Closed Circuit Television (CCTV) - Seminar Paper

Closed Circuit Television (CCTV)
         As the name implies, Closed Circuit Television (CCTV) is a system in which the circuit is closed and all the elements are directly Connected. Directly connected in this context includes systems linked by (CCTV) is the use of video cameras to transmit a signal to a specific place, limited set of monitors
        This is unlike broadcast television where any receiver that is correctly tuned can pick up the signal from the airwaves. It differs from broadcast television in that the signal is not openly transmitted, though it may employ point to point wireless links. CCTV is often used for surveillance in areas that may need monitoring such as banks, casinos, airports, military installations and convenience stores.

       A monitor and a camera are the two prerequiste devices required to build up a CCTV  network or a system.
            The starting point for any CCTV system must be the camera. The camera creates the picture that will be transmitted to the control position. Apart from special designs CCTV cameras are not fitted with a lens. The lens must be provided separately and screwed onto the front of the camera. There is a standard screw thread for CCTV cameras, although there are different types of lens mounts.
              Not all lenses have focus and iris adjustment. Most have iris adjustment. Some very wide angle lenses do not have a focus ring.
              The 'BNC' plug is for connecting the coaxial video cable. Line powered cameras do not have the mains cable. Power is provided via the coaxial cable.

              The picture created by the camera needs to be reproduced at the control position. A CCTV monitor is virtually the same as a television receiver except that it does not have the tuning circuits.

             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. Diagram 3 shows such a system. Probably the earliest well-known version of this was the Pye Observation System that popularised the concept of CCTV, mainly in retail establishments. It was an affordable, do-it-yourself, self-contained system.
             The next development was to incorporate the outputs from four cameras into the monitor. These could be set to sequence automatically through the cameras or any camera could be held selectively. Diagram 4 shows a typical arrangement of such a system. There was even a microphone built into the camera to carry sound and a speaker in the monitor.
               The speaker, of course, only put out the sound of the selected camera. There were however a few disadvantages with the  system, although this is not to disparage it. The microphone, being in the camera, tended to pick up sound close to it and not at the area at which it was aimed. There was a noticeable, and sometimes annoying, pause between pictures when switching. This was because the camera was powered down when not selected and it took time for the tube to heat up again.
              The system was, though, cheap to buy and simple to install. It came complete in a box with camera, 16mm lens, bracket,switching monitor and 12 metres of coaxial cable with fitted plugs. An outlet socket for a video recorder was provided, although reviewing could be a little tedious when the cameras had been set to sequence.
              There are now many systems of line powered cameras on the market that are more sophisticated than this basic system. Most of the drawbacks
mentioned have been overcome.Cameras had been around for a long time of course, before this development. The example is given to show the simplest,
practical application. The use of some line powered cameras can impose limitations on system design. They do though, offer the advantage of ease of installation.

               The basic CCTV installation is shown in diagram 5 where the camera is mains powered as is the monitor. A coaxial cable carries the video signal from the camera to the monitor. Although simple to install it should be born in mind that the installation must comply with the relevant regulations such as the Institute of Electrical Engineers latest edition. (Now incorporated into British Standard BS7671). Failure to do so could be dangerous and create problems with the validity of insurance.
               This arrangement allows for a great deal more flexibility in designing complex systems. When more than one camera is required, then a video switcher must be included as shown in diagram 6. Using this switcher any camera may be selected to be held on the screen or it can be set to sequence in turn through all the cameras. Usually the time that each camera is shown may be adjusted by a control knob or by a screwdriver.

                   With this arrangement the pictures shown during play back will be according to the way in which the switcher was set up when recording. That is, if it was set to sequence then the same views will be displayed on the monitor. There is no control over what can be displayed.

                So far all the cameras shown have been fixed with fixed focal length lenses. In many applications the area to be covered would need many fixed cameras. The solution to this is to use cameras fixed to a movable platform. This platform can then be controlled from a remote location. The platform may simply rotate in a horizontal plane and is generally known as a scanner. Alternatively the platform may be controllable in both horizontal and vertical planes and is generally known as a pan, tilt unit.
Cameras may be used indoors or outdoors. When used outdoors they will always require a protective housing. For indoor use the environment or aesthetic constraints will dictate whether a housing is needed. Systems may contain a combination of both fixed and movable cameras.

