Developments in CCTV recording devices over the years
CCTV is defined as Closed Circuit Television, which works on a closed or private network to a limited number of monitors, as against broadcast Television, which is transmitted openly so that almost anyone can access it.
The first recorded use of CCTV was in 1942 by an engineer in Nazi Germany, to observe the launching of V2 rockets. The first commercial use of CCTV was in 1949, by a company which advertised it as not requiring a Government permit, as it was ‘closed’ or private.
Early uses of CCTV were limited, because there was no system for recording, so it needed constant live monitoring.
When reel-to-reel video recorders were developed, it enabled the recording of video, but was limited by the small capacity, and therefore the quality of the pictures was kept low, to prolong the recording time. When a tape was full, an operator had to manually wind a new tape to continue recording. Because of these limitations, CCTV was not widely used at first.
The innovation of VCR technology in the 1970s, made it easier to use, and helped the initial take-up of CCTV, mainly by large corporations or local municipal authorities.
Larger scale application of CCTV was held back until the new millennium, when the use of computer hard disks began to be used, and DVRs (Digital Video Recorders) were produced, enabling digital recording. Analogue signals from the cameras was transmitted over coaxial cable direct to the DVR, which used Multiplexing technology to split the display to enable 4, 8 or 16 cameras to be displayed on the same monitor.
Even these early DVRs were fairly limited, due to the high cost of Hard Disks, and the limited sizes available at that time. To enable recording for longer periods, usually the resolution was limited to CIF which was 352 x 288 pixels, and frame rate was cut down to 6 or so fps, and in some cases even to one fps.
As Hard Disk technology improved, prices came down and for a long while the standard recording resolution was D1, or 720 x 576 pixels. Frame rate was gradually increased to a maximum of 25fps. Also, to compete with IP cameras, the recording devices themselves usually include a network card, so that they can be connected to a local network for access by computers on the network, and over the internet when configured correctly.
Whilst analogue cameras were the standard for smaller installations and private systems, from the late twentieth century a pure digital technology, IP or Internet Protocol cameras were being established, which had the advantage of higher resolution and no compression, providing a very much clearer picture than analogue. One of the main obstacles to wider uptake of IP was that the cameras were much more expensive than analogue, and because they used network or internet technology, they were not as secure as the totally closed analogue type. Plus, there was no available technology for recording, other than on a computer connected to the same network, so they were originally restricted to users who could provide full time live monitoring.
IP cameras have improved, and the prices have reduced, but in general they are still more expensive than analogue. Implementing an IP network is also more complex, as each camera has to connect to a network, usually through a router, and each camera has to have a unique IP address to identify it. Network Video Recorders have improved in recent years, and serve as a central recording source for IP cameras on the same network, however, there is still a higher overhead in setting up the system because of the complexity. Also, with IP network cameras there is always a slight delay or latency, which can be annoying.
The need for higher resolution and clarity at more reasonable prices resulted in the development of new technologies since 2012, to improve the end result and keep the prices down whilst making use of existing cabling, which was usually Coaxial Cable. There were three main technologies being developed by different companies: HD-SDI (High Definition Serial Inerface), HD-TVI (High Definition Transport Video Interface), HD-CVI (High Definition Composite Video Interface) and AHD (Analogue High Definition). These technologies needed new recording devices, to be able to communicate with the cameras and to make the most of the better performance. In the early days each company developed DVRs to suit their own cameras, but which would not communicate with any other type, so upgrading from older systems was expensive and involved being tied to one manufacturer or another.
HD-SDI tended to be more expensive, so uptake was slow, and gradually the other formats became more popluar. Initially, CVI and TVI were considered superior, as they could support higher resolutions, whereas AHD was restricted to 720p (1280 x 720). However, AHD soon caught up, and there are cameras available for each technology which will record 1080p 2MP cameras (1920 x 1080) and even 4MP cameras. Meanwhile, the development of recording devices was also progressing, such that they could record a mixture of these technologies plus analogue, making the updating of existing networks easier, as the cameras could be replaced over time.
CVI was only produced by one company, whereas TVI and AHD developers offered open access to the technology, so multiple manufacturers are available.
To overcome the dilemma of committing to one technology or another, in recent times, manufacturers have been producing 4-in-1 cameras, which can be changed via a switch between Analogue, AHD, CVI and TVI. This gives the best of both worlds.
To take advantage of this innovation, the latest recording devices are also multi-purpose – usually called XVRs. These can record a mixture of cameras, Analogue, AHD, CVI, TVI and even IP cameras. There are restrictions, in that each technology has to be in groups of two – i.e. channel 1 and 2 the same, 3 and 4 the same etc. This gives the consumer the best of all worlds, such that they can change the cameras and recorders to suit themselves, and decide which suits them the best.
To summarise, there are now five main types of CCTV available, Analogue, AHD, CVI, TVI and IP. Which of these is best for a particular application is where the system designer comes in. The fact that cameras and recording devices can be multi-purpose, means the supplier only has to stock one range of cameras/recorders, (other than IP cameras), which can then be configured as required for a specific job. Obviously, there are still decisions to be made, such as the night vision required, the angle of view for the camera, and for the recording device how many channels are required (4, 8 or 16 normally).
Footprint Security stocks 1 and 2 MP IP cameras, both domes and bullet type, and a full range of 4-in-1 cameras, complemented by a range of XVRs to cover 4, 8 or 16 channels, and in either 720p, 960p or 1080p configurations.
We offer free expert advice, and can help you decide which technology and camera types are best for your individual application.
For further information, give Hugh a ring on 1300 852 400, or email to firstname.lastname@example.org for free, no obligation expert advice.