Incorporating information technology into electronic security systems can bring you two welcome results: improved security capabilities and lower costs. In this article we’ll look at some of the technology breakthroughs that are bringing these results today.

Power Over Ethernet
The telecommunications industry has used a version of electrical power over network connections for many years to allow telephone service to continue i

That requires cameras and network infrastructure that are compliant with IEEE 802.3af, the standard published in mid-2003 that specifies how switches, routers and hubs should deliver power over standard Ethernet cabling to devices like IP phones, security systems and wireless LAN access points. In addition to the security benefits, eliminating separate power cabling to end devices such as cameras can cut installation costs by 50 percent or more.

Axis Communications, Sony and Toshiba have recently introduced PoE-compliant network cameras. “Power is the weakest link in a video surveillance system. PoE strengthens that link,” said Joe Cook, product manager for Toshiba Security & Network Video. Another benefit for video systems is that changing a camera position no longer requires a new AC power installation. PoE makes it easier to experiment over time with camera positions to achieve ideal coverage results. Power can even be extended to selected access control devices.

802.3af defines a way to build Ethernet power-sourcing equipment (such as routers and switches) and powered terminals (such as IP telephones and IP cameras). The specification involves delivering 48 volts of AC power over unshielded twisted-pair wiring. It works with existing cable plant, including Category 3, 5, 5e or 6; horizontal and patch cables; patch-panels; outlets and connecting hardware, without requiring modification.

802.3af power sourcing equipment contains a detection mechanism to prevent sending power to noncompliant devices. Only terminals that present an authenticated PoE signature will receive power, preventing damage to other equipment.

More information on PoE can be obtained from the Power Over Ethernet Web site (see Quicklinks, p. 34), which publishes a regular newsletter related to PoE.