PRELIMINARY
Document type: Title: Revision date: Revision:
User's Manual (MUT) Mod. V1729 4 Channel 12 Bit Sampling ADC 22/06/2005 3
NPO: Filename: Number of pages: Page:
00109/04:V1729.MUTx/03 V1729_REV3.DOC 38 20
3.3.2 Calibration of the pedestals
For this, a calibration of the baselines is necessary. This operation will be necessary
following all changes either in the frequency of sampling, or in the bandwidth of the write
amplifier (BWL), or in the read modes (FAST READ MODES). It will consist in realizing a
mean measurement over a few tens of raw acquisitions of the baselines for all of the
cells (disconnected or grounded inputs). The trigger must then be either automatic, or
external.
The acquisition procedure is the same as for a standard acquisition, but the reading of
TRIG_REC can nevertheless be skipped. Of course not the least temporal correction is
made on the data. At each acquisition, the table of the means will be computed and
finally recorded for an eventual subtraction by software from the unaligned raw data. This
calibration operation lasts less than one second.
In cases where the input is connected to unlikely physical signals, it is also possible to
realize this calibration without disconnecting the input. However, it will then probably be
necessary to increase the number of acquisitions in order to diminish the effect of the
induced additional noise.
Our experience shows us that this calibration remains valid several weeks.
3.3.3 Temporal calibration between different channels
See 3.1
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