NEO-M9N - Integration manual
example at 47 degrees north the full constellation can be observed in approx. 12 hours with full sky
view.
The calculations required for
AssistNow Autonomous
are carried out on the receiver. This requires
energy and users may therefore occasionally see increased power consumption during short periods
(several seconds, rarely more than 60 seconds) when such calculations are running. Ongoing
calculations will automatically prevent the power save mode from entering the power-off state. The
power-down will be delayed until all calculations are done.
AssistNow Autonomous should be enabled if the system has sporadic access to the
AssistNow Offline service. In this case the receiver will intelligently choose the more
reliable orbit predictions for each satellite. This way the autonomous prediction can provide
performance improvements if the offline data grows old or gets outdated.
3.10 Save-on-shutdown feature
The save-on-shutdown feature (SOS) enables the u-blox receiver to store the contents of the
battery-backed RAM to an external flash memory and restore it upon startup. This allows the u-
blox receiver to preserve some of the features available only with a battery backup (preserving
configuration and satellite orbit knowledge) without having a battery backup supply present. It does
not, however, preserve any kind of time knowledge. Save-on-shutdown must be commanded by the
host. The restoring of data on startup is automatically done if the corresponding data is present in
the flash. Data expiration is not checked.
The following outlines the suggested shutdown procedure when using the save-on-shutdown
feature:
• With the UBX-CFG-RST message, the host commands the u-blox receiver to stop, specifying
reset mode 0x08 ("Controlled GNSS stop") and a BBR mask of 0 ("Hotstart").
• The host commands the saving of the contents of BBR to the flash memory using the UBX-
UPD-SOS-BACKUP message.
• For a valid request the u-blox receiver reports on the success of the backup operation with a
UBX-UPD-SOS-ACK message.
• The host powers off the u-blox receiver.
The startup procedure is as follows:
• The host powers on the u-blox receiver.
• The u-blox receiver detects the previously stored data in the flash. It restores the corresponding
memory and reports the success of the operation with a UBX-UPD-SOS-RESTORED message
on the port on which it had received the save command message (if the output protocol filter on
that port allows it). It does not report anything if no stored data has been detected.
• Additionally the u-blox receiver outputs a UBX-INF-NOTICE and/or a NMEA-TXT message
with the contents
RESTORED
in the boot screen (depends on the configuration of the port and
information messages) upon success.
• Optionally the host can deliver coarse time assistance using UBX-MGA-INI-TIME_UTC for
better startup performance.
Once the u-blox receiver has started up it is recommended to delete the stored data using a UBX-
UPD-SOS-CLEAR message. The u-blox receiver responds with a UBX-ACK-ACK / UBX-ACK-NAK
message.
UBX-19014286 - R07
3 Receiver functionality
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