Timex Intelligent Quartz Instructions Manual page 16

COMPASS CALIBRATION
Before use, the compass must be calibrated.
Since a compass uses the earth's magnetic field, you
must be aware of large metallic objects, such as vehicles
or bridges, or objects that give off electromagnetic
radiation, such as televisions or computers, which
could affect the magnetic field around the watch. If the
compass is calibrated near such objects, it will only
work properly in that same location. If the compass
is calibrated away from such objects, it will not work
properly near them. For best results, calibrate in the area
of intended use.
In calibrating and taking headings, it is important, as with
all compasses, to keep the compass level. Calibrating or
taking a heading when the watch is not level can result
in large errors. Also avoid areas that may exhibit higher
26
than normal concentrations of hard and soft iron, as they
may cause inaccurate headings. Whenever a heading is
suspect, recalibrate.
Do not store the watch near any source of magnetism,
such as a computer, appliance, or television, as the
watch can take on a magnetic charge, yielding inaccurate
headings. Typical accuracy of wrist-worn instruments is
within +/- 10 degrees.
To calibrate the compass:
1. Pull the crown to its middle position and wait for the
indicator hands to stop moving.
2. Keep the watch level or place it on a level surface (if
the band interferes, place the watch on an inverted
cup). The watch may be face down, but take care to
protect the watch face.
27