Articles and whitepapers

Control Systems for the Modern Home (2/2/2004)

By Martin Noar

Most of us are aware of the growing trend towards integrated entertainment and communication systems for our homes, and as the demand for flat-panel televisions soars, so does the idea of home cinema. We are now well-accustomed to using individual remote controls for TV, VCR and Sky, but as we run out to buy the latest DVD player, add a Sky+ decoder, Freeview Digital receiver and surround sound amplifier, we suddenly find the sofa littered with seven or eight remote controls. The concept of consolidating all your remotes into a single unit seems an attractive option.

There are a large number of low cost 'universal' remote controls on the market, many of which can be programmed to send the correct codes to your television, VCR etc. The low-cost options however, are reduced if you also want to control your Sky box , DVD and amplifier from a single remote control. Although these entry-level units are generic devices aimed to meet most customer requirements, you will inevitably end up with a number of unused buttons and features. Whilst the remotes are pre-programmed with codes for a huge variety of equipment from a range of manufacturers, it can still prove difficult to achieve your ideal solution, and it is likely that you will end up with a compromise. This may be that you have reduced your eight remote controls down to two or three.

Line-of-sight

It is important to note that these remote controls transmit their signals directly to the equipment via infra red. This means that there must be a line-of-sight to the equipment. By the time each piece of equipment has been wired to the surround sound amplifier, there will be a considerable amount of cabling. It might therefore be desirable to place the whole system into a cupboard, but you will lose your line-of-sight, and while there are infra-red repeaters available to help this problem, they must be carefully placed to avoid interference from unwanted signals. These signals can emanate from direct sunlight, and especially from plasma displays - so take care!

Custom Remote Controls

Until a few years ago, if you wanted a fully custom remote control system, the options were limited to the likes of AMX and Crestron. These are the ultimate custom control systems and often use wireless, colour touch panels that are popular with high-end, high-budget home installations. With such systems, you would be looking to spend a few thousand pounds for a fully-programmable control system and the specialist programming to go with it. These high-end systems typically use two-way communication between wireless touchscreen and a processor unit. In addition to sending infra-red signals to your AV equipment, the processor unit can also be programmed to send and receive RS232 control data, and to close or open relays.

A typical high-end control system comprising a touchpanel on the left, and controller on the right

For the mass home market, there are now a small number of programmable touchscreen remote controls that bridge the price gap, such as those by Marantz and the Philips Pronto range. They are an ideal solution for controlling all of your systems from a single device. As with the more expensive systems, these devices also use touchscreens that can be laid out to your requirements. These therefore will require programming, although by comparison, this is relatively straightforward.

The object of the exercise is to produce a clear and logical layout, presenting the customer with a remote control that looks good and can be used without training. It is also important to ensure that when programming the unit, infra-red codes are learnt accurately - do not attempt to learn your codes whilst sitting next a 50-inch plasma TV on a sunny day!

A typical macro using a one-touch of the 'Sat TV' button may be:

- switch on the TV.
- switch on the AV amplifier.
- select the correct input on the AV amplifier.
- select the correct audio decoding (i.e. stereo, or a surround sound format).
- change the touch panel display to the satellite decoder control functions.

You would then want to display a screen with the relevant satellite control buttons, including favourites, as shown below.

Examples of mid-priced custom touchpanel layouts

All well and good, but beware - life is never quite that simple. Many manufacturers of audio-visual equipment still use toggling buttons for their equipment. For example, it is common to find a single button on your remote control for 'power' - press it once and the device switches on, press it again and the device switches off. This has caused many a programmer's brain to simply implode with frustration given the challenge of automatically turning the TV on as part of a macro. One cannot simply send a POWER command each time 'DVD' or 'TV' is selected, because if the TV is already on, it will switch off!

For some devices, discrete infra-red codes for 'power on' and 'power off,' amongst others, do exist, but have not been implemented by the manufacturer on the supplied remote control. I have never been able to extract information directly from the manufacturers, and usually end up surfing the Internet for many an hour tracking these down.

Several of these controllers offer the distinct advantage in their ability to transmit using radio frequencies to a small receiver unit, which converts the signal back to infrared. This of course means that you no longer require line-of-sight between the remote control and the equipment. One must be aware however, that radio frequencies are also prone to interference, especially as these devices share frequencies with garage door openers, wireless alarm systems and the like.

Many customers have extended their home automation ideas to include lighting systems, electric curtains, electrically-operated gas fires, heating and ventilation. Although this level of complexity is probably more suited to one of the two-way high-end solutions described above, it is amazing what can be achieved using custom interfaces with lower-cost touchscreen controllers. It is entirely possible to use infra-red signals to trigger relays or to send a string of RS232 data to a lighting controller.

Further information on this subject is available on request from the author.

Martin Noar is the owner of Libra Solutions. Libra offers complete home technology solutions including audio-visual, lighting and control systems.

Telephone 020 8428 2776
www.librasolutions.co.uk