Re: [LAD] Harmonic generator and transfer function

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From: <fons@...>
To: <linux-audio-dev@...>
Date: Wednesday, December 1, 2010 - 12:00 pm

On Wed, Dec 01, 2010 at 01:16:07PM +0300, Andrew Gaydenko wrote:

> I need just

If that is what you need it's simple enough to compute...

But it won't give you a_1 second harmonic distortion, a_2 third
etc (although for small values of 'a_i' you could get near).
The Chebyshev way allows you to control each harmonic independently
(provided the input is a sine).

This is because for the n-th Chebyshev polynomial T_n ()

T_n (cos (x)) = cos (n * x)

The polynomials are very easy to compute using recursion:

T_0(x) = 1
T_1(x) = x
T_N(x) = 2 * x * T_{N-1}(x) - T_{N-2}(x)

etc.

This is simple enough to do directly on the signal, no need
to compute the explicit polynomials.

> Will I get HF hum? Please, direct my nose to an approriate reading! :-)

You will get aliasing if you try to generate anything above Fs/2.

Ciao,

--
FA

There are three of them, and Alleline.

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Messages in current thread:
[LAD] Harmonic generator and transfer function, Andrew Gaydenko, (Tue Nov 30, 1:51 pm)
Re: [LAD] Harmonic generator and transfer function, Erik de Castro Lopo, (Tue Nov 30, 11:33 pm)
Re: [LAD] Harmonic generator and transfer function, Andrew Gaydenko, (Wed Dec 1, 10:16 am)
Re: [LAD] Harmonic generator and transfer function, , (Wed Dec 1, 12:00 pm)
Re: [LAD] Harmonic generator and transfer function, Andrew Gaydenko, (Wed Dec 1, 12:13 pm)
Re: [LAD] Harmonic generator and transfer function, Andrew Gaydenko, (Wed Dec 1, 2:21 pm)
Re: [LAD] Harmonic generator and transfer function, Andrew Gaydenko, (Tue Nov 30, 3:35 pm)