Connecting the Dots

Specifiers scrambling for solutions to link analog, digital equipment

The evolution of video surveillance systems to IP-based systems will be application-, budget- and choice-based. It’s not only a choice of product, but also a choice of transmission media.

To maximize the customer’s technology options at the camera, transmission system and head end, CCTV system specifiers are scrambling to provide solutions that fill the gaps between installed analog and digital equipment. They want to be sure their system choices provide an upgrade path that is forward compatible to include a fully digital architecture in the future, without throwing out perfectly good analog equipment.

Most people don’t know it’s possible to use the same transmission media for both analog and IP systems. The transmission media becomes the bridging point to implement a cost-effective surveillance system that gives customers the product choices they need. This bridging system is commonly known as a hybrid IP system or just a hybrid system.

The typical hybrid medium is unshielded twisted pair, though a hybrid system can include fiber as well. The UTP hybrid system choice can support today’s cost-effective analog camera and recording systems while providing an IPready, standards-based cabling infrastructure when a switchover occurs. The following are key points of a hybrid surveillance system:

Structured cabling should be used in all surveillance systems. In a hybrid system, the media being deployed can drive down system cost and increase product choice whether the end user is using analog or Ethernet as the video transmission method. Structured cabling has been used in the LAN data and telecom world for decades. It is quick to install and easy to change, and it can be performance-certified to an industry standard. This performance standard rating is dependent on whether Cat-5e, Cat-6 or augmented C6 components are used and EIA/TIA installation rules are followed.

Future proof by avoiding coax. By using a structured cabling system, a customer can deploy an analog system on UTP and reuse the cabling plant when the end user migrates to an IP-based surveillance system. If coax is used as the method for wiring analog cameras, when the customer decides to migrate to IPbased surveillance, all of the coaxial cable will have to be removed.

In 2002, the National Electric Code was modified to require the removal of communications cables that cannot be tagged for future use. The mandate was meant to reduce fire loads in commercial structures. Coaxial cable has no future use, so it will have to be removed.

Four-pair UTP cable is the basis of all structured cabling plants. Since only one pair of UTP is needed to transmit analog video, it allows the other pairs under the jacket to be used for other things—typically, one pair for video, two pairs for power (mid-span power injection) and one pair for telemetry. So, with a single four-pair UTP cable pulled to a camera site, it is possible to power the camera, bring the video signal back and control the PTZ camera.

Normally, the end user would have to pull three separate wire types to get the same functionality. The same advantages of four-pair UTP cable apply to IP-based systems; a single four-pair can transport the video signal back, power the camera (with PoE) and control the PTZ camera.

Structured cabling can be an economic choice. Installation labor is a big part of the cost of any wiring job. The cost of the individual components represents a small percentage of the overall system cost. When deploying an analog camera system, large cost reductions can be achieved by using a multi-pair UTP cable (25, 50, 100 or 300 pair) between the IDF and MDF. Since analog video only requires one pair for transmission, a 50-pair UTP cable carries 50 channels of video. The integrator can pull a 50-pair cable in one pull, but it’s not possible to pull 50 coaxial cables at one time. So the savings come from the reduced labor of pulling a single multi-pair cable versus multiple pulls of coax.

Consider fiber. Alternately, fiber can be used to connect the IDF and MDF. To truly future proof an installation, the end user would also have to pull a “dark” fiber between the IDF and MDF. The conversion to IP lights up the dark fiber. That might mean removal of the multipair UTP cable if it is not tagged for future use. Since it is a UTP multi-pair cable, there is likely a future use—such as phone systems, access points or any other device that uses UTP.

Be aware that there are choices regarding the media used for cabling infrastructure, allowing the end user more flexibility in future systems’ needs and choices. The most common media for IP transmission is UTP. Whether deploying an analog, a hybrid or a purely IP-based system, UTP is worthy of consideration.

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