One of the systems created today to control and monitor the living and working environment as well
Security and comfort are most commonly used in CCTV systems, or CCTV systems. These systems are also referred to as video surveillance systems or sometimes CCTV equipment. Depending on the settings on the cameras
And other equipment can be done. These systems are in different weather conditions and have good performance day and night. Some of the places where these systems are used are as follows:
Banks Schools & Universities Factories Department stores, department stores
Such as gold shops, supermarkets – on the roads and streets to control traffic – parking lots – public places such as airport halls, railway stations and city trains, etc.
Therefore, the use of CCTV systems is growing day by day and according to
Its manufacturing technology, which is based on the electronics and computer industry
The production of equipment for these systems is constantly evolving and progressing, and we try in this brief
We have provided the general principles and general facilities of these systems for informing and familiarizing students
Dear, let’s present.
Principles of operation of CCTV systems
The general working principles of CCTV systems are that first the images by
The cameras are then prepared and transferred to a monitor or TV for display and playback.
Also to record or change the way it is displayed on the monitor and simultaneously play back the images of the cameras
There is also equipment and facilities on the monitor and remote control of the cameras. According to the possibilities
Available on CCTV recorders capable of moving within range
Under the supervision of a warning and alarm system or stimulated by special sensors
And start recording videos from the place. To control the entry and exit of people to a place and for
Control large areas with multiple cameras and simultaneously display their image and audio-visual monitoring from a distance via local area network (LAN) or telephone lines without the need for physical presence of the controller
In places and in devices that have not been visually controlled by humans or
Surveillance camera systems based on how the image captured by the camera is sent
The control center can be divided into the following types:
Systems that transmit the image by coaxial wire (coaxial cable).
These systems are the least expensive type in terms of equipment cost, but in their implementation
Wiring problems and the problem of image quality loss at long distances (more than 300 meters) and in
The result is a sending distance limit. The following figure shows an example of these systems
Example of a system that transmits an image by coaxial wire (coaxial cable)
Systems that transmit images wirelessly. The cost of running these systems
Due to the use of antennas and equipment, radio receivers and transmitters are higher, but
The problems of the previous type of systems have been solved to some extent. In the figure below in
Some parts of the system use wireless equipment:
CCTV systems can be a combination of wireless and wired systems
Design and implement.
Surveillance camera equipment
The following equipment is commonly used in CCTV systems:
Image display (TV or monitor)
Camera stand (Mount- Bracket- BASE)
Image Selector (Switcher)
We now turn to a detailed description of each of the above sections:
Cameras used in CCTV systems in different types and with different possibilities
Made and commonly known as CCTV Camera.
The main function of the camera is to generate a video signal from a controlled location to send or display
Monitor or TV.
Types of cameras
Types of cameras used in CCTV systems in terms of application and
The possibilities are as follows:
* Pinhole cameras
These cameras image through a small aperture on the front of the camera
They take. Because of their small size and the possibility of hiding them more as a hidden camera or
Used for espionage purposes. These cameras are also available wirelessly
You can see an example of this camera below:
Some of these cameras are for hiding inside alarm or detector detectors
Fires are embedded. You can see examples of them in the following figures:
Small and inexpensive cameras are more common in CCTV systems
Small are used. Most have fixed lenses and their image output is used. One
Examples of these cameras can be seen below:
The following figure shows the power input and output of the camera’s audio and video:
In these cameras, features such as interchangeable lenses and the ability to adjust the lens and aperture and
There are image quality adjustment keys. You can see the image of the industrial camera below:
Some industrial cameras have the ability to adjust the lens in terms of magnification (zoom) and image resolution (focus) by
They have a controller, which is shown in the following examples of this type of camera:
Night vision cameras:
These cameras have an optical sensor (photocell) to detect ambient light and when it is dark
The air emits infrared LED lamps that emit infrared rays and
They also provide the ability to shoot at night for the camera. The figure below shows these two parts
On the camera:
It is usually not possible to change the lens on these cameras, but it is possible to apply settings on the lens
And the image quality is present in some models. The construction of these cameras against water penetration and
Moisture and dust are protected and can be installed outdoors
They are installed on the ceiling and wall. The following is an example of these cameras
Fixed ceiling (DOM) and fast (Speed Dom) cameras
These cameras are mounted on the ceiling or on a hanging base. If
They have a controllable base that allows the camera to move quickly throughout
Directions that provide 360 degrees are called fast ceilings. The possibility of adjusting the lens in terms of
There is also the distance and amount of ambient light in these cameras. Control of these cameras by the device
The controller or recorder or using special software on the computer.
* Wireless cameras:
These cameras have a transmitter (TX) inside the camera and a separate receiver (RX)
Depending on the power of the transmitter in a certain range, they can capture the image without the need for wiring
The image below shows some of these cameras with the receiver
Motion Detection Cameras (MAD)
These cameras are designed to start moving in the environment
They film. In the figure below, two types of eyes detect motion with a camera
It is given to start when the camera moves and bring the image to the device
The recorder sends:
Other types of cameras also capture images in their internal memory. In addition
It is also possible to transfer the image from the camera with a mobile phone SIM card via MMS. One
You can see an example of this type of camera below
These cameras are installed inside the front door of apartments, suites and private homes.
It is necessary to explain that a camera may have several types of features, for example
Has night vision and wireless or has the capabilities of industrial cameras.
Different parts of the camera
The camera consists of 4 main parts:
2- Image sensor
3- Electronic circuit
We will now describe the above sections:
1- Camera lens
In the camera, the passage of light into the camera and its features affect the quality of the image created
This part includes the lens and the light passage valve and to this set
The so-called camera lens. Depending on the type of camera and the facilities required and the location
Installation Different lenses are used on the cameras. Lenses are available at focal lengths
2.5, 8.2, 3.5, 4, 6, 8, 12, 16, 25, 35, 50 and 75 mm are made. The greater the focal length of the lens, the greater its magnification. Telephoto lens
This lens shows distant objects closer and better, but instead offers a smaller viewing angle. Conversely, the smaller the focal length of the lens (Wide lens), the better the close-up images are.
Its viewing angle is wider. For example, the focal length of the human eye lens is 17 mm and its viewing angle is 30 degrees. While a lens with a focal length of 4 mm and a viewing angle of 62 degrees.
The IRIS is responsible for determining the amount of light passing through the lens into the camera.
In the dark, the aperture should be larger to allow more light to enter the camera
In bright environments, to prevent the image from turning white, the aperture should be reduced to allow less light to pass through.