0
$\begingroup$

I have a question which is closely related to this one: FFT Processing Gain

^that discussion is a bit general so I want to ask a very objective question to see if I can apply that knowledge:

If I collect one million time samples and perform a one million point DFT, roughly what DFT processing gain (in dB) improvement can I expect to achieve in pulling a weak spectral component up above background noise in comparison to a 100 point DFT?

I guess that answer is 100,000. isn't it?

we have 9999910 more bins.

Improve this question
$\endgroup$
6
  • 1
    $\begingroup$ For a single sinusoid, the link in the FFT processing gain discussion suggests a gain of: $10log_{10}(M/2)$. $\endgroup$
    – learner
    May 25, 2014 at 7:27
  • $\begingroup$ So, to be explicit, in the example i was considering would it be: 10log10(1,000,000/2) M is the number of DFT bins right? I always see M written as the frequency bin number being considered. So I just do that 10log10(m/2) calculation for both sizes and then compare them? is that correct? $\endgroup$
    – user8769
    May 25, 2014 at 11:23
  • $\begingroup$ Yes, M is the total number of bins. You are right, do the calculation for both sides and compare them. What I think is that gain is valid only for a single tone. You might prove me wrong. $\endgroup$
    – learner
    May 25, 2014 at 12:29
  • $\begingroup$ Please forgive me but I don't quite understand, what does that mean, 'gain is valid only for a single tone' ? $\endgroup$
    – user8769
    May 25, 2014 at 12:40
  • $\begingroup$ you mean for a single frequency component and not for the number of DFT points being considered as a whole? $\endgroup$
    – user8769
    May 25, 2014 at 13:12

0

Reset to default

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge that you have read and understand our privacy policy and code of conduct.