"Bulldogs Three Level Stadium"
Dec 12,2014 by Dan Daley
Sanford Stadium implements multiple digital networking platforms.
Like all of college football's classic stadiums, UGA's Sanford Stadium is nearing its centenary mark, and like its aging siblings, it remains a remarkably robust work in progress. The 85-year-old stadium in Athens GA (home to the famed Georgia Bulldogs) has undergone numerous updates and upgrades; in this century alone, it added a second upper deck on the north side and 27 new north-side Sky Suites, bringing the new stadium capacity to its current 92,746. That makes it the fifth largest on-campus stadium in the country and the seventeenth largest in the world. Architectural plans have been on the table for some time that could take it past the 101,000 mark.
Its AV systems have similarly undergone major renovations. For instance, in 2005, installation of a new Daktronics video display on the west end zone was completed, and ribbon boards were also added along the sides of the stadium. Six years later, the video board underwent a $1.4 million overhaul before the 2011 season that saw the screen's size expanded from 25'x46′ to the current 52'x76′, with full HD capability added.
But the most recent round of updating reflects the more nuanced and technologically diffuse times that modern major sports venues inhabit. In addition to conventional items found on such equipment lists, such as the huge horn-based Danley Jericho loudspeakers and four BC415 subwoofers that went into the new sound system in the scoreboard, or the Barco custom 4mm LED display that's now installed in the football program's practice facility, there are also Cisco and Extreme Networks Ethernet and Gigabit switches. These accommodate the use of three distinct digital audio networking protocols (CobraNet, AVB and Dante) that are integrated into the system design. This is a rarely seen combination and a portent for what the future of large sports venue systems will look like.
Audio & Video
The conventional systems are interesting. The Danley Jericho speakers are arrayed in a point-source configuration mounted within the scoreboard structure, except for three boxes, which are hung from the bottom along a grated floor and anchored to the superstructure. Pete Dugas, President of TSAV (tsav.com), the AV integrator whose backyard the stadium is just about in, said that, although the simple, straightforward horn design of the speakers gives them much of their effectiveness, the system design was a bit more complex, but ultimately reaped additional efficiencies.
“It's a huge bowl to fill with sound. One approach might have been to just throw gear at it, but that's not the way to achieve cost effectiveness," said Dugas. Instead, despite a tight project schedule, engineers from TSAV and Danley took acoustical measurements, with the former using AFMG's EASE and Bose's Modeler software, and the latter using both EASE and the company's own proprietary modeling program. The intent was to have two teams acoustically model the field separately, then overlay the results on top of each other, with their conformities constituting a design path. That task fell to Dugas, who offered that the few differences betweenthe two outcomes were negligible compared to how much the two measurements conformed to each other. “They were so similar that the probabilities of those being accurate were very high," he said. “Basically, we were leveraging our resources at each company and creating a synergy that ended up giving us a design we had a lot of confidence in and one that would also save the client money."
Critical Speaker Aiming
There is little opportunity for acoustical treatment in this massive a bowl, so speaker aiming became critical for avoiding reflections and standing waves, particularly off the four stories of glass-fronted Sky Suites that occupy one side of the stadium. And this project encountered an odd but not-unheard-of issue: low-frequency energy from subwoofers mounted in scoreboards as part of point-source systems. In this case, the solution included reinforcing the scoreboard itself and adjusting the subs' crossover point.
Although the point-source system manages to cover the vast majority of the open areas of the stadium, a substantial number of fill speakers was still needed to cover under-balcony areas. These were Electro-Voice PRO-8AT30 eight-inch coaxial speakers. “Every seat that you can't see [from the scoreboard] is covered by a perimeter speaker," said Dugas, who stated that the total count is right at 500 (60 new PRO-8AT30s and the rest reconditioned existing speakers), underscoring how challenging the Sanford bowl really is.
The new video addition is an 18-foot-wide Barco 4mm dot-pitch LED screen installed in the stadium's practice facility on campus. The 16:10-aspect ratio screen reaches a respectable 720p but was not intended to be a very high-definition display. It is used primarily for replays and other teaching content for the team, as well as serving as the video backdrop when the facility is used for live events for alumni and team supporters. The practice facility is also one of several sports venue “nodes" on the campus' broadcast network, including its baseball, softball and soccer fields that have fiber home runs back to both the central broadcast control center and the stadium.
Networking is first encountered with the PA system. TSAV chose the Dante platform as the protocol over which to transport the stadium's main bowl audio from the house mix position and other key audio sources to the system's racks. However, the Danley sound system's amplifiers are only compatible with the CobraNet platform. The translation between the two formats occurs at the network switches, where Dante's Layer 3 protocol meets CobraNet's Layer 2.
