About video surveillance
Digital and analogue video surveillance: description of video surveillance devices.
Video surveillance systems (English abbreviation CCTV — Closed Circuit TeleVision — Closed Circuit Television Systems) — are intended for organizing
video surveillance at critical facilities.
In recent years, video surveillance has become an integral function of a complex facility security system, since modern video surveillance equipment
allow you not only to observe and record video, but also to program the reaction 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. Analogue systems are used where it is necessary to organize video surveillance in a small number of premises and record information from video cameras on a VCR. To ensure safety especially
responsible or geographically distributed objects use digital video surveillance systems for video surveillance, which, as a rule, are integrated into comprehensive security systems. Such complexes capture, record and analyze information coming from video cameras, readers of access control systems, security and fire sensors, and also “make decisions” to protect the protected object autonomously or at the direction of the system operator.
The digital video surveillance system is used in security systems of geographically distributed facilities, as well as in security management complexes of global companies. Today, digital video surveillance technologies are gradually “squeezing out” analog systems in terms of functional and technical characteristics, and at their price they are already approaching the cost of analog video surveillance systems.
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, DVRs, video recorders] and video information display devices . In larger video surveillance systems, additional control and auxiliary devices are installed — matrix switchers, video camera control keyboards,
video printers, distribution amplifiers, modulators, telemetry receivers and transmitters and other security devices.
Analogue video surveillance cameras
Currently, analogue video surveillance cameras are usually installed in video surveillance systems, 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
through a lens and a group of lenses and falling on this matrix. CCTV cameras are also produced that have a built-in unit for converting analogue video signals into digital ones. Such video cameras can already be connected to digital video surveillance systems.
We offer our clients video cameras, which, depending on the tasks performed in the video surveillance system, are divided into groups:
Unframed cameras are, as a rule, the size of a matchbox, supplied by the manufacturer without a housing and can be mounted in any interior items of a room protected by a video surveillance system.
Miniature video cameras — they are small in size, have their own housing and can be installed both on brackets and on rotating devices.
Hidden video cameras have the smallest dimensions and are used for covert video surveillance.
High-speed dome video cameras are usually equipped with a high-speed rotating device, thanks to which the video cameras can rotate at speeds of up to 400?/s in the horizontal plane and rotate 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 represent the most popular class of video surveillance cameras because they have a low price and, as a rule, are
the basis of a video surveillance system. Depending on the purpose, black and white video cameras are divided into models for indoor and outdoor use.
Color video cameras are used in a video surveillance system when it is necessary to transmit an image in color to a video monitor and record it 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
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, and also where it is necessary to create geographically distributed video surveillance systems. Typically, digital cameras have analog and digital outputs.
Lens for CCTV cameras
Lenses are installed on video cameras in order to increase the range of its operation, improve technical parameters and adapt the video camera to specific operating conditions. For video surveillance of moving objects, zoom lenses are used. In conditions of rapidly changing illumination, lenses with an auto-diaphragm are used.
Pin-Hole type lenses are installed on hidden cameras of a hidden video surveillance system.
Rotating devices for CCTV cameras
To expand the viewing angle of the video camera and track moving video surveillance objects, cameras are installed on rotating devices. The rotating device mechanism moves the video camera in horizontal and vertical directions, and allows the video surveillance system operator to view fairly large areas of the protected area with one video camera.
Video signal processing devices
Video signal processing devices [multiplexers, quadrators] 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.
Quadrators are video surveillance system devices that allow you to simultaneously display images transmitted from 2, 3 or 4 video cameras on video monitors.
Multiplexers allow you to simultaneously display images from 4 to 32 video cameras on a video surveillance monitor (simplex multiplexer), while sequentially recording these images on a VCR or built-in video recorder (duplex multiplexers), as well as viewing them on a video surveillance system monitor, simultaneously with “live” video, previously recorded video fragments (triplex multiplexers).
Recording devices for video surveillance
Video recording devices (DVRs) are designed for recording, storing and subsequently reproducing images coming from both cameras and the multiplexer of the video surveillance system.
Digital recording devices (video recorder, video drive 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 responds to movement in the frame —
motion detectors, and automatically recording this video, and also have a network card for connecting the DVR to the video surveillance system via a LAN/WAN network. There are single-channel DVRs and multi-channel ones.
Color and black and white video monitors
CCTV video monitors are designed for 24/7 display of images from CCTV cameras. Depending on the requirements for the system and the video cameras used, black-and-white or color video surveillance monitors are used.
Matrix switchers
Matrix switches of a video surveillance system are electronic switches that can connect any of their inputs to any of their outputs,
while maintaining the matching mode loads. In a video surveillance system, such switches connect different video surveillance cameras to video monitors, video recorders or multiplexers. As a rule, matrix switchers are used in large video surveillance systems with more than 32 video cameras.