Can anybody please give me the CODE for the below question in matlab?. urgently

find and sketch the phase and magnitude of DTFT of X[n] sin(n*pi/6) over a period -2pi to 2pi

[Wayne King]

Sounds very much like a homework problem; so you should try on your own and show people where you get stuck with your own MATLAB code.

[nihal]

its my assignment .and tomorrow is the deadline..so i have to submit it by tomorrow and our professors have not taught anything about this.so can you please help me.?

[Umair Nadeem]

I'll give it a try and let you know

[nihal]

Thank you

[Image Analyst]

You're supposed to tag your question as homework so you don't trick people into doing your homework for you. http://www.mathworks.com/matlabcentral/answers/8626-how-do-i-get-help-on-homework-questions-on-matlab-answers. I'll tag it for you.

Answer 1

[Umair Nadeem]

I tried it myself and I came up with this. I had to assume a few things but it works with what seems to be your problem. Hope it helps

clear all;
clc;

fs = 1000;      % Assumed Sampling frequency

ts = 1/fs;      % Sampling rate

n = (-360:360); % duration/index

% Assuming pi = 180 --> pi/6 = 30

% It gives the frequency of signal = 30 Hz

xn = sin(n * 30 * ts);

plot(n, xn)

title('Plot of Signal from -2pi to 2pi')

xlabel('Samples')

ylabel('Magnitude');

% Total duration of signal

dur = length(n);

% NFFT = Duration which can be represented in the power of 2

NFFT = 2 ^ nextpow2(dur);

% Compute Fast Fourier Transform using number of points = NFFT

xn_freq = (fft(xn, NFFT))/dur;

% Calculate the points of x-axis in frequency domain

x_axis = (fs/2) * linspace(0, 1, (NFFT/2) + 1);

figure (2);

subplot 211;

% Selecting half points (N/2+1) only because the other half is a replica

plot(x_axis, 2 * abs(xn_freq(1 : NFFT/2 + 1)));

max_mag = max(2 * abs(xn_freq(1 : NFFT/2 + 1)));

fprintf('Maximum Magnitude is = %f', max_mag);

xlim([-360 360])

grid on;

title('Magnitude of Frequency Domain Spectrum (Peak at Signal Frequency)');

xlabel('Frequency from -360 to 360 (Hz)');

ylabel('Magnitude');

% Computation of phase

xn_ph = unwrap(angle(xn_freq));

% Computation of horizontal points to correctly represent the data

f_dom = (0:length(xn_freq)-1)'/length(xn_freq) * fs;  

subplot 212;

plot(f_dom, xn_ph);

grid on;

xlim([-360 360])

title('Phase of Frequency Domain Spectrum (Peak at Initial Phase)');

xlabel('Frequency from -360 to 360 (Hz)');

ylabel('Phase');

[Image Analyst]

http://www.mathworks.com/matlabcentral/answers/13205-tutorial-how-to-format-your-question-with-markup

[nihal]

thank you so much

[Umair Nadeem]

There was a mistake in fprintf please correct it

[nihal]

Thanx a lot. But i have a small doubt My question was regarding DTFT but you have used NFFT in your answer..so will that make any difference?

[Umair Nadeem]

That was just a name for a variable for number of points of FFT, you can gve it any name you want.