4 Proven Strategies for Fighting Video Wall RF Interference

1. Find the Interference.

Before you can fight interference, you must find it.

Finding a source or spurious radiation is not easy, no less on a stage crammed full of video walls, cables, and other stage machinery, because radio waves are invisible and inaudible.

A wireless receiver, on the face of it, provides only one clue—signal strength. And spectrum analyzers, even the pricey ones, can’t locate the source of interference all on their own.

But with a little help from you, and a directional antenna, both wireless receivers and spectrum analyzers can be transformed into powerful interference hunting tools.

The same RF tracking techniques used by wildlife biologists can be used by audio professionals
to locate RF interference.

We’ve written about the process at length before, without mentioning spectrum analyzers (which make the process a hell of a lot easier, btw) as well as the technique of “frequency dependent attenuation” DFI using a DIY tool: the handheld transistor radio.

The gist is that since directional antennas amplify radio signal in front of them, and attenuate radio signal arriving from the sides, they can be used as a kind of spotting scope for RF.

By connecting a directional antenna to the input of a spectrum analyzer or receiver and sweeping the antenna back and forth, you’ll either see (if looking at a spectrum analyzer or signal strength indicator on a receiver) or hear the interference (if listening on headphones or PA) when the antenna is pointed in the direction of the source, since the receiver/analyzer is “seeing” through the directional antenna.

Once you’ve got a direction where the interference sounds or looks strongest, walk forward a few steps, and repeat. The interference will continue to get stronger and stronger the closer you get, until you’re standing on top off, underneath, or in front of it.

Then the fun begins.

Sometimes, very rarely, you might know exactly what part of the device is the source of the leak, and rewire or solder it to a resolution.

Other times, also very rarely, you might be able to get permission to turn the device/component off or have it replaced, but only with political leverage and the good graces of a video director willing to forgo that component. (translation: impossible)

But for the most part you will have to use tools and techniques at your own disposal to resolve the interference without changing anything on the wall.

2. Use Blackwrap to Contain the Interference.

Blackwrap is a thick, black aluminum foil commonly used by lighting departments to wrap searing hot light fixtures up in the cats, to control stray illumination, etc.

Black wrap can also be used to control stray radio frequency electromagnetic waves, as well as light.

You are probably very familiar with blackwrap. But I, a lowly blogger, am not. I ordered some just to get my hands on it, and to do a crude demonstration of how one might go about wrapping a radiating component here at the office.

If you locate an offending device, cover as much the device as possible in blackwrap, or gaff tape a piece of blackwrap over the top.

Take this junction box for example:

It’s filled with electronics spitting out RFI.

And…

Voila! A newly shielded junction box—using nothing more than blackwrap and gaff.

The blackwrap acts as supplementary RF shielding and absorbs and reflects stray radio waves back at the device or inside the chamber of the blackwrap cocoon, instead of spewing out into the air and all over your receive antennas.

It’s best if you can cover the device in a way that the wrap makes minimal contact with metal components and connectors on or connected to the offending device’s enclosure. Contact with these parts could, under some circumstances, lead the blackwrap to function as an antenna and simply re-radiate that energy back out into the environment as if there were no blackwrap at all.

3. Use RF Attenuators to Push Down the Noise-Floor.

When broadband RFI from video walls raises the noise floor, but you still have good to great RF levels at the receivers, you can use fixed attenuators on your receive inputs to push the noise floor down closer to its native level or below the sensitivity of the receiver.

The signals get pushed down as well, of course, but because of the way receivers calculate acceptable signal strength and under what conditions to squelch, you’ll get improved signal out of your receivers.

Here’s how Radio Active Designs Chief Operating Officer James Stoffo (who gave me the tip), explains it:

“If the levels on your receivers are all pegged, which they should be, then you can put on attenuators, 3, 6, to even 10 db attenuators at your antenna input, and that pushes down the noise floor enough that, by adding 10 db of attenuation you increase range and increase audio quality.”

