CCTV - Closed Circuit Television (Video Surveillance)
Examples of hidden dome Cameras
Dome Camera

CCTV is a television system that operates on a 'closed loop' basis. Unlike broadcast television, which is available to anyone with a suitable receiver, CCTV pictures are only available to those connected directly into the loop.

CCTV was first used in the 1950's and has since become an essential element in any professional security system. It allows both premises and the people within them to be constantly surveyed, giving security teams and property managers' tighter control over access and a means of meeting the challenges posed by the rising crime rate.

In most installations, the loop is a physical link - a cable that carries the picture from the camera(s) to the viewer(s).

Increasingly manufacturers are able to increase the flexibility of CCTV systems by replacing all or part of the physical link with microwave, laser, or other connections.

As well as the wide range of property security applications, CCTV offers benefits in many other areas:

  • Assisting Police authorities in the monitoring of traffic flows and the implementation of prompt action in the case of accidents and other emergencies.
  • Supporting process industry managers as they control the flow of work, identify bottlenecks and take corrective action.
  • Monitoring of hostile environments that are not accessible to man, such as nuclear reactors, furnaces, etc.

The versatility of CCTV is being applied to a growing range of commercial and scientific applications, helping organisations to improve performance and security and control costs at the same time.


Security and surveillance are the most accepted applications for CCTV systems. With the aid of CCTV managers and supervisors can control risks and minimise costs efficiently and with the minimum of disruption.


As well as an effective deterrent, CCTV helps managers to monitor:

  • Access to secure or private areas
  • Unauthorised activities
  • Theft or criminal damage
  • Personal safety


CCTV has many applications in public safety; helping officials to monitor changing conditions and decide on corrective action in areas such as:

  • Traffic control
  • Crowd control
  • Public access
  • Staff control
  • Car park security
  • Shopping precinct security
  • Industrial process control


CCTV offers organisations increased efficiency and the faster detection of problems. As a result, its benefits include:

  • Reduced security running costs
  • Faster response to problems
  • Increased peace of mind Simplicity and reliability
  • Improved quality of environment for owners, operators, and the public
  • Easier identification of suspects

Many systems are available from small, one camera modulated B & W systems which connect into the television sets within the home, through video gate/door cameras/intercoms with individual screens to specific rooms, to full, time-lapse recorded, multi-camera colour systems giving surveillance and identification capabilities from a central control point, and even signal transmission off site.

With newly developed digital recorders (see example at right), reviewing the recorded footage has become fast and simple along with built in features such as full multiplexing facilities, motion detection / activation, 100Gb expandable hard drive archive, time-lapse recording, motion activated recording, split screen review and zoom features. Simply type in the time and date the review is to start from and the recorder will instantly locate and play the desired footage. The ability to rapidly fax or email an image, (using the appropriate interfaces), to Security or Police can be a major factor in apprehending offenders.

The comparison between standard VHS VCR time-lapse and digital recorders is exactly the same as the difference between music cassette and CD players with all the same benefits of instant search, fast review etc.


In larger premises, cameras are often less visible. Covert cameras may be mounted in smoke detectors, sprinkler heads, thermostats or clocks. It is popular to mount cameras in ceiling tile domes (see example at right), they are bubble-like and tinted so no one can see where the camera is pointed. From this vantage point, a pan / tilt / zoom camera can be moved to follow someone around the premises. (If security is not monitoring and operating the camera, it can be set up to operate automatically but will not follow someone around the store.)

Video cameras used for security purposes don't look anything like the video camera your family has at home - they're becoming smaller and more specialized. A standard surveillance camera might be in the neighbourhood of 4 inches long by 2 1/2 inches wide with a lens on the end.
In circumstances requiring surveillance of trouble areas, more obvious cameras mounted in clear domes or special outdoor housings are generally proposed due their deterrent effect.

For reasons of security and protection we recommend that cameras be mounted in such a way that they give a complete field of view over the trouble areas. This generally means that a higher position on a pole or building is better.


The human eye and the camera lens operate on completely different lines. Although the human eye adjusts automatically to varying light conditions, the camera is inherently less flexible. In a CCTV system, lighting has to be 'designed in' from the beginning if the best results are to be obtained. The type of lighting used, and the correct positioning are vital to maximum security.

Everyday 'white light' is actually a mixture of colours of different frequencies. CCTV is more receptive to certain colour combinations than others. The best results are usually obtained by matching the spectral response of the camera to the light illuminating the scene.

The amount of light reflected from an object determines how 'bright' it appears. Below are some typical reflective figures:

10 - 20%
Red brick
50 - 75%

To assist in achieving good quality recordings of the subjects, it is strongly recommended that lighting throughout the complete area covered by the camera is of a better standard than required as a minimum for the camera operation, (i.e. a good quality black and white camera will require 0.05 lux at F1.2 and a good quality colour camera will require 0.7 lux at F1.2. To give you an idea of what lux means see the table below.

50,000 Summer sunshine 5 Typical side road lighting
5,000 Overcast sky 2 Minimum security risk lighting
500 Well lit office 1 Twilight
300 Minimum for easy reading 0.3 Clear full moon
50 Passageway / outside work area 0.1 Typical moonlight / cloudy sky
15 Good main road lighting 0.001 Clear starlight
10 Sunset 0.0001 Typical starlight / cloudy sky

As you can see 300 lux is generally considered to be the minimum required for easy reading, and good main road lighting is about 15 lux, so we recommend that a minimum of 2 lux be maintained over the total coverage area, (including at the periphery), to ensure that you achieve your objective.


DVR Networking Structure

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