A Brief Overview of CCTV

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Closed Circuit Television (CCTV), as the name implies, it is a system in which the circuit is closed and all the elements are directly connected. This is unlike broadcast television where any receiver that is correctly turned can pick up the signal from the airwaves. Directly connected in this context includes systems linked by microwave, infrared beams, a fiber optic cable etc. which carries the picture from the camera to a monitor. This article introduces the main components that can go to make up CCTV systems of varying complexity. The main activities of CCTV is very simple. A video camera is used here. It counts the real time to capture the image of the reading material and display it on a monitor. Alternatively, CCTV is a video magnification system consisting of a video screen interfaced with a video camera. Video magnification is achieved in two ways - the electronic conversion from the small camera image to the large display screen and the optical effect of the camera zoom lens. The stand mounted CCTV can be configured with television receivers, video monitors or computer monitors. The CCTV system provides high contrast, inverse video display, gray scale, false colors, and natural colors to control of contrast level and brightness.

Types:

1. In-Line CCTV: These are the "traditional" models of CCTV. The monitor or video display is mounted over the camera.
2. Out-of-Line CCTV: These models have a camera unit and generally use a television as their display.
3. CCTV use Computer Monitors: These are connected to a computer monitor. They are not interchangeable with a television.

Simple CCTV Systems:

The simplest system is a camera connected directly to a monitor by a coaxial cable with the power for the camera being provided from the monitor. This is known as a line powered camera.

System with Movable cameras:

This system use cameras fixed to a movable platform. This platform can be controlled from a remote location. The platform may simple rotate in a horizontal plane and is generally known as scanner.
Alternatively, the platform may be controllable in both horizontal and vertical planes and is generally known as a pan, tilt unit.

Bandwidth:

The composite video output from the average CCTV camera covers a bandwidth ranging from 5Hz to many MHz. The upper frequency is primarily determined by the resolution of the camera and whether it is monochrome or color. For every 100 lines of resolution, a bandwidth of 1MHz approximately is required. Therefore, a camera with 600 lines resolution gives out a video signal with a bandwidth of approximately 6MHz. This principle applies to both color and monochrome cameras.

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