Articles and whitepapers

Home Networks - the cables are just as important as the hardware!

By Chris White, In Touch Technologies (UK)

After the glut of granite work tops and luxury bathrooms, the home network is starting to feature as a valuable addition to apartment blocks and housing developments. The key to it becoming a 'must have' item has to be the flexibility of cabling infrastructure, allowing a buyer or resident to add their choice of hardware to the system. Proprietary systems and cables that need any extra hardware will turn off both developers and end users, damaging our image and industry.

With so many systems and solutions available, how do you identify the best and most cost-effective solution for the application? A one- or two-bed, key-worker apartment or house does not need the fully patchable single-cable system that would be used in a luxury five-bed house.

While there are many different cables and standards available, we would always advocate the use of industry-standard cable as these have been proven over time and will be the first to see any new developments. There are also some common, basic rules that should be applied to any installation:

1. Maintain 5cm/2 inches separation and 90 degrees crosses between any 230V power and home networking cables to minimise interference.
2. Install the deepest back boxes possible to allow more space for cables and future upgrades.
3. Try to use different cable colours for different services to help identify them in the cabinet.
4. Always label the cables at both ends to reduces time wasted on site tracing unidentified ones.
5. Test all cables for at least continuity and correct pairing to prevent faults occurring later.
6. Make and keep drawings as these are invaluable if you have to go back to the system later in its life.

Cable types

Cat5e, Cat6 and Cat7 are the data cable types that are used throughout the world. Cat5e and Cat6 have a bandwidth (frequency range, not data capacity) of 250MHz and 350MHz respectively. They have been used in business applications for the past ten years and offer a well-proven backbone to a domestic distribution system, although Cat6 really does not offer anything extra for the additional cost. The Cat7 cable infrastructure has a bandwidth of 1GHz (1000MHz) and just been approved and ratified by the European standards agency. This is not however, used with the common RJ45 presentation the industry is used to, but a more proprietary outlet and connector. A number of manufacturers, including the Square D Lexcom brand, have adopted the cable, using a wideband RJ45 outlet to pass data, telephone, TV and audio signals.

The CT100 range of coax cable is a brand name that has become synonymous with a cable type - much like Hoover. It is available in 100, 125 and 167 flavours, each increasing in performance and therefore the distance it can pass a signal. In the UK, the 100 range is most commonly used in domestic systems and most brands are CAI (Confederation of Aerial Industries)* approved for satellite TV and Freeview reception. RG59/6 series cable is a US cable type and is only approved for cable TV and CCTV uses, although much of the custom installation market uses it for baseband video and audio distribution. Both cable types will work for CCTV, Freeview and satellite TV applications, but be aware that warranties and support may not be provided if a non-approved cable is used.

Hybrid systems

There are a number of different cabinet solutions that provide home networking, and they can be split in to either a 'hybrid' or a 'dedicated' category.

A hybrid system uses a mix of cable types to distribute the services and signals throughout a property. Although this may seem a little restrictive, a well-designed network will provide a perfectly flexible solution for small- to mid-sized dwellings. A hybrid system will typically use Cat5e for data and telephone services, coax for TV and satellite distribution, Cat5e for line level audio and either speaker cable or Cat5e for basic speaker level connection. The cabinets are usually compact in design and either surface- or flush-mounted on a wall, such as the Home Network Sciences system or the ACA-Apex CRIS and Spider systems.

The ACA Apex Spider Box, a compact and cost-effective hybrid system

The telephone, data and TV distribution panels are typically grouped in fours, sixes or eight's and are usually for a specific signal type. These lend themselves perfectly to wiring each outlet for a specific service, which reduces the need for dongles (adaptors), and in turn makes each service easy to identify by its unique outlet, such as RJ45 for data, LJU/RJ11 for BT and coax for TV. These hybrid systems are perfect for the volume developers who want to offer a basic system whilst minimising the level of knowledge required to use or support the system.

In a hybrid system, the coax system is normally based around a 'Loft Box' system. This was originally developed by Global Communications in the 90's and is designed to distribute the satellite (Sky) and terrestrial TV signals throughout the house. TV, FM, DAB, modulated CCTV and satellite TV signals all sit in different frequency domains and this allows them all to be combined together at the first half of the Loft Box and passed down to a main reception point, typically the lounge. At this point, the signals are split back out into individual outlets, allowing the satellite signals to be decoded. A returning cable from the main reception point feeds the second half of the Loft Box with the decoded channels from the satellite receiver and the off-air TV channels, and redistributes them to the rest of the property.

