MIA-M10Q - Integration manual
satellites) repeats every 24 hours. Hence, when the receiver «learned» about a number of satellites
at some point in time, the same satellites will in most places
not
be visible 12 hours later, and the
available
AssistNow Autonomous
data will not be of any help. However, after another 12 hours, usable
data would be available because it was generated 24 hours ago.
The longer a receiver observes the sky, the more satellites it will have seen. At the equator, and
with full sky view, approximately ten (GPS) satellites will show up in a one-hour window. After four
hours of observation approx. 16 satellites (i.e. half the constellation), after 10 hours approx. 24
satellites (2/3rd of the constellation), and after approx. 16 hours the full constellation will have been
observed (and
AssistNow Autonomous
data generated). Lower sky visibility reduces these figures
(i.e. the number of satellites seen). Further away from the equator, the numbers improve because
the satellites can be seen twice a day. For 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performance improvements if the offline data becomes old or gets outdated.
2.14 Data batching
2.14.1 Introduction
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.
lists all the batching-related messages:
Message
Description
UBX-MON-BATCH
Provides information about the buffer fill level and dropped data due to overrun
UBX-LOG-RETRIEVEBATCH
Starts the batch retrieval process
UBX-LOG-BATCH
A batch entry returned by the receiver
Table 27: Batching-related messages
2.14.2 Setting up the data batching
Data batching is disabled per default and it has to be configured before use via the CFG-BATCH-*
configuration group.
The feature must be enabled and the buffer size must be set to greater than 0. It is possible to set
up a PIO as a flag that indicates when the buffer is close to filling up. The fill level when this PIO is
asserted can be set by the user separately from the buffer size. The notification fill level must not
be larger than the buffer size.
If the host does not retrieve the batched fixes before the buffer fills up, the oldest fix will be dropped
and replaced with the newest.
UBX-21028173 - R01
2 Receiver functionality
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