[Halld-tracking-hw] preamp/ADC range

[Gerard Visser]

Hi Lubomir,
	Yes, indeed, it was a typo in my email.
	So this was a software issue of some sort? I'm glad to hear it, I was getting 
slightly worried.
	Thanks,

		Gerard


Lubomir Pentchev wrote:
> 
> 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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