Gibson HomeBuilders

Today’s topic is Structured Wiring.
My guests today are Tim Roe with Alamo Electrical Contracting Services and Jean Gibson, Vice President of Gibson Home Builders

WHAT IS STRUCTURED WIRING?
Present structured wiring is a method of providing the communications infrastructure of your home in a well organized, easy to understand, and thorough way to provide a general solution to your present and future needs. The structured approach is to consistently run a full bundle of wire to every significant room. The Basic full structured bundle consists of two 4-pair Cat 5 cables and two coax cables (usually RG-6), and optionally two multi-mode optical fibers. The basic structure will introduce HDMI cables and connectors in the equation as time goes forward. Depending on what you are planning to control in your house will dictate the actual types and number of cables needed. In more and more homes today you will be able to control any of the mechanical functions of the home from anywhere in the world. In this article we are going to just talk about the basics (computers, TV’s and phones) or the basic communication network.

WHY THE 2+2 STRUCTURE?
The two coax cables provide a down stream and an upstream signal path. You can get everything you want down a single coax including cable channels, satellite signals, and your own closed circuit channels for your front porch, front yard, and back yard cameras. The upstream cable is used to carry additional closed circuit channels, such as a baby crib camera, or a VCR feed to your video distribution hub so that any TV in the house can tune to these feeds.

The two Cat 5 cables are for telecommunications and networking. The term Cat 5 refers to an industry standard for twisted pair cable construction that is capable of supporting data speeds of up to 100 Megabits per second (MB/S). This is the highest speed normally used in small office and residential applications. The most popular configuration for Cat 5 cables is four pairs, or a total of eight conductors. With two of these cables in the 2+2 structured cable, there are a total of eight pairs available for carrying telecommunication or networking signals. This is way more than is normally needed, but since the cost of including extra pairs is low, the convenience in organization that is provided by this arrangement makes it the configuration of choice.

Cat 5 Wire
It takes more than just quality Cat 5 wire to make computer networks achieve speeds of 10 or 100 MB/S and beyond. The connectors must be rated at Cat 5, and the patch cables used to go from wall outlets to network equipment must also be Cat 5 rated. In addition, the connectors must be carefully attached to make sure the twist in the wire is maintained to within a half inch of where it is punched down into the connector. There can be no splits or Tees in the Cat 5 path between an active network hub and the terminal equipment. Because of the strict rules that apply to Cat 5 network transmission lines, most installers will allocate one of the Cat 5 cables in a structured cable to network use, and allocate the other to telecommunications and control applications. Since telephones and network signals provided by your telephone company, including DSL, operate at frequencies much lower in the spectrum than Ethernet networks, you can bridge telephone lines, use Tees, and attach multiple extensions without a strict observance of the rules needed for high frequency data transmission. Installation and maintenance is greatly simplified by allocating one Cat 5 cable to networking and the other to everything else. With four pair in each cable, there are plenty of signal paths for either application.

THE 2+2+2 STRUCTURE
In addition to two Coax, and two Cat 5 cables, many homeowners install two optical fiber runs. This is often referred to as the 2+2+2 structure. There are differing opinions on the need for fiber in the house. The argument for adding fiber is that the potential bandwidth is much greater than twisted pair. People see fiber used at work and are convinced that it is just a matter of time before it is needed for residential networks.

To add to the confusion, people see fiber service being provided to the house by service providers in places like Palo Alto, California. There is even a standard acronym used in trade journals: FTTH for Fiber To The House. Where FTTH service is available, once the fiber enters the house from the street, the first place it goes is into a fiber modem where the signal is converted to 10BaseT or 100BaseT Ethernet. It is then transported through the home network on twisted pair copper Cat 5 cables. The argument has existed for a number of years where the proponents feel that copper will not provide enough bandwidth for future applications. During those same years, new designs of networking equipment have steadily pushed the upper limit of copper ahead of practical needs. The outcome so far has been that the much lower cost of twisted pair copper equipment continues to rule the market. You might say, “Why then is fiber used for networks at work?” A big reason is that twisted pair Ethernet solutions, 10BaseT and 100BaseT are by specification limited to a distance between terminal equipment of 90 meters (approximately 300 feet.) That distance limitation can be a problem in large buildings and industrial campuses, but is rarely a limitation at the residential level.

