Articles and whitepapers

CAT8 High-Bandwidth Multimedia Networks

By Gavin Duffy, Wired House

Traditionally, there was very little choice in the type of transmission medium used for the design and creation of the infrastructure of a true multimedia networked home. For audio, there was speaker cable. For video and RF (radio frequency) signals there was coax. Analogue voice and fax used POTS (plain ol' telephone system) cable, also known as CAT2. For computer data there was CAT5, with any proprietary system control data being squirted along whatever bit of wire the manufacturers had designed-in/guessed at/pulled out of the bin for the purpose. Everything else, such as door entry, alarm system, intercoms, etc, tended to be lumped down CAT2.

Audio cables

This all added up to enough copper in the home to ensure that you and your descendents should never suffer from arthritis. The more flexibility you wanted from your network, the more cabling you had to stuff behind the walls, resulting in an almost linear relationship with cost in terms of material and labour, as well as the number of wall outlets or 'wall acne' that had to be installed.

Within the last few years, the increasingly innovative use of CAT5e cabling for combined multiroom audio, voice and data network systems has meant a marked reduction in the 'copper impact' on the home, but these systems still make use of either coax or software/hardware compression such as MPEG for video distribution. CAT8 high-bandwidth cabling on the other hand, offers the developer/installer a real alternative to multiple cable installations. CAT8 cable has the inherent capacity and the flexibility to allow the developer, and ultimately the homeowner, an unprecedented freedom of choice. In terms of cost, simplicity of installation and sheer capacity, CAT8 is leagues ahead of other grades of cabling. If there are any issues with this cabling technology, they have yet to be found - although supply within the UK could be one possible problem if demand for the product were to rise sharply.

What is CAT8?

CAT8 cable represents the current evolutionary cutting edge of twisted-pair copper data communications transmission technology that originated back with CAT5 cable. Indeed all of these cables use four twisted pairs in their construction. Of the older cable grades, CAT5 can take a maximum bandwidth of 100MHz, CAT6 is capable of 400MHz and CAT7 625MHz. CAT8 is capable of carrying a bandwidth of up to 1400MHz, so it easily meets and exceeds the IEC 61156-7 standard that sets the benchmark for multimedia cables at 1200MHz.

CAT8 is normally referred to as 1.2GHz cable, and is capable of taking a standard European TV signal with a bandwidth of 862MHz without any form of signal manipulation. It should also be more than capable of taking the satellite signal from the proposed Sky HDTV broadcasts that are set to start in 2006.

CAT 8 construction

CAT8 cable achieves its groundbreaking signal capacity by virtue of its precision manufacture. The 8.5mm diameter cable is constructed from four colour-coded 22/1 AWG copper insulated pairs. These are twisted together to incredibly tight tolerances to provide the maximum balance and coupling out of any induced noise. Each pair is then wrapped in its own aluminium bonded polyester tape shield. The four foil-screened pairs are then twisted together to provide a single robust core element that is covered with a tinned copper wire braid for additional shielding. The cable core is then enclosed within an off-white/cream-coloured (RAL 1015) outer sheath. This sheath is made of a zero-halogen, low-smoke and flame-retardant compound that is fully verified for compliance with all relevant international standards. Furthermore, CAT8 cable is specifically designed to be easy to install, with a minimum bend radius of 4cm (although an 8cm bend radius is recommended).

CAT8 cable

CAT8 infrastructure

In terms of quantity, quality and type, the real beauty of a CAT8 multimedia infrastructure lies in the services it can carry. TV, video, satellite, audio, CCTV, RF, DAB, voice, infrared, computer data, fax, S-video, USB and FireWire can all be carried, with each single CAT8 cable capable of taking up to four services.

Using the DKT MediaX system as an example, for maximum flexibility, the cables are laid in a star topology from a cabinet or patch panel that is located centrally within the premises. The rule of thumb is to have two cables going to each single-gang universal socket, with normally two single-gang outlets being located at diagonally-opposite walls in communal rooms such as lounge, kitchen, office, and family room. Dependent on use, all other rooms would typically have a single universal socket, but obviously, if the home owner were planning a media room, then it would be advisable to load that room with more universal sockets. In addition, places such as the garage and the conservatory should not be overlooked - just because you do not see the need, does not mean that your customers will not. The more sockets you install, the more flexible the system becomes.

Each single-gang universal socket allows up to eight (yes 8!) services to be taken simultaneously from it, thus removing the 'wall acne' issue totally. A room adaptor handles the connection from the universal wall socket to the homeowner's own equipment. This connection method allows for almost infinite connectivity, no matter what the age of the consumer equipment.

A Kerpen universal wall socket showing devices connected to three of the eight outlets.

The flexibility inherent in the CAT8 cabling infrastructure supports sophisticated multiroom AV. Should your clients have specific wishes for a proprietary AV system, then speak to your cable supplier, since CAT8 is reverse-compatible with ALL datacomms legacy applications that normally use lower cables grades such as CAT5 or CAT6.

CAT8 for new build

For developers, house builders and electricians, the adoption of CAT8 cabling in new build homes means that staff require almost no specialist technical knowledge - they are simply installing the infrastructure into the fabric of the building during construction. Any competent electrician can install and terminate the cables and panels, requiring no special tools, no software, no commissioning, and no worries. For your sales staff, the concept behind the system is so easy to grasp that they can be plugging the benefits and features to your potential homebuyers like 'pros' after only a couple of hours' training. After-sales care could be easily managed by your systems integrator, who will posses the specialist knowledge and skills and can source additional multimedia kit, if required, to allow your home buyer to take full advantage of their new multimedia network infrastructure.

CAT8 residential networking is now cost-effective enough for architects, developers and self-builders to consider its inclusion into even the most modest of new build homes or renovation projects, with off-the-shelf network packs available from at least one manufacturer for those on a tight budget. When you look at the cost of CAT8 cabling, it would only take up a tiny fraction of the total build cost for the home. For more prestigious developments, CAT8 multimedia cabling will compliment, enhance and lift structured wiring installations such as KNX/EIB to totally new levels, allowing almost complete interaction with the home.

Conclusion

We are now on the very cusp of a residential multimedia network infrastructure revolution as we reach convergence of ICT (Information and Communications Technology), electrical and residential engineering technologies. The costs are now low enough that this technology is teetering on the brink of going mass market. To date, the adoption of CAT8 infrastructure is sporadic, more due to the fact that the technology is so new that it is taking time to establish. Sources of the kit in the U.K. are few and far between, and tend to be left to pioneers such as DKT, Laird King and Wired House. As a house builder, developer or electrician however, dare you ignore CAT8?

Gavin Duffy is an accomplished stage rally co-driver and the proprietor of Wired House, provider of smart home technology and multimedia network infrastructure sales and system integration engineering.

www.wiredhouse.co.uk