Analog cameras are used for video surveillance and control due to their sensitivity and signal transmission in a wide dynamic range. These devices became widespread due to the good price-to-quality ratio of the installed video surveillance system.
Composition of the security video system
Video recorder - the basis of surveillance equipment built on video cameras. Being a VCR with additional functional add-ons, the device registers, reads, records the incoming signal. PAL/NTSC analog video cameras are connected to the DVR to transmit images with recording and viewing on the monitor. The components of the system operate using a power source, the design and power of which depend on the required conditions. Using cables, connectors, signal receivers and transmitters, the DVR and cameras are combined into a single network.
Features of technology with a continuous video signal
Physicaldata transfer from the sensor to the recorder in the form of a continuous signal is obsolete, but is still used due to the simplicity and low price of devices operating on this principle. The use of analog video cameras reduces the cost of installing and maintaining small surveillance systems or when expanding them. Surveillance using analog video technology is carried out over large areas, when the control center is located at a considerable distance from the surveillance zones.
Differences from digital video equipment
Different types of video equipment differ not only in the way the optical image is transmitted. PAL/NTSC cameras appeared earlier, but now they are obsolete. The digital image is obtained without noise and interference, but the cost of purchasing components increases by two to three times. The use of analog video cameras does not allow analyzing streaming video for fire or smoke, or automatically recognizing numbers or faces.
Each individual camera unit is connected using its own coaxial cable, unlike digital cameras that can operate from a single network interface over a twisted-pair UTP cable. The operation of an analog system without a DVR is not possible, and some digital models are capable of recording video in the built-in memory. All devices of the PAL/NTSC band security system need to install separate power supplies for network components, and digital video equipment is powered by a cable that transmits the signal.
Advantages of PAL/NTSC Camcorders
Despite the outdated technology, analog video surveillance is popular not only due to the low price of components, but also due to several positive qualities of the system. The signal from the cameras is transmitted directly, without delay and transformation, and the image is recorded by a video recorder, which also displays it on the monitor. If necessary, additional elements are connected to the DVR, for example, motion sensors. Maintenance and configuration of the system does not require high qualifications, therefore, along with low costs for purchased equipment, the cost of specialists is reduced.
The distance of outdoor analog video cameras from the control center is 300-350 meters versus 90-100 meters of digital models, which allows you to cover a larger area for surveillance. The resulting image takes up less space in the recorder's memory, allowing you to record longer videos or install more cameras at the same recording time.
Application of PAL/NTSC video equipment for surveillance
A relatively small budget limits the choice of equipment for protection and monitoring. Sometimes it is better to install more cheap cameras than to use expensive components that are difficult to set up. Analog video surveillance is suitable for areas remote from the city, where there are problems with Internet access and building a remote network - in summer cottages, country houses, garden societies.
Protection of large perimeters imposes restrictions onuse of digital cameras. The maximum length of the coaxial cable allows you to operate security video systems at large facilities with a small number of cameras.
Using AHD cameras
From the user's point of view, digital and analog camcorders differ in image quality and price. The market of security systems has replenished with AHD-equipment, combining the advantages of analog systems with digital FullHD quality. Installing a DVR using AHD technology makes it possible to install analog cameras of the old and new models at the same time. This expands the scope of analog surveillance systems, combining the low cost of components with high quality of the signal output to the monitor. The range of signal transmission over the coaxial cable increases to 500 meters, but the required amount of memory for recording video becomes larger. AHD equipment is more expensive than classic, but cheaper than digital.
