This brief guide will help you understand the basic elements of a typical CCTV system.
It is important that we choose the correct type of camera for each specific installation as the specifications of CCTV camera’s vary enormously. We select cameras and lenses that offer the best quality picture for your specific environment, but we ensure this is achieved inline your budget requirements, hence ensuring you get the best picture possible for your money.
At the heart of the CCTV camera technology is a CCD sensor that converts light into an electrical signal. This electrical signal is then processed by the cameras electronics and converted to a video signal that can then be either recorded or displayed on to a monitor.
Types of CCTV Camera
These cameras sometimes called body cameras, C cameras or 1/3 cameras (due to the size of the CCD element) are still widely used. They come in many shapes and sizes but generally follow the form of the camera displayed. Many types of lens can be used to complement the camera and many advanced options let the installation technician change the settings to best suit the environment in which they are placed. Outside these cameras are fitted in larger more obvious heated housings.
Many types of Dome cameras now exist, but fundamentally any camera that is encased in a spherical housing is classed as a dome camera. Theses cameras offer the advantage of been virtually maintenance free and importantly hide the angle and position of the camera they contain. Dome cameras are quickly becoming the number one choice for shops, pubs, and schools.
Bullet Cameras tend to have fixed lenses that do not require manual focussing and are manufactured in many styles. Usually waterproof and optimized for exterior use, their a suitable choice for most domestic properties and some small businesses. Over the past year these types of camera have become more technically able and can now offer a quality alternative to the traditional C camera. Many newer models also come equipped with IR illumination like our very popular Sony chipped double barrelled IR camera shown below in the Infra Red section.
PTZ stands for Pan Tilt and Zoom; these cameras and special housings are usually installed where a system will be manned by staff or security guards.They allow the user to control the exact position of the camera along with the focal length via a computer or joystick mechanism. The application of such devices is wide ranging from schools to shopping centres. We now also have a low cost automated PTZ dome solution that can be used in retail environments, and allows the user to track shoplifters exact movements.
Covert Cameras, in essence, are a means of offering undetected surveillance. Suitable for use in a broad range of applications, these miniature Cameras are hidden in every day commercial and domestic objects. Covert cameras tend to be used where there is a requirement to achieve particular objectives. For example hiding a camera in a stock room will help catch rouge employees.
Generally cameras with higher resolutions will produce a better picture. A common measure of resolution is TVL(number of TV lines the camera generates), i.e. a camera with a 300 TVL image is generally not as effective as a camera with a 480 TVL image. Most cameras over 400 TVL will offer an excellent picture. The overall quality of picture is dependent on the type of camera lens, wiring, monitor and recording system.
Monochrome or Colour Cameras
The human eye remembers and recalls things better if they appear in colour – it’s easier to track down a brown-haired person wearing a red coat and blue jeans than a dark, grey-clad figure that would be produced in monochrome. Colour cameras are generally more expensive compared with monochrome cameras, but are also less light sensitive making night usage an impractical option unless good lighting is available. Monochrome cameras can also offer Infra Red (IR) sensitivity allowing them to be used with covert IR illumination. This can be particularly useful where extra lighting may be impractical or where the security requirement is such that intruders should not be alerted to the existence of CCTV surveillance.
Cameras at night, Infra Red Lighting
The range that your camera will see in the dark will depend on the sensitivity of the camera, the ambient light and lens combination. Where additional lighting is unsuitable infra red provides the best solution. The human eye cannot see infra-red light, however most monochrome CCTV cameras can. As such the invisible light can be used to illuminate a scene; this allows night time surveillance without the need for additional artificial lighting. Infra-red lamps cannot work with colour cameras, therefore the best alternative is to use a dual technology camera (colour by day, monochrome at night) together with IR lamps. These cameras are called Day/Night cameras and we install these as standard in the majority of installations.
Recording and Viewing your Image
Recording the image is one of the most important parts of the system, and this can be done in one of two ways, digitally via a DVR (hard disk recorder) or if price is an important factor by the traditional video method. Although over the past few years digital recording solutions offer real advantages over time lapse Videos. Not only are the recorded images superb but they offer many functions and facilities that Time lapse video recorders simply don’t provide. We predominantly install DVR based systems as we can now offer entry level DVR technology at similar prices to outdated VCR’s. Using Time Lapse videos is still the most cost effective method if your requirement is for a single camera system. The screen that you use to monitor your pictures is another important factor, we offer monitors that range in size from 5” to 42” plasma screens. Many customers are now choosing TFT screens, these are particulary beneficial where space is a premium.
Digital Video Hard Disk Recorders (DVR’s)
DVR’s are excellent at reproducing high quality images with little noise or picture degradation and are extremely useful in calling up an event or moment in time. Fundamentally DVR’s allow you to record several images at once, this information is stored digitally on a Hard Disk rather than a tape. The advantages over VCR’s are many, VCR tapes begin to wear and deteriorate from the moment they begin recording while Hard Disk recording remains at the same high standard throughout it’s working life. In addition to the obvious quality benefits DVRS offer a number of additional features not available with Multiplexers and VCR’s. Certain DVR’s make it possible to view and control your CCTV system from computers around the world.
Quality of Installation
An often over looked area, but system installation can have a huge impact on performance. It is important to understand video transmission in order to select the most appropriate installation method. Using the wrong cables, poor camera positioning, bad connections will affect the overall picture quality . Our fully qualified engineers understand video transmission and posses many years worth of experience to ensure each of customers receive the best installation possible.