Introducing GNSS Protection Level: a new feature from u-blox
ZED-F9P
MAX-M10S
1. What is GNSS Protection Level?
Protection Level increases trust in the sensor and improves the quality and efficiency of systems.
The u-blox Protection level feature now available on the u-blox F9 and M10 modules provides a Position Protection Level which enables a 95% confidence that the location is accurate.
2. How do I configure GNSS Protection Level?
Enable UBX-NAV-PL message in U-center messages view for PL to be output on GNSS receiver
Current Circular Error Probable (CEP) is accurate to 2.5m. However benchmark accuracy is measured under specific conditions:
– Static Situation
– Open sky line of sight scenarios with many satellites in view
– High RF input level with a good quality antenna
In reality, static accuracy is rarely the application’s use case. Points 2 & 3, are dynamic depending upon the equipment location and operating conditions.
3. Why is protection level important?
The reported position is usually not the true position of the device. A wide range of applications require more accurate and reliable position estimates. Actual position error can be much worse in challenging conditions (non-line-of sight scenarios)
4. How does it protection level (UBX-NAV-PL) compare to u-blox accuracy estimate (UBX-NAV-PVT)
UBX-NAV-PVT outputs position, velocity and time accuracy estimates with a 68% vertical/horizontal confidence level.
UBX-NAV-PL outputs the position protection level with a 95% vertical/horizontal confidence level.
Protection Level is better than using Accuracy Estimates or using fixed/float status (PL provides more meaningful figure of merit for PVT values being reported, and hence allows the application to have more confidence in those PVT values generated by the receiver).
5. How will it benefit me?
The Protection Level feature provides defined performance criteria, validated for key GNSS use cases. This is indicated as a Protection Level (PL) message if the module is not confident in the actual position fix, for instance in non-line of sight locations (possible Multipath effects) or when a low number of satellites are available, providing higher confidence than with traditional GNSS positional fixes.
6. What are some examples of usage applications?
Protection Level is useful where applications require a better than average position fix. These include:
– Vehicle or micro-mobility applications where poor line of sight or multipath signals are present
– Ground robotics navigation including remote lawn mowers – device enforces policy to operate only in designated lanes
– Pet/livestock/asset geo-fencing – Reporting of geo-fence violations
– UAVs such as aerial drones – Device collects exact data under drone or fly in close formation, or synchronized with sports vehicles or race participants.