DVI (Digital Visual Interface)
The Digital Visual Interface - also referred to as DVI, has been appearing on home theater gear for quite a number of years. It was originally developed by DDWG (Digital Display Working Group) in 1999. It brought about numerous different types of DVI cables and connectors to support the various signals that can be carried over a DVI interconnect. However, it did not take long before this whole new mess of interconnects complicated it even further. Soon, we saw the advent of a new digital interface that is closely related to DVI (High Definition Multimedia Interface) or simply HDMI, and with it a whole new range of HDMI interconnects - HDMI to DVI cables, HDMI splitters, adaptors and HDMI connectors.
DVD players, digital cable and satellite set-top boxes, High Definition plasmas and LCD TVs, and home theater projectors, all represent prime targets for these digital connections.

Originally released in December 2002, ver. HDMI 1.0 -- short for High-Definition Multimedia Interface -- is the first industry supported interface that carries uncompressed all-digital audio and video over the same interconnect.
By end 2003, we started to see the first HDMI-enabled consumer products on stores shelves. Since then, HDMI saw an exponential rise in the rate of annual growth of HDMI-enabled products, and is fast becoming the standard for HDTV connections. It is estimated that today, there are some 100 million HDMI-enabled devices, and this figure is expected to double by end-2008!

The HDMI standard was founded by leading consumer electronics manufactures - Hitachi, Panasonic, Philips, Sony, Toshiba, Thomson and Silicone Image. Because of its HDCP (High-Bandwidth Digital Content Protection) compliance, which provides copyright protection, it is also fully supported by major motion picture producers like Fox, Warner Bros, and Disney, as well as by system operators like DirecTV and Echo Star.

The principle idea behind HDMI is the use of a single interconnects instead of several cables when connecting an audio/video source, such as a set-top-box or DVD player and an audio and/or video monitor, such as a plasma TV, over a single HDMI cable.
The use of a single HDMI cable that replaces the maze of cabling behind home entertainment centers is the primary advantage brought about by this new standard. This is not the case with DVI; DVI supports digital video only - hence, a separate audio cable is needed to transport digital audio when a DVI cable is used.

The HDMI specs support standard NTSC and PAL, enhanced, and high-definition video formats (720p, 1080i, and 1080p up to 60Hz), plus 8-channels, of 192kHz, 24-bit uncompressed digital audio on a single HDMI cable. And still, there is bandwidth to spare to accommodate future enhancements and new requirements.

HDMI and DVI - Differences and Similarities
HDMI uses the same digital encoding scheme used by DVI-D in the transport of digital video. This explains why all that is required to hook up a DVI device with HDMI-enabled equipment, is a simple DVI to HDMI cable adaptor with a DVI-D plug on one end and an HDMI connector on the other. In this case however, digital audio will have to be carried separately since DVI does not support audio over the same interconnect. This would not be the case in HDMI to HDMI cable, where the digital audio signal is carried along with the digital video over the same interconnect. The fact that HDMI is equivalent to DVI-D, implies that it is limited to that format only. In other words, there's no way to adapt an analog VGA signal to go in through an HDMI connection as one can with a DVI-I interface.
Note however...Actual performance constraints due to cable length, are similar to DVI in view that HDMI uses the same encoding protocol over the same twisted copper pair. The use of twisted copper pair to carry high bit-rate digital data without error correction can lead to severe problems with signal degradation over distance. It is for this reason that the HDMI specifications standard does not state a maximum cable length - but rather indicates the expected supported cable length using affordable high quality HDMI cables.