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By Mike Tosch,
Frequency Coordination Team Member and KPBS-FM Chief Engineer
Frequency Coordination at SuperBowl XXXII consisted of two teams working together. They are the Helmet Communications Team and the Frequency Coordination Team. The Helmet Team takes care of communications for each quarterback who has a receiver in his Helmet to hear the plays given by the sideline coaches. He cannot talk back. This system uses encrypted audio to protect it from reception. Each NFL team has a small repeater and the special helmets to do all this. The Helmet team had one person on each sideline during the game and one person to be in the press box area and run around to chase interference if needed.
The Frequency Coordination team also had three people. We had three DF (direction-finding) stations to monitor and locate any possible interference in the 450- 800 mHz bands, during the game. Two of the DF stations are actually in the stadium and one outside in our co-teams trailer in the International Compound where NFL Films was HQ-ed.
The locations in the stadium were pre-selected before I had arrived to be on the team. They were located in the press box area, on an overhanging camera position at about the Denver 35-yard line. This location was just below the CBS Radio broadcast team. The second stadium location was at the east end of the Stadium, next to big scoreboard, on a 30-ft. high, raised scaffold.
The Frequency Coordination team was lead by Karl Voss, an engineer from KPNX-TV in Phoenix. He has done this job for the last three Super Bowls. John Weigand of channel 69, KSWB, is the local San Diego County Frequency Coordinator and was on the team. I was the final member of the team.
During the game, Karl was inside the trailer with a DF station and a spectrum analyzer. In the stadium, John was stationed at the pressbox location and I had the scaffold location. Our DF gear consisted of an Icom general communications receiver, Doppler Systems DF Unit and antenna system, a Communication Specialties PL/DPL/DTMF decoder, a two-way radio for our own coordination and a set of Sony headphones to be able to hear all this during the noisy game.
The antenna system consisted of four rubber-ducky style antennas mounted in a square on a common ground plane "plate". The plate was mounted on a very sturdy, photographic style tripod. All this gear was designed and put together by Control Dynamics of Philadelphia. This company was led by Harvey Shuhart, who also led the Helmet Communications Team.
The DF equipment was designed to work mostly in the 400-800 mHz communications band. Its primary use was to be able to deal with interference to the Helmet radios, coordinated two way radios and any of the zillion wireless mic freqs in use during game week activities and during the pre-game, half-time and game-times.
The NFL is very concerned about interference, as it should be. They would like to go so far as to have DF stations and frequency coordination teams and DF equipment in every stadium for every NFL game. Until this is funded, the Super Bowl gets the prime treatment, at least. Frequency Coordination begins far in advance of the actual event and encompasses many hours of work for Karl Voss, the Super Bowl Frequency Coordinator.
All frequency users from "DC to daylight" had to submit requests for their respective spectrum needs to Karl Voss months ahead of time. He compiled these into a database and assigned open frequencies as needed. He was made aware of local users by the local Coordinator, John Weigand and coordinated visiting media to other frequencies. Local licensees were free to use their own two-way, wireless mic, IFB, ENG, STL, and ICR without any notice to Karl. If local users could give up their frequencies, the offer was taken and re-assigned to others as needed. Even with all this ahead-of-time planning, minor problems and last minute requests are quite usual. Coordination conflicts and last minute requests were handled by Karl himself, having the database knowledge to find a channel. When conflicts are presented, Karl attempted to always handle them in a cordial and professional manner. No role of Frequency Police was assumed or performed and the goal was to get all parties to cooperate and work things out to the best ability of everyone involved.
At times, I would see Karl on the phone, endlessly trying to have someone exchange a frequency or make sure they were off the air at a certain time, so as to share a common channel. This was mostly the case with the 2-2.5 GHz ENG channels used for video.
Other efforts were to listen to channels on the trailer DF unit and attempt to talk to offending users. Karl had programmable two-way radios that he could use to get on any frequency that was being interfered with. He would gracefully talk to the offending user and try to assign them a new channel.
Most two-way radios were distributed to users on site by a rental company or were brought to Super Bowl already re-programmed to coordinated frequencies. Wireless mics also have the ability to be frequency agile, so these were programmed according to coordination. Most video ENG transmitters are also agile and the assigned channels were, for the most part, graciously accepted and used.
By now, most large media organizations that show up at this caliber of an event understand the concept of frequency coordination. That is not to say they were not problems. Some problems were resolved and some un-resolved, or some went away without our understanding of what had occurred.
One such instance involved a local radio station using their TV station's 7 GHz STL subcarrier for their digital audio STL path. Karl arrived at the trailer the very first day and was handed a phone to call the station engineer to discuss this problem. The alleged interference to the STL had made the link unusable. This problem persisted and then we heard no more about it. The interference was not found to be Super Bowl related and the station resolved the complaint themselves.
