RTK is a differential correction for using GPS and/or GLONASS. The base station will receive it's location data from several satellites. The receiver on your equipment will receive that same data from the same satellites. Since the base station is a fixed location that never moves, it sends a correction differential via UHF or 800, 900 MHz every second. This increases your accuracy to within 1 inch. If you're moving the "base station" around, then you will need to set it up to do "quick survey" instead of "base station". You will also need to know what correction frequency is being used. RTK is incredibly accurate. I've never had it be off more than an inch in either direction. Whereas SF2 can be off by 3 to 5 feet and SF1 could be off by as much as 10. The following images show my set up and the frequencies used for the RTK base station and the correction frequency.
To answer your question, RTK can use UHF, 800 and 900 MHz. You will definitely need a license. And you may be better off finding the RSS and a programming cable for that radio in order to read it to find out how it's set up.
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