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We know a musician’s world is full of difficult choices – regular or decaf? Rent or gear? Rehearsal or girlfriend/boyfriend? Adding to the complication is your wireless mic purchase – VHF or UHF?
However, a vital difference between systems is the broadcast frequency range that the system uses to transmit. Two ranges, specified and regulated by the Federal Communications Commission, exist: VHF and UHF. You’ll notice that UHF systems tend to cost more than VHF units. Here’s the difference between the two, and why one might be more applicable to your needs over the other.
VHF, or “very high frequency” is a range of radio frequencies between 49 and 216MHz. The FCC divides VHF into a low band (49-108MHz) and a high band (169-216MHz). Low-band VHF is filled with cordless telephones, walkie-talkies, radio controlled toys, television channels 2-6, and “assistive listening” wireless systems. 88-108MHz is the commercial FM radio broadcast band. In general, it’s not a good range for interference-free wireless mic use.
High-band VHF is widely used for professional applications, and includes two bands that are FCC-approved for wireless microphone users. The first of these, from 169-172 MHz, includes eight specific frequencies designated for wireless mics used by general business. These are often referred to as “traveling frequencies, ” because they can (theoretically) be used throughout the US without concern for interference from broadcast television. Unfortunately, the primary users in this band include businesses and government operations such as digital paging services, forestry, hydroelectric power stations, and the Coast Guard. The potential for RFI is always present. Finally, due to the limitation of available frequency bandwidth and the spacing of the prescribed eight frequencies, it is only feasible to operate, at most, two or three units simultaneously on traveling frequencies.
The second high-band VHF region, 174-216MHz, is designated for broadcast and commercial film/video production. Primary users of this band are television channels 7-13. High quality audio is possible, transmission losses are minimal, and acceptable antenna sizes are possible. Interference from other users and general RFI exists, but it is much less likely than for low-band frequencies. In addition, there are ample frequencies available (mainly locally unused television channels) in almost any part of the US.
The UHF region also contains several bands that are available for wireless microphone systems. The primary physical characteristic of UHF radio waves is their much shorter wavelength (one-third to two-thirds of a meter). The visible proof of this is the much shorter length of antennas needed for UHF wireless microphone systems.
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