[time-nuts] EFC tracking

[Chris Stake]

Here we go again
C

-----Original Message-----
From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
Behalf Of Poul-Henning Kamp
Sent: 26 June 2010 21:06
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] EFC tracking

In message <4C265BB1.8090902 at earthlink.net>, jimlux writes:

>sound card ADCs, the high end 24 bit ones, are pretty darn linear [...]

That is actually a very debatable proposition, a lot of them are
tracking types that conveniently cover up any lack of linearity
on the analog side of the fence.

The major problem with using sound ADC's is that their references
has absolutely no long term stability, so you will see your EFC
wiggle and wander all over the place, even when it stays perfectly
still.

I would find one of those cheap-ish DVM's with a serial or USB port...

-- 
Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
phk at FreeBSD.ORG         | TCP/IP since RFC 956
FreeBSD committer       | BSD since 4.3-tahoe    
Never attribute to malice what can adequately be explained by incompetence.

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