Specifying CCTV Systems
Firstly, as with all sales you need to ask the obvious question – “what is the system for?” This is actually more important with CCTV than with many other aspects of security in that CCTV systems are often badly sold and the customer often has unrealistic aspirations of what they can achieve.
Essentially they fall into one of three categories:
Audit trail systems – usually comprises of a number of static cameras connected to a DVR so that in the event of an incident the recording can be viewed and acted upon. It is important to look at the limitations of a static camera as even with a wide angled lens they rarely view more than 75 degrees. If you compare this to normal human vision of nearly 180 degrees you can see how you will need multiple cameras to cover even one elevation of a building.
Surveillance systems – usually consists of an number of static cameras backed up by fully functional domes (or traditional pan tilt zoom camera units). The operator will generally use the static cameras displayed as a multi-screen image to give an overview of the site and then on a separate monitor pick up and follow a live incident with the fully functional dome. The reason that it is necessary to have both audit trail cameras as well as fully functional ones is simply that if your powerful fully functional camera is viewing a gate 100 metres away it is obviously not covering the rest of the area.
Remote monitored systems – Similar to the live surveillance systems but with alarm triggers to activate the ARC (Alarm Receiving Centre) and local alarms to operate the presets on the functional dome. A preset is a pre-programmed location that the camera will rotate and zoom into as a result of some form of alarm input. The inputs can be virtually anything; a door opening, a movement detector activating, a smoke detector going into alarm, etc. Presets are useful in both surveillance systems and monitored systems in that they move the functional dome to the required location faster and more effectively than an operator could.
The easiest systems to fit and the least regulated are the audit systems which can even be bought in kit form and fitted in small commercial and domestic properties.
Kit cameras need very little set up and the DVRs can be mastered with a little training. Ensure you have enough light for your cameras or that your cameras have an IR (infra red) capability with leds (light emitting diodes) built into the camera housing. These cameras will switch to monochrome automatically when the light level reduces. Only then will the IR leds work. If you want colour images then you must provide white light.
Often these kits are fitted as a standalone systems with their own monitor and recording device. They can with a little bit of experience be patched into a domestic AV network so that the pictures can be displayed on the customer’s television. The next stage is to connect them to a LAN or broadband line so that the pictures can be viewed from a remote computer. This will take a lot more training and there are a number of issues regarding routers and IP addresses that are often best left with specialist contractors.
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