Contemporary Research QMOD-SDI Integration Guide - Manual (Page 10)

Contemporary Research 10 QMOD-HD Integration
RF Integration
In this section, we will discuss the basics of RF distribution. We encourage integrators to learn more
about RF systems, Blonder-Tongue is one company that offers many resources and seminars. In
addition, providers such as Toner Cable can offer design assistance, RF distribution components,
and testing tools.
Channel Architecture
In baseband video, such as video cable or Cat5 systems, one cable can carry only one signal. To
deliver multiple sources or channels of media there must be a video switcher, with an input for
every possible source, and an output for every possible destination.
In broadband video, or RF (Radio Frequency) systems – such as off-air TV or cable; video and
audio are modulated, changed to be easily broadcast within a 6 MHz channel.
As shown above, each channel starts at a different frequency. When you change your TV tuner to
Channel 5, you’re selecting a different frequency. That’s how TV and cable can support so many
channels on a single cable. A typical in-house cable system will use about 115 channels, also called
a 750 MHz system. A really well-designed system can top out at 870 MHz, older systems and coax
cable types will carry less channels. The best approach is to use the lower channels for your QMOD
system, that offers less stress for RF broadcasting, and modern cable system uses low frequencies
for local analog TV channels – easy to block and re-use for your channels.
The key benefit of broadband RF is that one cable can carry all the channels, and all you need to
receive them is a standard TV tuner. In the analog era, there were many trade-offs in the quality of
the signal, but with HDTV, RF coax can carry HD media with much less loss from the original.
The other benefit is distance; RF coax can be driven for hundreds of feet, many miles using optical
fiber. Cable providers carry channel over entire cities, so engineering an RF delivery system for
homes, companies, and college campuses is not challenging.
Broadband is more flexible than other AV carriers, able to combine analog, SD digital, and HD
digital media.
System economy is fully scalable. You can originate a mix of analog/SD/HD modulators where
appropriate. Broadband coax is easy to expand through branching – new home run wiring is not
needed. Tune into channels using standard HDTV tuners. And you can manage displays and
channels over the same coax using our Display Express through-the-RF control system.
Wherever you need to send a mix of channels to many destinations in one facility, allow for easy
expansion, and a pathway for centralized control, broadband RF can offer a viable solution over
Cat5 baseband video and IPTV.