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Re: Progress on Compressors
Dear Fred,
TThe change is in the concept:
Before when wee were filling the compressor's FIFOs we sent at the same the compressed
data to the SIS FIFO continuously. In this mode we had no dead time and you could by
polling test the status of the SIS FIFO so as to leave it free for a continuous filling
from the compressors. That was our first idea. This way we have no dead time.
During the last run, we discovered that the electrical noise pick up on the input of the
compressors (via the chambers? we do not know, and nor reproducible in Louvain), was
reduced when no transfer occurred from the compressors to the SIS FIFO. So a proposition
of Peter was to have a data taking period and a transfer period SEPARATED in time. And
there comes the generation of a macro dead time each time me empty the compressors.
Clear enough?
René.
Fred Gray a écrit :
> > A real macro dead time free mode is possible if one uses the previous compressor
> > mode but then the DAQ must poll or be interrupted at the half full of the SIS FIFO
> > sending a TIMECLEAR signal at every readout and an INHIBIT level generated only
> > when the DAQ is stopped or overloaded
>
> Dear Rene,
>
> Thanks for your comments, which I'm still trying to digest. My overall question
> still remains: as you said (above), a deadtime-free readout is possible with the
> previous mode. Tom and I now have the software set up to continuously poll on
> the CAEN TDCs, and presumably the same technique would work with the SIS FIFO.
> Meanwhile, this new mode introduces difficult-to-avoid deadtime. I really am
> curious about what led to this change.
>
> I don't think we have benchmarked the VME transfer rate from the SIS FIFO, but
> my guess is 5 to 10 MB/s, i.e. less than 20.
>
> Thanks,
>
> -- Fred
>
> -- Fred Gray / Visiting Postdoctoral Researcher --
> -- Department of Physics / University of California, Berkeley --
> -- fegray@socrates.berkeley.edu / phone 510-642-4057 / fax 510-642-9811 --
--
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René PRIEELS Universite Catholique de Louvain
email: prieels@fynu.ucl.ac.be Departement de Physique / FYNU
Tel : ++ 32 (0)10 / 47 32 09 Chemin du cyclotron, 2
Fax : ++ 32 (0)10 / 45 21 83 B-1348 Louvain-la-Neuve - BELGIUM
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