Closed Circuit Television, also known as CCTV, is a private video system within a building or complex used to visually monitor a location for security or industrial purposes. A CCTV system can be recorded and viewed on-site or viewed remotely through the use of telephone lines.
What are the Basic Components of a CCTV System?
CCD (Charged Coupled Device) Camera
The modern CCTV video camera is available in both monochrome (black and white) and color. Cameras can be set in fixed positions or placed on pan-and-tilt devices which will allow the camera to be moved up, down, left and right. Using a zoom lens will allow a closer view of the person or object you wish to see.
Monitor
A monitor is very similar to a standard television set. However, it lacks the electronics to pick up regular television. Monitors are available in both monochrome and color versions.
Time-Lapse Recorder
The video recorder commonly used in the security industry has the ability to record up to one week of video on one tape. The most commonly used timing is the 24-hour mode. Having to change tapes only once a day while retaining large amounts of information are advantages of using this type of recorder.
Coax Cable
Coax cable is the standard means of transmitting video in a CCTV system. Coax is the same type of cable used by cable companies to send television into homes.
Control Unit
If a CCTV system has more than one camera, there must be a way to control each video signal going to the VCR and the monitor. There are three basic types of Video Control Units:
- Switchers: Units that provide full screen images, one camera after another, typically for 3 to 5 seconds each. When one camera is on the screen the other cameras are not being recorded.
- Quads: A Quad sends up to four cameras to the screen and to the recorder at the same time, each camera gets a quarter of the screen. All of the information from each camera gets recorded but only in small quarter-screen clarity.
- Multiplexers: These units are high-speed switchers that provide full-screen images from up to 16 cameras. Multiplexers can playback everything that happened on any one camera without interference from the other cameras on the system.
What is Resolution?
Resolution is a measure of how clear and crisp an image on the monitor appears. Each piece of CCTV equipment in a system plays a part in the overall image quality, and the final image will only be as clear as the piece of equipment with the lowest resolution. If you are using a high-resolution monitor and a low-resolution camera, the monitor will display the image quality of the lower resolution camera. This becomes even more important when recording. The image quality when playing back a tape is typically half that of your normal monitor image. Be sure that the resolution of a system will fit your needs before you install the system.
What is Remote Transmission and Alarm Verification?
Remote Transmission and Alarm Verification are new CCTV technologies that allow a CCTV system to be monitored and alarm conditions to be verified from a professional central monitoring station anywhere in the world. The central monitoring station responds to alarm situations not only by viewing the site but also by turning on lights, opening or closing gates and doors and even interceding with live audio. While this technology cuts down on false alarms and gives authorities better information, such as license plate numbers and physical descriptions, it also gives companies the ability to "look in" on inventories, point of sale displays and employees.
Where is CCTV Being Used?
CCTV is being used effectively almost everywhere. From airports to day care centers, even in our homes, we are finding benefits to seeing the person at the front door or watching the baby. You will find cameras protecting parking garages, apartment complexes and many of our workplaces. You'll find cameras in many police vehicles to document incidents and help to keep our roads safe.
For More Information
Please contact Christina Bagby, SIA Manager of Marketing and Member Services, at (866) 817-8888 or (703) 647-8494 or via email at cbagby@siaonline.org.