Working with the DRS evaluation board we noticed some funny behavior: See attatchment 1. In about 1% of scope traces we see the first and last bin take on a value substantially different from the baseline, note the small spikes on the end of the traces. These spikes occur across all channels and either appear in all channels or in none. Attachment two shows what several thousand scope traces look like. You can clearly see that some of the traces are offset from the normal base line. Has anyone observed this behavior before? Any ideas?
see https://muon.npl.washington.edu/elog/g2/Detectors/550 for full discussion.
Actually the first and last sample are even more off the baseline, so I cut them out in software in the DRSOscilloscope. So actually the chip has only 1022 "usable" cells. It might happen in some rare cases that more cells are affected, although I have not yet seen this (maybe I did not look close enough). So I propose that you cut out one more bin at the beginning and the end, so a total of 1020 cells, and you should be fine.
Thanks for the quick reply. Our quick fix was to do just that.
We've encountered similar issues with board v2.0. Cell #2 across all channels would occasionally go full negative amplitude (0 I guess).
I don't remember if calibration fixed the problem, might have.