CCTV is one of the fastest growing regions in the security industry. As the name implies CCTV (closed circuit television) is a system in which elements are directly connected but the circuit is closed. This is different from regular broadcast television where the receiver which when correctly tuned can pick up the signal from the airwaves. Direct connection in this framework includes systems connected by microwave, infrared beams, etc.
CCTV technology was first used in the 1940s to monitor the testing of V2 missiles. The first US manufacture of CCTV equipment was established in 1946 by a major manufacture of large power plant boiler systems to fill a need that was not available on the commercial market. By the 1960s, officials in the UK began installing CCTV systems in public places to monitor crowds during rallies and appearances of public figures.
In the past it was assumed that CCTV was too expensive and too complicated so there was nothing to get involved in it. Also there were concerns with regards to privacy issue. Over the years it has become far more affordable and simpler to install. This article introduces the main components that are needed to make up CCTV systems of changeable complexity.
CCTV technology was first used in the 1940s to monitor the testing of V2 missiles. The first US manufacture of CCTV equipment was established in 1946 by a major manufacture of large power plant boiler systems to fill a need that was not available on the commercial market. By the 1960s, officials in the UK began installing CCTV systems in public places to monitor crowds during rallies and appearances of public figures.
In the past it was assumed that CCTV was too expensive and too complicated so there was nothing to get involved in it. Also there were concerns with regards to privacy issue. Over the years it has become far more affordable and simpler to install. This article introduces the main components that are needed to make up CCTV systems of changeable complexity.
THE BASICS OF CCTV
1. THE SCENE AND LIGHT:
The scene refers to the area that is under the observation of CCTV cameras. The scene often contains different colours, surfaces, and materials that reflect light of varying level. It is necessary to determine the minimum lightning level at both day and night time that will reach the camera lens so that proper equipment can be easily selected. The scene can be illuminated by natural or artificial light sources which include sun, moon, stars, incandescent, sodium, florescent, infrared and other man made lights. A proverb in CCTV security says that: The better the Light, the better the Picture.
2. COLOUR:
The colour cameras require greater amount of lightning as compared to Black and White cameras. Colour produces a more natural and richer image than black and white camera and keeps the operator interest for longer periods of time. It also makes easier to detect subjects that can be any person, place or anything. While the use of colour camera is growing, black and white cameras continue to offer some distinct advantages. The Black and White cameras are better suited for extremely low light situation. This ability to capture good quality images in low light situations increases the cost of both the cameras.
3. CAMERA:
The most basic operation of cameras in CCTV is to convert the visible scene captured by the lens into an electrical signal and transmit that signal to the monitor for viewing. Apart from their special designs, they are not fitted with the lens. The lens needs to be provided separately and screwed on the front of the camera. Several considerations should be taken for proper selection of camera. When the level of available light changes, a camera equipped with automatic iris control helps to assure consistent image quality. This automatic iris control enables the camera to open and close automatically with the amount of light passing through it. In the bright sunny atmosphere the auto iris lens camera will close to protect camera from strong light and at night it will open to allow greater amount of light to enter the camera.
1. THE SCENE AND LIGHT:
The scene refers to the area that is under the observation of CCTV cameras. The scene often contains different colours, surfaces, and materials that reflect light of varying level. It is necessary to determine the minimum lightning level at both day and night time that will reach the camera lens so that proper equipment can be easily selected. The scene can be illuminated by natural or artificial light sources which include sun, moon, stars, incandescent, sodium, florescent, infrared and other man made lights. A proverb in CCTV security says that: The better the Light, the better the Picture.
2. COLOUR:
The colour cameras require greater amount of lightning as compared to Black and White cameras. Colour produces a more natural and richer image than black and white camera and keeps the operator interest for longer periods of time. It also makes easier to detect subjects that can be any person, place or anything. While the use of colour camera is growing, black and white cameras continue to offer some distinct advantages. The Black and White cameras are better suited for extremely low light situation. This ability to capture good quality images in low light situations increases the cost of both the cameras.
3. CAMERA:
The most basic operation of cameras in CCTV is to convert the visible scene captured by the lens into an electrical signal and transmit that signal to the monitor for viewing. Apart from their special designs, they are not fitted with the lens. The lens needs to be provided separately and screwed on the front of the camera. Several considerations should be taken for proper selection of camera. When the level of available light changes, a camera equipped with automatic iris control helps to assure consistent image quality. This automatic iris control enables the camera to open and close automatically with the amount of light passing through it. In the bright sunny atmosphere the auto iris lens camera will close to protect camera from strong light and at night it will open to allow greater amount of light to enter the camera.
Some very wide angle lenses do not have a focus ring. The 'BNC' plug is used for connecting the coaxial video cable. Line powered cameras do not have the mains cable there power is provided via the coaxial cables.
TYPES OF CAMERAS:
1. FIXED AND PTZ CAMERAS:
CCTV cameras can be fixed, have pan, tilt and can have zoom capabilities. Fixed cameras are mounted on fixed brackets and cannot move. PTZ cameras are motor driven and can move left, right, up and down and can also zoom in and out.
