Spleen, I would say that your 484.4 MHz wide band is probably correct. Most of these professional wireless intercom systems use frequencies in the UHF TV band, not the regular land-mobile bands. Many are FCC Part 15 devices, but a lot are actually a few watts and are licensed (or should be). They use wide band modulation to enhance fidelity, which is important to users of these systems.
They are not in the 450-451 and 455-456 band reserved for broadcast remote pickup because the users are mostly not in the broadcasting business themselves. If this is indeed the big screen cameras and director, they would be most likely working for stadium management or the home team. Many stadiums now are running fixed and wireless cameras that just feed the big screens.
Just FYI, the latest generation of pro wireless intercom systems are using some sort of digital format over 2.4 GHz wi-fi. Wireless mics are also going digital and offer encryption, but they continue to use the UHF TV bands...