abc -MEMS User Manual page 29

The log interval is only relevant when recording statistics. When recording raw signals the time between
two successive samples is simply the sampling period.
The log interval can be adjusted from 125 ms to 2 H in increments of 125 ms.
When recording statistics the amount of memory consumed is inversely proportional to the log interval.
The Memory-Depth indicator in the Setup panel automatically calculates the overall recording time as a
function of the selection.
8.3.5.1.6 Signal Selectors
The Record-Type selector specifies whether raw signals, signal statistics or RMS level statistics are
being recorded.
In either case the user must choose the axes, and optionally the types of statistics to record. To select
or deselect an axis or statistic, simply press on the corresponding checkmark.
Note: In order to record inclinations select "Acceleration", then select "Signal Statistics" and select at
least the X-avg, Y-avg and Z-avg selectors. The inclinations are calculated from those acceleration
measurements.
The amount of memory consumed while recording is proportional to the number of channels and
statistics selected. The Memory-Depth indicator in the Setup panel automatically calculates the total
recording time as a function of the selection.
8.3.5.1.7 Low-Pass Time Constant
When recording RMS level statistics, the instantaneous RMS signal is low-pass-filtered with an
adjustable time constant.
The time constant is only relevant when recording RMS level statistics, and is only used to detect min
and max values. The average is calculated by a rectangular integration over the log interval. A shorter
time constant should be chosen to detect sharp transients. Otherwise the measurements will be
smoothed out. On the other hand, when the RMS levels are slowly varying, a longer time constant will
provide more precise values.
Typical fast time constants are 100 ms and under.
Typical slow time constants are 1s and over.
8.3.5.1.8 Closing the Window
The adjustments are only implemented when the OK button is pressed. In order to forego any changes,
simply close the window without pressing OK.
If any setting requires the user's attention a warning window is open to display the warning. The
settings are still in effect though, and the user can either heed the warning and go back and modify the
settings, or ignore the warning and leave them as they are.
8.3.5.2 Calibration
Pressing the Calibrate button launches the calibration procedure. Once the calibration is started simply
follow the on-screen instructions to accurately calibrate the instrument. The calibration can be
performed at any time. The calibration requires the instrument to be placed in three different positions,
successively placing one of its axes in the vertical position, while the other two stay horizontal.
User's Manual
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