CCTV Systems Go Digital

Digital video delivers improved quality, which enables more details and changes in images.

With the introduction of network cameras and PC-based image processing and storage, Closed Circuit television systems are destined to become 100 percent digital. As modern security management insists on more video surveillance, and legacy CCTV systems wear out and require repair and upgrades, the...

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Video display, recording and recording are the remaining processes involved in a video system. The hardware and software to accomplish these processes are going through a constant revolution with new developments being announced on just about a daily basis.

IP-Based Networks

IP is an abbreviation for Internet Protocol, the most common protocol for communication over computer networks and the Internet.

Network cameras are a fast-growing product category, another clear indicator that IP-based CCTV systems are poised to take over. Because of its scalability, IP-Surveillance is an attractive technology not only for enhancing or revitalizing existing surveillance and remote monitoring applications, but also for new installations.

Network cameras are connected directly to an IP-based network and integrate to applications on the network, enabling users to install cameras at remote locations and view, store and analyze live video from another location, or multiple locations, over the network/Internet.

An IP-Surveillance device creates digitized video streams that are transferred via a wired or wireless IP network, enabling monitoring and video recording as far away as the network reaches, as well as enabling integration with access control and other systems.

Digital Video Recorders (DVRs) are port-configured hardware solutions which may offer advanced features such as motion-detection, software matrix creation and network storage and connectivity (network borne input/output and control). Even as DVRs are replacing VCRs as the basic video component, DVRs themselves are being supplanted by network-based solutions. NVR & NVMS (Network Video Recorder / Management Systems) are software solutions which use generic computer and IT hardware.

This renders the limitations of NTSC and PAL irrelevant. Several new resolutions derived from the computer industry have been introduced, providing better flexibility. Moreover, they are worldwide standards.

Power Over Ethernet Technology

Power over Ethernet is an upcoming power solution for network video devices because it consolidates power and data and simplifies installation and deployment.

IEEE 802.3af standard defines the specifications to deliver power over standard Ethernet cables. It was approved on June 12, 2003, by the Institute of Electrical and Electronic Engineers (IEEE).

Power Over Ethernet technology allows appliances such as network cameras to receive power as well as data over existing LAN cabling, without needing to modify the existing Ethernet infrastructure.

NTSC and PAL Resolutions

In North America and Japan, the NTSC standard (National Television System Committee) is the predominant analog video standard, while in Europe the PAL standard (Phase Alternation by Line) is used. Both standards originate from the television industry. NTSC has a resolution of 480 horizontal lines, and a frame rate of 30 frames per second (fps). PAL has a higher resolution with 576 horizontal lines, but a lower frame rate of 25 fps. The total amount of information per second is the same in both standards.

When analog video is digitized, the maximum amount of pixels that can be created is based on the number of TV lines available to be digitized.

With digital cameras and imaging, the terms NTSC and PAL become irrelevant because analog video monitors are replaced with computer monitors.

Render Unto Video

Two different techniques are available to render the video: interlaced scanning and progressive scanning.

Interlaced scanning is a technique developed for CRT-based TV monitor displays. It is comprised of 576 visible horizontal lines across a standard TV screen. Interlacing divides these into odd and even lines and then alternately refreshes them at 30 frames per second. The slight delay between odd and even line refreshes creates some distortion or 'jaggedness.'

With the introduction and growing use of Liquid Crystal Display (LCD), Thin Film Transistor (TFT)-based monitors, DVDs and digital cameras and progressive scanning, an alternative method is becoming more common.

Progressive scanning scans the entire picture line by line every 16th of a second. This technology eliminates flickering and improves image detail, which is critical in surveillance applications. A high quality monitor is required to get the best out of this type of scan.

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