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Entry  Tue May 27 13:46:18 2014, Dominik Neise, Spikes in DRS4 data on custom baord. 
    Reply  Tue May 27 16:07:17 2014, Stefan Ritt, Spikes in DRS4 data on custom baord. 
Message ID: 349     Entry time: Tue May 27 16:07:17 2014     In reply to: 348
Author: Stefan Ritt 
Subject: Spikes in DRS4 data on custom baord. 

Dominik Neise wrote:

We see quite some spikes in our DRS4 sampled data in FACT.  We see different types of spikes:

  • single cell spikes, usually showing a large amplitude of 200mV
  • double cell spikes, usually only in the order of 20mV.
  • Even triple and quadro cell spikes are rarely seen.

The double cell spikes often occur as symmetrical double cell spikes mirrored at cell 512. quadro cell spikes seem to be nothing else, than connected symmetrical double cell spikes. For the triple cell spikes we have no idea.
Currently we use simple filters to get rid of these spikes, this workes rather well for the large single cell spikes, but with the occurance of tripples and quadros we started to worry about higher multiples and revived our DRS4 spike investigations.

Now I was told, that you Stefan know already where these spikes come from and even a paper exisits. Unfortunately so far I was unable to find it.
I wonder if it is possible to predict the occurance of these spikes, so one does not have to search for them anymore and can get rid of the filters.

Best regards


All I know is that the  "20mV" spikes are always symmetrical around cell #512, that they are typically 17.4 mV in height, and that they occur always in all 9 channels simultaneously. They cannot occur in all locations, but there only like 32 possible locations where they can occur. With this information it should be easy to fix them by filtering.

200 mV spikes are new to me. I do not see them in our boards, so it must be related to the board readout and not to the chip.

Best regards,

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