Articles and whitepapers

2/5/2003

Home Networks - An Installer's View

ByBruce Elliott

This paper outlines current networks in dwellings of various sizes. Clients have various requirements and there are a range of solutions to these needs. The size of the property and the ancillary areas have significant impact on the networks required and the control systems employed. Intuitive handling of the control and external communications is essential for client take-up of the services on offer. An outline of the networks currently utilised in a residential situation and their integration into a cohesive system is presented.

Home Control Networks

The original home control network went by a number of different names: Hudson, Jeeves, Charles, Oy You! were among predecessors to Crestron, AMX, X10, EIB etc. The butler was the head of a network of staff who ensured that the homeowner did not have to illuminate the house, light fires and keep the house warm or cool, open and lock doors, oversee security and safety, fill baths, open and close curtains, water the gardens, arrange the music for the dance or party and countless other tasks that today, can all be controlled electronically.

The large country houses often had staff in excess of one hundred people. The late Duke of Beaufort when it was suggested that a cut back of fifty percent in the number of pastry cooks would be a wise economy measure was heard to lament, "Can't a chap even have a biscuit nowadays?" A large house these days would be in excess of five thousand square feet, and to minimise the effort to run a house of this size, a number of networks are being installed.

Current Networks

A basic system in a new house or apartment would have facilities outlets for voice, data and television (radio frequency distribution) in every room, with additional facilities in the study/home office, and entertainment facilities in the main living room. There would often be a system for sharing the output of the audio system into a number of rooms via passive network controllers.

The main cables used are Category 5e (Cat 5e) Un-Twisted Pair (UTP) cable or Screened Twisted Pair (STP) four pair cable, CT 100 co-axial cable for radio frequencies, and screened twisted pair for infra-red. As the size of the house increases and more rooms are added, the size of the networks and their number and complexity increase. A summary of the main networks follows:

Heating Ventilation Air Conditioning (HVAC)

The preferred heating is generally under floor - despite the inherent latency of this system and its antipathy to solid wood flooring. Each room or zone has its own sensor and control for the set point (target temperature), and these are run back on a Cat 5e data network to the Controller. This will also have a sensor for the external temperature. The Controller is generally microprocessor-based with a modem fitted for external software updates and control. From the Controller, a collection of boilers, chillers, valves and manifolds are controlled by addressed devices on the network.

Air conditioning is much more common in new houses in the United Kingdom than one would think. Foreign buyers and the tendency for warmer summers has led to a substantial proportion of new build having comfort cooling, if not full air conditioning.

The latest HVAC controllers enable each room or zone to be treated individually. When not in use, guest rooms and formal entertaining rooms can be kept at a significantly lower temperature in order to minimise energy consumption. Likewise, staff wings or annexes can be kept up to temperature when the rest of the house is dormant during a holiday. The system will run towel rails at a different temperature dependent on the outside temperature, and can remotely control bath fillers, spa systems and swimming pools. The system can be addressed from the outside world by laptop, palmtop or mobile phone, and will call an external service centre if a fault develops.

Security

Most security systems have a number of addressable sensors and alarm points on a network that runs around the dwelling. The sensors will be monitoring for fire, smoke and motion, and the alarm points will be panic buttons by doors and in bedrooms. The alarm system will notify its central station when enabled and also when disabled or if an alarm is triggered. This link is often via ISDN or ADSL, which also allows interaction with the manufacturer/installer for software upgrades etc.

These systems typically have an interface with other systems in the house in order, for example, to activate the external lighting or flash the internal lighting when an alarm is detected. Home control systems will have a button marked 'EXIT' which will set the alarm system, switch the lights to 'away' mode, turn the audio and video systems off, and perhaps activate other security devices such as roller shutters for window protection.

Closed Circuit Television (CCTV) is widely used for surveillance of properties. The system is activated by motion sensors, and records the camera output for further investigation. The camera output can be modulated onto the TV radio frequency (RF) distribution channels and viewed around the house if required, and this can also be done with the video entryphone system. Camera points are also typically located in the nursery to allow video surveillance of a sleeping child on television, throughout the house.

The output of the CCTV system can be viewed over the Internet, and many clients utilise this to keep an eye on holiday homes or to check the progress of the garden whilst abroad. Although webcams can also be used for this, they do not include the security recording functionality.

Blinds and Curtains

Curtains can be electrically closed and opened, and the control for this tends to be low voltage closing contacts or mains voltage motor control. Blinds are used to protect rooms from overheating due to solar gain, to protect furniture and works of art, and to reduce the light levels within a room to allow a home cinema projector to function at its best. External roller shutter blinds are a popular security method in urban areas.

