-1

I've been doing a lot of research on this topic and I'm finally getting somewhere. Below is two complex numbers from the java code I'm using: -9771.0 - j2125.0 -16184.09634718744 - j53968.71008512241

I know the amplitude/magnitude can be computed by doing the sqrt(a^2 + b^2) and this as far as I've gotten with this. I've read about sample rate but I'll need a better explanation of this alone and would like to be pointed in the right direction to obtain the knowledge. I've done the powerspectum graph but I need to do this on paper so I'll know how to obtain the frequency.

1 Answers1

1

Applying Fourier Transformation to two values is pretty meaningless. You apply it to series of values (signal), then frequency starts to make sense. You can't speak about frequency in series of two values.

Andrey
  • 59,039
  • 12
  • 119
  • 163
  • I have more than two values... I put those down as an example... i can post more if you need it. I just have the code printing out two so I can see how to compute frequencies from there. –  Jun 14 '11 at 23:52
  • @Daniel Crain what actually would you like to know? "Obtain frequency" - signal usually doesn't have one frequency except harmonic signals. – Andrey Jun 14 '11 at 23:55
  • It's from a guitar... I have the frequencies for the guitar but computing them from an audio file is a different story. So it's 17 seconds on guitar e scale. I've did a great amount of research on how to obtain the frequencies. however I'm trying to do them by hand so when I have to sit down and write the program for it. I'll know where I'm going. I've gotten this far with little help and now I'm looking for ways to compute the frequency. –  Jun 15 '11 at 00:00
  • @Daniel Crain I can't understand what do you want from us. Just check: http://www.google.ru/#q=discrete+fourier+transform there is a lot of information there and code samples. – Andrey Jun 15 '11 at 10:36
  • Thanks Audrey... I will take a look at this. I'm trying to find a way to calculating frequencies by hand from complex numbers. –  Jun 15 '11 at 21:21
  • @Daniel Crain btw I can't understand where did you get complex numbers if you have audio signal. There are no complex numbers there, only real. – Andrey Jun 15 '11 at 21:46
  • -9771.0 - j2125.0 -> form real + imagery * j Using FFT –  Jun 15 '11 at 23:17
  • @Daniel Crain I know the form. I am saying that audio signal has only real part. Imaginary part is equals to 0. I have a strong feeling that you should start with complex analysis to get from the basics. – Andrey Jun 16 '11 at 10:20