“It’s counterintuitive, but by adding attenuation you increase range, and that’s because analog receivers squelch on SINAD, so by adding attenuation, you’re increasing your SINAD ratio and getting better range and getting better audio.”

4. Use Directional Antenna Coverage Patterns to Your Advantage.

You can find interference using directional antennas, and you can avoid interference using directional antennas as well. In receive applications, by using directional antennas you can create selective cones of coverage that reach the performer and their beltpack or handheld, but not the video wall.

The directional coverage pattern of a helical antenna.

When it comes to using directional antennas specifically for avoiding video wall interference, circularly polarized helicals like the CP Beam and PWS Helical seem to be the weapons of choice.

Here, showing is much better than telling.

Again, much credit to James Stoffo for rig number one, and credit to Communication Handled and Stoffo for rig number two.

The green triangles represent the beam width of the helical antennas (not to scale). The pointy end is where the antenna is located, and the wide face that gradually tapers to white is the direction the antenna is pointed in.

Want better wireless? Download our eBook on three essential concepts for correctly deploying and maintaining interference-free wireless audio systems.

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Video wall backplane image courtesy Sergio Leenan.

Audio Gloss Comments Are Now Live

Yes, after much fumbling and tinkering, comments, in the form of a Disqus plugin, have returned to the bottom of every post on this blog.

We used to have comments on the old system, but then we entered an autocratic period when there were no comments, and no opportunities for you, the people, to express diverse opinions on wireless audio.

Now you can say whatever you want, however frivolous, however vain; I have the moderator settings set to as low as they can possibly be, and you can comment anonymously as a guest.

In all seriousness, actually, we decided to return comments because in the past we have had valuable contributions from generous experts, as well as genuinely useful observations from all sorts of audio professionals, even if they contradict or correct what we’re saying.

That’s something we want to cultivate.

As is our policy at RF Venue, we prefer collaboration and open lines of communication over competition and one-way, top-down control.

So comments there are!

For the people!

[UPDATE: We’ve discovered that if you are arriving on Audio Gloss via our weekly email, comments will not show up. Simply refresh the page, and they will.]

Leading moshing imagery courtesy Goth Eric. Thanks Eric.

Unplugging the Mystery Behind (and Inside) Video Wall RF Interference

RF interference (RFI) from LED, LCD, and other types of display walls used in productions is a big problem for wireless audio. Some say the problem is getting better. Others say the problem is only getting worse. While few can say exactly why display walls create the type and quantity of interference they do.

But there is no denying the problem exists.

This article is about what display wall interference looks and sounds like, and what causes it. Our next article will provide detailed instructions on how to configure wireless audio systems to minimize the problem, so stay tuned.

Because video display walls are almost always on, around, behind, or (why not?) in front of performers and crew members using microphones, wireless monitors, and comms, this is a very tricky problem to solve since the source of interference is so proximate to the receivers or receive antennas in use. As we have said before there is almost no intentional or unintentional interference related problem that can’t be solved with creative use of the inverse square law. But because video walls are right next to performers, it’s difficult to get the beltpacks or antennas far enough away from the walls.

We’re not talking about a single LED display panel that you get at Best Buy, or even the expensive kind you might spec into an install. Here, we’re talking about walls. Giant video walls that have been torn down and built up from modular or independent components, or walls made from 10s or 100s of individual panels, like this:

What does display wall interference look and sound like?

Generally, wall interference is:

  • Low Level. Video wall interference is usually low in strength or amplitude.
  • Broad-band. Video wall interference almost always has a broadband footprint; it exists across a wide swath of the UHF spectrum, sometimes 100 MHz or more.
  • Near-field. Video wall interference only lives within, approximately and conservatively (your video wall will vary), a 40 foot radius of the video wall or offending video wall component. Put another way, video wall interference does not travel far.

(But, there are exceptions, which we explore below.)

Here’s a simplified illustration of what you might find in a well-attenuated facility without any wall interference.

