Yo Gary
The surveyor is my younger brother
The device was developed because of him and a comment from him that it is impossible for a GPS to be sub meter accurate without assistance.
Well challenge accepted and the device was developed and is sub-decimeter accurate.
"If you can't measure it, you can't improve it." - Lord Kelvin
This is from your email and very true.
Suffice to say that the one element that finally determines the accuracy of position from any receiver is TIME.
If you study the post processing and RTK processes they both have one thing in common and that is time. The better the time synchronisation the better the position that is the long short and tall of it
The arguments about what WGS84 etc are all irrelevant and purely academic and have nothing to do with the position the receiver provides me with.
As long as the coordinates the vehicle navigates from and to are in the same datum there is no problem
Sincerely
Anton