Monday, June 26, 2006

There Is No Power Without Interference

Broadband over power lines (BPL) has been touted as a viable alternative to DSL and cable, but suppliers have wrestled with the challenge of getting high-speed signals through power networks (called access BPL) and into homes and businesses (in-building BPL) reliably. The way they do it is by converting the binary data stream to a radio signal. The problem is that the frequencies used for BPL are some of the same frequencies used for amateur radio and other wireless services. In tests, BPL put out extremely high amounts of interference—so much so that the FCC forced BPL suppliers to go back to the drawing board.

In October 2005, the city of Manassas, Virginia and COMTek , a BPL-based ISP, announced that high-speed Internet services were available to the city’s 12,500 households. Apparently, the interference problems with amateur radio were solved. Apparently not. Today, the Amateur Radio Relay League (ARRL) released the text of two letters sent to Manassas’s city government and COMTek by the FCC, ordering them to either resolve the interference complaints of six amateur radio operators or prepare to shut down their BPL system.

This is far from a death sentence for either BPL in general or Manassas’s system in particular, but it does show that the industry still has a way to go in order to prove both the technical and business viability of BPL products. It may well be possible to implement an access BPL system that doesn’t cause unacceptable interference, but the BPL industry had better deploy one soon. BPL vendors have to demonstrate that they can actually deliver what they’ve been promising, or the utilities and their customers will soon lose interest.

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