Typically, when a video display is on, you’ll see something like this:

To make matters worse, this interference is often present even if there is no image on the screen, and can vary wildly in its characteristics depending on the type of video signal being fed to the displays, and even the colors and movements of the images moving across the screen.

“What video wall interference generally does is raise the noise floor of the wireless,” says James Stoffo, Chief Operating Officer at Radio Active Designs. “Which gives you a poorer signal-to-noise ratio, which is going to reduce your range, and it’s also going to add audio noise to your system.”

James works on the high end of the production world. The interference he sees is coming from top quality displays, and display components, which usually produce this signature of a broadband, low-level “blanket” of spurious RF over the noise floor, and nothing else.

However, we have seen and heard considerable evidence from other professionals that poor quality, cheap display walls, especially LED walls, are capable of producing much more sinister narrowband RF “spurs,” which Ryan Sartell of Communication Handled described to us as LED “garbage.”

Here’s an illustration of what these spurs look like in some cases that we’ve seen:

These spurs can be very loud. Their amplitude may approach or exceed that of actual transmitters!—so they need to be addressed as if they were transmitters, carefully tuning around them and including them in IMD calculations.

They can also be quite wide. Pete Erskine of Best Audio sent us this scan he took at an event in Montpellier, France, which he reports, “almost destroyed my show.”

This is the third image we have seen showing these spurs. At Pete’s show, there were 5 MHz wide spurs every 20 MHz. Other scans show spurs with different widths and spacings, but they are definitely real.

What causes these spurs? We don’t know, exactly. Tim Vear at Shure has speculated LED drivers are the source of the spurs. Pete thinks they could possibly be from badly filtered switching power supplies with non-shielded connectors (more on these in the next section BTW).

If you think you know the answer to the spur mystery, please tell us more in the comments below.

Display wall interference also has a characteristic sound if the RF demodulates and makes it into the audio. Some have told us the worst audible artifacts sound like “digital jittering” (though we don’t have any recordings to give you unfortunately). Other describe it as being like the sound of light sabers.

James explains that the higher RF noise floor also creates a low level rise in the audio noise floor that sounds like “increased breathing and pumping in the audio.”

“Since this interference is broadband, you can’t filter it out, or you’ll filter out your mic,” so you’re stuck with both compromised reception and constant audible artifacts.

All told, video walls can be just about the worst thing that can happen to an audio department.

What causes display wall interference?

This was not an especially easy question to answer. Although everyone who works in production audio has encountered display wall RFI, very few seem to know why it occurs. And the people who do know have slightly differing opinions.

It should be said blame for RFI is not always easily pinpointed to one person, device, or company, but is the product of an accumulation of causes that begins when a panel is being designed, continues through how they are manufactured, and ultimately ends in how they are configured and installed at the venue by the crew.

Likewise, a video wall used in production, as compared with one single panel, is a system of interlocking parts that all use electricity which all have the potential to create interference, so it’s not easy to simply point to one individual electronic component and say, “yep, there’s your problem.”

Let’s begin with a summary of possible causes, and then move on to in-depth analysis with expert testimony.

  • Power supplies: Power supplies are always a common source of RFI. Today’s video displays are truly gigantic, and all that video needs a lot of electricity, which means a lot of power supplies. LEDs especially need sophisticated power supplies that contain, in addition to the usual suspect components like transformers, switching regulators and other dense circuitry that can, if poorly designed, contribute RFI.
  • Poorly or unshielded cable: Display walls use an absurd amount of cabling, cables of all types and sizes, that crisscross one another: a recipe for RF disaster. Potential offenders might include high voltage lines, all the way down to the thin cables that are carrying high frequency signal to individual diodes.
  • Electrical junction boxes: Which may be on the wall itself or somewhere else on or underneath the stage.
  • Unshielded connectors: Connectors are a great spot for RFI to leak out of. Display walls use a lot of connectors to snap together all of the parts listed above.
  • LED drivers: LED walls create moving images by chopping video signal into on/off signals sent to individual diodes using pulse width modulation (PWM), at (relative to standard 60 or 120 Hz video signal) very high frequencies, up to 3000 Hz. These drivers can create interference by themselves if poorly designed or programmed, or if the wires delivering their high frequency signals aren’t properly configured.
  • Poorly shielded or non existent backplanes: Electronics that emit large amounts of spurious RF use PCB boards, either functionally or as a protective groundplane, built with many layers of copper to keep the RF contained within the device, or to absorb the RF and diffuse it through the ground. The more layers you have, the better the protection, but, the higher the cost.

