ZED-F9R-Integration manual
Figure 11: Misleading information
The output of the protection level is published through the UBX-NAV-PL message.
Protection level computing can be disabled through the CFG-NAVSPG-PL_ENA
configuration item. See the applicable interface description [2] for availability of the
configuration item.
TMIR is specified in one dimension for PL. It is not specified as a horizontal 2D or 3D value.
The protection level values (UBX-NAV-PL.plPos1/2/3) are confidence intervals around the
reported position (for example, UBX-NAV-PVT or UBX-NAV-HPPOSLLH).
The target misleading information risk is provided in exponential notation (UBX-NAV-
PL.tmirCoeff and UBX-NAV-PL.tmirExp), for example UBX-NAV-PL.tmirCoeff=5 and UBX-
NAV-PL.tmirExp=0 results in 5e0 (= 5).
The user may have a threshold defined for the largest acceptable position error for their application.
This threshold is known as the Alert Limit. If the reported PL exceeds this threshold, the user shall
consider changing the mode of operation of the system or in the worst case declare the system
unavailable. Examples of a change in the operating mode of the system could be stopping, reversing
the direction of operation, slowing down or calculating a new acceptable error threshold appropriate
to the mode of operation. This state is also known as the receiver being unavailable (see Figure 12).
In case the PL is smaller than the alert limit, the receiver is said to be available (see Figure 12).
UBX-20039643 - R06
3 Receiver functionality Page 47 of 119
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