01/13/2026
GNSS surveyors should be aware of possible wrong fixes.
Many surveyors rely heavily on the reported fix status to decide whether a measurement is usable.
In reality, that alone is not sufficient.
Inside a GNSS receiver, multiple hypotheses are evaluated before reporting a fixed solution.
One key check is the ratio test — verifying whether the estimated carrier phase ambiguities are close enough to integer values.
In challenging environments such as tree canopy or urban obstruction, signals can be delayed by unknown distances.
Sometimes, these delays coincidentally align close to an integer number of wavelengths — causing a false fix.
When that happens, the reported “fixed” solution can still be 15–20 cm(even more) away from the true position.
There are mitigation methods:
Monitoring per-satellite indicators like C/N₀
Cross-checking geometry and constellation consistency
However, none of these fully eliminate the risk.
In practice, experienced GNSS users still need to judge the environment before accepting a solution.
The good news is that with today’s AI techniques, we can analyze all available signals and patterns together to make fix validation far more reliable.
That’s exactly what we do in our G1000 geodetic receivers and Astra1 mobile visual RTK.
It’s not magic — and not 100% perfect — but it rejects the majority of wrong fixes, helping surveyors maintain field-grade reliability where it actually matters.
