Larson Davis 831, User Manual

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Model 831 Manual Model 831 Specifications A-17
Time of Day Drift
The Model 831 displays the time of day and also time-stamps various single events (i.e. maximum
level) and records.
Time-of-day clock accuracy is shown in Table A-14 (applies only to instruments serial number 2089
and above with firmware version 1.600 or above).
Table A-14 Time of Day Drift
Time Variations Between Session Log and Overall Start Time
The Session Log and the Run/Stop record in the Time History contain the time when the
9 ?
RUN/
PAUSE button was pressed. The Overall display shows the time when logging begins. Since it takes
some time before data is available to be logged after starting to run, there can be a small difference
between these times.
This discrepancy can show up on the Model 831 where time resolution is in seconds. An example of
would be when the
9
(RUN/PAUSE) button is pressed a moment before the seconds digit
transitions. Data to be logged is available a moment later but the Seconds digit has changed. In this
situation the difference will appear to be a full second. In actuality the difference is closer to 1/10 of a
second.
Temperature
Drift per Day
(seconds)
Drift per
Month
(seconds)
Drift per Year
(minutes)
ppm
25

C


1




2
2.0
-10 to +50

C






2
2.8
-40 to +70

C






2
3.5