I think that you can find a good answer at:
Pasavant,Prussag Noel.
they have good expereince with PLC,Analog-Digital signals
in rotating machines.(water treatment plants)
Hire an expert and sue them when you don't get the results you are looking for.
Anyway In the wire and cable industry we have had experience with data communication (AB PLC's) transferring critical information at 800 RPM and no we did not utelize RF.