CCTV is different from broadcast television as all the equipment is directly connected together with cables or wireless transmitters that can not be received by standard television aerials or equipment.The transmissions of the video signals are only intended to be accessible by the equipment on its dedicated closed circuit.
CCTV is generally used in areas where there is an increased need for security, such as banks, airports and town centres. CCTV was initially developed as a means to increase security for banks but over time it has developed into a cost effective means of general video surveillance and home security.
A basic CCTV system comprises of the following:
- Camera, lens and power supply.
- Recording device, VCR or a digital video recorder.
- A monitor.
CCTV Camera’s Features :
CCTV Cameras are available in colour, monochrome or cameras that have the ability to switch between colour and monochrome (day/night cctv cameras). The cctv cameras that switch between colour and monochrome are intended for environments of low lighting at various times. There are 2 reasons for using a cctv camera that can switch between colour and monochrome, monochrome cctv cameras are much more sensitive to low lighting environments, and monochrome cctv cameras can also be used with Infra red lighting. When there is adequate available light there is the added advantage of using a colour cctv camera for recording colour information, for example the colour of a car or a person’s clothing.
The primary function of a cctv camera is to convert light into a video signal, all cctv cameras require an optical lens to focus the light onto an image sensor located directly behind the lens inside the cctv camera.
There are two types of image sensor available, a cctv camera with a CMOS (Complementary Metal- Oxide Semiconductor) image sensor chip and the other more common type that uses a CCD (Charge Coupled Device) imaging sensor chip. The majority of CCTV cameras and Video Camcorders use a CCD imaging sensor, whereas CMOS imaging sensors are more commonly used in webcams, budget home security cameras and digital photography cameras. CCD cameras are capable of creating a much clearer and higher resolution image.
Different types of cctv cameras are Board Cameras,C Mount Cameras,IR Cameras,IP Cameras,Zoom Cameras,Speed Dome Cameras.
All cctv cameras require a power supply, these are usually 12 volts DC, 24 volts AC or 240 volts AC.