There is wide, wide variability in the quality of display panels available for sale. Generally, it seems that price is correlated with the care of electronics design; poor shielding and grounding and sloppy PCB design leads to RFI, plain and simple.

Older panels, and panels manufactured in Asia tend to create more RFI than newer panels, and panels made in Europe or the US.

“A lot of LED products that might come out of China use the minimum minimum minimum number of PCB layers possible, just to make it inexpensive,” says Jeremy Hochman, who currently leads creative LED product development at VER. “They’re using the minimum you need to make it operational, and that’s it. You then have very high-speed signals in the megahertz range going through the board that are all just on the surface of the PCB, or coming out through cables, going who knows where, and making weird patterns, that contribute to interference.”

Jeremy, who like James Stoffo works with and designs some of the best panels available, claims that from his frame of reference, things from manufacturers are getting better.

“I would say 90% of the products I see these days are LED, and things there are actually getting very good. LED drivers are doing a lot more of the smarts close to the LED, so the signals running on the PCBs are not so high-speed. That reduces EMI. The enclosure technology is getting better. Better groundplanes are being put on the LED boards.”

While the design of individual display products, especially cheap ones, do cause some of the problem, that’s not the entire story. The user also has something to do with it.

“There’s no way to know how an end user that might be decoupled two or three times from the manufacturer is going to end up putting this thing together,” continues Jeremy. “I don’t think this interference is particularly caused by the LED panels themselves. It’s the sheer volume of them. If you take 1000 toasters and put them in an array, they’re probably going to radiate in an unexpected way. If I set up 1000 projectors in a modular array, it’s probably going to interfere with you. Many older products weren’t intended to be set up on such a large scale, so if I set up an LCD wall that’s 300 feet wide, it’s going to radiate and interfere.”

Video departments are doing some very severe teardown and rebuilds of video components to get their displays just they way they want them. They may be replacing or adding power supplies, gutting and re-wiring diodes or panels, or even swapping out or re-programming drivers—and they aren’t checking to make sure their Frankenstein creations, however gorgeous the image, are conforming to FCC certifications for acceptable levels of spurious RF emissions.

James Stoffo has been singing this sad, sad song for a long time.

“When I originally started going up against video directors,” he remembers, “the first thing they would say is, ‘well, the equipment is FCC type accepted.’ They would point out the FCC acceptance label on the back of the unit.”

Since LED display walls used in production contexts are so much different than consumer LED or LCD display products used in the home, and since production caliber displays, even the best ones that are put together by expert video departments, are still causing devastating interference to the audio department, perhaps it’s time the FCC takes another look at how it categorizes and approves EMI on these types of products.

“The tolerance on the FCC type acceptance on this equipment needs to be tightened up,” James Stoffo asserts, “because even though it is type accepted, it is still creating harmful interference onto wireless mics, ears, and intercoms.”

Now might be the time to start getting tough on the problem of video wall RFI—before it gets any worse.

Leading image courtesy Lara Torvi.
Video wall backplane image courtesy Sergio Leenan.
Close-up of diodes courtesy “Syntropy.”
Video wall installation image courtesy Niv Singer.

Why Live Events Matter

The spectrum we use—the UHF broadcast band—is going away, and the devices we operate—analog FM radios—are ill-equipped for the digital and database controlled ecosystems they are increasingly asked to inhabit.

