DGPS [0] is a workaround for SA. If you can have a ground station with a known location somewhere in the same area - even 100 miles away should be OK - you can

DGPS [0] is a workaround for SA. If you can have a ground station with a known location somewhere in the same area - even 100 miles away should be OK - you can broadcast the correction. DGPS was already "good enough" in 2000 when SA was turned off, so I'd expect it could achieve very close to the same precision as regular GPS by now. [0] https://en.m.wikipedia.org/wiki/Differential_GPS https://en.m.wikipedia.org/wiki/Differential_GPS