FADC Data Format September 2, 2014

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Location and Time

Room: CC F326-327

Time: 2:00pm-3:00pm

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Agenda



CDC readout in spec 4.5, data type 7, word 2
Quantity field width (bits) field maximum scaling factor 1/n maximum before scaling
pedestal 8 255 4 1023
integral 14 16383 16 262143
amplitude 9 511 8 4095



Useful Links

Minutes

Present: Naomi (CMU), Beni, David, Cody, Lubomir (JLab)

  1. FADC125 status
    1. Beni has tested modes 1, 2 and 3 of the FA250-ported-firmware and they work as expected, he could change the sparsification thresholds and saw them taking effect. He found that the thresholds need to be absolute; the threshold should include the pedestal height. Mode 7 (described at the top of page 4 in https://halldweb.jlab.org/wiki/index.php/File:FADC250_modes_2.docx) should include 3 words in data formats 7 + 8 + 10 (pulse time, pulse integral, pulse pedestal) and this has to be enabled in the software library before it can be tested. After this, all being well, Cody would like to replace the bad cards which have been identified and upload the firmware onto the rest of the crates.
    2. Cody has started work on merging the new algorithm into the firmware for simulation.
  2. Data format
    1. We discussed the CDC pedestal readout range (see the table in the agenda) and decided to start off with a scaling factor of 1/4 which should give us a huge range of 0-1023. The scaling factor is to be a configuration parameter, but the field width is fixed. We hope that the variation in pedestal height (even in noise bursts) will lie within ADC range 0-255, so that we can later change the scaling factor to 1. This will be determined when we record pedestal data with beam on.
    2. We discussed the format document v4.5, there were a few changes suggested.