Keeping a close watch

Video surveillance has gained immense popularity across the globe due to rising concerns for security and safety. This has resulted in demand for technically advanced surveillance systems and the creation of significant growth opportunities. Paul Dawson of ESP takes a look at the sector and examines how electrical contractors can take advantage of this anticipated growth.

For those electrical contractors not already on board, the CCTV market presents them with a tangible opportunity for diversification. They will already possess the necessary skills to operate in this complementary and growing sector and are ideally placed to take full advantage of an extremely lucrative addition to their electrical business.

CCTV security systems can take the form of simple video surveillance systems for small shops and business premises to large complex projects such as urban traffic management systems, town centre surveillance systems and high profile buildings.

Businesses use Closed Circuit Television to protect and monitor their staff, their premises, their stock and their customers. From running a retail warehouse to managing local authority properties, CCTV lets you see exactly what’s happening without the need for a physical presence. It also provides effective protection for residents on housing estates, goods in shops and valuable assets in businesses. It also acts as an ever-watchful eye at remote sites or where staff levels are minimal and helps improve safety systems or assisting in traffic management.

Survey

Possibly the most important stage of any CCTV installation is the survey. Time spent understanding what the end user and operator of the system expect, will be of great benefit. The owner of the property to be protected will have the best knowledge of potential areas of risk and the usual daily movement of people and vehicles around the site. The installer can then assess, through further discussion, the coverage and, more importantly, image detail required.

A question often posed is “how far can the camera see?” The answer can be a little misleading. Virtually all cameras could provide an image of a vehicle entering a car park several hundred yards away but if the customer wants to clearly see what kind of car, the number plate or recognise the driver, then the camera selection will be very different.

Establish early in the survey stage two important facts for each area to be viewed. What is the distance between the target and the likely camera location? And what size will the target need to be to give sufficient detail on screen? For instance, to have the best chance of capturing a number plate, the whole image should not be much wider than the width of the vehicle itself, i.e. a target area of around 2m x 1m. Having these two facts in hand allows use of a simple calculation to discover the best choice of lens size and therefore camera choice.

Distance (camera to target) x 4.8 / width of target = recommended lens size in mm.

To work out the lens required to view a car number plate at a distance of 15m, the calculation would be 15 (distance) x 4.8 / 2 (width) = 36; therefore a 36mm lens.

If all that is required is observation of a vehicle entering an area, the target width could be much wider say 15m. 15 x 4.8 / 15 = 4.8.

Once the lens sizes are calculated the camera selection can begin. The first consideration is lens size itself and the readily available sizes are fixed 2.8mm, 3.6mm, 4mm, 6mm, and a range of vari-focal options that offer manual adjustment between 2.8 – 12mm, 9 – 22m and 5 – 50mm.

Considerations

The second consideration is image quality. Analogue cameras are measured in TVL (television line) – in other words the amount of single lines that are used to create the image and more lines create a better image. Ratings currently available run from medium quality 420 TVL up to the latest 700TVL units, which offer impressive images often along with additional built-in user adjustable controls to further enhance the image. Lastly there is the issue of body type. The choices can seem endless but really come down to bullet or dome style; with or without integral Infra-red illuminators; and then suitability for internal or external use.

Consideration then moves to recording the captured images. DVRs (Digital video recorders) are available in many different shapes and sizes. The choice of a suitable unit is made by deciding on three main factors. First of all there is the number of cameras in the system. DVRs are available in 4, 8 or 16 channel variants with larger 24 and 32 units now arriving on the market.

The second consideration is the size of hard drive and the image storage capacity. A 500 GB drive is perfectly adequate for 4 channel units, while larger units can offer space for drives up to 16TB. Drive requirement is controlled by how recording will occur; continuous recording of all channels will quickly use up drive space. Latest high resolution cameras feed more information to the DVR and therefore also use more space. As drive space becomes under pressure, motion triggered recording – a feature of most DVRs – is being widely used.

The third factor relates to the image record quality. Until recently most DVRs offered a standard record resolution know as CIF. The choice of quality standards available has now grown. D1 recording – effectively four times the quality of CIF – is now seen as the benchmark for all but the most basic of units. Higher grade products feature even higher resolutions – 960H to get the best quality playback and recording from 960h 700TVL cameras and the latest, and considerably more costly, HD–SDI DVR’s which need to be used alongside equally expensive HD cameras. The good news is that affordability of these higher resolutions is set to improve quickly. This in turn will increase the popularity of CCTV as customers realise the old grainy images are a thing of the past.

Following the selection of the most suitable Camera and DVRs, the next stage is to decide how the images will be viewed. Locally the best choice is a CCTV monitor designed for constant use (PC monitors are just not the same) and connected to the DVR through a VGA cable or ideally HDMI where available to get the best image.

Additionally most DVRs also offer the option to send the images through a router for distribution around a local network or via the internet to mobile devices using dedicated Apps. Network set up can seem daunting on the first attempt but soon becomes simple and offers the installer a real chance to impress the customer.

Cabling

The final stage is the cabling requirements. For many years coaxial cable has been used to link the various components of a CCTV installation. Over recent years CAT5 has become more widely employed due to flexibility and image quality over distance. New technology now enables use of Cat5 to provide power and video connection to cameras at distances over 300m or just video up to 1km.

The attractive opportunity to cable a CCTV system with easy to install and terminate Cat5e/6 has existed for some time. A balun is introduced at both ends of the CAT5e/6 run to enable transmission of the camera’s analogue signal. Whilst this is a successful way of handling the video signal, an issue exists with powering the camera. Cat5e/6 cable will induce voltage drop after as little as 30 metres. The current solution is to power the camera locally with individual supplies. However the cost and labour involved can be prohibitive.

Results

Good quality hard-wired cable will always provide the best results. However, where cabling between components is very troublesome or expensive, there have been great leaps forward in sensible wire free solutions.

These are usually in the form of standalone transmitter receiver sets to link single cameras to the DVR where needed. The latest digital based wire free products with channel hopping capability can be interference free at distances of around 150m in open space.

CCTV is firmly established as the first choice to both protect assets and provide vital information essential to solving crime. It also offers opportunities for staff and building management. Most importantly it can give all installers irrespective of previous experience a complementary income stream to their current business model.

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