Hi smontanus1
I think I remember reading that Capstone used the Universal Access Transmitter (UAT) version of ADS-B which broadcasts at 978MHz. RadarBox (and I think all other virtual radar systems) uses 1090MHz Extended Squitter (ES).
In the USA, UAT is an option for aircraft that don't fly above flight level 180, while ES is going to be compulsory for all aircraft capable of flying above that altitude, and is an option for lower-flying aircraft.
So RadarBox is fine for airliners, bizjets, etc, and remember that all aircraft operating in US airspace must be equipped with ADS-B by 1st January 2020, so Alaska will get more and more aircraft visible on RadarBox. So things can only get better!
At the moment we have one user in Anchorage who is visible on the sharing network (there may be others who don't share).
Hope that helps.
Rod