A data network interface with the home control system will ensure that these devices are integrated with the rest of the house so that curtains close at sunset and re-open in the morning. Garage doors will be closed when the house EXIT button is pressed, and will notify the security system if tampered with.

Telephone

Telephone is more often known as a 'voice network'. A structured Cat 5e cable system is run throughout the house in a radial fashion with a termination panel in the 'technical space'. This can be as small as a cupboard under the stairs or as large as a specific central apparatus room containing racks. In simple systems, the cables are linked together and a number of ordinary telephones (up to four, dependent on the REN) plugged into the sockets.

In larger houses is where we experience the transition from POTS (Plain Old Telephone System) to PANS (Pretty Amazing New Stuff). It is usual to have a number of incoming telephone lines, for private and business use, and a small analogue PABX (Private Automatic Branch Exchange) for intercom and paging facilities. Those with ISDN and ADSL will often have small digital exchanges with direct dial-in for a number of extensions, and the fax machine will generally be part of this exchange system. Some rooms, such as the home office, den, kitchen and living room, will require more than one voice socket, and allowance must also be made for DECT cordless phones, and satellite and terrestrial digital TV set top boxes that use a phone line as a return path for data input by the viewer.

Audio and video hard disk storage systems also require outgoing lines to dial Internet-based compact disc databases, such as 'cddb.com'. This provides artist and track information that can be downloaded and displayed on various screens throughout the house.

Data

A Cat 5e data network would be installed in all but the smallest house. Every room would have at least one RJ45 outlet, and the home office would have more. The network is run radially to the technical space and is either connected as a passive network, or run into a Cat 5e dual-speed Ethernet hub or switch/router for connection to the Internet. This will no longer be connected by a clunky analogue modem (56kb/s), but by high-speed ISDN, Home Highway or ADSL (512kb/s) for maximum speed Internet access. This network provides a data highway around the house enabling the sharing of computer files, printers and other peripherals such as scanners and digital cameras.

Interactive games can be played from different rooms or with friends across the Internet. High-speed access supports a vast number of radio and other entertainment channels simultaneously. Add a wireless network to the home, and your laptop becomes a portable radio. Alternatively, link your computer to the whole-house audio system.

Infra-Red

A network of twisted-pair cables will be run in conjunction with the TV and audio networks to enable bi-directional transmission of infra-red (IR) signals from room to room and to and from the technical space. This can also be enabled over the TV RF distribution system. Sky digital set top boxes have 'TV Link' built in, so all you have to do is put a TV Link receiver in whichever room you want to control the satellite box from, and it will run the IR signals back down the wire to the set top box.

The IR network enables control of shared equipment throughout the house. Audio systems can be concealed in cupboards and controlled from a number of rooms. Pause a video in the family room when you want to go to bed, and start it going again when you are in bed to watch the final half-hour in cosy comfort. It can work both ways, so that when you press the EXIT button by the front door, the specific IR signal to turn off the TV is sent to each TV throughout the house. Although infra-red seems an outmoded technology, using modulated IR over wires can be very powerful. Systems that store specific IR commands and can be activated by a contact closure or RS232 string to send the stored command to a specific control centre, have many applications in home automation.

Television and Video

Despite many other options, distribution of TV and video is still largely via co-axial cable such as CT100, from a central distribution amplifier. This wideband RF system will have other channels modulated onto it, in particular the output of the satellite or digital terrestrial TV set top box. Only in the largest premises is the incoming signal frequency shifted to prevent ghosting. Whilst it is possible to send the RF signal over Cat 5e cable, this is not currently popular, although it may become so as the technology improves.

For video storage, there are hard disk-based storage devices available with the ability to store films and programs. The Sky+ box for example, has an onboard storage system that allows a film to be recorded with Dolby digital 5.1 surround audio. Imerge has a video server that will store up to fifty hours of films or programmes recorded off air.

The most popular medium for watching films however, is DVD. Most houses will have at least one room set up as a 'Home Cinema', although this is one of the most abused terms in current use. A widescreen CRT television and a few plastic speakers do not a home cinema make. For the experience to have some impact, the picture needs to be BIG and the audio full frequency and capable of substantial dynamic range including a lot of low-end thump. ('Thump' is a scientific term that quantifies the American 'Bang for your buck!').

Big pictures from DVD are fine, but when you invite your friends around to watch the match, don't forget what 625 lines spread over a projected picture of more than one metre in height looks like. The video processor and line doubler/quadrupler are essential here. Most clients will have at least one plasma screen, if not two or three. As the prices have tumbled, these are commonplace in larger houses, especially where the noise that a video projector makes would be obtrusive. The top-end home cinema is an opportunity for the client to flaunt their disposable income: "My screen's bigger than yours" has been heard more than once!

