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Home Automation > Video Distribution
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With the price of great TVs coming down we have more TVs in more places around the home. But what if you want more than basic cable for all those TVs? It's now possible to distribute HD video from your cable box and Blue Ray/DVD player to all the rooms in your home using inexpensive Cat5 or Cat6 cable, or even wireless!
Video distribution is all about getting a strong clear signal, of all channels (regardless of the source), to all video destinations within the home. This involves three general functions: Gathering, and in some cases creating, the signals in one area; Combining, conditioning, and amplifying the signals; And distributing the signals to their destinations.
The first thing your need to know about video distribution is that what you are really distributing is Radio Frequency (RF) signals. The RF signal is sent through shielded coaxial cables. Apart from the distribution task itself, the two most important parts of creating a video distribution system are to keep your signals inside the cables, and to keep other signals out of the cables!
A single coaxial cable can carry 130, or more, standard channel frequencies. Each channel includes video and audio components. With MTS encoding, each channel can even have stereo audio.
Contrary to an RF channel, which can coexist on a coaxial cable with many other channels, "baseband" video takes the whole cable, and doesn't even include sound! Baseband video and audio is what comes out of the RCA (a.k.a. "phono") jacks on the back of your VCR. Since it takes two coaxial cables to transport a single baseband video and audio source, you generally want to convert baseband into RF as "early" as possible. Which means as close to the source as possible.
You convert baseband to RF with a device called a modulator. Most modulators today are simple little digital boxes that are similar to, but the reverse of, a cable box. They have inputs for video and audio, and an output for RF. (RF is almost always an "F" type connector.) You can use one or more modulators to create your own "in-house" channels. In effect, you create your own cable TV company.
From a "block diagram" standpoint, there are four key pieces to any video distribution system: The coaxial cables themselves, which serve as a conduit for the RF signals and allow interconnecting the other key pieces; RF Amplifiers that "boost" the RF signals to make up for the signal losses the other pieces impose; Combiners which "add" two or more cables together to create a single output that contains all channels from both input cables; And splitters that take a single input cable and distribute the same signal to two or more output cables.
Planning a video distribution system is not difficult. You need to understand what the key pieces do, have a blueprint of your home, and be able to do a little very simple math. That's it!