The growth of HDTV in the home entertainment market coupled with the developments in home wiring technology have sparked an increased demand for connecting component video via pre-existing Category 5 copper twisted pair cable. This article provides a brief snap-shot about how to support component video connections via Cat5 cable.
Component video connections are often required in multi-room applications. For example a DVD player or satellite receiver may need to be connected to one or more screens in different rooms. The problem is that connecting component video cable around the house can be costly and messy, not to mention the fact that the distance between the source and receiver often exceeds the distance limitations of even the best component video cable.
Component Video Balun:
Enter the component video balun. Used in pairs, component video baluns are capable of providing a point-to-point connections for RGB and YPbPr video via three (3) twisted pairs. This means that instead of running three component coaxial cables, only one 4-pair Cat5 cable is needed. The following photos show two configurations for a component video balun; modular and screw terminal.
The balun options for making the connection depend on the application. If a simple point-to-point connection is required, then a modular balun that handles all three component signals may be used without the need for special tools. Termination on the UTP side is via RJ45 modular jack. Pre-terminated RJ45 Cat5 cables may be used to make the connection between the baluns. The advantage of this approach is the simplicity and modularity. The trade-off is that it leaves one pair of the Cat5 cable unused and possibly inaccessible.
For more flexibility, individual component baluns may be used for each signal and terminated directly on the twisted pair. Each balun pair handles either Y(Green), Pb (Blue) or Pr ( Red). Three balun pairs are required to support the full RGB or YPbPr channel, leaving one extra pair available. By accessing the individual twisted pairs, it is possible to use the spare pair for a different service such as digital audio.
In regard to performance, component video baluns on the market today generally support only 480i/p resolution due to bandwidth limitations. It is expected that component video baluns that support HDTV (720p and 1080I) will begin to appear on the market in 2005.
In regard to 480i/p, distances over 500 feet have been successfully achieved in MuxLab facilities. However, as cable length approaches the limit, there will be noticeable loss of color and sharpness. Nevertheless, at distances under 500 feet, where most applications reside, the performance has proven exceptionally good.
In summary, component video transmission via copper twisted pair and passive balun technology is a viable option for residential AV installations and customers can expect to see innovative products that support this environment in the coming years. For more information it is recommended to contact your local custom home installer.
The balun is a device that converts an unbalanced video signal to a balanced video signal to support transmission via unshielded twisted pair cable. The balun, coupled with the twisted pair provides overall noise immunity that compensates for the lack of an overall cable shield normally provided with audio-video cable.
MuxLab is a designer and manufacturer of CCTV and audio-video connectivity solutions for copper twisted pair cabling. Jeffrey Herman is a Product Manager at MuxLab Inc (www.muxlab.com). He may be contacted at firstname.lastname@example.org or at 514-734-4320.