The need for coordinating license-free devices in the 2.4GHz band
Aug 18, 2011 12:35 PM, By Larry Estrin
In recent years, there’s been an explosion in license-free devices using the Wi-Fi 2.4GHz spectrum. These devices have been billed as “plug and play,” resulting in a serious misconception about the need for frequency coordination throughout the production industry. That misconception hinges on the flawed belief that the absence of a license means interference is impossible. Simply put, that belief is dead-wrong.
While it is true that a specific license to use the product is not required, there are a significant and growing number of instances in which there may be upwards of more than 50 2.4GHz devices operating in relatively close proximity to one another. These locations include almost all motion picture, television production and news studios, college and professional sporting venues, as well as live performance theaters. One of the best ways to combat this issue isn’t through a technical solution. It’s communication between all of the parties involved in the broadcast or event to ensure frequency channels do not interfere with one another.
2.4GHz devices are everywhere
The 2.4GHz spectrum is used for hundreds of devices, including portable billing devices, surveillance systems, restaurant and service facilities, and more. Of course, every user believes he has the most optimal use of the spectrum. A primary purpose of coordination is to allow the maximum use of as many devices as possible without interfering with each other. Most of these devices have multiple channel settings within the 2.4GHz spectrum. Coordination in advance allows for all the devices to work without conflict or disruption.
No production is immune to interference. Sometimes, however, it is at larger events where frequency coordination is paramount. A recent example of this can be seen when technicians were coordinating wireless devices for the recent telecast of the NHL draft.
“At the recent NFL draft at Radio City Music Hall, a 2.4GHz wireless intercom system was fired up,” recalls Ralph Beaver, manager of the NFL Game Day Coordinators. “Immediately, the NFL IT people were trying to find out why more than half of their many, many laptops in use in the hall had slowed or stopped.
“CP Communications technicians on-site immediately recognized the problem and very quickly changed the settings on the wireless intercom system so as not to occupy that much of the Wi-Fi band. At the same event, a 2.5GHz wireless camera was turned on in the theater. The camera wreaked havoc with the other wireless devices until it was adjusted so that it would not conflict with the 2.4GHz devices.”
Human element is key to coordination
Michael Mason, president of CP Communications, believes that one of the best ways to work through this issue is simply communication.
“The fundamental principles of coordination are cooperation and the sharing of information,” he says. “There is no difference if you are using 500MHz or 2.4GHz. All parties using RF need to communicate with each other so a plan can be put together to ensure a successful show.”
“The challenge with the 2.4GHz band, as well as all other license-free bands, is the lack of understanding that license-free does not mean coordination free. In large venue events, such as NFL’s Super Bowl or MLB All-Star Game, great expense, (both time and money) is put forth on frequency coordination,” explains Mason.
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