           Probably the most widely known use of CCTV is in security systems and such applications as retail shops, banks, government establishments, etc. The true scope for applications is almost unlimited. Some examples are listed below.
1- Monitoring traffic on a bridge.
2- Recording the inside of a baking oven to find the cause of problems.
3- A temporary system to carry out a traffic survey in a town centre.
4- Time lapse recording for the animation of plasticine puppets.
5- Used by the stage manager of a show to see obscured parts of a set.
6- The well-publicised use at football stadiums.
7- Hidden in buses to control vandalism.
8- Recording the birth of a gorilla at a zoo.
9- Making a wildlife program using a large model helicopter.
10- Reproducing the infrared vision of a goldfish!
11- Aerial photography from a hot air balloon.
12- Production control in a factory.
The list is almost endless and only limited by the imagination

1- Crime prevention / evidence:
            Outside government special facilities, CCTV was developed initially as a means of increasing security in banks. Experiments in the UK during the 1970
and 1980s (including outdoor CCTV in Bournemouth in 1985), led to several larger trial programs later that decade.

            Industrial processes that take place under conditions dangerous for humans are today often supervised by CCTV. These are mainly processes in the chemical industry, the interior of reactors or facilities for manufacture of nuclear fuel. Use of thermographic cameras allow operators to measure the temperature of the processes. The usage of CCTV in such processes is sometimes required by law.

           Many cities and motorway networks have extensive traffic-monitoring systems, using closed-circuit television to detect congestion and notice accidents. Many of these cameras however, are owned by private companies and transmit data to drivers' GPS systems.
           The London congestion charge is enforced by cameras positioned at the boundaries of and inside the congestion charge zone, which automatically read the registration plates of cars. If the driver does not pay the charge then a fine will be imposed. Similar systems are being developed as a means of locating cars reported stolen.

           A CCTV system may be installed where an operator of a machine cannot directly observe people who may be injured by unexpected machine operation. For example, on a subway train, CCTV cameras may allow the operator to confirm that people are clear of doors before closing them and starting the train. Operators of an amusement park ride may use a CCTV system to observe that people are not endangered by starting the ride.
         A CCTV camera and dashboard monitor can make reversing a vehicle safer, if it allows the driver to observe objects or people not otherwise visible.

 Computerised monitoring :
          The first CCTV cameras used in public spaces were crude, conspicuous, low definition black and white systems without the ability to zoom or pan. Modern CCTV cameras use small high definition colour cameras that can not only focus to resolve minute detail, but by linking the control of the cameras to a computer, objects can be tracked semi-automatically. For example, they can track movement across a scene where there should be no movement, or they can lock onto a single object in a busy environment and follow it. Being computerised, this tracking process can also work between cameras.
          The implementation of automatic number plate recognition produces a potential source of information on the location of persons or groups. There is no technological limitation preventing a network of such cameras from tracking the movement of individuals. Reports have also been made of plate recognition misreading numbers leading to the billing of the entirely wrong person. In the UK, car cloning is a crime where, by altering, defacing or replacing their number plates with stolen ones, perpetrators attempt to avoid speeding and congestion charge fines and even to steal petrol from garage forecourts.
          CCTV critics see the most disturbing extension to this technology as the recognition of faces from high-definition CCTV images. This could determine a person's identity without alerting him that his identity is being checked and logged. The systems can check many thousands of faces in a database in under a second.
           The combination of CCTV and facial recognition has been tried as a form of mass surveillance, but has been ineffective because of the low discriminating power of facial recognition technology and the very high number of false positives generated. This type of system has been proposed to compare faces at airports and seaports with those of suspected terrorists or other undesirable entrants.
           Computerized monitoring of CCTV images is under development, so that a human CCTV operator does not have to endlessly look at all the screens, allowing an operator to observe many more CCTV cameras. These systems do not observe people directly. Instead they track their behaviour by looking for particular types of body movement behavior, or particular types of clothing or baggage.
           The theory behind this is that in public spaces people behave in predictable ways. People who are not part of the 'crowd', for example car thieves, do not behave in the same way. The computer can identify their movements, and alert the operator that they are acting out of the ordinary. Recently in the latter part of 2006, news reports on UK television brought to light newly developed technology that uses microphones in conjunction with CCTV.
            If a person is observed to be shouting in an aggressive manner (e.g., provoking a fight), the camera can automatically zoom in and pinpoint the individual and alert a camera operator. Of course this then lead to the discussion that the technology can also be used to eavesdrop and record private conversations from a reasonable distance (e.g., 100 metres or about 330 feet).
            The same type of system can track an identified individual as they move through the area covered by CCTV. This is being developed in the USA as part of the project co-funded by the US Defense Advanced Research Projects Agency and, in France, by a company called Keeneo. With software tools, the system is able to develop three-dimensional models of an area, and to track and
monitor the movement of objects within it.
            To many, the development of CCTV in public areas, linked to computer databases of people's pictures and identity, presents a serious breach of civil liberties. Critics fear the possibility that one would not be able to meet anonymously in a public place or drive and walk anonymously around a city. Demonstrations or assemblies in public places could be affected as the state would be able to collate lists of those leading them, taking part, or even just talking with protesters in the street.

