Timex M640 - Manual (Page 5)

• The S+D Sensor will shut itself off automatically if any of the
following events occur:
— The battery becomes exhausted.
— No motion is detected for 15 consecutive minutes.
— No GPS signals are detected for 15 consecutive minutes.
Wearing the Speed and Distance S+D Sensor
For best results, strap the S+D Sensor to your upper arm. You may
also clip it to your waist. Wear your watch so it is always within
1 meter (about 3 feet) of the S+D Sensor. Be sure the sensor is
right side up so the GPS logo can be read by someone facing you.
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S+D Sensor ON/OFF
Removable Arm Band Battery Hatch
• For shortest GPS lock times, try to minimize movement while
the indicator light is flashing red.
Operating the S+D Sensor
For best results, the Sensor needs a clear view of the sky.
• Press and hold the S+D SENSOR ON/OFF button to turn on the
receiver. You should be outdoors in an open area. If the button
light glows red immediately (continuously, not flashing), the bat-
tery is exhausted to the point where GPS operation is not possi-
ble and the battery must be replaced. The
ON/OFF button on
the S+D Sensor will initially flash red while the S+D Sensor cal-
culates its position relative to the GPS satellites. The text
“SEARCHING” may appear on the watch display if using a com-
patible Timex® watch.
• The ON/OFF button will flash green when the S+D Sensor has
successfully acquired signals from the satellites. Speed and
distance information is now being transmitted to the watch (or
other device).
• To turn off the S+D Sensor, press and hold the S+D SENSOR
ON/OFF button for one second. The button will glow red while
you are holding the button and then go out, indicating that the
S+D Sensor has shut down.
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