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3
System integration
This section presents system integration methods for achieving low power and high performance.
Many aspects affect the system performance and power consumption of the ZOE-M8B GNSS SiP:
• The ZOE-M8B is intended to be run in Super-E mode and defaults to this mode on power up. The
Super-E mode provides the best balance between low current consumption vs. performance.
• Using Multi-GNSS Assistance data on receiver start-up can improve the start-up performance.
Multi-GNSS Assistance data ensures minimal power consumption, since A-GNSS enables the chip
to maximize its power-optimized period.
• For specific power saving applications, the host processor has an option to put the receiver into
backup state. All essential data for quick re-starting of navigation can be saved either on the
receiver side or on the host processor side.
• The data batching feature allows position fixes to be stored in the RAM of the receiver to be
retrieved later in one batch. Batching of position fixes happens independently of the host system,
and can continue while the host is powered down.
Running the receiver in Continuous mode gives the best GNSS performance for sensitivity and
accuracy during acquisition and tracking phases. However, the ZOE-M8B GNSS SiP is intended to be
run in the Super-E mode and defaults to this mode on power-up. The operating mode must be either
explicitly changed with an UBX message after receiver startup, or stored as part of current
configuration to an external SQI flash.
3.1 Backup and time aiding for power off
By default, the receiver does not have information about GNSS time or satellite navigation data when
it starts up. Receiving this information from the satellite broadcasts takes a long time and requires a
high GNSS signal level.
Using a backup mode is a way to turn off the receiver while maintaining the knowledge about satellite
navigation data. Additionally RTC or time aiding can be used to maintain the information about GNSS
time. Using these methods leads to better acquisition sensitivity and TTFF for the receiver start-up.
When using HW backup mode or SW backup mode the navigation data (GNSS orbit data) is
maintained in receiver backup memory while the backup supply powers the backup power domain.
The difference between these two modes is that the receiver enters HW backup mode automatically
when main power supply is no longer powered. It enters SW backup mode when the host directs the
receiver to go to backup mode with a UBX message.
The backup power domain must be supplied during HW or SW backup state. This also enables the use
of an external RTC oscillator to maintain the GNSS time.
If the receiver is completely turned off, so that the backup power domain also has no power, then the
navigation data can be stored on host or on the SQI flash. In this case, the receiver also no longer has
knowledge of the GNSS time. Thus, the host processor must provide the time to the receiver on start-
up, or the receiver must get this information directly from the satellite broadcast signals.
Impact on backup duration and time accuracy:
• Backup-state duration from 0 to ~15 min: the GNSS time accuracy after restart is still better than
1 ms and all ephemerides are still valid. The acquisition sensitivity and TTFF are then improved
(due to better search windows).
• Backup-state duration from ~15 min to ~2–4 hours: the GNSS time accuracy after restart is worse
than 1 ms but all ephemerides are still likely to be valid. The TTFF is still improved (the receiver
does full window searches, but can do a fix before data decoding).
UBX-17045131 - R04
Production Information
ZOE-M8B - System Integration Manual
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