[jrockway]

The error beyond this level is due to local ionospheric conditions rather than the protocol. Corrections can be transmitted to interested receivers, WAAS is an example of such a system.

cm level accuracy is available with RTK. It works by comparing GPS signals from a known nearby location with that of a mobile receiver, providing what amounts to especially good correction. It works fine and you can get started at home for <$100.

A new protocol that does better than what we have right now will take some major breakthroughs.

[tecleandor]

Any recommendations on what hardware or project should I look for to "start at home"? Sounds interesting...

[modernerd]

http://rtkexplorer.com/how-to/posts-getting-started/