And it is not necessary to stare intently at the video monitor: the system will warn us in time about events occurring behind the lenses of video cameras. And if we want, we can play the necessary part of the recording using a video recording device.
But video surveillance systems are many, and they are different. How to choose the right one? We will try to answer some questions thesis.
Which video system is needed, black and white or color?
The black and white camera has a higher resolution, higher sensitivity, it is cheaper.
Color - more informative.
What should be the focal lengths of the lenses?
The smaller the viewing angle, the longer the lens should be. If this value is not known in advance, you need a zoom lens with manual servo control.
What should be the resolution of a video camera?
It should be chosen with a certain margin, since the resulting resolution of the entire video system will be worse, because all elements from the lens to the video monitor affect it, for street cameras, as a rule, they should be higher.
How to provide adaptation to changes in light?
When installed indoors, the camcorder's electronic shutter suffices, and when installed outdoors, it controls the auto-iris lens.
What should be the design?
In the case (for standard implementations);
without case (for flush mounting);
What could be the specific system requirements?
The presence of built-in IR illumination;
ability to connect to a computer or computer network.
Type of aperture.
Fixed (the level of illumination on the object is known and constant);
manually controlled (light level is constant);
How to provide for the adaptation of a video camera to environmental conditions (temperature, humidity, dust, chemically active substances, etc.)?
built-in power supply;
glass cleaner washer;
glass cleaner cleaner;
What should be the mount of the camcorder (thermal)?
Fixed (bracket or fixture for mounting on the wall, ceiling, mast, pole);
permitting a change in the position of the video camera (turning system)
What should be the turning system?
For closely located video cameras - a rotary device with a remote control;
for a large number of remote cameras - turning devices, remote control signal receivers and a controller;
speed dome cameras.
What should be the principle of processing visual information?
Parallel, without loss of information (“video” monitor is connected to each video camera); sequential (using a video switch);
Quasi-parallel up to 4 inputs (screen divider);
Quasi-parallel-serial up to 8 inputs (two-page screen divider);
quasi-parallel, as a rule, up to 16 inputs (videomultilpeksor).
How to display visual information?
You need a normal video monitor or a video monitor with additional functions (built-in video switch, screen splitter, audio channel, etc.) - if there should be several video surveillance posts, the availability of video cameras for each post should be specified (better in the form of a table), observation time during the day (functioning in alarm), a computer with a video input card.
How to make a video?
You need a security video recorder and video multiplexer, or a digital video recorder (video recorder on a hard disk, computer).
It is convenient to display the video recording time for each video camera as a table, alarm recording, activity mode (in the case of several video multiplexers in a large video system, to reduce the strobe effect of the video camera, recorded at night, it is better to connect to one video multiplexer, and recorded during the day, to another - decrease number of video inputs in the switched sequence).
What do you need to transmit video signals?
Coaxial cable (in the case of considerable distances - video amplifiers), or fiber optic cable, twisted pair cable, telephone network, computer network, radio channel.