VHF vs. UHF: What Wireless FM System is Ideal for You?
Posted on Tuesday, May 3, 2011
Category: Assistive Listening Devices, FCC Wireless Rules, FM Wireless Systems, Tour Guides, Wireless Listening Systems, Wireless Microphones
If you’re in the market for a wireless microphone (or assisted hearing system), chances are you’ve checked out both VHF and UHF models.
And, chances are, you’ve noticed some key differences: Not the least of them being price.
What’s the difference between VHF and UHF wireless systems, and which is the ideal choice for you?
What’s the Difference Between the VHF & UHF Bands?
All FM wireless microphones and transmitter/receiver systems operate using radio waves, which (in modern times at least) are measured in cycles per second. These waves are measured in megahertz (mHz, or millions of hertz).
VHF (Very High Frequency) transmissions occupy the frequency bands from 30 to 225 mHz. Some of this bandwidth was once taken up by the pre-digital TV channels 2-13, but now almost all of it is used by low-power wireless devices, FM radio and other communications, emergency providers, and some digital TV stations.
UHF (Ultra High Frequency) transmissions start where VHF ends, and go all the way up to 3 gigahertz (gHz), where microwaves take over.
Should You Choose a VHF or UHF device?
The technological hurdle for wireless devices using these bands is power: UHF requires much more power to generate higher-energy waves. This requirement, in turn, leads to extra cost.
On a practical level, this means that lower-power VHF systems are far more economical than high power UHF wireless systems. In addition to the short-term cost of components, there’s also the long-term benefit of increased battery life.
VHF bands also escaped recent FCC regulations re-allocating radio frequencies, which means that it’s still possible to use an older VHF microphone system, while UHF systems of a similar vintage may use a newly prohibited frequency (specifically, the 700 mHz band).
UHF waves, by contrast, are shorter (and possess higher energy). As such, they are far less likely to encounter interference, and can use smaller antennas to deliver the same quality of reception.
For this reason, UHF wireless microphone systems tend to be the choice for live music venues and other operators for whom sound quality and interference-free performance is key.
To sum it up: If you’re on a budget, operating in a small space, and don’t need to provide audiophile sound, a VHF system is your best choice.
If music-quality sound is important to you – or if you’re operating in a large venue – consider a higher quality UHF wireless system.
A Word on Assistive Hearing Systems
What about FM assisted hearing devices like tour guide and other personal transmitter/receiver systems? Most of these devices operate in the VHF frequency ranges of 72-76 mHz and 216-217 mHz.
These frequencies were allocated by the FCC to minimize interference with other devices, although of these two ranges, 216-217 offers better reception.
Recently, devices like the Williams Sound Digi-Wave system have edged their way into the higher reaches of the UHF band. Users can likely expect to see more UHF listening systems offering improved reception & sound quality in the not-too-distant future.
Have experiences with UHF or VHF wireless microphone or hearing systems? Tell us about them in the comments!