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Video transmission methods have come a long way since the days of coaxial cable, which was invented about 120 years ago. Coaxial, however, still remains the least expensive transmission method for short distances (400 to 1,200 ft.) and a workhorse of connectivity. But cost is not the only aspect to take into consideration to get video from Point A to Point B. Interference, distance, environment, bandwidth and video quality are also critical factors to consider.
New technologies are changing the industry and some of the older stalwarts are still quite deployable. Twisted pair cabling has been around nearly as long as coaxial technology but has numerous advantages over its older counterpart. The flexible and slim cable makes it easier to run between walls — yet it is susceptible to electromagnetic interference.
The cable technology with better resistance to interference and even higher bandwidth is fiber optics, which uses thousands of pulses of light within a single cable. It is an excellent choice for transmission of high-quality video, even over long distances, although it is definitely a more expensive option compared to coaxial and twisted pair.
Another viable alternative
Cabling is not always possible however, and wireless transmission methods such as radio frequency have entered the market to fill this need. Although bandwidth capabilities are high, some systems can be difficult to set up and may even require a license from the Federal Communications Commission. Systems are more reliable than ever, but interference is a possibility. Firewalls may also be necessary for sensitive or ultra-secure applications.
Compression technology has enabled computers to take over the new generation of video transmission. Video data can now be transferred over an Internet protocol (IP) network in a cost-effective manner and this is truly one of the hottest trends in the industry. Cameras can be added to a corporate security system and managed through the information technology (IT) department's Local Area Network (LAN). The IP video's digital data can then be analyzed with software or sent to PCs, laptops, PDAs or mobile phones.
Digital video can even be transmitted wirelessly through point-to-point or point-to-multipoint networks. These work by allowing video transmission through a connection between a base node and satellite nodes. It is a relatively inexpensive solution when cabling is not possible.
Mesh moves to mainstream
A more reliable, but more expensive method being used by an increasing number of city and campus security systems is mesh networking. Similar to point-to-point and point-to-multipoint, mesh networking includes many, possibly hundreds, of nodes to transmit the video data. If a node fails to transmit, the data moves on to the next node in its configuration and so on, until the video reaches its destination.
One other technology used only by the government or large corporations is satellite transmission, which is prohibitively expensive for most users. Data is transmitted to a satellite orbiting the earth, then beamed back down to a different location on earth. Another less common method is microwave transmission, which requires a direct line of sight to relay video data.
Video transmission is a crucial part of any security system. Many security systems use more than one of the different video transmission methods described. Work with your client to evaluate the priorities, considering cost, reliability, video quality and bandwidth to determine which method best suits the application.
Tom Asp is president and chief operating officer of VTI Security Integrators, a member of SecurityNet. He joined VTI in 1986 and works in the corporate office located in Burnsville, Minn.
author: By Tom Asp