As an increasing number of clients opt for wireless over wired microphone solutions, both systems contractors and manufacturers are seeking ways to cram as many frequencies into an already overcrowded RF spectrum. High-traffic areas, such as New York's Broadway district, have traditionally presented frequency coordination issues, and with digital television coming online (by February 2009, all stations are supposed to go digital), locating an operational frequency is a complex endeavor.
"The problem with a digital TV station is that is takes up the entire six MHz TV channel," noted Steve Savanyu, marketing manager for installed sound, broadcast and theater at Audio-Technica in Stow, OH. "In the good old days, you could fit wireless in around the TV stations and not have too much of an issue. Now, in some areas, if you've got four digital TV stations, that might take up an entire band where you used to be able to run wireless." In some places, he adds, there is more difficulty running more than one or two wireless systems at a time. The FCC is currently considering opening up any unused frequencies to those with unlicensed devices, which, if it happens, will exacerbate the dilemma.
To address these challenges, manufacturers have developed a number of features, such as automatic frequency scanning, which Savanyu notes is available in Audio-Technica's entry-level devices, as well as the company's high-end products.
Shure's UHF-R Series was also developed with the crowded RF spectrum in mind, notes Stephen Kohler, director of marketing strategy and planning at Shure Incorporated in Niles, IL. "We have come out with a number of solutions that have not only more frequency agility but some other RF technology that allows our users more flexibility in the face of a very congested environment," he said. "Track tuning is a technology in our UHF-R Series that allows our customers a lot of flexibility as it relates to being able to find a channel, or a group of channels, that will work in a congested environment."
Sennheiser has upped the ante by offering end users literally thousands of frequencies to choose from. "In our equipment, years ago we gave users the option of choosing from 16 different frequencies to operate on," said Joe Ciaudelli, consultant for the professional products industry team at Sennheiser in Old Lyme, CT. "Now, you can tune our equipment in five kHz steps within a 36 kHz window, which gives them the choice of 7,200 different frequencies."
With the help of the manufacturer-or a qualified frequency coordinator-users can shift the frequencies as well. "If some new DTV stations come on line in a user's area that totally clog that frequency range, they can send their components to us, or if they are a competent RF technician, they can shift that 36 MHz window over a large portion of the UHF spectrum," Ciaudelli explained. "They can slide that 36 MHz window so that it's up to 600 to 636 MHz. We are giving users the flexibility to not only choose their frequencies, but to actually move their frequencies."
In the near future, RF congestion will drive manufacturers to develop sharper filtering, according to Ciaudelli. "As the spectrum becomes more congested with digital television channels, emergency communication channels and even new forms of communication, including wireless networking for home automation, the winner of the game will be those that can filter out those potentially interfering signals so that you can reliably operate your wireless microphone system," he said. "Sharper, narrow filters are the key." Consumer electronics-such as cell phone technology-will also trickle into the professional audio world.
Bob Lowig, conferencing and presentation business manager at beyerdynamic in Farmingdale, NY, notes that security will play a role in future developments. "There is a growing demand for wireless microphones that offer security against eavesdropping-especially in the corporate and military markets," he pointed out. "In this respect, I believe that digitally encrypted transmission of wireless signals will be the next breakthrough in wireless technology."
Contractors should advise their clients on how multiple systems can work together, Savanyu notes. "In the old days, a church system would include one wireless mic for the pastor, and maybe a handheld vocal mic for the soloist. Now churches are looking at anywhere between six to 30 wireless systems-especially if they are a contemporary church that is doing lots of drama. The person that used to hope that he could find enough frequencies, stack the systems up at the back of the church and make them work is finding this a lot harder to do," he illustrated. "Contractors need to provide instructions on how to use these wireless systems together, and specify accessories that can help make multiple wireless systems work together, and what cables to use."
Some manufacturers, such as Electro-Voice, offer seminars highlighting wireless microphone operation that adds to their value to the client. "Systems contractors can learn more about intermodulation-the problem that limits the number of units (in one space)-and the TV environment in their area," said Dave Egenberger, wireless product manager at Electro-Voice in Burnsville, MN. "By understanding the nature of the challenges and the tools to overcome them, the contractor becomes a valuable resource for the customer."
Ultimately, a simple demonstration could prove to be the systems contractor's most useful tool, according to Gary Gunn, market development manager for installed and tour sound at AKG Acoustics in Nashville, TN. "The best way for contractors to benefit is to train, demonstrate, and show that quality can be achieved," he declared. "There is no substitution like the end user hearing the difference in a good full frequency wireless compared to a limited response unit."
