Monday, March 27, 2006

Broadband over Power Lines: Causing Static?

In 2004, the Federal Communications Commission set up a rules for companies rolling out tests of a technology called Broadband over Powerlines (BPL). BPL, commonly referred to as HomePlug or powerline communication (PLC), is a technology that uses radio waves, transmitted over power lines, to provide broadband Internet or other data connectivity.

BPL is attractive because of the power grid's ubiquity. It has been touted as a "third wire" into the home and a way to bring high-speed service to rural areas underserved by cable and phone companies. Such ubiquitous availability would make easier to attached other electronics, such as televisions, to a network. BPL offers obvious benefits over regular cable or digital subscriber line (DSL) connections since an extensive infrastructure is already available.

BPL service is established by inserting a radio-frequency signal on to the power line, much like a high-frequency signal is applied to phone lines to create DSL. The college radio station I worked at utilized a similar technology called carrier current to broadcast one of our stations to the dorms.

Unlike phone and cable wires, power lines that run above ground can act as large radio antennas, emitting the high-frequency signal as radio waves. In order to get broadband speeds, BPL uses a large number of frequencies. However, radio waves can create interference in other electronics. This is why air travelers are instructed to turn off their electronic devices during take off and landing. CableTV-based broadband gets around this by placing cabling with shielding underground. If interference continues to be a problem for BPL, it could result in upgrades to power networks and eliminating the cost effectiveness of BPL. The actual BPL signal itself could also be interfered with by other outside sources.

According to the American Radio Relay League , the national ham radio association, radio waves from an improperly designed system can drown out amateur radio within a quarter of a mile. A report issued by the National Telecommunications and Information Adminstration (NTIA) concluded that a BPL transmitter operating within limits would significantly increase the noise for a vehicle-mounted receiver operating in a residential neighborhood next to a BPL-energized line and that it "may experience harmful interference" depending on the frequency.

While the technology has great potential to close that final mile we will have to wait and see if it cleans up its signal enough for widespread deployment. Sphere: Related Content

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