phase Spectrum vs f')
Please refer the below documentation for more details about the FFT function:

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