Power Hurdles

Manufacturers of power-line products adhere to the HomePlug 1.0 specification (www.homeplug.org) to ensure compatibility. The standard provides for a theoretical maximum data-transfer rate of 14 Mbps. Actual transfer rates are more in the range of 4 to 6 Mbps. There are also provisions for fallback to slower rates (as low as 1 Mbps) in cases of poor line quality or interference.

Power-line manufacturers have had to overcome some daunting hurdles to make their technology work. In addition, along the way, they've been able to miniaturize the implementation of the technology and then build it into specialized ASICs (application-specific integrated circuits) that handle the sophisticated signal processing required. They've also implemented what's called adaptive processing, which is able to reduce interference from electric motors, fluorescent and halogen lighting, power supplies, and dimmer switches in real time, and the resulting noise reduction has allowed the devices to attain more stability and higher throughput.