Hardware Components
© 2016 Pulsar Informatics, Inc.
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On-wrist
The band detects whether it is being worn using a proximity sensor embedded on
the inside surface of the band. When the band is being worn, the presence of the
wrist close to the band is measured. The on-wrist sensor uses a capacitive proximity
field and does not require the wrist to be in direct contact with the surface of the
band, but if the band is worn loosely it may result in intermittent spuriuous off-wrist
measurements.
Accelerometer
A three axis accelerometer measures motion of the band along the X, Y, and Z axes
as shown in the figure below. The raw acceleration signals are measured at a
sampling rate of 50Hz or above, and later processed to generate derived activity
count metrics. The sampling rate and range setting of the accelerometer are
selected at the time a recording is started. The default settings are 50Hz, and ±4g.
Setting
Values
Description
Frequency
50Hz, 100Hz, 200Hz Rate at which raw acceleration values are
measured. Higher rates reduce battery life.
