- Analog CCTV Cameras
- Digital camcorders or ip camcorders
- Digital cameras have more options
- Objects for which analog video surveillance systems are better than digital
- The world of the future – intelligent technology
- Colored or black and white
- Summarizing the analysis results
From this article you will learn: how analog and digital video cameras work and how they work; how video surveillance systems are built; capabilities of analog and digital video cameras; objects for which analog surveillance systems are preferable; when a color image is needed, and when black and white is enough; is it possible to integrate analog video cameras into a digital video surveillance system.
From Greek mythology, we know a giant named Argus – a creature of really large size, but this was by no means the main thing in his description. Argus, according to information from various sources, had from four to many eyes, he never slept – no mortal could get close to him. This was the ancient concept of the ideal watchman.
The problem of looking after movable and immovable property, the problem of finding witnesses to the fact of a crime was, is and will be. Today, the owners’ property is vigilantly guarded by sensitive automation, including one consisting of video surveillance systems – a whole complex whose task is to record everything that happens in the viewing area of security cameras, saving this information for later study. The eyes of the tracking complex are video cameras presented on the market by analog and ip cameras. What is the difference between them – the answer in this article.
Analog CCTV Cameras
Video surveillance systems based on analog cameras are used today mainly in facilities with a small number of monitored rooms. These can be small offices and parking lots, warehouses, cafes, etc. Analog cameras owe their popularity to their relatively low cost and good performance in terms of price / quality ratio. Their design is reliable and simple, tested by time and difficult operating conditions.
The principle of operation of analog video cameras: the luminous flux passes through the lens, then through a group of lenses and enters the CCD-matrix, converting it into a video signal, which is fed through a coaxial cable to a cassette video recorder (recording device) and a monitor. If necessary, it is possible to upgrade analog video cameras in terms of signal transmission – installation of a conversion unit that changes the analog signal to digital, which makes it possible to use a multiplexer and a single video recorder for several analog surveillance cameras.
The main convenience of using analog video cameras is the simplicity of their setup and use, they do not require complex programming due to the small number of working algorithms..
The choice in favor of analog video cameras is also based on their wide range – each user will be able to choose a camera at will, of any size, which IP cameras cannot yet boast of. In analog CCTV systems, you can easily combine cameras from different manufacturers.
The undoubted disadvantage of analog cameras is the lack of signal encoding during transmission, i.e. the signal can be intercepted and replaced by an outsider, which is often used by attackers from Hollywood movies (for example, in the blockbuster Ocean’s 11).
The NTSC and PAL standards used in analog cameras keep the vertical resolution of the video signal within strict limits, so it is technically impossible to see the small details of the tracking object (for example, a car license plate from a certain distance or an intruder’s facial features).
Digital camcorders or ip camcorders
The device of ip cameras: the light flux passes through the lens and lenses, is projected onto a photosensitive matrix (mainly semiconductor CCD or CMOS matrices are used), which converts the light signal into an electrical signal, then into a processor that processes the video signal, then through twisted pair or wi -fi to the multiplexer and, finally, to a DVR equipped with a hard disk of a certain capacity (exactly the same as a PC’s hard drive) and a monitor.
Digital cameras have more options
Some models of ip-cameras are equipped with an audio output and a microphone for building audio communication in both directions, i.e. you can conduct a remote dialogue with an interlocutor who is in the field of view of such a camera. In addition, almost all models of digital cameras support the possibility of installing an audio communication kit on them (the cost of such audio devices is low). No, it is also possible to install equipment for two-way audio communication on analog video cameras, but it will require an additional audio signal transmission cable (in digital cameras “transport” is one twisted pair).
Some models of digital video cameras are equipped with a RAM that stores temporary data, as well as a video buffer – a temporary storage of video frames with their cyclic storage (a new frame is written over the old one). Flash memory stores long-term data such as control software and camera settings.
Any ip camera can be connected via a network interface to an ethernet network (10/100 Mbps).
Digital surveillance cameras are equipped with alarm inputs / outputs to which alarm sensors are connected. Triggering of any alarm sensor will cause an immediate reaction of the ip-camera processor: upon its command, the last set of frames contained in the camera’s video buffer before the alarm, at the moment and after the alarm, will be compiled and sent to the specified email address (by e-mail or FTP).
Any digital camera has its own processor, IP address and firmware, it can act as an FTP or web server, FTP client, and e-mail client.
Objects for which analog video surveillance systems are better than digital
The advantage of digital tracking systems in some cases becomes their disadvantages: the compression of the video stream used by them removes “unnecessary” information from it, i.e. performs some “rounding” of the stored data from fractions of a second to minutes (depending on the specific system). For this reason, at those facilities where it is important to completely preserve video data (without any “rounding”), only analog video surveillance systems (analog camera + coaxial cable + cassette video recorder) are used.
An example of such an object is any casino on our planet, because a professional needs fractions of a second to commit fraudulent actions with cards, which the casino security service cannot in any case miss..
In addition, it is better to present an analog recording as evidence of a committed crime in court: experts can establish its authenticity with 100% certainty, easily detecting the fact of installation or gluing.
The world of the future – intelligent technology
Comparing analog and digital video surveillance systems from this point of view, the superiority of the latter is undoubtedly – ip-video cameras can be easily integrated into almost any modern systems, be it a “smart home”, an automatic checkpoint controller and even a “smart city” system. Due to the software settings of digital systems, the percentage of false alarms is much lower than that of analog ones. In other words, such a system will not react to a sudden sunbeam or a leaf falling from a tree..
Colored or black and white
Transferring a color image increases the load on transmission channels and takes up more space on DVRs, if there is no special need for it, it is better to refuse color video cameras. Nevertheless, the color image can be extremely important, for example, when accurately identifying an intruder – the color of hair, clothes and shoes, especially if dozens of people are in the video camera’s field of view every minute. This condition is also relevant for surveillance cameras on motorways.
If the cost of color surveillance cameras just a few years ago differed from the cost of black-and-white video cameras at times, today the difference in price is, as a rule, no more than 20%.
Summarizing the analysis results
Surveillance systems based on digital video cameras are now comparable in cost to analog ones only in cases where the system contains 16 cameras and more. The range of capabilities of ip cameras is much wider than analog cameras, they have great prospects – in the near future, digital video surveillance equipment will completely replace analog systems from the market. Today, if there is no need for image detail, and the main task of video cameras is to simply record general events occurring in the field of view, analog cameras with low resolution are quite suitable..
The most optimal is a video surveillance system that combines both analog and digital devices, for example, such a solution: an analog camera + an adapter to a digital signal + twisted pair + a video capture card on a regular PC (it must be allocated only for video surveillance) + specialized software.