2. DOME CAMERAS:
Many PTZ cameras now days come in dark colored domes. They offer 3 main advantages: Deterrence- Domes make it virtually impossible to detect where the camera is pointing. Aesthetics- Dome covers all the internal equipment in a clean shell. Smoked Plexiglas bubbles- have the same effect as wearing sunglasses. As it reduces the amount of light reaching the lens that can affect the colour accuracy picked by the camera.
3. CAMERA SENSORS:
Two types of camera sensors exist. The Complementary Metal-Oxide Semiconductor (CMOS) sensor produces low to medium quality images at a low cost. The Charged Coupled Device (CCD) sensor produces the higher quality footage compared with CMOS sensors. However, CCD sensors are more expensive. Most CCTV providers recommend image sensors between 1/3” and 1/4”. The larger the sensor, the better is the image quality.
4. LENS:
The primary function of it is to collect light from scene and focus a clear, sharp image on camera’s imager. Typically more the light passes through the lens; the better is the quality of the picture. The camera lens can be typically divided into two parts: Fixed focal whose focal length remains constant and verifocal whose focal length can be changed.
5. LENS MOUNTS:
Camera lenses generally come with either a C-mount or CS-mount and they must match approximately to the camera’s mounting requirements. The difference between the two is the distance of the lens option from the camera’s imager.
6. VIDEO TRANSMISSION METHODS:
The main purpose of the transmission medium is to carry the video signal from the camera to the monitor. There are many video transmission methods like: fiber optic, coaxial cable, microwave, phone lines, and radio frequency. The choice of transmission mediums mainly depends on factors such as distance, environments, cost and facility layout.
1. Coaxial Cable: A coaxial cable is one that provides a continuous physical connection - or closed circuit between the camera and the monitor. The cable is shielded to minimize interference from any nearby electronic devices or electrical wires. For traditional CCTV systems, as well as many applications today, this is the most common economical method of signal transmission over relatively short distances.
2. Fiber Optics: Fiber optic technology changes an electronic video signal into pulsed or laser light and transmits it into one end of a glass rod (the fiber optic cable). At the other end, a receiver translates the pulsed light back into an electronic signal capable of being displayed on a monitor. Fiber optics offers a cost-effective method of sending large transmissions over long distances.
3. Microwave: If already in place, microwave can be a very efficient and cost-effective method of delivering black and white or colour video. Microwave turns the video and data signals into high radio frequency signals and transmits them from one point to another via free air and space. A receiver then converts the transmission back into the video and data signals and displays the scene on a monitor.
7. MONITOR:
The image created by the camera needs to be reproduced at the control position. The monitor receives the transmitted electronic video signal from the camera via CRT (Cathode Ray Tube) to display an image to the viewer. Although it is similar in function to TV, it provides higher lines of resolution and accepts only video signals rather than RF/antenna signals. Most CCTV system uses both dedicated monitors and call up (switchable) monitors. A dedicated monitor displays the video from only one camera while call up monitors enables the monitor to switch multiple cameras into view. Generally call up monitor is larger than dedicated monitors and gives operator the ability to view multiple images at the same time.
TYPES OF CAMERAS:
1. FIXED AND PTZ CAMERAS:
CCTV cameras can be fixed, have pan, tilt and can have zoom capabilities. Fixed cameras are mounted on fixed brackets and cannot move. PTZ cameras are motor driven and can move left, right, up and down and can also zoom in and out.
2. DOME CAMERAS:
Many PTZ cameras now days come in dark colored domes. They offer 3 main advantages: Deterrence- Domes make it virtually impossible to detect where the camera is pointing. Aesthetics- Dome covers all the internal equipment in a clean shell. Smoked Plexiglas bubbles- have the same effect as wearing sunglasses. As it reduces the amount of light reaching the lens that can affect the colour accuracy picked by the camera.
3. CAMERA SENSORS:
Two types of camera sensors exist. The Complementary Metal-Oxide Semiconductor (CMOS) sensor produces low to medium quality images at a low cost. The Charged Coupled Device (CCD) sensor produces the higher quality footage compared with CMOS sensors. However, CCD sensors are more expensive. Most CCTV providers recommend image sensors between 1/3” and 1/4”. The larger the sensor, the better is the image quality.
4. LENS:
The primary function of it is to collect light from scene and focus a clear, sharp image on camera’s imager. Typically more the light passes through the lens; the better is the quality of the picture. The camera lens can be typically divided into two parts: Fixed focal whose focal length remains constant and verifocal whose focal length can be changed.
5. LENS MOUNTS:
Camera lenses generally come with either a C-mount or CS-mount and they must match approximately to the camera’s mounting requirements. The difference between the two is the distance of the lens option from the camera’s imager.
6. VIDEO TRANSMISSION METHODS:
The main purpose of the transmission medium is to carry the video signal from the camera to the monitor. There are many video transmission methods like: fiber optic, coaxial cable, microwave, phone lines, and radio frequency. The choice of transmission mediums mainly depends on factors such as distance, environments, cost and facility layout.
