Visual learning delivered on Cat 6A cable

A close-up of a Lynx hub on an equipment rack.

Two months before the completion of a new district office building for California’s Manteca Unified School District (MUSD) in the summer of 2008, a decision was made to install TVs for key administrators to stay informed on important matters affecting the 36 schools in the district. Making the project all the more challenging, the three-story building did not include an infrastructure for a TV system.

Enter Eric J. Marshall of E.R.I.C. Consulting from nearby Modesto, who specializes in designing technology structures for buildings and has provided consulting and design services for 12 MUSD school projects. One of those was the Mossdale K-8 School, which served as an example for the district office. Both facilities are in nearby Lathrop.

Like the district office project, Marshall was contracted after construction of Mossdale was well underway. In fact, three of the buildings on the school’s campus were already partially built and had a three-quarter-inch conduit infrastructure already installed.

Bottom line: Marshall was able to make significant upgrades to Mossdale’s technology infrastructure before the school’s completion in spring 2007. Two key elements of his solution were Sc/FTP cable from Siemon Cable and RF baluns from Lynx Broadband.

“The tools that helped my company get creative with both projects were hubs and baluns from Lynx Broadband,” Marshall said. “I used them before and found them to be extremely reliable because they’re well-designed and have no moving parts. They’re also easy to install on a rack in a wiring closet, where they convert television on coax to television on Cat 6A.”

The biggest difference between Mossdale and district office projects was how they each receive TV signals. The school uses Comcast cable TV that delivers 72 channels and requires a tuner at each teacher station for channel selection. However, cable is not available in the area of town where the new district office is located, so it uses satellite TV from DISH Network, which needs a receiver to unscramble channels and convert them to baseband video.

Delivering TV signals over data cable

The original plan at Mossdale, which was designed by an electrical engineer, called for Cat 5E cable to each room. The plan also included coaxial cable to a TV outlet for a wall-mounted TV monitor next to a whiteboard.

However, long after construction had begun, the district wanted to upgrade the video infrastructure plan and deliver TV signals through a computer at a teaching station in each classroom to the room’s A/V system. In addition, the district wanted to upgrade the data infrastructure to support 40 GB capability at a later date.

E.R.I.C. Consulting’s recommendation to use Cat 6A and Sc/FTP cabling allowed faster transmission speeds and the flexibility to modify teacher stations as technology changes. But the solution appeared to create another a major problem, namely pulling those two cables through the conduit that had already been installed left no room for coax cable to deliver TV signals.

Marshall knew Lynx video hubs and baluns would remedy the situation. The baluns convert unbalanced signals from cable, satellite and other video sources into balanced signals. They are then sent over Cat 6A, thereby eliminating the need for coax in the conduit.

According to Marshall, there were three main reasons for delivering TV signals through a computer at the teacher station. First, the computer could record programming like a DVR, which in turn provided real-time control of the signal during class (play, pause, rewind, fast forward) and the ability to record programs during non-school hours.

Second, the TV could be seen on the computer screen, as well as run through a ceiling mounted projector and shown on a large (8 ft. x 6 ft.) screen, so students could watch from their desks anywhere in the classroom. The A/V system also included overhead speakers.

Marshall said the third reason for this infrastructure change was to save lamp life, because the teacher can preview programs after hours without turning on the overhead projector. In addition, this setup saves on the cost for purchasing and mounting TV monitors.

Connecting all the dots

The Mossdale School is now fully enrolled with more than 600 students from a community of 16,000 residents. The campus includes a kindergarten building with four classrooms, three separate wings with 10 classrooms each, another wing with two science rooms and four classrooms, a multi-purpose facility, and an administration building.

The main cable TV signal comes into a headend closet at Mossdale’s administration building. From there, it’s delivered by single-mode fiber cable to a fiber receiver in a closet in each building on campus. Next, the signal travels over coaxial cable to a Lynx hub, which converts it to a balanced signal and sends it through a patch panel to a classroom. There the signal goes through a balun that converts it back to an unbalanced signal before it enters a computer equipped with a WIN tuner card. (See diagram below)

The administration, kindergarten, and multi-purpose buildings each have one Lynx eight-port hub, while the four classroom wings each have a 16-port hub. The hubs provide more ports than are currently needed, which means Mossdale can easily add additional computers and video projectors.

“Teachers and administrators have all stated positive feedback and are very happy with the system,” said Sandy Dwyer, MUSD’s director of facilities planning. “The hardest part was getting them (teachers) all trained and understanding the system. Once trained, they love it.”

All told, the technology structure at Mossdale cost approximately $35,000. This included Marshall’s consulting and design fees, cabling, equipment, installation, and testing.

Doing it themselves and saving big

The price tag for designing and implementing the satellite system at the new district office building was less complex and cost about $5,000, Marshall estimated. The main reason was the district used his simple design to install all the cabling and equipment themselves.

Marshall’s plan called for TV programming to computers in offices of four key administrators to help them stay abreast of news and events that might affect the school district, including weather, emergencies, and special events.

Another important benefit was the ability to record and preview educational programming for possible use in the district, which operates 21 K-8 and nine high schools, an adult learning center and other facilities.

The administrators also needed the flexibility to select their own channels. In addition, they wanted to be able to move computers between offices and meeting rooms for presentations.

After evaluating several complex technology structures, Marshall designed a relatively simple solution, using another unique Lynx product called the Bobcat. The small device receives a composite video signal on a standard coax cable from any source, in this case from a satellite receiver.

The Bobcat converts the signal and sends them over a Cat 5E cable to another Bobcat unit, which converts them back to coaxial form for use by a computer equipped with a video card. The Bobcats also transport an IR remote control signal from the user’s location to the satellite receiver (on the same Cat 5E cable).

“Users simply click the icon on their computer to open their TV browser and use the satellite receiver remote control, which is identical to the ones they use at home,” he explained. “The rest of the equipment requires very little space in a wiring closet or on an equipment rack.”


The Manteca Unified School District

GREGG KELLEY is National Sales and Marketing Manager for Lynx Broadband in Burnsville, Minn. In addition to consulting with E.R.I.C. Consulting on the Manteca projects, he has been involved in several Lynx installations at schools around the nation. He can be reached at

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