Wireless microphone manufacturers are innovating, and end-users are changing how they deploy equipment for greater efficiency. But those changes won’t come fast enough. It is of great importance that regulators give wireless audio devices a gradual, lengthy transition out of UHF spectrum and, eventually, new spectrum elsewhere that is either exclusively for wireless audio, or can be shared with other devices without sacrificing the technical requirements demanded by our applications.

Making the case for why regulators should do that is difficult.

Although wireless audio devices are genuinely valuable, their user base is small when compared to other users, like cellular, and the value of wireless audio is harder to concretely quantify than the monetary value the incentive auctions will ascribe to UHF frequencies through free market forces—which does not mean that value does not exist.

Purely monetary arguments are bound to come up short, because we essentially have to make the case that a handful of wireless mics should be able to use spectrum worth billions of dollars to someone else for free, while other types of users, like LPTVs, are given the boot.

For wireless audio to move forward, we must communicate to regulators why wireless audio devices—the type we use right now—are uniquely indispensable to corporations, governments, non-profits, and society as a whole.

If you peel back the layers of rhetoric that have bounced around since the auction of the 700 MHz band a few years ago, you realize the case for wireless microphones doesn’t have much to do with the devices themselves, but rather the context in which they’re used: live events.

To understand why wireless microphones are important, you have to understand why live events are important, not just to the industries that produce them, but to everyone.

Those who work in the industry carry this knowledge implicitly. What we do is important. Right? It’s so inherent and obvious, that I think at times nobody thinks to state the obvious, because we assume it has been said before.

But if we are to be successful, we have to make that implicit knowledge explicit, and legible, to regulators, to everyone, and deeply explore why live events—of which wireless audio is an integral part—are valuable, ensuring that we look beyond easy definitions of “value” to include the other, non-tangible, but still real forms of value.

So, why do live events matter? Let me count the ways.

Proximity in the Internet Age

Digital media platforms and social networks have changed the way people everywhere perceive reality, and the way organizations do business.

The broken record spins: many of our interpersonal interactions now occur online. How does this bode for the “real” world, of handshakes and eye-contact?

Since the dawn of IT, pundits have predicted the decay of face-to-face interactions and events due to modern communications, and the rhetoric has not stopped. Forums, social media networks, Youtube, etc, suffer straw man arguments that point to digital interactions as the root of poor social skills and isolation.

And yet, face-to-face is not dead, or dying.

To the contrary, face-to-face is at a premium.

Corporations invest ungodly sums in lavish spaces that encourage “spontaneous interactions” between talented employees.

Urban life has exploded into a new golden age in every country.

Corporate events keep growing in complexity and scale, and trade shows are still a crucial part of marketing strategies.

Pollstar, which tracks the financial health of the concert industry, estimated that ticket sales to concerts and festivals reached $6.2 billion in 2014, up from $5.1 billion in 2013, and only $1.7 billion in year 2000. In fact Pollstar has reported staggering and nearly uninterrupted growth in the concert industry since 1990. And it’s not just because the music industry can’t make money selling records anymore. If concerts were overpriced, people wouldn’t go, and yet ticket prices have skyrocketed right alongside attendance!—from $41 in 2000 to $71 in 2014.

These days, organizations have so many different avenues for communicating a message and building a brand, but clearly still expend resources on the production of face-to-face gatherings because live events offer something that other forms of media and communications do not.

“There’s nothing that beats the live experience,” says Jim Kelley, Vice President of Industry Relations at PRG. “Face-to-face engagement is where the rubber meets the road, where you really start driving positive outcomes. Human beings like to be engaged with other human beings, whether that’s at a meeting or a concert.”

There is something inherent about face-to-face that ensures its relevancy as long as people continue being people.

But there is also something qualitatively different about why people go to live events in a contemporary, digital society that explains the quantitative growth.

Live events are powerful because they provide a caliber and quality of experience that digital mediums lack, one that is rooted in the “real.” A “real” life experience, especially one with others, is now a type of novelty, since we live so much of our routine lives alone in digital domains.

