ARRLWeb: BPL Tutorial

Broadband over Power Lines (BPL) also goes by a few other names and acronyms: Power Line Communications (PLC, Power Line Telecommunications (PLT), and Power Line Broadband (PLB) are terms also used. Most of these papers and links use the term "BPL." There are a number of types of PLC systems, using different approaches and architecture. All are "carrier-current" systems, a term used to describe systems that intentionally conduct signals over electrical wiring or power lines.

Figure 1: In-building BPL can be used to interconnect PCs or other devices within a building, using that building's electrical wiring. Access BPL extends that connection to the Internet, using electrical distribution wiring. This slide provided courtesy of Cosy MUTO, JH5ESM.

There are three major categories of PLC:

Access BPL uses electrical distribution lines, overhead or underground, to provide broadband Internet access to homes and businesses. Because their wiring is physically large, often overhead and extends across entire communities, access BPL systems pose a significant interference potential to over-the-air radio services. Amateur Radio is not the only potentially affected service from these types of systems. There are a number of different techniques used in access BPL, from spread spectrum to OFDM (multi-carrier signals). Studies done by amateurs in Europe, Japan and the US leave little doubt that access BPL that uses overhead electrical distribution wiring poses an interference risk to HF.

In-building BPL systems are designed to use the electrical wiring within a building to network computers. Most operate under the HomePlug specification. (See the HomePlug-related link following). HomePlug systems used within a building have notches in their product specifications, to protect over-the-air Amateur Radio operation.

Control PLC operates below 500 kHz, and is used by electric-utility companies to control their equipment using the power-lines as transmission lines. This type of PLC does not pose any significant interference risk to HF operation.

Additional Information

This mini-course in BPL technology covers the technical, practical and financial aspects of BPL.

Are you ready for BPL enablement of your home and neighbourhood?
This page by Owen Duffy, VK1OD, contains an article and series of graphs that shows the likely impact of BPL enablement on ambient noise levels over the HF range. The graph and article shows the expected receiver input power from the natural noise floor (galactic noise (from ITU-R P.372-8)); and the expected receiver input power from BPL that is of intensity sufficient to result in a maximum field strength of 30?V/m at 30m distance as specified by FCC Part 15.209. The article documents the assumptions underlying the model, and compares the model with measurements by Australia's communications regulator (ACA / ACMA) of an Australian BPL Trial of DS2 BPL. The graph's receiver power axis is scaled in both dBm and in "S-units".

Review of FCC Report & Order 04-245 on Broadband Over Power Lines (BPL)
July 29, 2005, Conformity Magazine -- This article is an excellent tutorial about BPL and the requirements of the FCC report and order. It outlines the spectrum that must be protected under the rules and additional spectrum that will need to be protected to meet the rules requiring that BPL not cause harmful interference.

An excellent article on BPL was published in the July/August 2004 edition of TCA, the Canadian Amateur, "BPL Interference: Fact or Fiction," Barry Malowanchuk, VE4MA. It contains a tutorial section that explains several different BPL technologies. A general tutorial on BPL is available at HowStuffWorks.com.

Anthony Good, K3NG, has written a "frequently asked questions page" about BPL.

This paper, presented by Gary Box, N0JCG, at the 40^th Annual Minnesota power Systems Conference (MIPSYCON), has a tutorial about broadband over power line and the new FCC rules restricting how it can be deployed.

Though written with an industry slant, this tutorial on the Wave Report website offers a technical description of several BPL technologies. Part II and Part III offer additional information. In Part III, Alan Scrime, Chief of the Policy and Rules Division at OET summed up the interference issue succinctly: "'If you are doing everything right, and existing regulations are sufficient, why am I up here asking you questions?' Brett Kilbourne, Director of Regulatory Services for UPLC, had the answer: 'Because there are incumbent users [of that spectrum] that you have a duty to protect.'"