PSN-L Email List Message

Subject: Re: 24bits A/D converters & seismology
From: Jim Hannon jmhannon@.........
Date: Thu, 04 Jul 2002 11:43:30 -0500

Most amateur systems work quite well with much less than 24 bits. In fact 
it is very difficult to build any electronics that will have noise low 
enough to work with 24 bits of resolution. Of course if you can it is nice 
to work with as much resolution as possible. It helps with not clipping on 
very large events or missing very small ones depending on how your system 
is adjusted. You don't have to adjust the gain of the system as carefully 
with more bits as you have more room for the signal to fit within the range 
of the A/D converter.

At 05:22 PM 7/4/02 +0200, you wrote:
>Hello dear all,
>could someone explain me why you need 24bits AD converters in seismology.
>Indeed it corresponds to 16.8millions points on a 2g scale, which thus
>corresponds to a resolution of about 120 nano-g (10^-12g !)
>Isn't the ambient noise much higher than this ?
>thanks in advance for "enlighting" me.
>, l'email gratuit le plus complet de l'Internet !
>vos emails depuis un navigateur, en POP3, sur Minitel, sur le WAP...

Jim Hannon


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