DSE ITALY - tutorial on wireless CCTV range

Line of sight range and indoor range

Line of sight range
This is the maximum distance between a camera and receiver when there are no obstacles between the two, ensuring that the radio waves can travel freely through the air. The line-of-sight range can be measured fairly accurately using the appropriate methods. It should however be considered an approximate figure, as it can vary according to environmental conditions and external interference.
Indoor range
This is the maximum difference between a camera and receiver when there are various kinds of obstacles in between, such as walls or furnishings. The indoor range obviously depends on the number and type of obstacles present, as well as reflections off walls, and is therefore difficult to measure accurately. The figures given are therefore only an approximate guide, and can vary up to 30%.

Transmission in line of sight

Transmitting audio/video signals via wireless guarantees results identical to hard-wired transmission, when there are no obstacles between antennas. More or less the same quality of video is maintained where there are only a few obstacles, such as two walls, near the receiver.
When designing your system, you should attempt to ensure maximum line of sight, to guarantee the best video quality possible.
However obstacles do exist and it is necessary to find a way round them. Every obstacle inevitably means a certain loss of signal, which is why it is important to ensure there are not too many, which would lead to a complete loss of signal.
Signal attenuation also occurs in hard-wired transmission, every additional metre of cable translates into a loss of signal, up to complete loss at around 200/300 metres of cable (read more about this in the tutorial on video signal attenuation)
Below are a few indications on how to deal with obstacles.

Obstacles to wireless transmission

What type of obstacles can influence transmission?
The obstacles which can influence wireless transmission from a Radioeye® camera are those located on the imaginary line between the receiver antenna and the camera antenna. Any other obstacle in the vicinity, or above or below, will have little influence. This is why the position of the camera is very important, as moving it by one metre can sometimes be enough to get around obstacles.
Metallic obstacles
Metal is the only substance commonly present in everyday applications which is capable of completely screening a wireless signal. If you were to shut a camera inside a sealed metal container, no signal at all would get through, even with the receiver right alongside. Fortunately it is rare to come across obstacles entirely composed of metal, but it is important to look out for large metal gates or metal shelves. It is also important to remember not to install the camera inside a metallic “cage” such as a lorry or closed cab, unless you are able to position the antenna on the outside, as described below.
Non-metallic obstacles
Non-metallic obstacles do not entirely screen wireless signals, meaning that the signal from a RadioEye camera will pass through. Each obstacle encountered does however introduce a certain level of signal attenuation. Thicker, denser obstacles, such as thick cement walls or roofing slabs weaken the signal more than less dense, thinner materials like wood, plastic etc.
The importance of the location of obstacles
There is a general rule here: the nearer the obstacles are to the transmitter (the camera), the weaker the signal will be. It is therefore a good idea to avoid positioning a camera immediately behind a wall (with respect to the receiver), because the signal would be weakened at the outset. The camera should be positioned in the most open location possible, pointing towards the receiver and ensuring there are no large obstacles near the transmitter, where the radio wave is narrower and it is more difficult to get round obstacles.

SLIGHT OBSTACLES WITHOUT CONSIDERABLE INFLUENCE ON SIGNAL RANGE	LARGE OBSTACLES WHICH AFFECT SIGNAL RANGE
Thin partition walls	External or very thick walls
Plasterboard partitions – Office dividers	Reinforced concrete pillars – Roofing slabs
Obstacles in plastic, wood or paper	Metal obstacles – metal doors – sheet metal gates
Obstacles located very close to the receiver	Obstacles located very close to the camera
Industrial warehouses – buildings with large empty spaces inside	Residential buildings – buildings with dense, complex internal structures

Maximum workable distances between camera and receiver

Wireless cameras or hard-wired cameras with RE-TX2 transmitters
The standard versions of RadioEye® cameras and receivers offer a line-of-sight range of around 100 m.

TYPE OF CAMERA	DESCRIPTION	LINE-OF-SIGHT RANGE No obstacles between antennas	RANGE WITH SLIGHT OBSTACLES Small number of thin walls between antennas	RANGE WITH CONSIDERABLE OBSTACLES Considerable number, or thick walls between antennas
Wireless camera or hard-wired camera with transmitter RE-TX2	RadioEye® cameras	100 m.	70 m.	Varies according to obstacles

Increasing range with directional antennas

Directional antennas and omni-directional antennas

RadioEye® cameras and transmitters come with omnidirectional antennas which transmit in all directions. However these can be replaced with a directional antenna (RE-YG1 or RE-YG2) which transmits in one precise direction. Directional antennas are usually connected to cameras and pointed in the direction of the receiver. Usually, in view of their size, they are installed externally and connected to the camera by means of a dedicated cable (RE-CA4/5/6). The antenna can also be installed indoors if a suitable position can be found. Using a directional antenna around doubles the range of a transmitter (whether indoor or outdoor). Fitting one to the receiver too offers around triple the range, but it should be remembered that the cameras have to point more or less towards the receiver, or it will be impossible to direct the receiver antenna correctly (antenna field is 55° horizontally).

PRODUCT	Antenna on camera	Antenna on receiver	LINE OF SIGHT No obstacle between antennas	SLIGHT OBSTACLES Small number of thin walls between antennas	LARGE OBSTACLES Considerable number, or thick walls between antennas
Wireless camera or hard-wired camera with transmitter RE-TX2	Standard	Standard	100 m.	70 m.	variable
	Directional	Standard	200 m.	100 m.	variable
	Standard	Directional	200 m.	100 m.	variable
	Directional	Directional	300 m.	150 m.	variable

Increasing range by avoiding critical obstacles

As a general rule, cameras should not be located close to obstacles as this would affect the outbound signal at the outset, preventing good signal propagation. However at times it is impossible to locate the camera in another area, due to the filming angle required. In this case it might be possible to leave the camera where it is and position the antenna elsewhere, in order to avoid the obstacle. We offer specific 0.3 and 1 m antenna cables for this purpose, but it should be noted that using these cables introduces a slight degree of signal attenuation, in proportion to the length of the cable. The cable used should therefore be as short as possible.
Another option is to use a hard-wired camera connected to a separate transmitter (RE-TX2) with an Audio/Video cable. This option is preferable, as unlike the antenna cable, the audio/video cable (RE-CT1) can run for a few dozen metres, without affecting performance in any way.

How to position cameras in order to optimize signal range

The optimum position for cameras, ensuring best performance, is in a circular pattern around the receiver, if possible with cameras equidistant from the receiver. In this way you can exploit the maximum range of the system (eg. 100 m in one direction and 100 m in another), and the cameras, being offset, ensure the best possible transmission quality.
Obviously this layout is not always possible, as the site in question may not be suitable, or the reception point may not be central. The RadioEye® system enables you to locate the cameras where you wish, but where possible the following set-ups should be avoided

Do not locate two cameras in line
You should avoid positioning two cameras along the same line, namely one behind the other, both pointing towards the receiver. The camera in front could interfere with the weaker signal coming from the further camera.

Do not position one camera close to the receiver and others much further away
A camera positioned 2-3 metres from the receiver could disturb the weaker signal from the more distant cameras. If this situation cannot be avoided it is advisable to remove the antenna from the nearer camera.