Field Guide · concept

Also known as: PoE

Power over Ethernet (PoE) delivers electrical power to a device over the same twisted-pair cable that carries its Ethernet data, so the device needs no separate power supply.1

Overview

Standardized in IEEE 802.3 (af, at/PoE+, and bt), PoE lets a power sourcing equipment device — a PoE switch or an inline injector — feed a powered device anywhere from about 13 W up to roughly 90 W, negotiating the level so it never over-drives a device that can’t accept it. This is ideal for gear mounted where a power outlet is awkward: wireless access points, IP cameras, and small computers all run on a single cable.

What it’s for

PoE collapses two cables into one, which is exactly the appeal for an antenna-side node. A GopherTrunk capture box built on a PoE-capable Raspberry Pi HAT can sit on a mast or in an attic with only a network cable run to it — data down, power up — instead of needing mains wiring at the antenna.

Sources

  1. Power over Ethernet — Wikipedia, on carrying power alongside data on Ethernet cabling. ↩

See also