Video surveillance. Analog and digital systems.
In recent years, video surveillance has become an integral function of a facility's integrated security system, since modern video surveillance systems allow 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 video surveillance systems are usually used for video surveillance with simultaneous recording of information on a video recorder. To ensure the safety of especially important objects, digital video surveillance systems are used, which, as a rule, are integrated into complex security systems. Such systems record, record and analyze information coming from video cameras, security and fire sensors, and also «make decisions» on the protection of the protected object.
- Digital video surveillance systems are used in security systems of geographically distributed facilities, as well as in security management systems of global companies. Today, digital video monitoring technologies are “displacing” analog video surveillance systems in terms of functional and technical characteristics, and their price is already approaching the cost of analog devices.
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 equipment [VCRs, video recorders] and image output devices .
In larger CCTVs, additional control and auxiliary devices can be used — matrix switches, video camera control keyboards, thermal printers, amplifier-distributors, modulators, etc.
CCTV cameras.
Video cameras are devices that generate a video signal from a light stream passing through the lens and hitting a CCD matrix.
Analog video cameras, widely used in CCTV, are characterized by their simplicity and have a low price.
Video cameras with digital signal processing provide higher quality video signal transmission and are intended for video surveillance of especially important areas of a protected facility.
By their design and video surveillance tasks, video cameras are divided into:
- Baseless video cameras
- Miniature video cameras
- Highly sensitive video cameras
- Dome video cameras
- Network video cameras that combine the capabilities of dome cameras and the dimensions of miniature video cameras.
- Lenses
Lenses are installed on video cameras, which increases the range of the video camera and improves its technical characteristics.
For monitoring moving objects, lenses with variable focal length are used — zoom lenses.
In conditions of rapidly changing illumination, lenses with an auto diaphragm are used. For a hidden video surveillance system, video cameras are equipped with Pin-Hole lenses.
Video signal processing devices.
Video signal processing devices [multiplexers, quads] are devices that process video images received from several video cameras, analyze the image and transmit it in a given format to a video monitor.
Depending on the type of video cameras used, black-and-white or color video signal processing devices are used.
- Quadrators are devices for simultaneously displaying images from 4 video cameras on a video monitor.
- Multiplexers are devices for sequentially recording images from 4 to 32 video cameras on a video recorder [VCR] and displaying these images on a monitor. Multiplexers allow you to view «live» video from several video cameras simultaneously and play back previously recorded fragments.
Video recorders.
Video recorders — are designed to record, store and subsequently play back images coming from both a video camera and a video signal processing device.
Analog video tape recorders can record up to 960 hours of video on one VHS standard video cassette.
The operating principle of a video tape recorder is the same as that of a video tape recorder, but the video recording is done in digital format directly to the hard drive.
As a rule, modern digital video recorders are equipped with a system that reacts to movement in the frame and automatically records these videos, as well as a network card for connecting to a video surveillance system via a computer network.
Video monitors.
CCTV video monitors are designed for round-the-clock and high-quality display of images from video cameras of a video surveillance system.
Depending on the video cameras used, black-and-white or color video monitors are used.
Our experts recommend using professional video surveillance monitors from Ikegami and JVC Professional.
Matrix switches.
Matrix switches are devices for outputting images from any video camera of the video surveillance system to any of the connected video monitors or video recorders.
Typically, matrix switches are used in large video surveillance systems with more than 32 video cameras.
Thermal printers.
A thermal printer is designed to print the necessary video fragments to document incidents, emergency footage, and any other interesting moments of the video recording.
Prints made by a thermal printer, are waterproof and UV-resistant, which allows them to be used in making ID photos.