Question:
VHF vs UHF vs ISM vs UWB: Which wireless system works best?
Answer:
The idea that UHF wireless systems are inherently better than VHF systems and that ISM (2.4 GHz) and UWB (6 GHz) systems are better than VHF and UHF systems is widespread.
But while each system does offer advantages, one is not automatically better than the others, as each system can be limited by wireless regulations and the physics of wireless signals. This is true especially now as UHF bands become more crowded and remain mired in regulatory uncertainty.
There are, in fact, a number of important factors to consider when choosing between VHF, UHF, ISM, and UWB, including where and how a system will be used, the number of systems needed, and, of course, the price.
In terms of traditional analog wireless systems (VHF and UHF), UHF systems do not hold any large technical advantage over otherwise similar VHF systems. However, interference due to electrical equipment, digital devices, computers and other electronic equipment is generally lower at UHF frequencies. This is because noise from these sources becomes less intense as the frequency increases.
Also, since VHF wavelengths are longer than their UHF counterparts, enabling them to travel greater distances and pass through obstructions like walls and ceilings, all types of interference will travel farther, and thus be more problematic, at VHF frequencies. But while UHF systems are less likely to suffer interference, cost considerations tend to favor the use of VHF systems.
Additionally, digital wireless systems (ISM and UWB) have advantages over the above systems. This too comes at the cost of decreased range in comparison to VHF and UHF. The advantages come into play with uncompressed (no compander), cleaner audio and, best of all, reliable internal frequency coordination.
Smartphone, smart home, and traditional wireless microphones are everywhere you look nowadays and with internal frequency coordination being done within the wireless system, the hard work of coordination is taken off the shoulders of the user.
Additional factors of note when choosing your wireless systems are:
—If choosing between UHF or VHF, diversity systems are highly recommended. Diversity is especially valuable for UHF systems because dropouts due to multipath are more troublesome at UHF frequencies.
—If the wireless equipment will be used in different cities, ISM and UWB systems’ internal frequency coordination will work around populated digital TV signals, which often overcome frequencies used in UHF systems. Additionally, VHF systems operating on the special frequencies in the 169-172 MHz range, known as traveling frequencies, will be a good economical choice (applicable in U.S. and Canada).
—Fixed-frequency (single channel) systems in the TV bands may not be good choices for traveling use. This is because most channels are used in one location or another, and frequency conflicts will eventually occur. Frequency-agile systems will be a better choice.
—UHF systems are good choices in situations where the smaller and less-visible antennas are highly important, such as when the transmitters must be concealed on the body. UHF may also be preferable if high-performance antennas must be used to extend range.
—ISM and UWB systems are recommend where remote antenna are required with distances over 100 feet. Remote antenna or receiver units may be relocated via Cat-5e or better cable with RJ45 connectors rather than RF cable which can be bulky and pricey.
In summary, the best choice among VHF, UHF, ISM, and UWB systems depends on your specific needs, desired features, and specific RF environment. Note that Audio-Technica offers systems serving all of these bands, and for a lot more information about wireless systems as well as microphones, feel free to contact the Audio-Technica Audio Solutions Team here.
Brent Chamberlin is an audio solutions specialist with Audio-Technica.
