Hi @j.dixon.au,
RTK requires 2 Reach units: base and rover. One Reach in a Single mode can provide only submeter accuracy.
However, you don’t always need 2 RTK receivers.
It’s also possible to use NTRIP caster via the Internet as a base station. It allows getting centimeter accuracy with only one Reach unit used as a rover.
So, if you’ve already got access to the NTRIP station, you can use it as a base.