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LISA-U series - System Integration Manual
UBX-13001118 - R17
Advance information
Features description
Page 157 of 190
4.
The visibility of multiple cells provides increased accuracy based on the intersection of areas of visibility.
CellLocate
®
is implemented using a set of two AT commands that allow configuration of the CellLocate
®
service
(AT+ULOCCELL) and requesting position according to the user configuration (AT+ULOC). The answer is provided
in the form of an unsolicited AT command including latitude, longitude and estimated accuracy.
The accuracy of the position estimated by CellLocate
®
depends on the availability of historical observations
in the specific area.
3.9.2
Hybrid positioning
With u-blox Hybrid positioning technology, u-blox cellular devices can be triggered to provide their current
position using either a u-blox GNSS receiver or the position estimated from CellLocate
®
. The choice depends on
which positioning method provides the best and fastest solution according to the user configuration, exploiting
the benefit of having multiple and complementary positioning methods.
Hybrid positioning is implemented through a set of three AT commands that allow configuration of the GNSS
receiver (AT+ULOCGNSS), configuration of the CellLocate
®
service (AT+ULOCCELL), and requesting the position
according to the user configuration (AT+ULOC). The answer is provided in the form of an unsolicited AT
command including latitude, longitude and estimated accuracy (if the position has been estimated by
CellLocate
®
), and additional parameters if the position has been computed by the GNSS receiver.
The configuration of mobile network cells does not remain static (e.g. new cells are continuously added or
existing cells are reconfigured by the network operators). For this reason, when a Hybrid positioning method has
been triggered and the GNSS receiver calculates the position, a database self-learning mechanism has been
implemented so that these positions are sent to the server to update the database and maintain its accuracy.
The use of hybrid positioning requires a connection via the DDC (I
2
C) bus between the LISA-U cellular module
and the u-blox GNSS receiver (see section 1.10).
See the
GNSS Implementation Application Note
[17] for the complete description of the feature.
u-blox is extremely mindful of user privacy. When a position is sent to the CellLocate
®
server u-blox is
unable to track the SIM used or the specific device.