Reusing Existing Twisted Pair CablingBy Ethan Ace, Published Feb 20, 2012, 07:00pm EST
Reusing analog camera cabling is a common topic in the surveillance industry, as recabling is a significant expense and disruption. This discussion normally centers on Ethernet over coax (EoC), however, as the vast majority of analog cameras are installed using coax. A similar technology exists for cameras installed on UTP, allowing these cables to be reused for IP cameras, which can also allow in-place telephone cables to be used for backhaul. In this update we will examine the basics of Ethernet over twisted pair, its most common applications, and manufacturer options.
Ethernet over UTP converters operate on basically the same principle as EoC converters. These units essentially use DSL protocols to transmit data at speeds of up to 100 Mbps over a single pair of copper cabling. This is most commonly Category 3 UTP, such as multi-pair telephone cables, though other twisted pair cables may work as well. Transmission distances of up to a mile are possible, however, like EoC, speed decreases with distance and cable type.
This technology should not be confused with the multitude of video over UTP products which are on the market, used for transmission of analog video and PTZ data over twisted pair. NVT is perhaps the best-known manufacturer of UTP video equipment, though they do not offer Ethernet over twisted pair products.
Though not as widepsread as EoC, several manufacturers provide Ethernet over twisted pair products. Much like Ethernet over coax, featureset varies from manufacturer to manufacturer. Some offer multi-port units, which consolidate space required at the head end, while some offer products with PoE out, which simplifies connections at the far end.
Some commonly-named manufacturers in Ethernet over twisted pair:
In general, Ethernet over twisted pair products are moderately more costly than their EoC counterparts. A pair of single-port extenders, for example, will cost about $500-600 online ($250-300 per end). PoE switch equipped models are slightly higher, in the range of $750-900.
Replacing Analog Cameras Using UTP
This application is most similar to the way EoC adapters are used. In some installations, typically larger, UTP is used instead of coax cable for analog cameras. This is done as transmission distance is greater over UTP, and cameras throughout a facility may be grouped together, homerun to the head-end using multipair UTP cable, reducing the number of homeruns required.
This is problematic when users wish to convert to an IP camera system, however, as many cameras are located well beyond the 100m distance allowed by Cat 5e/6 specifications. Normally this requires that data closets with new switches be created and connected, typically via a fiber-optic backbone, and new Cat 5e/6 homeruns pulled to each camera. This drastically increases cost and disruption to business. Using Ethernet over UTP adapters at each end, however, existing cables may utilized, eliminating the need to pull new cable to each camera or create new IDFs. It also reduces integrator time on-site, and disruption to business, since only the camera location and the head end need to be accessed, not the entire length of a run.
Utilizing In-Place Copper Cabling for Backhaul
The second instance in which Ethernet over UTP converters may be of use is in situations where multiple locations need to be connected, in order to backhaul video. Typically, in these instances, the Ethernet over UTP adapter is placed at either end of a cable, and connected to PoE switches, which camera runs are connected to. This eliminates the need to run new fiber between buildings, or turn to wireless for backhaul.
The most common example of this application is multiple buildings located on a single site. Today, when outbuildings such as garages, storage sheds, or maintenance facilities are built, fiber is often run in addition to UTP cabling. This was not always the case, however, with many buildings only being connected via UTP for telephones. Ethernet over UTP adapters allow this cable to be used for backhaul of cameras. For outbuilding applications, models of Ethernet over twisted pair adapter with built-in PoE switch may be ideal. This eliminates the need for an extender in addition to a PoE switch, requiring only a single piece of equipment.
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