So, how do you get beyond that 100-meter limit? Once answer is through fiber optics. Fiber optic cabling is an effective method to overcome the distance and bandwidth limitations of UTP, and media converters are a commonly used to integrate copper network equipment and fiber. Since DC power cannot be conducted over fiber, PoE media converters are the solution to extend network distances via fiber to remote IP cameras. A PoE media converter converts the fiber to copper, and sends DC power to the camera over the UTP cabling.
How PoE Media Converters Work
On the main article image/PoE schematic that appears at right (view a larger version here), an Ethernet switch with RJ-45 ports resides in a control room or data closet. The copper UTP cabling is converted to fiber with a standard media converter. The fiber is run a long distance to the PoE media converter located near a convenient AC or DC power source, where it converts the fiber back to copper UTP. The PoE media converter also functions as a power-sourcing mini switch, and injects PoE (DC power) over the UTP cable. At the other end of the UTP cable is the IP camera, located up to 100 meters away from the PoE media converter.
PoE media converters are available with Gigabit Ethernet and Fast Ethernet data rates and can support PoE (15.4 watts) or PoE+ (25.5 watts). PoE media converters function like PoE mini-switches, and are available in a variety of multi-port configurations, including dual RJ-45 and dual fiber ports. They can support fixed fiber connectors or small form pluggable transceivers.
To understand those power specifications, it’s worth knowing that in 2003, the IEEE ratified the 802.3af PoE Standard. That standard provides up to 15.4 watts of power per port. Late in 2009, the IEEE ratified the 802.3at PoE Standard known as PoE+ that provides up to 25.5 watts of power for each port. PoE+ can be required to power IP cameras with Pan-Tilt-Zoom (PTZ) capabilities, and weather-hardened cameras used in cold environments that feature blowers and de-icers.
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