Your Guide to Wireless Systems for Home Control
YOUR GUIDE TO WIRELESS SYSTEMS FOR HOME CONTROL
Installing a wireless system in your home, can appear daunting at first, but in fact, it’s much simpler than most people would think.
From managing the day to day use of energy in the home, to protecting it from undesirable visitors, it can make a huge difference and take the weight off your mind. If you forget to turn off the lights, it doesn’t matter, because your wireless home system will probably have that covered, operating lights whilst you’re not there.
Z-Wave technology is a great wireless system for ensuring energy saving within the home. Electrical appliances can be set to turn on or off, as and when you need them and all remotely.
With its modern design, it can give any home a contemporary feel, by automatically dimming the lights, closing the blinds, and switching the television on, when you settle down in the evening – all by remote control.
Z-Wave is also a reliable system to protect your home from unwelcome visitors. Whether you program the system to control your lights when you’re not home, or lock and alarm your entire home with a click of a remote control, you can guarantee your home will be protected 24 hours a day.
If you make the right decision, it can be a fantastic long term investment for your home, saving you money on your energy bills as well as being a great way to protect your home.
GENERAL APPROACH TO Z-WAVE NETWORK SET UP
Every Z-Wave network consists of controllers (or senders) and slaves (or receivers). All these devices need to be set in their final location in the home. Even if these products are already powered up, the devices will not be able to communicate with each other at this stage.
All devices need to be set up to speak the same language. This process is called ‘inclusion.’ The ‘inclusion’ is always initiated by one controller by turning it into the inclusion mode. All slaves are announced to the controller by triple press of a button.
The third step assigned certain meaningful functions and relationships to the network. This is called association. Association means to setup relationships in the way of “Press button A to Switch Device B.” Associations are initiated by the controller and confirmed by the receiving devices.
After inclusion of the devices and carrying out the associations, the network is ready to be used. After this basic setup, it is possible to add further devices at a later date.
However easy, or sophisticated your wireless system becomes, it all operates in a really simple way – via radio waves. This guide tells you more about radio waves, and what considerations you should make, whilst in the planning stages of wireless in your home.
WIRELESS SYSTEMS IN THE HOME – Radio Waves
In order to install an effective wireless communication system in your home, it is important to understand how the devices connect.
Z-Wave uses radio waves, and in comparison to other similar systems, proves to be stronger and more reliable.
In an ideal situation, radio waves spread out steadily like light waves in all directions, generating a spherical field. For technical applications the wavelength and the frequency are related to each other with the formula: λ = c / f
In contrast to infrared light, or light waves in general, radio waves can penetrate in ceilings, walls, pieces, of furniture and other objects. Such obstacles however weaken the radio signal and reduce the range.
Ideally, if you are going to install wireless components, the less obstacles there are, the more effective it will be. In practise, this means that wireless components should not be installed in random places.
Z-Wave uses the so-called ISM Band in Europe (Industrial-Scientific-Medical) which is open for various industrial and scientific applications. The frequency is 868.42 MHz which results in a wavelength of about 34cm.
Devices can use this band free of further certification and permits; however the maximum transmitting power and transmission time is limited. The transmission time is in Milli Watts and transmitters have to strictly regulate the maximum airtime to minimise interferences. Sending a permanent carrier signal is strictly forbidden.
Transceivers using the ISM band are permitted in most European Countries that have signed the CEPT agreement. Countries like UK, Germany, Netherlands, and even the Middle East have adopted the CEPT regulations into their national wireless band control scheme.
PLANNING YOUR WIRELESS NETWORK – Things to consider
When planning your wireless network, there are various aspects you need to consider. As with most installations, it’s all in the planning. The fitting is relatively easy after that.
The general basics to consider are as follows:
- Distance to disturbance sources;
- Effective wall thicknesses;
- Pay attention to shielding materials;
- Attenuation by building materials and furnishings;
- With a negative calculation result if necessary to check whether the radio transmission will function thanks to reflexions.
Here are some aspects explained...
The main thing to consider is the wireless distance between the transmitter and receiver. This distance needs to be shorter than the maximum distance of the technical device’s parameter (50m or 100m). Then every possible obstacle is determined between the transmitter and the receiver.
The table overleaf can determine the total attenuation of the radio signal.
|obstacle||Former distance||type||attenuation||New distance|
|No 1||30 m||concrete||30%||21 m|
|<< Take new value to next step <<|
|No 2||21 m||Glass||10 %||18,90 m|
|<< Take new value to next step <<|
|No 3||18,9 m||Plaster wall||10 %||17 m|
|<< Take new value to next step <<|
Work Sheet to determine the max wireless distance
If the radio signal penetrates the obstacle at a different angle (more than 90 degrees), then the attenuation effect, will be increased. If the range resulting in the end is bigger than the measured distance between transmitter and receiver, the components should function well.
