RAIM+ is receiver autonomous integrity monitoring running on the UAV’s GNSS receiver. It statistically tests every measurement, detects the ones that are internally inconsistent, and removes them before they reach the navigation solution. For a drone this matters more than it does on a vehicle: there is no driver to notice that the position has quietly gone wrong, so the receiver has to be the one that catches it.
Specifying GNSS for a UAV platform? Send us the airframe, mission profile and accuracy target and we will match a receiver to it — Request a quote or review the anti-jamming receiver range.
Why Accuracy Specs Alone Are Not Enough
A centimetre-level receiver is only useful if the centimetre-level figure is real at that moment. The failure that hurts UAV programmes is not loss of lock — a loss of lock is obvious, and the flight controller reports it. The expensive failure is a solution that still reads “RTK fixed” while one biased measurement has moved it away from the truth.
That is the case integrity monitoring is built for, and it is why the diagnostic workflow behind our satellite count and RTK-fixed analysis keeps pointing at the same root cause: the receiver accepted something it should have rejected.
What Goes Wrong on a UAV Flight
- Multipath off metal and concrete — flying an inspection line beside a structure, or lifting off from a container yard, puts reflected copies of the satellite signal into the antenna.
- Canopy and orchard work — foliage produces the same class of corruption at low elevation, where the signal is already weakest.
- Active ionospheric conditions — a disturbed ionosphere injects errors that look like nothing at all on a signal-strength readout.
- A single satellite carrying a bias — one bad carrier-phase measurement is enough, because RTK trusts the whole measurement set.
None of these necessarily drop the fix. They change where the fix says the aircraft is.
How RAIM+ Decides Something Is Wrong
Rather than filtering on signal strength, RAIM+ characterises the statistics of the observations and the error sources, then adapts that characterisation to the situation — ground speed, multipath density, atmospheric conditions and signal strength all shift it. Several statistical tests then check whether the measurement set is internally consistent.
When a test fails, the receiver raises an alarm, attempts to repair the solution by removing the offending measurement, and if it cannot, switches to another positioning mode instead of publishing a fix it cannot stand behind. The decision algorithms are tuned from extensive testing and field experience, and the strictness itself is adjustable through the SetRAIMlevels command so you can trade false alarms against missed faults for your application.
The Injected-Bias Test, in Plain Terms
Take a static site with fairly heavy multipath and watch the RTK fixed height deviation. At epoch 494000, a time-linear bias is deliberately added to the GPS PRN 19 L1 carrier-phase measurement. With the integrity layer disabled, that single injected bias distorts the solution badly. With it enabled, the height deviation stays inside the nominal error band and the bias never shows up in the output. Same input, same receiver, materially different answer.
What It Buys You, by Mission
| Mission profile | What integrity monitoring protects |
|---|---|
| Mapping and photogrammetry | Every geotagged frame in the block, because a biased fix corrupts the whole deliverable |
| BVLOS and corridor flight | The flight controller’s position source, with no operator watching for slow drift |
| Inspection beside structures | Fix quality exactly where multipath is strongest and the mission is closest to the asset |
| Precision agriculture | Pass-to-pass repeatability, which needs a fix that is genuinely fixed |
| Formation and swarm work | The formation geometry, so one corrupted node does not propagate through the control loop |
Integrator Checklist
- Ask what the receiver does at the measurement level when the environment degrades — not only what accuracy it quotes.
- Pair integrity monitoring with interference mitigation: one keeps the signal usable, the other keeps the solution honest.
- Log the solution-integrity indicators alongside position so post-flight analysis can see when the fix was stressed.
- On OEM builds, confirm the module exposes the integrity configuration — our HB59 OEM receiver and the HB10 dual-antenna receiver both run Septentrio Inside.
FAQ
Do UAVs actually need RAIM+?
Any UAV flying mapping, inspection, BVLOS or autonomous missions benefits, because the aircraft cannot notice a silently biased fix and the mission deliverable depends on the position being genuine.
Is RAIM+ the same as anti-jamming?
No. Anti-jamming works at the RF front end against interference and spoofing. RAIM+ works on measurement consistency and solution integrity. On a UAV you normally want both.
Does RAIM+ work with RTK?
Yes — the published behaviour is an RTK fixed solution whose height deviation stays inside the nominal error band even when a bias is deliberately injected into one satellite’s carrier-phase measurement.
Can I adjust how aggressive it is?
The SetRAIMlevels command tunes test strictness, letting you set the balance between false alarms and missed faults for the platform’s requirements.
Will it drop my fix more often?
That is the trade the tuning exists for. The design goal is that the receiver surfaces a problem or repairs it, rather than continuing to report a fixed solution that has moved.
Tell us your mission profile and we will recommend the configuration — request a quote or talk to our team.
