Coming to a smartphone near you. One-foot accuracy would be very useful in LEO (BTW, one concept I heard at the Space Settlment Summit last week was a concept for extending existing GPS to cislunar space with just a few additional birds). My question is: what velocities can it handle?
3 thoughts on “Superaccurate GPS”
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GPS has been used for the Space Shuttle in orbit though it probably takes specialized hardware. Conventional GPS (at least as of last decade ago) is usually speed and altitude limited so one can’t readily use off the shelf GPS gear for their own ICBMs and cruise missiles.
If the GPS satellites didn’t use directional antennas, they would already be useful for accurate positioning in cislunar space.
I think this is about using L5 for better multipath characteristics and ionospheric corrections. Doesn’t matter near as much in LEO. These two generally account for about 4 meters UERE in the solution. There’s about 3 meters error from other sources, and then it gets multiplied by DOP. So, color me skeptical of the claim of 1/3 meters accuracy for this new system.
LEO is low enough to be well within a GPS satellite’s antenna footprint. Depending on the positioning mode and receiving spacecraft antenna quality and calibration, centimeter accuracy would be routine, just as it is on the ground with surveying receivers.
The height and velocity restrictions are purely a firmware thing. High velocity-uncertainty increases acquisition time a little but otherwise has no effect.
L5 on phones should be pretty cool. Decimeter accuracy (using carrier-phase modes and assistance) is certainly in the cards I think. I wonder what they’re doing for the phone antenna?
As for cislunar, even existing GNSS can be pretty good. Yes, there is dilution of position at lunar distance, and the signal is weaker and more sporadic, but the moon is only 16 GPS-orbit-radii out. Would be a good exercise for a near-term lunar orbiter or lander, if it hasn’t been done already. Do you have a link to the Summit paper or poster?