At Thursday's open meeting, FCC commissioners adopted a Notice of Proposed Rule Making (NPRM) to establish rules for broadband over power lines (BPL). Users of the shortwave and low VHF portion of the radio spectrum have expressed concerns about interference from BPL. The FCC news release FCC Proposes Rules for Broadband over Power Lines to Promote Broadband Service to Underserved Areas and Increase Competition described how the proposed rules would protect existing spectrum users. BPL devices would have to employ "adaptive interference mitigation techniques" to prevent harmful interference. The FCC said these techniques would enable BPL devices to avoid operating on specific frequencies, dynamically reduce transmit power or cease operation altogether to protect amateur radio operators, public safety communications and other services sharing spectrum with BPL.
It isn't clear how these techniques would protect short wave radio listeners or Channel 2 TV viewers, since neither would be transmitting a signal detectable by the BPL device, although because BPL would be authorized under Part 15 of the rules, it would have to protect licensed users of the spectrum from interference. While it appears unlikely BPL operators would be willing to block out large portions of spectrum to accommodate shortwave listeners and over-the-air low VHF TV viewers, we will have to wait until the text of the NPRM is released to see how the FCC will handle this. Under the rules proposed, a public database would include information about the location, operational frequencies and modulation type of BPL devices. While this could be useful for amateur radio operators and public safety users, it probably won't be of much use to casual shortwave listeners and TV viewers.
The ARRL, in the article FCC Okays BPL Proposal; ARRL Officials Express Disappointment quoted ARRL CEO David Sumner, K1ZZ saying, "The Commission clearly recognized that the existing Part 15 emission limits are inadequate to stop interference, but it's placing the burden of interference mitigation on the licensed user that's supposed to be protected." During the commission meeting, FCC Commissioner Kathleen Abernathy asked OET Chief Edmond Thomas how an interference case would be resolved under the provisions in the NPRM. Thomas said a complainant would use the database to see if a BPL system was in operation in the complainant's vicinity. "If the answer is yes, they report the interference to the provider. The provider has the capability to adjust his power and the frequency of operation to mitigate the interference."
The NPRM asked for comment on RF measurement guidelines for BPL devices and other carrier current systems to ensure emission measurements are made in a consistent manner. The emission limits, however, would be the same as those currently specified in Part 15 of the FCC rules.
In his statement on the BPL NPRM, FCC Chairman Michael Powell said, "I am confident that the proposals we adopt today balance the potential benefits of BPL services and give careful consideration of the potential interference from BPL operations by establishing new requirements that will help minimize harmful interference that may occur and guidelines for measurement of radio frequency (RF) emissions from carrier current systems."
Commissioner Kathleen Abernathy, in her statement on the NPRM was hopeful the interference issues could be resolved. "One of the key issues in this proceeding is the potential for harmful interference by BPL systems to licensed spectrum users. Based on the record, it is appropriate that we are proceeding cautiously. I support our tentative conclusion to craft technical rules that minimize the potential for harmful interference to existing licensees and also ensure that any instances of interference are quickly resolved. I look forward to reviewing the comments on these technical proposals and am hopeful that we will be able to develop rules that protect existing licensees from harmful interference, while enabling a promising new technology to move forward."
Commissioner Kevin Martin noted that, "In this proceeding, we are considering how to facilitate deployment of BPL while ensuring that existing users are protected against interference. Most importantly, NTIA and FEMA have raised concerns about interference to Government operations, including some emergency communications." His statement continued, "In addition, many amateur operators fear that they
will experience unacceptable interference from BPL systems. I take these concerns very seriously. I am optimistic, however, that we can craft rules that will fully address these concerns and still allow BPL to flourish. I thus look forward to receiving comments in this proceeding."
Commissioner Jonathan Adelstein, in his statement, didn't seem sure the all the interference concerns were supportable. "While we must be mindful of harmful interference, we cannot let unsupported claims stand in the way of such an innovation as BPL systems. Provided that the engineering bears out, I believe that we need to push the boundaries to accommodate new technologies. A little noticed provision of the Communications Act, Section 157, reads that 'undefinedt shall be the policy of the United States to encourage the provision of new technologies and services to the public.' I am fully committed to that mission to promote new technologies, and to provide a framework for innovation so they can succeed. In order to do so, we must first resolve the technical interference issues addressed in this NPRM."
After the text of the NPRM is released, we will have a much better idea of how BPL interference will be controlled, both technically and legally. Look for details in a future RF Report.
