Aerial Video Systems Supports First Native HD Marathon
Monday, 28 December 2009 12:25
By: Carolyn Braff, Managing Editor | Sports Video Group | Published: December 22, 2009

Aerial Video Systems has been supporting the coverage of marathons since the company was founded in 1981, but on Sunday, Dec. 6, AVS took that coverage another mile. The company provided wireless HD camera links for the first successful native HD marathon production, the Rock ‘n’ Roll Marathon in Las Vegas, which aired live on KLAS-Las Vegas. The HD production utilized only terrestrial receive sites for all 26.2 miles.

“We’ve been able to do HD for four or five years now,” explains Randy Hermes, owner of AVS. “If the opportunity had come earlier, we would have done it earlier, but no one had wanted to pay for it before this.”

Bringing the cost down for the December production was new software and technology from Link Research and MRC. Link HD/SD 1500 microwave systems transmitted both video and audio signals from custom-equipped pickup trucks to receive sites located at The Hotel at Mandalay Bay and The Stratosphere. Each rooftop utilized four antenna diversity receivers with maximum ratio combining, one each for the lead female runner and lead male runner.

The receive sites were linked via microwave, using a new long-delay packet switching feature from Link Technology. That feature allowed AVS to “daisy chain” the receivers from both sites, creating a temporary cellular diversity system to automatically capture the signals from all eight antennas.

“On a normal system, you have a receiver that has four antennas, which is a complete diversity system” Hermes explains. “It combines the signals, picks the best, gets rid of the bad, and sends it out. We took that signal and hopped it over to the Stratosphere, where we had four more antennas.”

However, rather than merely switching between the two receive sites, as had been done in the past, AVS set up true diversity switching of the ASI feeds from all of the antennas on both sites.

“The system could have used one antenna from Mandalay and one antenna from Stratosphere, if those were the two best antennas, and made a signal out of it,” Hermes says. “In other words, there was no manual switching whatsoever. Complete diversity, eight antennas hooked together via microwave – that had not been done before.”

Once all of the signals were collected, the HD feeds from the lead female runner and lead male runner were then mixed together to form a single ASI stream, which was transmitted to the KLAS studio on a single microwave channel. At the studio, the stream was decoded back into the two individual HD signals.

“There’s always a problem with frequencies, so we wanted to use every bit of technology to make it work, and serve as a test, also,” Hermes says. “We could have done it much easier and safer by putting two paths up and sending two paths down from the last hop, one with the male and one with the female, but I wanted to take it to the next step, test ourselves, and see how much stuff we could jam in there.”

The Las Vegas Marathon utilized a staggered start, giving the elite women a 20-minute head start over the elite men, with the hopes of creating a dramatic foot race finish. To highlight that aspect of the race, KLAS utilized AVS’ GPS-driven marathon course map to plot the locations of the lead runners and their positions relative to one another. The result was picture perfect.

“We had 95 percent coverage, so the show was pretty perfect,” Hermes says. “The only challenge was logistics, getting all the people and equipment in all the different places it needs to be.”