Virtually all pro wireless systems operate on either the VHF (very high frequency) or UHF (ultra high frequency) bands. VHF wireless systems generally operate within the 174 to 216MHz range (the range of TV channels 7-13), while UHF uses the 470 to 805MHz range (the range for TV channels 14-69).
Traditionally, UHF has been used by higher-end wireless systems, and has the reputation for having more transmitter range and being less prone to TV interference. These are real advantages but need some qualification.
UHF-based systems are allowed more transmitter power by regulation, but that doesn’t mean that any given system actually has more power than a given VHF system. UHF also has more range than VHF, not because of power, but because the signals move through the atmosphere more easily. UHF also has up to eight times more frequencies available.
As for less interference, that situation is changing. As parts of the UHF range are being assigned to public safety communications and digital TV broadcasting, the band is becoming more crowded. Also, the highest end of the UHF spectrum (above 900MHz) is a general-purpose range used for cordless telephones, garage door openers, and ham radio, so it’s not advisable for wireless use as interference problems are very likely. Actually, both bands are becoming more crowded. As discussed in the next section, digital signal processing technology is playing an important role in dealing with interference.