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SA 2100 User Guide 47
Retain calibration data on restart
If enabled, the Accelerometer will be able to perform auto-calibration faster. This setting can be turned
on if the SA 2100 is in a fixed location in a particular vehicle. Otherwise, it should be turned off.
Quality factor
This is similar to a % confidence level for auto-calibration. If set to 75, then auto-calibration is
considered complete when the device calculates that there is a 75% probability that it is correct. Values
below 25% are not allowed because the results would be unreliable.
Mode
When Motion Detection is selected, this option generates events when the device is moved, regardless
of the direction of the motion. This is normally used when the SA 2100 is installed in machinery or a
vehicle which should not move, and you wish to be alerted if it does move.
Threshold
This value is the G force which will trigger a motion event. The following settings — Count and Hold
Time — are used to ensure that the motion event is genuine, rather than spurious.
Count
This refers to the number of consecutive samples above the threshold which are needed to trigger a
motion event. For example, if count is 100, and there are 98 consecutive samples above the threshold,
then 1 sample below the threshold, the count would be reset to 0, and no motion event is triggered.
Note that the sampling rate is 10 Hz (10 samples per second) so the “Count” may be converted to a time
interval (in seconds) by dividing the count by 10.
Hold Time
This is the delay, in seconds, before a motion event is cleared. This setting has two effects:
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The Accelerometer will wait for this time interval to determine if the event is finished. If
additional readings above the threshold are received during the Hold Time interval, they are
considered to be part of the same event, and the "Hold Time" timer will be restarted. When no
additional readings above the threshold are received for a period equal to the Hold Time, the
event is considered to be finished.
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Because of the delay to clear an event once it has started, this setting will also limit the number
of motion events which can be generated within a given time period. However, this is unlikely to
have much effect in practice.