SAM-M10Q - Integration manual
conditions. These conditions tend to be binary in nature, such as jamming has been detected, or the
minimum number of satellites is being observed. UBX-NAV-PL reports a PL validity flag (see UBX-
NAV-PL.plPosValid), which indicates whether the PL is usable. .
The protection level performance depends on many external and internal factors. Some
external factors such as a harsh GNSS environment may lead to degraded PL performance.
The protection level validity is not to be confused with misleading information and is
independent of misleading information.
PL validity values
Description
UBX-NAV-PL.plPosValid = 1
PL values are valid and can be used
UBX-NAV-PL.plPosValid = 0
PL values are invalid and shall not be used
Table 14: Position PL validity
2.11.3 Expected behavior
For each navigation epoch and for each coordinate axis, a PL value is provided. For example, if the
coordinate frame reported is North/East/Down, then the UBX-NAV-PL contents can be interpreted
as follows:
PL values
Description
UBX-NAV-PL.plPos1
1 stands for the north axis
UBX-NAV-PL.plPos2
2 stands for the east axis
UBX-NAV-PL.plPos3
3 stands for the down axis
Table 15: Position PL values
If the PL coordinate frame is set to invalid (UBX-NAV-PL.plPosFrame = 0), then the PL values shall
not be used. If the PL validity flag is cleared (UBX-NAV-PL.plValid = 0), the PL values shall not be
used. Both of these cases must be checked.
Only if the PL is set to valid (UBX-NAV-PL.plPosValid), the PL values (UBX-NAV-PL.plPos1/2/3) can
be used and are reliable with respect to the target misleading information risk.
2.12 Multiple GNSS assistance (MGA)
The u-blox AssistNow services provide a proprietary implementation of an A-GNSS protocol
compatible with u-blox GNSS receivers. The MGA services consist of AssistNow Online and Offline
variants delivered by HTTP or HTTPS protocol.
When a client device makes an AssistNow request, the service responds with the requested data
using standard UBX protocol MGA messages. These messages are ready for direct transmission
from the client to the receiver port without requiring any modification.
AssistNow Online optionally provides immediate satellite ephemerides, health information and time
aiding data suitable for GNSS receiver systems with direct internet access.
The AssistNow Offline service benefits u-blox GNSS receivers that only have occasional internet
access. Users request data from the service by specifying the time period for which they want
coverage (1 to 5 weeks). The data downloaded from the service is organized by date and encoded
into a sequence of UBX MGA messages. In addition there is an MGA feature called AssistNow
Autonomous which does not need an internet connection and runs entirely on the receiver.
below contains an overview of the different MGA services u-blox provides. Refer to the SAM-
M10Q datasheet for the supported GNSS signals by each MGA service [
].
UBX-22020019 - R01
2 Receiver functionality
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