Jacob,
The patent info is available online. If you wish to view it go to
http://patft.uspto.gov/netahtml/PTO/srchnum.htm and type in Rings patent number (8807487) into the search field. I never got some parts of the site to work properly but you can read the text part.
Your Free-mo friends are correct in principle, unless I'm gravely mistaken there is no radio device on earth that is completely immune to RFI, it's all down to how well the device is designed and built that determines how susceptible to RFI it is. I don't know about DigiTrax's radio system but I do know Ring employs some good RF design, such as the HC has access to 5 RF "channels". I don't know for sure but I imagine it hops between these "channels" frequently (there is a proper term for this but I forget what that is at this time of night!). There is probably a whole host of other things that TR has designed in well, along with how RP operates in general (ie, direct to LM, not all throttles to a single receiver) that gives RP what appears to be almost RFI immunity under normal circumstances.
- Tim
