As covered by Mike Freeman of UT San Diego…
The history of the development of technical means of video surveillance has more than 70 years. If we divide by generations the process of development of technologies in the field of video surveillance, at this point in time it consists of three generations.
The first generation falls on 1942-1970. These are primitive systems consisting of cameras and monitors connected by a coaxial cable. Each camera had to put on one monitor. Since these systems were quite expensive for those times, then they were used mainly on particularly responsible objects of military-state importance. The image quality of the cameras was so low (less than 0.3 Megapixels), that they did not even have to refer to their images as evidence. The image recording at that time was not technically possible. In the 1970s, multiplexers and video tape recorders appeared. Multiplexers allowed to display on one monitor the image of several cameras, and video recorders allowed to record the image on a magnetic tape. The disadvantage (from today's point of view) of these systems was the poor quality of recording on the magnetic tape, which was due, as well as the source of the image, and the recording process itself. Also to the disadvantages can be attributed and the technological impossibility of recording video by events and, accordingly, viewing events from the archive. There was no possibility of remote viewing of the image.
The second generation of a history of CCTV Cameras by MJ Security and systems is caused by the appearance in the 90s of hard magnetic disks in video surveillance systems, which eliminated the main problem for those times - the magnetic tape. Half-digital video surveillance systems have already been more flexible from a technological point of view. They could provide remote access through the TCP / IP protocol to view the image and archive of cameras. Hard disks could provide a more massive and higher resolution video archive storage. There was a possibility to record audio signal from cameras, the camera became controlled by position in space.
The third generation, which appeared quite recently, already consists entirely of digital systems. These are various IP cameras with a wide range of capabilities, universal cable infrastructures (twisted pair, optical and wireless communication lines), video registration software. A distinctive feature of the third generation of DVRs is the high integration ability. Now, for the organization of the video surveillance system, it is not necessary to lay separate coaxial communication lines from the camera to the server, the IP camera is connected to the existing local computer network of the enterprise and a video registration program is installed on any computer station (computer). Many manufacturers of IP cameras, complete with a camera, supply a free program for organizing video registration. Like in any system, there are some disadvantages in digital video surveillance technologies. One of the main today is the high technical requirements for hardware, in particular, the processor's performance.