Next, we'll take a look at the traditional CCTV coax-based system designs and explore some of the newer, more innovative approaches being implemented today.
Video Surveillance Designs for the 21st Century
As the video surveillance industry evolves and new digital and IP-based technologies are developed, the cabling infrastructures that support these advances must also evolve. As an end user, you have several decisions to make when it comes to selecting the infrastructure to support your video surveillance system. These decisions can be very difficult to make in an industry that is going through rapid change. Today, video surveillance infrastructures range from cabling systems such as traditional coaxial and multi-conductor cables, to unshielded twisted pair (UTP) solutions, to wireless infrastructure solutions. As a result, the biggest challenge faced by end users is selecting a video surveillance infrastructure that is cost effective, provides room for future growth and offers the ability to migrate to future technologies. The following overview of the various video surveillance infrastructures that exist today will help you choose the solution that best meets your current and future needs.
Traditional infrastructures have been the main distribution media in the video surveillance market for the past 20 years or so. These infrastructures basically involve sending video signals over a coaxial cable like RG59 or RG6, while power and control data are sent using multi-conductor cables such as two-conductor 18 AWG.
Currently, there are two methods of installing traditional infrastructures.
Ã¢â‚¬Ë˜ Home run approach. The most popular way of installing traditional infrastructure is to use bundles of "home run" cabling from every camera to a central security head-end location where monitors, controls and recording equipment are maintained.
Ã¢â‚¬Ë˜ Star wired approach. A "star wired" traditional infrastructure is not a commonly used design, but it does tend to be a more maintenance-friendly design. Rather than using home run cables, the star wired design uses wiring closets where the cable runs from each camera are terminated into a BNC patch panel. From there, bundled coaxial and multi-conductor cables are run in a backbone design to the security head end. The cables are finally terminated into another BNC panel for breakout to recording and monitoring equipment.
The drawback of implementing a home run cabling system is that there are no national standards for cable distance, installation practices or cable performance. A lack of standards permits poorly installed or poorly designed infrastructures. Video signal noise, power phase differential and unintended ground loops can be the result. Electromagnetic interference, unsynchronized power and ground loops are common in traditional video surveillance infrastructures and will result in video signal noise and loss of image quality.
Traditional infrastructures were also designed to support only 75-ohm analog video surveillance technologies and do not provide a migration path to future 100-ohm IP-based technologies. These traditional infrastructures are still popular in the video surveillance industry today. However, as more and more IP-based technologies appear, the need for traditional infrastructures will rapidly decrease. According to security industry researcher JP Freeman, 30 percent of video systems were connected to the LAN in 2002. In 2007, it is estimated that 71 percent of video surveillance systems will be connected to the LAN.
Wireless video surveillance infrastructures are perfect for customers that have widespread, multiple remote or mobile locations that are scattered throughout a town, city or large campus area. Wireless video provides a cost-effective method of distributing video signals over the air at great distances and in mobile applications where it is either too expensive or too difficult to install a cable infrastructure.