The only thing I can think is that they’re comparing with a single system (e.g. GPS or BeiDou), even though GNSS receivers will combine all four systems to get very high accuracy (a few metres).
GPS is actually far more accurate than that. There is deterministic jitter introduced to make civilian use cases precise to only a few meters, but military equipment has the algorithm to subtract that jitter and achieve precision measured in centimeters.
Anyway, that statement is highly misleading. They were comparing to previous inertial navigation systems, not GPS navigation.
Didn’t they turn all that jitter off like 15 years ago?
Edit: I ran a little experiment and zig-zagged up a bit of hill on the bike this morning and the GPS/Galileo/Glonass unit resolved it easily. However, it didn’t quite agree where the road was.
Is that true globally? I seem to remember that some ocean areas wouldn’t have as many satellites visible as e.g. polar orbits don’t visit all of the globe.
The only thing I can think is that they’re comparing with a single system (e.g. GPS or BeiDou), even though GNSS receivers will combine all four systems to get very high accuracy (a few metres).
They are comparing purely inertial navigation (I assume using the advanced nav boreas D90) and inertial nav combined with gravity map matching.
It is more of a demonstration than a comparison. Pure inertial nav has no way to re zero from an external reference so the error only grows.
Both of these systems are worse than any form of sat nav. But both of them keep working if the sat nav is jammed.
https://doi.org/10.48550/arXiv.2608.25563
20 years ago we had only GPS, and it already was accurate to 10 or 20 meters.
GPS is actually far more accurate than that. There is deterministic jitter introduced to make civilian use cases precise to only a few meters, but military equipment has the algorithm to subtract that jitter and achieve precision measured in centimeters.
Anyway, that statement is highly misleading. They were comparing to previous inertial navigation systems, not GPS navigation.
Didn’t they turn all that jitter off like 15 years ago?
Edit: I ran a little experiment and zig-zagged up a bit of hill on the bike this morning and the GPS/Galileo/Glonass unit resolved it easily. However, it didn’t quite agree where the road was.
The road, was pretty narrow.
Is that true globally? I seem to remember that some ocean areas wouldn’t have as many satellites visible as e.g. polar orbits don’t visit all of the globe.