Another problem that cropped up was interference of one of the small portable repeaters brought into the stadium for concessionaire personnel. It was being keyed up and not releasing after a two-way stopped transmitting. The repeater had just started doing this and it was thought that something to do with Super Bowl was at fault. Karl and the rental communication companies technician met up in the light ring where this temporary repeater was positioned. It was found that 40 watts of output RF was too much for the input receiver. Besides, 40 watts was not needed to cover the stadium! The repeater was being de-sensed by it's own output. Turning the output down to 20 watts was all it took.
In another instance, we discovered that the San Diego Police Department Helicopter was equipped with a video transmitter that fell almost, directly on video ENG channel 9. Channel 9 minus and 9 plus were assigned for use by two different blimps for NBC. The police were not coordinated, or licensed. Even John Weigand, the local coordinator didn't have this operation locally coordinated. Karl got on the phone with the police seargent in charge of this helicopter and got him to order another transmitter from the manufacturer to shift him to a different channel they were licensed for and everyone felt they could work with. The police ended up on 8 plus and the blimps stayed where they were originally assigned. By careful coordination with a local user, the blimps shared several channels together at different times. The whole situation was not without problems though. The police receiver on 8 plus was being bothered by a blimp on channel 9 minus and even a blimp that using 10 plus. One blimp did move to a local users channel to avoid this interference. The police did, finally, get a STA (Special Temporary Authorization) from the FCC for both of their channels.
The 2.0-2.5 GHz ENG band is very crowded, locally, and cooperation is a must. Another problem actually got the FCC involved the Saturday night before the big game. The B-2 Stealth bomber was to do a fly-by with a chase plane providing video to NBC via a ground-mounted military relay station. The link to the relay point was being interfered with by something the FCC DF-ed back to the area of the NBC compound. No direct cause was found and we have no further information on the incident. We do know the video from the chase plane, despite all the effort by the military was not broadcast as planned. I am sure Mr. Grigsby of the FCC did not enjoy being called to action late that Saturday night.
The last incident to share is an incident that proves the reason the whole Frequency Coordination team exists. On game-day morning, we discovered that one of the concessionaires had showed up with 160 two-way radios on a channel that was not coordinated for them. And they were using it. The channel they were using was the exact same channel as that of the quarterback helmet for the Denver Broncos! 160 radios had to be brought back in for reprogramming. Since these were programmable Motorola radios and the Helmet Team had the software and laptops, they met with the concessionaire's communication technician and began the process of reprogramming 160 radios. Each took about 30 seconds in clone-radio mode and the user was back to work. Apparently, 30 radios never made their way back, and could have caused a major headache. No transmissions were ever heard again.
One other item we were watching very carefully was the use of five FM broadcast channels for broadcast inside the stadium during the game. The use was meant to have four audio feeds for fans in the stadium to hear play-by-play provided by the two home team broadcasters, CBS Radio Sports, or NBC-TV. The fifth source was for the bathrooms, where small tuned FM receivers were mounted to allow fans to hear the plays at all times. The bathroom transmitter used a half-watt of RF power and a mag-mount antenna located just outside the main audio booth on press level. The other four signals were transmitted using Crown FM Exciter/Transmitters set for three Watts, each driving individual Scala single element folded dipoles, using simple RG-58 coax. These were hung from the press box level over the fans below, about 30 feet down. Every seat in the stadium was provided a souvenir cushion with miscellaneous handouts including a small FM radio, batteries and headphones. Frequencies were chose for these five transmitters so as not to interfere with local broadcasters. Most frequencies chosen were second adjacent to the locals.
During the game, everything was very quiet on the interference front. Karl sat in the trailer, listened to the game on the spectrum analyzers audio output and waited for problems to occur, while John and I manned our locations to wait for a call to action. While scanning around the band, I did identify what I thought was a motor-boating transmitter, keyed down in the 450-451 mHz band. A call to Karl in the trailer relieved the concern, as it turned out to be a coordinated channel carrying data for a blimp camera. We had wired the Sony headphones to be able to hear the two-way in one ear and the comm receiver in the other ear, with each receiver having independent volume controls. Those headphones also kept the stadium noise way down in my ears. I am thankful for that. I had brought earplugs, just in case.
While things were quiet, I was able to put the communications receiver in wide-band FM mode and listen to the temporary FM signals with play-by-play on them, and just watch the game. I took my camera and snapped many pictures for the picture album. I was probably the first to see the B-2 coming toward the stadium from the east. What a sight! The picture I have of the B-2 directly over the stadium with the scoreboard in the picture is a sight I will never forget. Too bad, NBC didn't give me a PL headset, as I could have alerted them to the B-2's sudden approach. It didn't make it to TV until it had flown over the stadium and into the fireworks smoke.
After the game, we packed our gear in the travel cases and had a cart pick us up. We were done. The big game went off without a hitch.
Proper planning and coordination for an event this massive is an absolute must. It is a very smart idea for the NFL and the media to support this concept. Next year's Super Bowl is in Miami.
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