[Halld-tracking-hw] preamp/ADC range

[Lubomir Pentchev]

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
>