The Wireless Dilemma

I think I have spent more time writing about and answering questions concerning wireless microphones than any other audio topic in the last 20 years. Not because I really want to mind you but because it always seems to be the cause of so much angst. A quick history of wireless microphones is in order.

History
Although several early references document the use of radio microphones beginning around 1948, it was an American electrical engineer by the name of Raymond Litke that invented and patented the first lavalier radio microphone in 1957 for use in classroom communication at San Jose State College. It was first brought to market by VEGA in 1960 and was used by the broadcast media that same year for the Democratic and Republican National Conventions. Wireless microphones did not come into popular widespread use until the mid 1970’s until John Nady (who founded NADY Systems) pioneered their use in the music industry. He was also the first to add a compander circuit that offered audio performance and dynamic range that came close to that of a wired microphone. Their use then spread quickly through the entertainment and broadcast industries.

Those first NADY transmitters (as pictured above) broadcast on any clear area in the FM radio band. It was shipped without a microphone or a receiver. All you had to do to use the transmitter was remove the 3 pin connector in the bottom of a SHURE SM58 microphone and slide in the unit. The early versions of the SM58 came with an extra set screw located at the connector so you could lock a mic cable to the mic and this same set screw enabled the NADY transmitter to be securely fastened to the mic. The recommended receiver (pictured to the right) was the ADVENT Model 400 Mono FM receiver designed by the legendary inventor and home audio pioneer, Henry Kloss, because of it’s renowned sensitivity, stability, and extremely low distortion audio output with a precision vernier tuning dial. Tuning the system was accomplished by setting the tuner to an unused frequency between stations (there was a lot of room back then) and then turn a small tuning knob that protruded from the bottom of the transmitter until the audio from the microphone could be heard from the receiver. Not a particularly painless procedure, but the result was amazing for the time.

These FM radio based transmitters were quickly replaced by crystal controlled fixed frequency VHF units that used unused TV channels. It was really a challenge to travel with these radios because you had to take extra systems to ensure a clear signal. However the output of the transmitter was significantly stronger and more stable than the FM radios they replaced. Further improvements were made by adding a second antenna to the receiver to help prevent dropouts from phase cancelation. Current wirelesses operate in the UHF frequency band, again sharing the bandwidth with the local TV stations. They use a frequency synthesis circuit that allows the flexible selection of frequencies giving some units a couple of thousand channels to build a clear reliable wireless system. It is these systems that have precipitated the huge expansion in the use of wireless systems allowing many transmitters to be used in close proximity to each other.

So, what’s all the fuss about?
The latest issue trust upon us is courtesy of none other than our Federal government, who in their ultimate wisdom have decided that we can’t live without digital television. So what exactly does this have to do with my wireless mic you may ask? Well, those seemingly essential audio tools that so many of us have come to rely on have been sharing the same airways that TV stations use for over the air broadcast. And unless you’ve had your head in the sand you should have noticed all of hoopla surrounding the switch from analogue to digital TV. It is this transition to digital TV that has put wireless microphone use in the spotlight.

Licenses are required to use wireless microphones on vacant TV channels in the United States. This application of a wireless device falls under the Broadcast Auxiliary Service (BAS) rules. Since their inception, wireless microphones have essentially operated as unlicensed pirate radio stations, except for less than 1,000 devices in the entire US that have applied for and been granted licenses. The tens of thousands of unlicensed transmitters in daily use have been largely overlooked by the Federal Communication Commission (FCC) who is responsible for code enforcement and only rarely shutdown or prosecuted. In the shadow of the stealth growth of wireless microphone usage, the neglect of the FCC to make the rules clear and their lack of enforcement, the benign use of this unused bandwidth has grown from a novelty to a huge community of users that rely on their wireless microphones.

So here’s the first problem
The FCC has sold the rights to the unused frequency spectrum that will be abandoned when TV stations turn off their analogue signals. So hence forth, Broadcast Auxiliary Services, such as your wireless microphones, will not be allowed to use the 698 - 806 MHz portion of the spectrum due to their auction of the 700 MHz band to buyers with really deep pockets. (We are talking Billions here.) So if you have any wireless transmitters operating in that space they have been effectively EOL’d (end of life) by the FCC.

Problem #2
There is still some discussion among the players in this drama as to the fate of the remaining TV spectrum. The discussion revolves around who will be granted access to this “white space” (the area between active TV channels) under existing BAS rules. Among those fighting for access is the entertainment & broadcast industries and high speed internet access, the outcome of which has yet to be determined. Complicating this issue is a new requirement that these new transmitters employ, yet to be proven, new technology that includes GPS location, spectrum-sensing, and location database access.



So what’s a wireless microphone user to do?
These regulations represent a moving target as to when they will be implemented and what the new rules will actually be. Nothing has been finalized yet and remember that this is a political issue and is subject to the whims of our government.

• Go out and by bunch of new expensive gear?
• Stake-out your wireless territory and try to get licensed?
• Run up the pirate radio flag and continue with business as usual?
• Go back to using wire?

A successful wireless strategy requires the combination of all four.

1. For the immediate future go ahead and continue to run the pirate flag. Your current wirelesses have worked for the last 30 years and are not going to suddenly self-destruct. The FCC isn’t adding a platoon of new enforcement officers to jail offenders. It’s the same old “if no one complains, no foul” as it has been for the foreseeable future.
2. Ultimately if you are using you’re wireless in a fixed location you should probably put a claim in to protect your airwaves by applying for a license. This will insure that if it does come down to a fight you are on the right side.
3. See if any of your current wireless mics operate in the 700 MHz band. I would not replace them yet if they are still in good shape and working but I would start a fund to replace them when they break. You will no longer be able to get them fixed.
4. This is a good time to seriously evaluate if you really need a wireless solution. Wired microphones still deliver superior performance to their wireless counterparts and they cost much less.
5. If you decide that you need to purchase new equipment this is no time to buy a cheep wireless microphone. It’s becoming a crowded field and only high end wirelesses have the flexibility and performance to have the best chance of survival.
6. And definitely seek the advice of a trusted professional wireless provider.

Tags: White Space, Wireless Microphones, FCC