u-blox 6
u-blox 6
u-blox 6
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Diagram of ON/OFF operation<br />
9.3.1.2 Cyclic tracking operation - short update period<br />
When the receiver is switched on, it first enters Acquisition state. If it is able to obtain a position fix within the<br />
time given by the acquisition timeout, it switches to Tracking state. Otherwise, it will enter Inactive for search<br />
state and re-start within the configured search grid. After a valid position fix, Tracking state is entered and the<br />
on time is started. In other words the on time is started with the first position fix that is not masked (the masks,<br />
for example 3d only, can be set with CFG-NAV5). Once the on time is over, POT state is entered. In POT state<br />
the receiver continues to output position fixes according to the update period. To have maximum power<br />
savings, set the on time to zero. This causes the receiver to enter POT state as soon as possible. If the signal<br />
becomes weak or is lost during POT state, Tracking state is entered. Once the signal is good again and the<br />
newly started on time is over, the receiver will re-enter POT state. If the receiver can't get a position fix in the<br />
Tracking state, it enters Acquisition state. Should the acquisition fail as well, Inactive for search state is entered.<br />
The diagram below illustrates how cyclic tracking operation works:<br />
Diagram of cyclic tracking operation<br />
9.3.1.3 User controlled operation - update and search period of zero<br />
Setting the update period to zero causes the receiver to wait in the Inactive for update state until woken up by<br />
the user. Setting the search period to zero causes the receiver to wait in the Inactive for search state indefinitely<br />
after an unsuccessful start-up. Any wake-up event will re-start the receiver. See chapter Wake-up for more<br />
information on wake-up events.<br />
External wake-up is required when setting update or search period to zero!<br />
9.3.1.4 Satellite data download<br />
The receiver is not able to download satellite data (e.g. the ephemeris) while it is working in ON/OFF or cyclic<br />
tracking operation. Therefore it has to temporarily switch to continuous operation for the time the satellites<br />
transmit the desired data. To save power the receiver schedules the downloads according to an internal<br />
timetable and only switches to continuous operation while data of interest is being transmitted by the SVs.<br />
Each SV transmits its own ephemeris data. Ephemeris data download is feasible when the corresponding SV<br />
GPS.G6-SW-10018-A Public Release Page 20 of 201
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