“There have been some studies that have shown the digital component has actually increased attendance at face to face events,” continues Jim Kelley. “In the sense that people are able to experience it and get their toes in the water and realize, ‘hey that was such a good experience online or digitally, that I now want to go experience the whole thing.”

Live events are where, suddenly, celebrities and leaders step out of fantasy to become an exhilarating physical object, previously existing only as a creature of shadow and color on a screen, or in memory. And to reinforce the existence of this new object are hundreds or thousands of other witnesses, all gathered within eyesight of one another around the same phenomenon.

Instead of keeping us isolated, for many, digital communication has had the counterintuitive effect of creating an impulse to come together. Gatherings are special and rare, and also foils of the digital mediums they complement.

Consequently, the expectations of audiences have risen; a spotlight and microphone are no longer enough. Central to meeting the expectation’s of today’s sophisticated audiences are the technically advanced and tightly coordinated entertainment technology products and services—wireless microphones and other audio devices among them—that make contemporary events so stimulating.

Live Events as Means of Production

We often think about the value of live events in terms of the money exchanged leading up to and during the event itself. And that is certainly one of the major and most easily measured kinds of value that live events offer. Construction companies are hired to build stadiums and theaters. Consultants and contractors and subcontractors and freelancers are hired and paid to coordinate and produce. Attendees pay for the event, and fan out before and after into surrounding communities, opening their wallets to local restaurants, bars, and parking garages.

But the value of live events does not end when the curtain closes. Many performances or presentations are professionally broadcast to a wider audience, or recorded for later rebroadcast, or diced, sliced, and blended into a dazzling variety and abundance of easily consumable free and paid entertainment products available across numerous digital and traditional channels, to be sold as a product, to increase a brand’s exposure and drive engagement, or to serve as fodder for news.

In other words, a major event (and all the technology used to put it on) is a kind of factory.

There is some monetary value in the actual event, but event stakeholders usually generate the majority of their revenues by producing entertainment products based off of that event, or by selling advertising slots appended to the event.

To illustrate this point, as an American, I have to jump straight to the NFL.

Bloomberg Business has called the NFL “the most popular show on TV and arguably the last totem of American mass culture,” whose revenues, though shrouded in mystery, may be somewhere north of $10 billion—which eclipses the total tax revenue collected by the country of Lithuania.

We like to think of football games as spontaneous play between honest contestants with a great deal at stake.

In reality, as much of what can be scripted is scripted and planned, to maximize theater that arises out of both anticipated and unanticipated turns of events within the game, which ultimately makes for a more compelling and watchable story, and therefore a more valuable product. The lenses of the cameras are carefully selected, the microphones are carefully coordinated and placed, the producers in the broadcast truck decide which feed should get pushed through, a broadcast mixer piping in the roar of the audience at key moments to heighten theatrical effect, etc…

What is so fascinating is that what is valuable is the continuity that is created between the real-time event and the ensuing entertainment products in the minds of consumers.

Sports broadcasts, and all the merchandised ephemera they generate, are worth paying for mostly because they take place in real time in front of a live audience of screaming fans. In fact, that may be the only reason they are worth paying for.

Sure, there is some importance in the characters who play on the field, and the way the game is played, as opposed to other games. But I think these differences only matter because they so happen to make the experience of watching sports live even more enjoyable.

Unlike something like, say, a theatrically released film, which has a beginning and an end, a football game is only one game of many games that serve to propel one of two teams onward to even greater victory in the future. At the end of the year, the game begins all over again. Football is such a powerful platform because it has no beginning and no end—only endless speculation, celebration, and analysis over relatively brief bursts of unpredictable live play.

Without the raw thrill of chance unfolding in real time on game-day, the discourse in-between games would not be nearly as intense, nor generate as many sales of TV subscriptions and merchandise. In-between games, you find a flurry of conversation and debate on past and upcoming games, on referee decisions, on the personal characters of certain players, on FM radio, AM radio, at the watercoolor, on ESPN. This stuff gets fans foaming at the mouth, so that when the actual game “the” game, is “on,” everybody is screaming and shouting as if their lives depended on it.

