[Halld-tracking-hw] preamp/ADC range

[Lubomir Pentchev]

Gerard,

We still worry about the high signal cutoff. I'm working on that. Beni 
just found the typo in our e-mails and I wanted to clarify this and make 
sure we are talking about the same problem.
   Lubomir

On Thu, 17 Jun 2010, Gerard Visser wrote:

> 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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>