Closed-circuit television actually got its start in the space program, with cameras that were deployed to watch a space launch. The system was created to allow engineers and scientists to watch the various details of the rocket’s launch, with an eye to determining the cause of any problems. While many of those cameras burned up in the heat of the launch, they did provide valuable information; even more importantly, they provided for the creation of CCTV to be used in other areas.
Today, CCTV is used predominantly for security purposes and fighting crime. Police agencies, stores, and other businesses install CCTV systems to help control anything from corporate espionage to crime. Many of these systems are tied into the Internet, allowing police instant access to recorded images of everything that happens in sight of the cameras.
While the basic concept remains the same, the technology has improved. Early CCTV systems used only black and white cameras with poor resolution. Recording was done on videotape, which was both expensive and limited the quality of recording that could be made to the format of the videotape. Today, the quality of image that cameras are able to produce is much more detailed, available in color and recorded electronically, reducing the cost and hassle of countless videotapes.
Modern CCTV cameras that are deployed for traffic control can easily identify a pedestrian at over a block away. This increase in resolution has made the systems much more effective, as the proximity of the camera to the subject is not the issue that it used to be.
Creating a CCTV System
In its most basic configuration, a CCTV system consists of a camera and a video monitor. The two are usually connected together with a 75 ohm coaxial cable, which uses BNC connectors to attach it at both ends. BNC connections provide a locking connection, which helps prevent inadvertent disconnects.
Most systems are more complex than this, as there is usually a need for more than one camera. Additional cameras require a video switcher to cycle between the cameras, allowing whoever is monitoring the system to see all of them in turn. Additionally, there is usually a desire to record the events happening before the cameras, necessitating the addition of a video recorder.
Today’s systems are considerably more complex than this, but all start from this basic concept. In most cases, the video switcher is replaced by computer software and the video recording is accomplished either on the computer’s hard drive or directly into the Internet cloud.
Literally any video camera can be used as part of a CCTV system. At the low end of the scale, standard webcams are usable, if one is willing to put up with low resolution and a slow frame rate. A wide variety of cameras are manufactured specifically for use with CCTV systems, many of which have specific capabilities that may be needed in their application. Some cameras have weatherproof shells, allowing them to be used outdoors.
Additionally, some cameras are remotely controllable, allowing the system operator to pan, tilt and zoom the camera to catch specific people or events of interest. It is not unusual for a system to combine fixed and remote controllable cameras, providing a range of options to the system operator. In many systems, these cameras can be programmed to move in a repetitive cycle, allowing the camera to cover a broader area.
IP cameras provide the capability of connecting the camera directly into a local area network, with its own IP address which can be accessed by the computer controlling the system. This saves on installation and wiring costs by utilizing the already existing network for the wiring.
Cameras are also created for handling low light situations and infrared. Some higher end cameras have multiple modes, allowing them to operate in normal, low light and infrared modes as the situation may warrant. By providing additional capabilities to the camera, the overall system becomes more effective. Reductions in cost have made it practical to use color cameras in many applications where only black and white was used previously due to the high cost of color cameras.
Some video cameras used in CCTV installations are wireless. This doesn’t necessarily mean that they don’t use any wires at all, as they typically have a power cable. However, the video signal is sent to the switcher or computer via radio waves, rather than via cables.
These wireless cameras are popular with security companies due to their lower installation cost. The extra cost of the camera is more than compensated for by the labor savings in not having to run wiring to all the camera locations. However, this capability comes at a price. Like anything else transmitted over the airwaves, the signal from these cameras can be picked up on by anyone who has the right type of receiver.
For those who already have cameras that are not wireless, there are adapters which allow those cameras to be used in a wireless system. The wireless system consists of small transmitters which are installed on each camera, and a common hub that receives all the signals.
For computers to be used as the main monitoring station of a CCTV system, security software has to be installed on the system. This has some distinct advantages over older systems, where a human operator was required to monitor the system.
One distinct advantage of computer monitoring on CCTV systems is the ability to incorporate motion sensing into the monitoring software. This causes the software to only record video feeds that are showing movement, reducing the workload of reviewing the video footage. When reviewing the video, time-lapse can be used, speeding up the action to the point where an event of interest happens. As the video has a time-stamp and location-stamp recorded with the image, accurate information about any security breach or crime can be defined and recorded.