Literally they are screaming about a carefully branded entertainment product louder than anyone has ever screamed about anything, ever. Last year, the Kansas City Chiefs broke the record for loudest stadium in the world, measured at 142.2 dB—on par with a jet turbine, shotgun blast, or small explosion. The OSHA scale tops out at 140 dB, the “threshold of pain.”

Not only was the Kansas City Chiefs’ new world record a great way to violate OSHA noise safety standards, but it was also living proof of the power of live events.

Enough about OSHA. Let’s do a little thought experiment. What would happen if for some reason the NFL decided only to pre-record games for DVD distribution, and stopped letting fans into stadiums?

Wait, we actually don’t have to speculate.

This April, amid the tumult of the Baltimore riots, the Orioles played a baseball game without fans. As NPR reported, no baseball game has ever been broadcast without a live audience in the stands. The media almost universally described it as “surreal.”

Why?

The rules of the game were the same. A team won, and a team lost. Bright lights flickered on the billboards.

April’s “surreal” Orioles game gave the live event and entertainment industry a rare experimental treatment against controls; What happens to the quantitative and qualitative value of an entertainment product when there is no audience to enjoy it?—even though the nature of the game is unchanged?

I think it would be difficult to say that the absence of Oriole fans increased the value of the game. Certainly, 50,000 fewer tickets were sold, stadium staff did not come to work, and local restaurants and businesses never received an influx of game day business.

For the baseball fan watching at home, an otherwise carefully packaged, consistent product was suddenly missing a key ingredient—people—and, aside from some rubbernecking, probably suffered for it.

Without people, even the most expensive athlete transforms into a lunatic mime.

Without people, there is no proof that an event is enjoyed. That a brand stands for something. That a politician’s ideas are supported by a majority of voters.

If in some alternate universe the NFL’s stadiums were suddenly empty, American football would transform into a game of glorified chess played by large, muscular men, watched by almost no one.

I don’t think these are trivial points. I’m making them because I want to show that the financial success of live entertainment products rest on fragile and (sometimes) non-obvious variables.

Whether attendees and television or digital viewers enjoy a live performance depends on their subjective impressions of the event—and those impressions depend in a large part on the perceived “liveness,” a sense of raw unfiltered reality and chance, of the thing in real time. A microphone dropout, an apathetic (or non-existent) audience, crew-members being unable to communicate on headset and missing a cue, a shaky or unfocused camera, and anything at all that interrupts the “instantaneous experience” of an event are not just frustrations or embarrassments, they severely damage the value of the product.

Access to UHF spectrum for wireless audio is one of the non-physical variables contributing value to one of America’s most important industries—entertainment products—and one of the strongest arguments for why it should be preserved for that purpose, even though the entertainment industry itself can’t match the communication industry’s bid for spectrum in an auction.

I was going to go on—go on to a third reason why live events are valuable, “Live Events as Displays of Power,” but, looking down at my watch, it’s time to stop. I may break this post up into three sections later on, and include that final reason as the third chapter.

Let me sign off with this:

Live events are not self-contained systems, and a lot of their worth is contained in intangibles, like emotional pleasure, social affiliation, and political clout—which are very real, but won’t show up in a spreadsheet.

For today’s high profile live events—the kind of sleek, seamless, coordinated ones which are valuable to large audiences, corporations, governments, and non-profits—wireless audio, and the spectrum that it uses, is not a needless luxury.

Wireless microphones, intercoms, and monitors are essential organs—kidneys, livers, spleens—that are required to maintain the illusion of instantaneous experience. They are not an appendix or earlobe which can be removed without consequence. The loss of just one threatens the existence of the organism as a whole, and when they operate at reduced capacity the health of the organism suffers proportionally.

It is—and will be—possible to change how those organs function—digital modulation, improved filtering, intelligent networking—that alter how efficiently wireless audio devices consume spectrum. But those changes won’t happen overnight.

Leading image courtesy Hsiung.