        The long-term storage and archiving of CCTV recordings is an issue of concern in the implementation of a CCTV system. Re-usable media such as tape may be cycled through the recording process at regular intervals. There also may be statutory limits on retention of data under some sort of Data Protection Act. However, individual recordings may be retained for indefinite periods for use in investigations or as evidence in legal proceedings.
         Recordings are kept for several purposes. Firstly, the primary purpose for which they were created (e.g. to monitor a facility). Secondly, they need to be preserved for a reasonable amount of time to recover any evidence of other important activity they might document (e.g. a group of people passing a facility the night a crime was committed). Finally, the recordings may be evaluated for
historical, research or other long-term information of value they may contain (e.g. samples kept to help understand trends for a business or community).
        Recordings are more commonly stored using hard disk drives in lieu of video cassette recorders. The quality of digital  recordings are subject to compression ratios, images stored per second, image size and duration of image retention before being overwritten. Different vendors of digital video recorders use different compression standards and varying compression ratios.
         The following formula can be used to determine the storage capacity required in binary gigabytes:
n: number of cameras
f: frame rate (number of frames per second)
s: average size in kilobytes of each compressed frame
a: activity time of each camera in percentage (e.g., use .60 for 60%)
d: duration in days
k: constant approximately equal to 1213.6 (exact value: 32768/27)

        A development in the world of CCTV (October 2005) is in the use of megapixel digital still cameras that can take 1600 x 1200 pixel resolution images of the camera scene either on a time lapse or motion detection basis. Images taken with a digital still camera have higher resolution than those taken with a typical video camera. Relatively low-cost digital still cameras can be used for CCTV purposes,using CCDP software that controls the camera from the PC. Images of the camera scene are transferred automatically to a computer every few seconds. Images may be monitored remotely
 if the computer is connected to a network.
        Combinations of PIR activated floodlights with 1.3Mpix and better digital cameras are now appearing. They save the images to a flash memory card which is inserted into a slot on the device. The flash card can be removed for viewing on a computer if ever an incident happens. They are not intended for live viewing, but are a very simple and cheap "install and forget" approach to this issue.
        Closed-circuit digital photography (CCDP) is more suited for capturing and saving recorded photographs, whereas closed-circuit television (CCTV) is more suitable for live monitoring purposes.

         An example of a CCTV camera with speakers attached, in Ipswich, UKA very special use of CCTV is at Hessdalen AMS where by it is used for discovery of unidentified flying objects. In the earlier days of television, some programs, and selected live sporting events, were shown on closed-circuit television in theaters across the United States. The 1952 Metropolitan Opera production of Bizet's Carmen was telecast complete by NBC on closed-circuit television. From 1965-1970, the Indianapolis 500 was shown live on closed circuit television in many movie theatres. The first few WrestleMania events were shown in such a way as well. The first six Super Bowls were shown at special closed-circuit TV gatherings in the host cities, where the game was blacked out by National Football League rules in place at the time. In the UK, some places have installed talking CCTV, where the operator can talk to the people they monitor.
        British author Chris Roberts quips that “Closed-Circuit Telivision Cameras are proving very useful to low-budget TV producers throughout the UK for programmes along the lines of World’s Rudest Drunks Outside Nightclubs in the North of England.”

          Unless physically protected, CCTV cameras have been found to be vulnerable against a variety of (mostly illegal) tactics:
               Some people will deliberately destroy cameras. Some outdoor cameras, such as those employed by the Chicago Police Department, have bullet-resistant housing.Spraying substances over the lens can make the image too blurry to be read. Laser pointers can temporarily blind cameras, and higher powered lasers can damage them. However, since lasers are monochromatic, colour filters can reduce the effect of laser pointers. For wireless networks, broadcasting a signal at the same frequency of the CCTV network is
reported to be able to jam it.

          As foretold  a day  arises when the whole world will be controlled by robots and electronic machines ,at that  moment  CCTV  replaces
the so called military forces which guards a nation.. Hence CCTV remains as the only hope for security of a nation...

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