What is Wireless DMX (WDMX) and How Does it Work?
In each of the major disciplines of the entertainment field, signal flow is the element that ties equipment together for a successful show. Signal flow is how the voice travels from a microphone to the sound console and back out to the speakers. Cameras require signal back to the switcher and on to the screens. It’s how the lighting console communicates with the fixtures and gives instruction to turn the light on or off, pan left or right, change color. Any break in signal flow is a break in the show, and this is something that we actively protect in our work for every client.
The building block of lighting signal flow is DMX, or digital multiplex, and this protocol was developed in the 1980s as a method of sending packets of data from the lighting controller to the lighting equipment. DMX is essentially a stranded cable consisting of 5 pins (to differentiate from audio’s 3-pin XLR connectors), but still mainly relying on 3 wires connected to the first three pins. DMX was standardized in 1990 by USITT and later as an ANSI standard for the industry. As moving lights gained traction through the 1980s, we began to have the need to distribute both power and DMX signal to the fixtures used in live events.
Wireless DMX technology came along a bit later in the game, and we started to see professional lines of Wireless DMX (or WDMX) transmitters and receivers in the early 2000s. The aim of Wireless DMX has always been to replace data cables with wireless technology to cut down on time and cost for live productions.
How Does Wireless DMX Work?
Wireless DMX (WDMX) uses wireless signal to rapidly transmit data packets from a transmitter (typically at front of house) to a receiver (typically within close proximity of lighting fixtures) and is utilized within a single event space to ensure that transmission does not break. Wireless DMX signal fits in a narrow window of radio signal as seen below:
WDMX also shares the 2.4GHz spectrum with smart devices, and this has led to advances in how radio signals are processed to better share the crowded space of this spectrum.
Early WDMX Devices – An Exercise in Madness
When the first wireless dmx transmitters and receivers were released we all marveled at the technology on display at trade shows like LDI. Through practical use would we begin to understand the limitations of technology at the time. Early WDMX was very expensive, and it was advertised to replace the need for long, expensive DMX cable runs.
The irony of this advertising was, of course, the practicality of a transmitter that cost around $2800 and a receiver that cost $2400 (adjusted for inflation, those items would cost $4600 and $3900 in 2023) to replace standard dmx cables and front of house snakes. What we found, and quickly, was that early WDMX technology was often very prone to failure and interference. Doing event work, it was not uncommon to pack WDMX for a show alongside the necessary DMX cables just in case of failure. A lighting system would work smoothly during load-in and rehearsal, and the system would fail as soon as the event was full of attendees with active cell phones. Even the shortest WDMX signal paths in breakout rooms would need to be replaced by a single 50’ DMX cable once the room was active. If your event was within range of any kind of radio or cell tower, the interference was just too great. Murphy’s Law was in full effect.
If you can run AC, you can run DMX!
This statement has held true for a very long time. Wireless DMX was not quite the instant revolution as advertised in the early 2000s, and the technology itself has had to go through many changes over the years to stay relevant in the market. Lighting technology is very typically outpaced when competing with other technologies, and WDMX is a very clear example of this. The Google purchase of the broadband spectrum in 2007 proved to be a challenge for WDMX manufacturers as they were forced to rethink how data packets and network space can be handled. Today we approach any WDMX network with caution, and there are some very clear pitfalls to avoid when working with Wireless DMX.
The Major Concern: Gear Choice
First and foremost, there are key elements of any show that must be addressed when planning to use WDMX. The biggest pitfall to avoid is utilizing lighting gear that does not hold DMX value when signal is lost. This is a big one, and more common than you might realize. When a lighting console is sending data to a dimmer rack, moving light, or LED fixture, a break in signal means the data is no longer sending, and control is lost. If the equipment is designed to hold its signal, then no immediate visual changes occur. Some older LED fixtures were not designed to hold signal, so the light ends up turning off when the signal is lost, and when signal is regained, the light turns back on. As a lighting designer, this is madness, followed by regret. Any fixtures that rely on WDMX signal must be able to hold value, no matter what.
The other point to be made is how the gear is utilized in show. Wireless DMX is typically used for items like uplighting and area lighting in order to reduce cables running across entryways and other walking paths. WDMX cuts down on labor, especially for shows with limited timeframes for installations. The line in the sand should be firmly drawn with key show elements like stage lighting. If you are expecting something important to happen on stage, then there should be no risk of losing control of the stage wash. You can’t go to a dark stage look for video, and then not come back from it with the presenter on stage simply because Wireless DMX failed. We just are not there yet with this kind of tech. If you can run power, you can run DMX!
Wireless DMX in Today’s Market
Over the last twenty years the industry has made some notable improvements in how Wireless DMX is utilized. Companies like City Theatrical, LumenRadio, and Swisson have led the way in developing powerful transceivers (receiver/transmitter units). Wireless radios can now handle multiple universes of DMX, and radios are also featuring the use of RDM (remote data management) which gives the console better control and communication with the lighting fixtures. LumenRadio’s Aurora is a prime example of advanced WDMX:
We have also seen an uptick in competition from generic manufacturers, and often you can even find Wireless DMX tech in the simplest forms for sale on Amazon:
Lighting Manufacturers like Chauvet have incorporated wireless DMX into their professional line of fixtures for over a decade. Battery-powered uplights like the Well Fit are crucial to the event world where power is limited, and load-in time is minimal.
The Chauvet Well Fit's modern design has eliminated the need for an antenna to transmit WDMX.
Lighting companies have also incorporated wireless technology into their outdoor-rated fixtures in order to reduce the need secure cabling at outdoor events.
The Astera Titan Tube is an outdoor-rated LED tube that also features on-board WDMX. The individually addressable segments of the Astera tube give it versatility for lighting and visual effects.
ETC has even taken aim at applying on-board WDMX to the workhorse instruments like the ellipsoidal and the par. Full theatrical installations will soon see on-board WDMX as a standard feature.
ETC's newest line of fixtures, the Color Source V, features a tiny WDMX transceiver on the back of the unit.
The incorporation of Wireless DMX has been an interesting journey for the last twenty years. When utilized appropriately, WDMX is an amazing tool that can save time and effort for a show. Cautious optimism should always be applied to this aspect of our industry, and as the tech industry grows, the lighting industry will continue to follow along.