Unlike our home TV, a closed circuit television or CCTV, does not commit to unrestricted transmission and entertainment broadcast. Instead, CCTV signals are directed from one place to another, used mainly for surveillance purposes. Germany gave birth to the earliest form of CCTV in 1942, for monitoring their V-2 rockets in Peenemunde. Subsequently, US liberates the use of such device from permit to non-permit require, leading to the eventual rise of commercial security systems in the 1960s.
New York City pioneered the installation of CCTV in public areas under the name of fighting crimes, even though the attempts proved no avail in lowering the rates. Nevertheless, the effort rippled as other cities began to eye on video surveillance as a more economically viable way to combat theft comparing to increase police force. On top of crime prevention, CCTV is also popular in keeping an eye on traffic flow, monitoring workers at work, ensuring transport safety, and to replace human in highly dangerous working environments.
Earlier form of CCTV was primitive in the sense that footages were not recordable and changing of recording tapes needed to be done manually. Hence regular manpower had to be employed and continuous supervision was pricey. However, as technology advances, CCTV evolves from mono-signaling to multiplexing, enabling different cameras doing simultaneous captures, independent of human command.
Recently, it has become more prevalent for CCTV to tie in with other technologies that permit accurate observation and convenient access. For example, coupling with Video Content Analysis (VCA), which mimics the visual system of a human, CCTV can now identify an object or event via its shape, size, colour, and movements. An alarm can also be programmed to go off if irregularities are detected. Another example is the Internet Protocol camera (IP camera) which transmits collected data digitally, so that users can gain access to footages via their 3G mobile phones or computers.
CCTV, no doubts, has become a cheap and easy source of “looking after our society” while we are asleep. In US alone, it is believed to house about 30 million surveillance cameras; many of which were privately installed with no prior approval. Likewise in UK, on average, the surveillance density is about one camera to every 32 people. In Canada, a special program known as “Project SCRAM” was put up by the local police force to ensure civilians understand and do not cross the thin line between invading privacy while ensuring safety; this was done by having public to register confidentially while they are installing home security systems.
Logically, all CCTV starts off with a camera, to capture images of a designated area it had been positioned. Focus or iris adjustment lenses are attached to one side of the camera body, providing a specific width and sharpness to the footages, while BNC plug is on the other side to be connected to a coaxial cable – a type of cable which is commonly used for signal transmissions. This coaxial cable will connect the camera to the monitor, which showcase all captured footages. The monitor looks exactly the same as a home TV, but comes in a much smaller size without circuits to tune for different channels. Thus, this camera, coaxial cable, and monitor trio will made up of what is being known as a simple line powered camera.
Variations of the above CCTV system kick in when more than one camera are connected to the same monitor, which results in two to four images showing on the same monitor at once. With this, usually more than one coaxial cable will be present and the monitor will also be equipped with switches to maneuver between footages captured by different cameras. Microphone can also be built within the camera and a speaker inside the monitor to acquire and play the recorded sounds. Similarly, instead of a monitor, the coaxial cables can also be connected to a video switcher, follows by an output cable from the video switcher to a video recorder, so that whatever that had been captured would also be recorded.
At one glance, installing CCTV may seem easy, because there is a fixed number of parts making up to the system and official approval is not obligatory. Indeed, a detailed manuscript is more than enough for a successful DIY. However, if capturing the wrong images or sounds, getting connected to the wrong cables, and unable to decide which camera is best for your needs, are some of the nightmares you refuse to dream of; do not hesitate and skip the step of consulting an expert. So, what are you waiting for?