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Recreate fundamental frequency from harmonics

post #1 of 3
Thread Starter 
The application I'm working on unfortunately has a significant losses in the low frequencies. Using an audio spectrum analyzer I can however detect the peaks of the harmonics in the frequency spectrum. I would like to use those to recreate the fundamental frequency to a greater accuracy. Since the harmonics in the non-troublesome region attenuate according to certain (yet to be determined) equation, I should be able to find the solution to the frequency that occurs at maximum in the troublesome band that is causing the losses.

I know there could be solutions for my problems with avoiding the losses in the first place, but I'm really interested in exploring the possibility of recreating the original signal from the harmonics.

Thanks y'all!
post #2 of 3
Do you have access to the original signal prior to loss? If so, you can profile it and assess its energy in low frequencies. Using that, then you can replicate it based on the spectrum that follows it. Study Spectral Band Replication. It is the reverse of what you want (creation of harmonics from fundamentals). But you should be able to apply it in reverse. Note that this is not a high fidelity solution. It is a coarse algorithm to recreate something that sounds better than not having it, but it is not he same as having the original.

And no, there is no simple math here as the relationship between the harmonic and fundamental is signal type specific. And at any rate, you will not know what is a harmonic vs fundamental in complex signals (e.g. music).

This type of work requires significant knowledge of signal processing. In some sense then, if you have to ask the question in a forum like this, the solution likely requires far more knowledge than you may have smile.gif.
post #3 of 3
Quote:
Originally Posted by daenku32 View Post

The application I'm working on unfortunately has a significant losses in the low frequencies. Using an audio spectrum analyzer I can however detect the peaks of the harmonics in the frequency spectrum. I would like to use those to recreate the fundamental frequency to a greater accuracy. Since the harmonics in the non-troublesome region attenuate according to certain (yet to be determined) equation, I should be able to find the solution to the frequency that occurs at maximum in the troublesome band that is causing the losses.

I know there could be solutions for my problems with avoiding the losses in the first place, but I'm really interested in exploring the possibility of recreating the original signal from the harmonics.

The device you may be looking for is called a "Sub bass Synthesizer". Google is your friend.
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