But we are concerned with wireless microphones, and this commercial uses a lot of wireless technology. All of the mics in the shot are live: Shure got 160 channels of wireless working in one location at one time! That's a lot of frequencies. In addition to making a nice feel-good commercial, it reportedly set some sort of record for the most wireless mics in use at one time. All of the wireless mics were from Shure's UHF-R series.
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First, here's the video from the 160-channel wireless shoot:
And here's Shure's press release for how it happened. It gives some of the technical details for the antenna distribution and frequency selection as well:
160 Channels of Shure UHF-R Wireless Used for T-Mobile Flash Mob Event
Shure Mics Performed Perfectly at the Largest Karaoke Event in the World
NILES, IL, May 19, 2009 — Hand Held Audio Ltd (HHA), a leading tour production company based in the UK, supplied 160 channels of Shure UHF-R wireless microphones for the latest T-Mobile flash-mob advertising event. Several Associates from Shure Distribution UK (SDUK) provided technical support for the karaoke style event, which was a world first and the largest RF event of its kind ever recorded.
Led by international pop/rock star Pink, more than 13,000 people descended on London’s Trafalgar Square to sing hits, including “Hey Jude” and “Is This the Way to Amarillo?” Members of the crowd were supplied with 160 Shure wireless microphones, including the Beta 58A® and SM58® models, each transmitting on independent RF channels. Footage from the event will be used to produce a series of television advertisements for T-Mobile, some of which can be viewed here: http://www.youtube.com/watch?v=orukqxeWmM0
HHA was responsible for deploying the wireless technology for the event and determined that 160 wireless channels were required to meet the needs of the project. Faced with such a massive technical challenge, HHA called on Shure to assist during the planning and to provide onsite support throughout the event. The final frequency plan comprised 162 channels (two extras for Pink) occupying 518 MHz to 865 MHz.
Providing coverage for all of Trafalgar Square, which measures 100 meters by 60 meters, presented a significant challenge because every microphone needed its own channel, as they would have to run alongside each other simultaneously all day. In addition, the busy RF environment in Central London and the potential inter-modulation between frequencies also compounded the problem of successfully isolating enough frequencies.
“We decided to use Shure UHF-R, as it offered the best in current radio mic technology and frequency ranges needed to make this work,” said Tarkan Akdam, Technical Manager at HHA. “The antenna system, designed to feed the 80 dual receivers, had to have enough gain to provide sufficient levels of coverage, but not too much that inter-modulation and RF interference would cause problems. It was a question of getting the balance right.”
“We opted for a four-way antenna system, with passive Shure wideband paddles [PA805SWB],” he added. “I designed and built a four-way wideband, low noise, high gain RF head amp system, all interconnected with over 400 meters of double shielded Triax cable.”
This set-up ensured that voice data from every microphone would be picked up, while minimizing interference from other RF channels. A second pair of Shure active wideband antennas were installed on the broadcast truck aimed at Pink’s podium to guarantee coverage for her microphone. To properly distribute the RF signal, Tarkan opted for 21 Shure UA845 antenna distribution units.
“Isolating 160 channels is a big task in any location, and being in the center of London made this an incredibly technical and precise task,” Akdam explained. “We faced several issues. Trafalgar Square is already a busy RF environment, with frequencies in use by local business, TV stations, and theater productions in the nearby West End. We needed to take into account any local TV transmitters so we didn’t interfere with anyone else whilst ensuring that the singers’ voices came through crisp and clear. Sufficiently strong wireless coverage, to ensure we picked up all the mics, was a must.”
Before the event, several field strength tests were conducted to check for potential interference and ensure that all 162 channels would run alongside each other.
“We ran tests initially with 40 channels, and the day before the event we had 160 running at once,” Akdam commented. “The task was incredibly daunting, but on the day it went off without a hitch, and we are very pleased with the result. The Shure mics and UHF-R equipment worked superbly, with voices of the singers delivered seamlessly to the receivers. In terms of size, we believe this is a world’s first in RF events.”
“Events of this nature require resources and having fewer things to worry about is always a great help,” he added. “I knew with Tuomo Tolonen from SDUK, I had the full backing of Shure…which in turn meant I was a lot more positive that we could achieve what we set out to do. Using the knowledge of the application engineers put me in a better position to cross any technical hurdles.”
Courtesy Shure Bros. Used by Permission.
As usual, if you have difficulty with the video, click on the article's title ("160 Channels of Wireless...").__________________________________________
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