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 http://www.lynxbroadband.com.