how can I do the fourier transform of triangular pulse using 'fft' function?

body of the function is- f(t)=[1-|t|/T], when|t|<T, else 0.

[Azzi Abdelmalek]

What is your problem? how to use fft function or how to generate a triangular pulse?. You have also, to specify the time interval

Answer 1

[Image Analyst]

Sounds like homework, though you didn't say. Hint: Try using linspace() to create rising and falling ramps, then stitch together.

risingRamp = linspace(0, 1, int(T/2));
triangularPulse = [zeros(1, N), risingRamp, fallingRamp, zeros(1, N)];

see what you can do with that. Then call fft(). Try it yourself.

[Tahiatul Islam]

i wrote a code--

N=1000;
    x=linspace(0,2,N);
    f1=linspace(0,1,N/2);
    f2=linspace(1,0,N/2);
    f=[f1 f2];
    subplot(2,1,1);
    plot(x,f);
    ft=fft(f);
    subplot(2,1,2);
    plot(x,ft);

but it doesn't make the proper graph of frequency domain. I just don't understand why it's not happening.

[Cedric]

Type

 doc fft

in your command window and look at the example; it will help you understanding how to plot the output of FFT (and you'll get the sinc^2 that you are looking for).

[Image Analyst]

I'm at a computer without MATLAB at the moment. Sometimes fft gives a complex result. Try taking the real part of it with real(). Sometimes there is a big spike at zero so try taking the log of it before plotting. Also, you didn't pad with zeros so your triangle is really like a triangle wave rather than a pulse. Those are some things off the top of my head that you can try.

[Tahiatul Islam]

thank for your suggestion,, it's working now, at last

[SIBI CHAKRAVARTHY]

Hey can you post your code for fft of a triangular pulse

[Image Analyst]

Try this

ft = fft(triangularPulse);

[SIBI CHAKRAVARTHY]

Thank you. I am trying to create a time-shifted triangular pulse with 16V peak amplitude

[SIBI CHAKRAVARTHY]

Is the fft of a triangular pulse square of sinc function

[Image Analyst]

No. Since the fft of a rect function is a sinc, and two rects convolved with each other give a triangle, then the fft of a triangle will give the multiplication of the ffts of a single rect, in other words, it will be a sinc squared.

ft(rect) => sinc

rect ** rect => triangle

ft(triangle) = ft(rect ** rect) = ft(rect) * ft(rect) = sinc^2

Answer 2

[Priya Kasture]

Find FOURIER TRANSFORM of triangular pulse x(t)= triang(t/2pi) using heaviside function. Pls solve stepwise and show.

[Image Analyst]

This is not an answer to Tahiatul Islam's question (who hasn't even been here in 7 years).

If it's your question, see this link.