A one hundred-inch screen will drop out of the ceiling or appear from concealment in large faux bookcases. Projectors pop-up from coffee tables, or lower from the ceiling on lifts. These set-ups, with a substantial investment in audio technology, certainly live up to the description of 'home cinema'. Respected acoustic consultants are involved in the construction of these rooms and will work with the interior designer to ensure high sonic integrity. The industry has been aided by the THX-quality standard laid down by the film industry for domestic applications.

Audio

The major audio source is compact disc. This can be played singly or stored in a compact disc jukebox of 100 discs or more. These can be connected together to provide a large library of music of differing genres, controlled by a bewildering array of different software packages that offer displays on television, computer and touchscreens, and access by artist, title, track and type of music. This enables instructions such as 'Find Kiri te Kanawa singing a jazz-funk version of Pinball Wizard.'

The next generation of audio storage system loads the compact disc onto a hard disk drive 'server' for storage and access by hand held GUI (Graphical User Interface), computer, or touchscreens located throughout the house. These units will contact a database and download the artist and track list information. The audio server will feed a central audio controller and then be distributed around the house in a number of different ways.

Other sources of audio will be a number of radio tuners, both digital and analogue, satellite systems and computers. Radio from the Internet and the soundtracks for computer games, sound very different played through big loudspeakers.

Audio from a central source is generally distributed around the home on Cat 5e four-pair cable to locally sited pre-amplifiers and power amplifiers. The four pairs provide two pairs for balanced audio and a pair each for data send and return. Smaller amplifiers are powered from the central position with larger amplifiers requiring local 240V power. As ever, the quest is for the audio Holy Grail, namely the shortest speaker lead!

Some systems take an alternative approach and have centralised power amplifiers running substantial speaker leads up to 20m. There are even a few Luddites using 100V line distribution which, although not particularly applicable to domestic stereo purposes, can work well in the garden or pool installation.

Zones

An average home will have four zones on the ground floor, namely family room, drawing room, kitchen and dining room. As the size increases, the following may be added: study, snooker room, games room, utility room, conservatory, etc. On the upper floors, it is common for the master suite of bedroom, dressing room and bathroom to be at least one zone, if not three. Some have a private drawing room as well. Each principal bedroom will have its own zone with extension speakers in any ensuite bathroom. These zones will all have access to the central sources with independent level control. Dependent on the sophistication of the audio system, various level presets, as well as 'sleep' and 'night time' functions, can be programmed. The system can be overridden from certain controls for 'party' mode or 'goodnight' functions.

Integration

This is where the fun starts! All the aforementioned systems can be integrated by a home control system that is programmed to minimise the effort involved. Touchscreen systems, such as those by Crestron and AMX, are common for this application.

The most obvious example is the home cinema. This often comes with more than half a dozen remote controls for screen, projector, DVD player, lights, blinds, audio system, etc. Far simpler to press a button on a touchscreen marked 'Watch a Movie.' This will power up the projector, DVD and audio system, select the DVD input on the audio system and the video input on the projector, lower the screen and projector to the correct height, lower the blinds, and dim the lights. Then, when you press 'play', it's show time! The system can also mute the telephone sounder and turn off any noisy fan-driven heating/cooling systems.

Using a touchscreen in each room to control lighting, HVAC, audio and security enables one button to be used to shut the room down on leaving. The Exit button would commonly shut off lights, audio, and television, and in some rooms, the heating would also drop in temperature. This Exit function can also be made global at the exit doors, so all the lights go off and all entertainment within the house is switched to standby. Indeed the lights could be put into a 'vacation' mode which replays the lighting changes that the system has recorded over the past fourteen days. The global Exit button will arm the security system, which will integrate with the lighting control to turn certain circuits on in the event of an alarm being triggered. The external lights could come on, and the house lights near to windows could flash.

The possibilities in residential systems integration are only constrained by the funds available and the cost/benefit analysis. The challenge for the integrator is ensuring that the system is intuitive, elegant and provides the homeowner with benefits they are comfortable with - a system designed for the 'techno-boffin' member of the anorak-wearing classes may be substantially different from the requirements of an international investment banker! It is the integrator's task to fulfil each and every vision.

Bruce Elliott is a Residential Systems Integrator. This paper appears courtesy of Bruce Elliott and the AES (Audio Engineering Society). It was first presented at the 2002 AES UK Conference on Audio Delivery.

bcle@bruceelliott.biz
www.bruceelliott.biz

www.aes.org