Steps; Inclinometer - ActiGraph wGT3X+ User Manual

Steps

Step counts are accumulated on a per-epoch basis and are based on accelerometer data collected on
the vertical axis. An algorithm present in the device firmware filters out the accelerometer's baseline
noise level to help accurately accumulate the steps-per-epoch.

Inclinometer

The inclinometer feature can help users identify the orientation of the device and, more importantly,
when the device itself was taken off. Each epoch is flagged with a number (1 through 4) to indicate the
orientation of the device during that epoch. For wGT3X+ and wActiSleep+ devices, this is done within
the ActiLife software when converting the *.gt3x file to *.agd format. As noted, the inclinometer
feature is only valid when the device is worn vertically on the point of the hip. More details are
available in the Inclinometer
Important The inclinometer feature is only valid if the device is worn on the hip
with Axis 1 upward facing.
(Stored with each Epoch)
Off Indication on wGT3X+ and wActiSleep+ versus other devices
The Inclinometer feature offers researchers the ability to detect periods of time during which the device
was not worn. For devices other than the wGT3X+, wActiSleep+, GT3X+, and ActiSleep+, the
inclinometer algorithm makes this prediction by examining the angle at which the device is placed. In
the wGT3X+, wActiSleep+, GT3X+, and ActiSleep+ devices, off detection is performed by analyzing both
the angle at which the unit is placed as well as the length of time the device remains still. Absolute
49 E. Chase St.
400
1,000
10,000-25,000
32,000-130,000
Table 1 – Lux Level Interpretation Estimates
Whitepaper.
Inclinometer Code
0
1
2
3
Table 3 - Inclinometer Definitions
Pensacola, FL 32502
Sunrise/sunset
Overcast day
Full daylight
Direct sunlight
Interpretation
Device Off (Not Being Worn)
Subject Standing
Subject Lying Horizontal
Subject Sitting
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