CCTV Digital Surveillance Professional Training
CCTV systems are often the prime focus of security personnel as they tend to be the eyes and ears monitoring activity throughout the property. New digital technology, such as high-definition and larger digital storage options have changed the way this technology can be used in these monitoring systems. For example, high-definition gives security teams the ability to zoom in on facial details and compare them to the past records. This often helps law enforcement with their investigations.
There are two types of Closed Circuit TV (CCTV) systems: Digital and Analog. In the past, the latter was the only option and video surveillance was based on analog technology – closed circuit television (CCTV), and then recorded on video tapes. This system is simply recorded in the moment activity for future access. However, since it does not broadcast actual live information, it is not practical for monitoring stores from a remote location. The picture quality is also low and often unusable, and it relied on human reliability as well, such as changing the tapes regularly. Analog technology at one time served a purpose for security monitoring, but now digital CCTV is revolutionizing security measures and technology has evolved to allow for a more diverse security monitoring system.
With digital CCTV, a digital camera views the scene in front of the lens and broadcasts the video images as a digitized signal over a LAN line (Local Area Network) where it is then transmitted to a computer or server. In turn, the server manages all of this information. Depending upon the software used to manage the digital images, it can record, display or retransmit the images to anywhere in the world. Even more, the software package can be upgraded to allow for data analysis, such as selecting specific flagged items to monitor, in addition to a host of other functions that truly make it a customizable security tool.
True IP-based digital surveillance uses CCD cameras that employ signal processing with the purpose of sending packetized video streams over the LAN through a Cat 5 cable rather than a coax cable network. This system provides more intelligent data mining and information retrieval. If security is an issue, full digital surveillance offers the added advantage of data encryption opportunities to protect against image tampering; something not possible with analog recording. Recently, a few companies such as D-Link and Linksys have developed fully digital cameras that have completely integrated, built-in web servers so that external computers are no longer required. In this case, the signal is transmitted directly to the terminal location for storage or play-back.
The main difference between the two camera types is the way in which the video signal is delivered. Analog cameras turn the video signal into a format that can be received by a television or other receiver such as a VCR or monitor. An IP-based camera, also known as an IP network camera, digitizes the video signal using a specialized encoder that contains an on-board web server. This allows the IP camera to act as a network device, thus allowing captured video images to be viewed not only through an existing network, but also through a web browser that can be accessed through the Internet.
Even at the highest resolution available for CCTV, the clarity of rapidly moving objects, such as a person running or speeding car, has long been problematic in security and surveillance applications. In an analog CCTV environment, a rapidly moving object will appear blurry. This is because the video signal, even when connected to a DVR, interlaces to create the images. Interlaced images use techniques developed for analog TV monitor displays, made up of visible horizontal lines across a standard TV screen. If you happen to have shopped for a new TV lately, you are probably aware that 1080i is not nearly as good as 1080P. Interlacing divides images into odd and even lines and then alternately refreshes them. The slight delay between odd and even line refreshes creates some distortion – only half the lines keep up with the moving image while the other half waits to be refreshed.