Low Power Tracking - Sierra Wireless AirPrime XS1110 Product Technical Specification

Product Technical Specification
Rev 4.0 Jul.20

Low Power Tracking

Figure 1-3: Power Consumption in Low Power Tracking
When low power tracking of XS1110 is enabled, in the beginning, it keeps
receiving a GNSS navigation message. This GNSS navigation message is
continually received for about 12 minutes and 30 seconds and includes the
ephemeris, almanac, and satellite health in open sky.
After that, the module runs to cycle between Sleep (15 secs) and Exec (30 secs)
as shown in Figure 1-3.
Before the XS1110 module enters into a sleep state, it outputs
"GNSSLOWP,ENTRY,OK" messages in NMEA sentences to indicate that sleep
mode will be executed. Once the XS1110 wakes up, it outputs "GNSSLOWP,
WAKEUP, OK" to indicate that the module has woken up and will start updating
the navigation message.
The module executes hot start internally after waking up every time, then it
acquires satellite information for about 30 seconds to update the TOW (time of
the week).The module will check all of the satellite ephemeris status and ensure
that all updated data is the latest. Once update is complete, the modules enters
into the sleep cycle. If it doesn't, it will keep acquiring satellites in an exec status
until all the navigation messages are completely updated as this is helpful for
ensuring positional accuracy.
The module will hot start after waking up from an intermittent behavior and, within
30 seconds, track satellites to update the TOW (time of the week). Then the
module will check all of the satellite ephemeris to ensure data update is complete.
If there are no issues, the module gets into the next sleep cycle. Otherwise, the
module will switch into continuous operation and keep tracking until data update
is complete.
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