About video surveillance.
Digital and analog video surveillance: description of devices for video surveillance.
Video surveillance systems (English abbreviation CCTV — Closed Circuit TeleVision — Closed Circuit Television Systems) are designed to organize video surveillance at critical facilities.
In recent years, video surveillance has become an integral function of a facility's comprehensive security system, since modern video surveillance equipment allows not only to monitor and record video, but also to program the response of the entire security system when alarming events occur.
Depending on the type of equipment used, video surveillance systems are divided into analog and digital.
Analog systems are used where it is necessary to organize video surveillance in a small number of rooms and record information from video cameras on a video recorder.
To ensure the security of especially important or geographically distributed objects, digital video surveillance systems are used for video surveillance, which, as a rule,
are integrated into complex security systems.
Such systems record, record and analyze information received from video cameras, access control system readers, security and fire sensors, and also “make decisions” on protecting the protected object in autonomous mode or at the direction of the system operator.
Digital video surveillance systems are used in security systems of geographically distributed objects, as well as in security management systems of global companies.
Today, digital video surveillance technologies are gradually “displacing” analog systems in terms of functional and technical characteristics, and in terms of their price they are already approaching the cost of analog video surveillance systems.
The functions, characteristics and configuration of video surveillance systems depend on the customer's requirements for the security of the facility.
As a rule, the minimum configuration of such a system includes: video cameras, video signal processing devices [quadrators, multiplexers, etc.], recording devices [VCRs, video recorders, video recorders] and video information display devices .
Larger video surveillance systems are equipped with additional control and auxiliary devices — matrix switches, video camera control keyboards, video printers, amplifiers-distributors, modulators, telemetry receivers and transmitters and other security devices.
Analog video surveillance cameras.
Currently, video surveillance systems usually install analog video surveillance cameras, which are distinguished by their simple design and low price.
These video cameras are optical devices whose CCD matrices form a video signal from the light flux passing through the lens and a group of lenses and falling on this matrix.
Video surveillance cameras are also produced that have a built-in unit for converting an analog video signal into a digital one.
Such video cameras can already be connected to digital video surveillance systems.
Caseless cameras— are usually the size of a matchbox, are supplied by the manufacturer without a case and can be mounted in any interior
objects of the premises protected by the video surveillance system.
Miniature video cameras — are small in size, have their own case and can be installed on both brackets and rotary devices.
Hidden video cameras — are the smallest in size and are used for covert video surveillance.
High-speed dome video cameras are usually equipped with a high-speed PTZ device, thanks to which the video cameras can rotate at a speed of up to 400 ?/s in the horizontal plane and turn in the vertical plane up to 160 ?
These video cameras are usually mounted on the ceiling and are installed in video surveillance systems of banks, casinos, supermarkets and other facilities.
Black and white video cameras are the most popular class of video surveillance cameras, since they have a low price and, as a rule, form the
basis of a video surveillance system.
Depending on their purpose, black and white video cameras are divided into models for indoor and outdoor use.
Color video cameras are used in video surveillance systems when it is necessary to transmit color images to a video monitor and record them on a video recorder of the video surveillance system.
Digital video cameras.
These video cameras have a digital signal processing unit, a built-in web browser and generate a higher quality image that can be transmitted as a digital signal over LAN/WAN networks of the video surveillance system.
Digital or network video cameras are used in small facilities equipped with local computer networks, as well as where it is necessary to create geographically distributed video surveillance systems. As a rule, digital cameras have analog and digital outputs.
Lenses for video surveillance cameras.
Lenses are installed on video cameras to increase their operating range, improve technical parameters and adapt the video camera to specific operating conditions.
For video surveillance of moving objects, lenses with variable focal length — zoom lenses — are used.
In conditions of rapidly changing illumination, lenses with an auto diaphragm are used.
Pin-Hole lenses are installed on hidden cameras of a hidden video surveillance system.
Rotating devices for video surveillance cameras.
To expand the angle of view of the video camera and track moving objects of video surveillance, cameras are installed on rotary devices. The mechanism of the rotary device moves the video camera in horizontal and vertical directions, and allows the operator of the video surveillance system to view quite large areas of the protected territory with one video camera.
Video signal processing devices.
Video signal processing devices [multiplexers, quads] are devices that process video images received from several video surveillance cameras and transmit them in a given format to video surveillance monitors.
Depending on the type of video cameras used, black-and-white or color video signal processing devices are used.
Quads (device obsolete) are devices in the video surveillance system that allow images transmitted from 2, 3 or 4 video cameras to be simultaneously displayed on video monitors.
Multiplexers allow simultaneous display of images from 4 to 32 video cameras on a video surveillance monitor (simplex multiplexer), while sequentially recording these images on a video recorder or built-in video recorder (duplex multiplexers), as well as viewing previously recorded video fragments on a video surveillance system monitor, simultaneously with “live” video (triplex multiplexers).
Recording devices for video surveillance.
Video recording devices video recorders are designed to record, store and subsequently reproduce images coming from both cameras and the multiplexer of the video surveillance system.
Digital recording devices (video recorder, video storage device or video recorder) record video information in digital format directly onto a hard drive.
As a rule, the latest models of digital video recorders are equipped with a system that reacts to movement in the frame — motion detectors, and automatically records this video, and also have a network card for connecting the video recorder to the video surveillance system via a LAN/WAN network.
There are single-channel and multi-channel video recorders.
Color and black and white video monitors.
CCTV video monitors are designed to display images from video cameras of the video surveillance system around the clock.
Depending on the requirements for the system and the video cameras used, black and white or color video surveillance monitors are used.
Matrix switches.
Matrix switches of the video surveillance system are electronic switches that can connect any of their inputs to any of their outputs, while maintaining the load matching mode.
In the video surveillance system, such switches connect different video surveillance cameras to video monitors, video recorders or multiplexers.
As a rule, matrix switches are used in large video surveillance systems with more than 32 video cameras.