1. Coaxial Cable: A coaxial cable is one that provides a continuous physical connection - or closed circuit between the camera and the monitor. The cable is shielded to minimize interference from any nearby electronic devices or electrical wires. For traditional CCTV systems, as well as many applications today, this is the most common economical method of signal transmission over relatively short distances.
2. Fiber Optics: Fiber optic technology changes an electronic video signal into pulsed or laser light and transmits it into one end of a glass rod (the fiber optic cable). At the other end, a receiver translates the pulsed light back into an electronic signal capable of being displayed on a monitor. Fiber optics offers a cost-effective method of sending large transmissions over long distances.
3. Microwave: If already in place, microwave can be a very efficient and cost-effective method of delivering black and white or colour video. Microwave turns the video and data signals into high radio frequency signals and transmits them from one point to another via free air and space. A receiver then converts the transmission back into the video and data signals and displays the scene on a monitor.
7. MONITOR:
The image created by the camera needs to be reproduced at the control position. The monitor receives the transmitted electronic video signal from the camera via CRT (Cathode Ray Tube) to display an image to the viewer. Although it is similar in function to TV, it provides higher lines of resolution and accepts only video signals rather than RF/antenna signals. Most CCTV system uses both dedicated monitors and call up (switchable) monitors. A dedicated monitor displays the video from only one camera while call up monitors enables the monitor to switch multiple cameras into view. Generally call up monitor is larger than dedicated monitors and gives operator the ability to view multiple images at the same time.
CCTV DESIGN PROCESS/ WORKING
In the CCTV design process, several steps must be followed to ensure successful implementation and for proper operational capabilities. Many of these steps, such as power and communication requirements, must be addressed early in the design process.
In the CCTV design process, several steps must be followed to ensure successful implementation and for proper operational capabilities. Many of these steps, such as power and communication requirements, must be addressed early in the design process.
TYPES OF CCTV SYSTEMS
1. Simple CCTV System:
The simplest form of CCTV camera is connected directly to a monitor by a coaxial cable with the power for the camera provided from the monitor. This is known as line powered camera.
1. Simple CCTV System:
The simplest form of CCTV camera is connected directly to a monitor by a coaxial cable with the power for the camera provided from the monitor. This is known as line powered camera.
The next development was to integrate the outputs from four cameras into the monitor. The selection could be automatic or could be held selectively. Even microphone was even included in camera and speaker in monitor.
2. Main powered CCTV System:
Here the camera is also mains powered as monitor. The coaxial cable carries the video signal from the camera to the monitor. Although it is simple to install, but before installation must comply with the relevant regulations. If it is not done then problems with validity of insurance can take place.
Here the camera is also mains powered as monitor. The coaxial cable carries the video signal from the camera to the monitor. Although it is simple to install, but before installation must comply with the relevant regulations. If it is not done then problems with validity of insurance can take place.
When more than one camera is required in this system, video switchers can be used. Using this video switcher any camera can be selected to be held on the screen or a sequence can be set in turn through all the cameras.
3. Systems with Video Recording:
The next development of the basic system was to add the video recorder. With the arrangement shown in figure, the pictures that will be shown during play back will be according to the way the switcher was set up when recording. This means, if the set of sequence was set then the same views will be displayed on the monitor.
The next development of the basic system was to add the video recorder. With the arrangement shown in figure, the pictures that will be shown during play back will be according to the way the switcher was set up when recording. This means, if the set of sequence was set then the same views will be displayed on the monitor.
4. Movable Cameras:
So far all the cameras were 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.
So far all the cameras were 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.
APPLICATIONS
· Security: observation of car parks, hotel lobbies, building halls, buildings, public places etc.
. Industry: observation of stock, car parks, warehouse, receptions etc.
· Data Center: observation of network equipment, access control for staff etc.
· Private Property: observation of houses, yachts, garages etc.
· Tourism: ski resorts, hotels, holiday resorts, monuments, city centers, zoos, theme parks, etc.
· Events: concerts, sports events etc.
· Public Information: live weather conditions, exhibitions, road traffic levels etc.
· View Process: while working from home or at desk in the office, it can save both time and money. A network camera or video server over viewing a particular process allows video images to be transmitted and made available to several users over a local network.
. Monitoring: of construction work, production line, industry process, nursery, child care, queues at cashier in local super market.
Author - Er. Shurvi Sisodiya
· Security: observation of car parks, hotel lobbies, building halls, buildings, public places etc.
. Industry: observation of stock, car parks, warehouse, receptions etc.
· Data Center: observation of network equipment, access control for staff etc.
· Private Property: observation of houses, yachts, garages etc.
· Tourism: ski resorts, hotels, holiday resorts, monuments, city centers, zoos, theme parks, etc.
· Events: concerts, sports events etc.
· Public Information: live weather conditions, exhibitions, road traffic levels etc.
· View Process: while working from home or at desk in the office, it can save both time and money. A network camera or video server over viewing a particular process allows video images to be transmitted and made available to several users over a local network.
. Monitoring: of construction work, production line, industry process, nursery, child care, queues at cashier in local super market.
Author - Er. Shurvi Sisodiya
