Who Stole My Bandwidth; or Wireless Device Management

June 12, 2009 was a historic day marking when broadcasters switched from analog to digital transmission of on air programming. Previously, the frequencies (54 MHz-806 MHz) encompassing TV channels 2-69 in the VHF and UHF spectrum were no longer available to musicians, AV companies and TV/film production houses. In fact, we had to send our old wireless mics to Shure for shredding.

With the switch to digital transmission, broadcasters are required to operate between 54 and 698 MHz. This leaves the 700MHz bandwidth open for the FCC to broadcast public safety messages. It's now illegal for AV production and rental houses to use the this bandwidth range, causing a major overhaul of costly UHF wireless systems. The switch from fixed to frequency agile systems also became paramount for users because of the reshuffled D-TV transmissions.

The new UHF bandwidths designated for wireless audio systems are low-band UHF (450-698 MHz) and high-band UHF (900-1GHz). The 900 MHz bandwidth is undesirable for wireless manufacturers because it already has primary and secondary users, including STL (studio to transmitter links), and consumer products like cordless phones and home AV repeaters.

This leaves the low-band UHF (450-698 MHz) for the growing number of wireless devices. The average corporate production is comprised of many wireless microphones and instruments, IEM’s (in ear monitors) and more. This leaves an AV specialist with the daunting task of managing as many as 20+ frequencies within a narrow bandwidth, all while dodging around the local D-TV transmissions.

Luckily, computers come to the rescue! Computerized scanning software and hardware (i.e. free download, Shure Wireless Workbench) help AV specialists see what signals are present. These programs help bundle channels in non-interfering groups.

Some programs will automatically assign frequencies to open units allowing for the maximum number of devices in a given bandwidth. There are also new high-tech systems that detect outside frequency interference and warn the AV specialist; or automatically switch to a clear frequency making it undetectable to the listener. These new systems are costly, but it will ensure that your chairman or CEO's mic will not fail.

High-tech systems notwithstanding, your best solution to wireless device management is careful planning and coordination before load-in. Implementing both will ensure a flawless presentation and impress your client.

______________________________________________________________________________
Craig Vlasic | Technical Director/Audio

Joining WAV in 1982, Craig was the first full-time employee. In 30+ years, Craig has engineered over 700 meetings with audiences ranging from 20 to 35,000 people. While current in the latest audio techniques and theories, he brings knowledge in fundamental audio logic to every production from corporate talking heads to rock-n-roll bands.