The use of two separate networking platforms underscores how that aspect of system design is changing. Where before a single network type might have been chosen for an entire project, with that choice of platform based on compatibility with key system components, in this case, the networks were chosen based on applications. “The Dante is a more robust platform, and that's what we wanted for the main audio transport," said Dugas. “We wanted to have our control elements [including the Crestron CP3 control processor and the 50 five-inch control touchpanels located throughout the facility] on the Dante network. The Danley amplifiers are not compatible with Dante at this time–that's in their future roadmap—but we had to accommodate what was available, so we had to interface the Dante with CobraNet at the amplifiers."Done Between Switches
That was done between the Cisco and Extreme Networks switches, the ones recommended by Biamp's engineers for use with its Tesira processing system that was part of the system design. Dante is also compatible with the Yamaha CL1 48 mono/eight stereo channel FOH console at the stadium, which uses an Audinate 16-channel Dante I/O card. Keith Reardigan, TSAV's Project Engineer, amplified that, saying, “We are uplinking the Dante Network via the 100MB uplinks to another set of control-network switches at the amp and processing racks. These network switches are connected to the CobraNet connection of the amplifiers for the sound system's main speakers. We are not using the CobraNet audio protocol, but rather leveraging the CobraNet control protocol for amplifier on/off control, temperature and fault monitoring.
“The Dante primary and secondary switches are QoS-commissioned for Dante; control/CobraNet traffic is not allowed on the Dante switches. Control/CobraNet and Dante traffic are shared on the fiber connection between amp and processing racks, but the Dante traffic is prioritized. It was a little tricky to commission and would have been easier if the proprietary amplifiers were Dante enabled, but it's solid as a rock now that it's up and running," Reardgigan explained.
Extreme Networks L3-capable Gigabit switches are the interface between another pairing of disparate networks, where the Dante signals met up with those using an AVB network. AVB was used for audio signal transport across the 50 Sky Suites in the stadium, managed by the Biamp Tesira processor. The Sky Suites system design was based on the need to support a particularly UGA tradition, one of listening to local AM and FM radio announcers calling the game, even if one is doing so from the lofty perch of a luxury stadium suite that might offer its own HD televisions. That entailed getting eight centralized radio tuners to feed the 50 suites' touchpanel controllers. Dugas said that the AVB portion of the network “worked very well to shield the radio signals from the sheer amount of RF that crisscrosses the stadium."
Dense RF Environment
The already dense RF environment of a mega sports stadium is becoming even more so, with the addition of more WiFi and cellular signals. That was the case at Sanford, where AT&T has invested $10 million to alleviate connectivity issues for its customers who attend football games at the stadium. The company has installed a new head end and distributed antenna system (DAS) that is designed to greatly enhance the mobile internet coverage during games and reduce the drop rate to almost zero. The key is the more than 400 antennas installed throughout the stadium to handle the demand of phones in specific areas. AT&T also doubled the wireless capacity outside the stadium, and in and around Athens, to improve coverage as spectators tailgate and drive into the stadium area, according to The Atlanta Journal-Constitution.
TSAV's interaction with the DAS installation came in the form of it becoming one more installation vertical that was taking place as the AV systems were going in. Dugas said that TSAV was hanging speakers off the scoreboard at the same time that AT&T and Verizon crews were installing their repeatersand antennas. “We had a great cooperative experience with them but, just as you need to have with electrical or mechanical contractors, it required a high level of coordination between everyone," he said, “especially because the idea of DAS in such a large facility is still pretty new. Between broadcast, intercoms, athletics radios, even Homeland Security, RF in sports venues has become, well, 'interesting.'"
Looking back at the networking aspect of Sanford Stadium, Dugas sees a threshold crossed, with the integration of three distinct digital audio networks, two of which are still relatively new in the AV systems environment. Getting them to play well with each other required a higher level of interaction and engagement between a wider array of entities; According to Dugas, TSAV engineers were in regular contact with their counterparts from Audinate, Danley, Yamaha, Extreme Networks, Cisco, Biamp and other manufacturers involved in the project, sometimes having to get different parts of the answer to a single question from multiple sources. Fitting those kinds of pieces together is going to be a regular part of the next iteration of AV systems designs and installations, he believes.
“There were a lot of different aspects to this that covered AV equipment and networking, and control and processing, all at once," he said. “For instance, how not to saturate the Crestron control network over so many end points alongside the AVB and Tesira platforms meant interacting with a half-dozen manufacturers just for that piece. It's a tremendous amount of work. This was a time-compressed project where the ratio of hours to days was pretty high. But that's what it takes when you're working across this many different platforms. The payoff, though, is a much more efficient and cost-effective system. The finished system is impressive and works very well."
Dan Daley has covered the confluence of technology, business and culture for almost 30 years. He has also been a successful composer and recording studio owner, and authored the book, Unwritten Rules: Inside the Business of Country Music.