[Halld-tracking-hw] preamp/ADC range

[Lubomir Pentchev]

Gerard, we both meant the cutoff at 11000, i.e. at high amplitudes, not 
at 1100, right? Beni found the mistake.
   Lubomir

---------- Forwarded message ----------
Date: Wed, 16 Jun 2010 12:55:13 -0400 (EDT)
From: Lubomir Pentchev <pentchev at jlab.org>
To: Gerard Visser <gvisser at indiana.edu>
Cc: FDC email list <halld-tracking-hw at jlab.org>
Subject: Re: [Halld-tracking-hw] preamp/ADC range


Gerard,

I put an entry in the logbook with one event showing saturation of the
pre-amp cards and the cut-off of the fADC. The problem is I don't see that
many events like this with saturated signals at 2275V and don't have an
explanation for the cutoff at about 1100 in the spectrum.
   Lubomir

On Wed, 16 Jun 2010, Gerard Visser\ wrote:

> Hi Fernando, Lubomir,
> 	In the FDC logbook record 468, top plot, the cutoff at about 1100 is
> evident. Is this corresponding to the saturation level of preamp output? And
> it looks a little 'odd' in that the spectrum cuts off without an accumulation
> of 'maximum-amplitude' events - do we understand why it looks like this?
> 	The ADC itself should saturate only upon reaching 16384. This has of
> course been tested with other (non-preamp) input from fuction generator.
> [Reminder to all that at least with interim readout firmware and software the
> 12-bit ADC is mapped to 14-bit values.]
> 	Sincerely,
>
> 		Gerard
>
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