Pieces of furniture, installation of radio components, metal coatings, plantings and high air humidity should all be considered when planning the best route for your wireless system. Because these attenuations are approximate, a test is recommended before the fixed installation is made.
|1||Wood||< 30 cm||10 %|
|2||Plaster||< 10 cm||10 %|
|3||Glass (without metal coating)||< 5 cm||10 %|
|4||Stone||< 30 cm||30 %|
|5||Pumice||< 30 cm||10 %|
|6||Aerated concrete stone||< 30 cm||20 %|
|7||Red brick||< 30 cm||35 %|
|8||Iron-reinforced concrete||< 30 cm||30 ...90 %|
|9||… Ceiling||< 30 cm||70 %|
|10||... Outer wall||< 30 cm||60 %|
|11||... Inner wall||< 30 cm||40 %|
|12||Metal grid||< 1 mm||90 %|
|13||Aluminium coating||< 1 mm||100 %|
Attenuation by building materials
- Radio receivers should be attached in a distance of minimum 50 cm from other radio sources. Examples of radio sources are:
- Microwave devices;
- Electronic transformers;
- Audio equipments and video equipment;
- Pre-coupling devices for fluorescent lamps.
The distance to other wireless transmitters like cordless phones or audio radio transmissions should be least 3 metres. As well as this, the following radio sources should be taken into account:
- Disturbances by switch of electric motors;
- Interferences by defective electrical appliances;
- Disturbances by HF welding apparatuses;
- Medical treatment devices.
EFFECTIVE THICKNESS OF WALLS
The locations of transmitter and receiver should be selected in such a way that the direct connecting line only runs on a very short distance through material, which causes attenuation.
Metallic parts of the building or pieces of furniture shield the electromagnetic waves. Behind a structure like this, there may be a so-called radio shadow, where no direct reception is possible.
Despite radio shadow, it is possible for wireless signals to be reflected by metal structures and still reach the final destination. Reflections are unpredictable and it is recommended that you test your systems until you create a more permanent fixing.
Interference can occur in different phase situations which are caused by different run times and by the way the radio waves are increased or attenuated.
Interference can be resolved by changing the positions of the transmitter or receiver slightly. Even a couple of centimetres may work. It really is a process of trial and error to see what works for you in your home.
If motion detectors are mounted outside the house, the assembly height is critical. If the motion detector is mounted next to a floor or ceiling level, then the radio signal has to penetrate the concrete of the floor/ceiling. This will be ineffective as this will result in very high attenuation of the signal.
From infra red, to Bluetooth, to Z-Wave, there are numerous wireless messages flying through the air. It’s bound to be a concern whether it can affect users’ health.
Radiation power from radio transmitters is a critical factor. As most of us use mobile phones, a comparison can be drawn.
Mobile phones transmit a constant radio signal with a peak capacity of 2000 mW into the brain. Without any other protection and mostly it’s operated next to your ear, a human will consume about 100 mW into their head. This exposure continues throughout the whole telephone call!
Z-Wave is nowhere near as much of a threat, as mobile phones. The system works with peak transmission power, of a maximum of 10mW at a short time. This corresponds to an average radiation power of only 1mW. This is because neither a radio remote control, radio switch, nor a radio transmitter from a motion detector operates directly in or close to the body.
The signal attenuation which is generated distance of only 1 m causes another reduction of the radiation power around the factor of 40. The human body is only hit by a radiation power of 0.025 mW. This is about 1: 4000 lower than the emission of a mobile phone.
Taking further into account that the radio signal will only be transmitted during a short period of time when a button is pressed or a sensor signal is transmitted, the electromagnetically emission of a Z-Wave network does not contribute to the general electromagnetic pollution in a home and does not have any negative effect to human beings.
Z-WAVE AND RADIO WAVES
Z-Wave uses the ISM frequency band in Europe which is fixed at 868.42 and uses a very robust frequency key modulation (Gaussian Frequency Shift Keying), which allows transmitting data with up to 40 KB/s. Older devices still use 9.6 kb/s so that (for backward compatibility reasons), all devices also understand a line encoding based on 9.6 KB/s.
The new hardware family Z400, which was introduced in 2009, offers an additional radio, using the frequency of 2.4 GHz
A good antenna for 868 MHz will allow a bridging distance of up to 200 metres outdoors. However, inside buildings the maximum distance is limited to 30 metres or even below, depending on the structures and the levels of attenuation in the building.
Generally though, all devices use compatible hardware so therefore the details of modulation and line encoding is not of interest to the end user.
WIRELESS TECHNOLOGY IN YOUR HOME
The great aspect of wireless technology, is that whilst it’s a sophisticated way of running your energy consumption and home security, it still remains simple, and personal to you.
You can plan your system to suit you and your home. As this guide explains, there are many considerations, but many ways of achieving optimum performance if planned correctly.
Every home is different, in terms of its layout and its requirements. The wireless system is versatile and makes itself at home in your home, very easily and effectively.
Copyright 2012 Vesternet Ltd.