User's Manual

SIGFOX US demonstrator – User guide v1.1
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1 ANNEX 1: GPS behavior
After powering up of the demonstrator, the GPS undergoes a Cold Start. The initial phase that can last a maximum of 8 minutes
might appear as tedious but is crucial for the GPS to acquire and update its almanac and ephemeris.
Once the GPS has acquired this data, it is put in low-power mode in order to preserve the battery. It is then woken up every
minute during a maximum of 15s in order to refresh the device’s position. If the GPS had acquired enough data during the initial
phase, it should be able to re-synchronize under those 15s. Nonetheless, depending on environmental conditions, it might not
always be the case. It is possible that some frames won’t contain any GPS information.
IMPORTANT:
When the demonstrator hasn’t been used for a long time (days) or has been transported on a long distance (city to city or country
to country), the satellite data previously acquired by the GPS module will not be valid anymore. In this case the GPS will
encounter difficulties to synchronize, it won’t be abnormal if the GPS takes a few minutes (>5min) to re-synchronize during the
initial phase.
It is also possible de deactivate the GPS if this functionality is not desired.