Prepare now for the arrival of DTV

On Feb. 17, 2009, in accordance with federal law, all television broadcast stations in the U.S. will stop broadcasting in analog and begin broadcasting in digital format only. This changeover will free up crucial frequencies for public safety communications by police and fire departments and will enhance consumers’ experience by delivering improved picture and sound quality.

But the switch to digital also has profound implications for organizations that have developed infrastructure based on an analog TV delivery model, such as school districts. After Feb. 17, schools still relying on a traditional radio-frequency (RF) coaxial cable infrastructure for broadcasting television might find they are no longer able to access any television content in their classrooms.

The traditional RF coax model was initially designed only for real-time receiving of video in the classroom, and it was limited to a television display in the classroom or hallway. To use this RF model in today’s classrooms already requires a stand-alone television tuner or tuner card in every teacher’s computer to access television channels–a costly solution that is hard to operate and support. Include a media retrieval system, school news channel, and other visual resources, and this traditional model presents even more challenges to support and use. With the new standard of DTV, the requirements to make video delivery work on a district’s present RF network will require additional major updating.

While some schools will have 1 GHz RF networks that can support digital TV, the traditional model of RF cabling in most schools uses a trunk-based configuration with a series of taps where cables drop off for each display device; thus, one classroom accesses the content stream before it reaches the second classroom, which accesses the content stream before it reaches the third classroom, and so on. Most trunk-based systems in schools are insufficient for schools to run digital broadcasting content.

Not only is there loss of power at every tap, making it difficult for the signal to be accessible at more than a few classrooms down the line, but the system was likely not designed to carry digital signals in the first place. The coaxial cable and network used in most schools have a bandwidth of 750 MHz or less, while 1 GHz or better is required for DTV. School districts must ensure that key system components–including amplifiers, taps, end devices, and tuners–are digital-ready, or else upgrade them to accommodate DTV. Finally, the system must be rebalanced to handle the new digital load.

Installing or upgrading to a digital-ready system is necessary not only to access digital content, but also to take advantage of the other services that DTV can provide. There are 18 formats in DTV, including SD (standard definition) and HD (high definition), and all of these formats provide a way to send other digital information as well.

Take what the Wisconsin Educational Communications Board (ECB) is doing with data casting, for instance. Data casting is a means of sending data such as documents, video, and still images over part of the DTV channel for storage. ECB is using it to send video with teacher guides and other information to all the schools in Wisconsin via digital broadcast. Each school has an antenna that receives the information and puts it on the school’s video network server for playing whenever a teacher or student needs to access it. 

HDTV is the highest quality of picture that DTV provides, with more than two million pixels of screen resolution–four times the quality of traditional television. This is the quality of picture that our students have come to expect. With educational broadcasters such as PBS taking a lead role in producing content in HD, and with the end of analog transmission in February, I project that most stations will be producing as well as transmitting in HD by the end of 2010.

So what is the new model for schools and districts that will accommodate the required change to DTV? As districts move to Gigabit Ethernet as their network standard for local and even wide-area networks, the LAN or WAN becomes the driving force for all visual resources. Schools’ IP networks can bring information into the classroom in a way that is cost-effective, easy to use, and based on standards the district can support, unlike a separated cable system such as RF coax. Some school districts, like those in Kirkwood, Mo.; Garland, Texas; Volusia, Fla.; and Chicago already have or are installing high-speed networks, and they are now seeing the benefits of having their television broadcast on their WAN network. 

Centralizing equipment to support TV channels at a single point could save millions for larger districts. No longer do they need to provide separate networks for RF and for data, nor do they need to provide separate equipment for receiving the signal. There is also the benefit of providing centralized management of this information and delivery to and from all the schools in the district from a central point. This model of network delivery enables the implementation of a district-wide video-on-demand and digital media management system, a solution that facilitates visual instruction and learning in the classroom.

DTV and its integration into school networks is the future of receiving, managing, and providing broadcast resources in our schools. The traditional RF cable system will not be supported or maintained in schools; its limited delivery, as well as the cost to upgrade, will make it useless. Districts must look ahead to their new school construction projects and renovations to make sure they are putting in or upgrading delivery systems that can support the classroom needs of both today and tomorrow.

Tim Beekman is president of SAFARI Montage for Library Video Company