Diagram showing the function of a Loft Box

The clever thing about these style of TV distribution systems is that they are designed to add the radio signals to the outgoing feeds for the rest of the property and support remote control extenders (Sky eyes) fitted in the additional rooms. When the RF2 output of a Sky receiver is connected to the returning feed, the additional Sky eyes allow the receiver to be remotely controlled from the other locations. However, in order for this to work correctly, the remote outlets must be non-isolated TV outlets, allowing them to pass both the power and signals required.

Dedicated systems

The dedicated system uses a single cable type to distribute the services and signals throughout the property, with the outlet terminated as a generic RJ45 outlet. To connect to and use a specific service, a dongle is required at the outlet location and a patch connection is made between the distribution hardware and the outgoing patch field in the central cabinet. This solution provides a very flexible solution for all properties, although the costs and basic knowledge required can be significantly more than for a hybrid solution.

Cat5e-based dedicated systems are great solutions for data, telco and basic audio services, but TV/FM distribution requires specialist electronics at the central hub, and satellite distribution is not possible. Cat5e cable does not have the bandwidth to pass any UHF TV signals, but it can be used to distribute single composite AV signals to an outlet.

AV distribution over Cat5e cable using the AVNex Nexus

To be able to pass a TV channel, a matrix and tuning facility is required at the central hub. The tuning functions will select the required channel and break it down to a composite signal which the matrix will route to the desired location. Unfortunately, this makes the tuning function in any television used redundant and a central tuning function is required for each unique viewing location. The advent of cheaper Freeview (or digital terrestrial television (DTT)) receivers has made this a lot more cost-effective, although it does raise other issues.

To be effective, the system also needs to pass IR (Infra Red) remote control signals directly to the source it is watching, but if the signal is not routed or targeted properly, then it will broadcast to all the source equipment connected to a matrix. This causes a problem when two or three identical sources are used. For example, when using two or three Freeview boxes from the same manufacturer, a single channel change instruction could be broadcast to all of them, changing the channel on all the boxes. Ideally, IR signals should be targeted, meaning that the signals are only sent to the device that is being used by that specific location at that time.

Cat7 is the latest, high-end cable being adopted for dedicated systems. Cat7 cable specifications have just been approved and can be tested, however the standard does not use traditional RJ45 presentation. To maintain industry continuity, home network systems using Cat7 cable are described as wideband, dedicated systems and do use RJ45 presentation throughout a property. The big advantage of using a Cat7-based system is that the cable can pass the full TV signal without the need for expensive central electronics. Cat7 does however, still require dongles for format conversion and again, satellite TV distribution is not possible.

In both hybrid and dedicated systems, audio signals can be distributed in the same way. There are three basic levels of solution that can be offered with any system, namely passive distribution, single-source multiroom and multi-source multiroom.

Passive audio distribution

Passive audio distribution is the most basic offering that uses a simple speaker or Cat5e distribution network to share 'speaker level' (amplified) audio throughout the property. This has the limitation of not only being able to listen to what is being played at the source, but only being able to hear it at the volume being used at the source end. Whilst it is possible to add passive volume controls, these are only used to 'turn down' the volume being received in that location.

Single-source multiroom

Single-source multiroom systems are commonly based around the 'A-bus' technology that allows a line-level signal to pass through to a local room-based amplifier and in turn the room speakers. This does allow each room or location to have full and individual control over the volume of the source. The volume control electronics are usually based in either a standard wall outlet or within ceiling-mounted speakers.

Multi-source multiroom

Multi-source multiroom is a natural progression from the previous system, and most single-source systems offer an upgrade path that just requires a change to the central equipment. By receiving a number of line-level audio sources at the central location, an audio switch/matrix can be used to select different sources for different speaker/amplifier locations around the property. Each location is usually supplied with a remote control and/or a wall-mounted keypad, allowing control of the central hardware.

All these music distribution systems can be wired to allow the remote control signals to pass through to the source equipment, although as discussed, the individual control of similar equipment can be an issue.

*See www.cai.org.uk for a list of approved cables and Freeview aerials.

Chris White is the Director of In Touch Technologies (UK) Ltd, specialist wholesaler and distributor of communication and control systems for residential and commercial property developers.

www.intouchtech.co.uk