[sdiy] VCO Accuracy

[Magnus Danielson]

From: Andre Majorel <aym-htnys at teaser.fr>
Subject: Re: [sdiy] VCO Accuracy
Date: Tue, 1 Jan 2008 16:33:10 +0100
Message-ID: <20080101153310.GA9231 at aym.net2.nerim.net>

> On 2008-01-01 00:36 -0500, Roy J. Tellason wrote:
> > On Monday 31 December 2007 04:29, Andre Majorel wrote:
> >
> > > You don't have to tune by ear. There are very precise digital
> > > frequency counters. The bench ones only display the frequency in
> > > Hz but some of the software ones show note number and offset in
> > > cents.
> >
> > First I've heard of that.  Anybody know of any software ones
> > that run under linux?
> 
> There's this :
> 
>   http://www.teaser.fr/~amajorel/misc/aufreq-standalone-2008-01-01.tar.gz
> 
> You need OSS emulation in the kernel (/dev/dsp).
> 
> >From the tests I've made with mathematically generated sines, it's
> accurate to at least 0.0001 cents between 10 Hz and 1 kHz. Above 1 kHz,
> the accuracy goes down fast. At 20 kHz, it's only accurate to
> about 1 Hz or 0.1 cents.

The sample rate clock crystal will thus be the main source of error.
For most purposes it is well than enought.

Cheers,
Magnus