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    User name E.Chudakov

    Log entry time 19:00:53 on April 22, 2008

    Entry number 233801

    This entry is a followup to: 233649

    keyword=Time structure of helicity signals

    The time structure of the helicity signals has changed with respect to June 2007 and earlier times. There are 3 signals:
    1. Helicity signal in 33 ms long windows
    2. MPS: a signal 250 μs long, at the beginning of each helicity window
    3. QRT: a 33 ms signal overlapping with the first-in-the-train helicity window. The train is normally a quadruplet of 33 ms windows
    It turns out that the MPS is now comes 25 μs earlier than the helicity flips. Before, they used to come synchronously. The QRT is synchronous with the MPS. This happens to affect the Moller DAQ, since the helicity status is read out at the MPS front time. Before, it read out the NEXT window helicity with respect to the scaler information. Now, it is the same window helicity. The software can be adjusted to this change. The present scheme might be more consistent than the old one.

    A copy of this log entry has been emailed to: gorbenko@jlab.org, romanip@jlab.org, glamazdi@jlab.org, rom@jlab.org, nanda@jlab.org



    Figure 1