Home Automation
Video Distribution
Our video distribution system is made by Channel Plus. A central system mounted in the basement takes inputs from various locations (VCR in the master bedroom, control computer in the basement, TV antenna, and (hopefully soon) front door camera and DSS satellite system) and sends them back out to all the TVs around the house.
The video distribution system takes broadband video (antenna, cable TV) on all its inputs. To distribute the output from a VCR or door camera, the composite video (and audio) must first be modulated onto a TV channel. This modulation is performed by a separate device that has discrete inputs (video, audio left, and audio right) and a single broadband output. Our distribution system is currently set up (via a filter) to get channels 1-64 from an antenna and combine them with the modulated video from other sources (VCR, control computer, etc.).
It also includes an infra-red distribution system which does the same thing with signals from IR remote controls. This allows you to control IR devices throughout the house from any location with an IR target (generally mounted on the TVs). For example, we can play a CD on the stereo in the master bedroom through the speakers in the den, and control the CD player using a remote control in the den. The infrared signals are picked up by the target and transmitted to the emitter which is attached to the CD player.
The IR system will also eventually be used along with the control computer in the basement which will also control various devices via X-10 to handle operations such as playing a video, which would do something like the following:
- Turn on the TV (if not already on)
- Tune to the proper channel
- Turn on the VCR (if not already on)
- Turn on the stereo (if not already on)
- Set stereo volume, mode, and source
- Slowly dim the lights until they are off
- Start the video
Another useful addition will be the front door camera. The output from this camera will be modulated to an unused channel and fed into the video distribution system. This will allow us to see who's at the door before we get up to answer it. Eventually, this operation will be integrated into the automation controller so that the TV is automatically changed to the door camera channel whenever the doorbell rings for a few seconds.
The video distribution system will also be used to provide feedback from the control computer via the TVs. The video output from the computer is fed into the video distribution system and made available on all TVs throughout the house. This will allow monitoring of system status, and possibly even minimal control of the system through "universal" IR remote controls.
Miscellaneous Information
The system is wired in a "home run" configuration - all wall jacks are wired down to the basement, where they are connected to the video distribution panel. This style of wiring provides a maximum amount of flexibility for the future, as opposed to "point to point" wiring.
Be sure to keep the infrared targets out of direct sunlight. The sun (as well as other ambient lighting) can overload the IR distribution system and cause it to stop passing "real" IR signals.
There are two major types of IR emitters - those that attach directly to the equipment to be controlled, and those that "broadcast" the signal through the air. I originally thought that the second type made more sense - after all, if you have a TV, VCR, stereo and CD player all near each other that you want to control, one broadcasting emitter would handle them all. There are two problems with this. First, if someone is standing between the emitter and the device (changing the video for example), the device will not receive the signal. Second, if you are using the remote in the same room as the device, you may run into a problem where the signal from the remote is received directly at the device, but is also received at the IR target, sent through the IR distribution system, and then broadcast to the device - in effect, the device receives two signals, slightly delayed from each other. This will probably result in the device not accepting or misinterpreting the signal. The directly-mounted stick-on emitters get around both these problems.
The video distribution system allows you to act as your own cable TV company (inside your house, of course). What we do is take a broadband signal from a standard TV antenna (another annoyance of a new neighborhood - no cable TV yet), filter out all channels above 64, and mix it with the discrete modulated signals from other sources (control computer, master bedroom VCR, door camera, DSS receiver, etc.). This combined signal is then distributed to all the cable TV jacks around the house. You then simply tune your TV to the desired channel. Of course, if we had scrambled cable TV channels (HBO, etc.) which required a cable decoder box, this would be a bit more complicated (well, expensive, anyway).
Most modulators on the market are not stereo. For example, the modulator on the control computer has separate right and left audio inputs, but the audio is combined and sent out as mono. Stereo modulators cost a good deal more than mono ones, and we felt that they were not required in our case. If we ever decide to modulate something like a DSS system, we will definitely want to get a stereo modulator.
