From the ARRL Letter: The ARRL has questioned the veracity and technical competence of the company operating a Westchester, New York, BPL field trial. It's also faulted the FCC for not shutting the system down. In December, after an on-site determination by ARRL Lab personnel and a local amateur that BPL interference on 14 MHz had reappeared, the League renewed its request that the FCC rescind its Part 5 Experimental license for Ambient Corporation's BPL pilot in Briarcliff Manor. Ambient told the FCC in October that it had addressed Amateur Radio interference complaints through improved software and notching, and it repeated that claim January 6, saying it was unable to detect the interference ARRL reported hearing. In a strongly worded rebuttal that cited "obvious and preclusive" interference along one BPL-active stretch of road, ARRL General Counsel Chris Imlay, W3KD, questioned Ambient's credibility and competence. "Ambient's claim that it was unable to find that noise in December is not credible," Imlay wrote January 7 on the League's behalf. "If they were in fact unable to find the noise, their technical staff is not competent." The League said that Ambient's October 12 representation to the FCC that it had corrected "all harmful interference" from the system "has proven most assuredly false." Additionally, the League noted, an FCC Enforcement Bureau staffer also has visited the site and could attest to the interference observed on 14 MHz. In its January 6 response, Ambient claimed it was "unable to confirm the high signal levels" and said 80, 40, 30, 20, 15 and 10 meters "continue to be notched." Ambient also objected to ARRL's assertion that the signals constitute "harmful interference" and suggested the League was improperly using the FCC's complaint procedures. The League said its measurements on 20 meters along one stretch of BPL lines were "between 20 and 40 dB higher" than when the BPL signal was not present, and it invited FCC officials to review a video on the ARRL Web site (click on "Videos of interference in Briarcliff Manor, NY") documenting the interference. ARRL accused Ambient of not only failing to remedy the interference but of stonewalling by arguing that the signals ARRL detected ought not be considered "harmful interference" under FCC's Part 15 rules. Westchester County ARES Emergency Coordinator Alan Crosswell, N2YGK, routinely travels on the roads in question and has just as routinely experienced interference in those areas, the ARRL said. The League took strong exception to Ambient's attempt in its January 6 letter to minimize the issue of interference to mobile stations. "Ambient's flippant suggestion that interference to Mr. Croswell's mobile Amateur Radio communications is not an issue, and that he should merely 'drive away from it' is not well taken and is unacceptable to ARRL," Imlay wrote. "It should be unacceptable to the Commission as well." In any case, given that the ARRL measured interference-level BPL emissions up to three-quarters of a mile from a BPL modem at Briarcliff Manor, the League noted, driving away would not be a practical remedy. "The system needs to cease operating on all Amateur bands instead," The ARRL asserted. Crosswell, who's also Westchester County RACES Officer, has documented BPL interference, complaints and related information on his "BPL in Briarcliff Manor" Web site <http://www.columbia.edu/~alan/bpl/>. The League said the lingering Briarcliff Manor BPL situation underscores the "fundamental incompatibility" between Amateur Radio HF operation and "unlicensed (and apparently unregulated) operation of BPL systems." The ARRL also faulted the FCC for its "notable inaction over a period of many months in responding to complaints" regarding the Briarcliff Manor BPL project. "Ambient clearly is not in compliance [with FCC Part 5 Experimental rules], and the Office of Engineering and Technology needs to, in this most egregious case, finally do its job and shut this station down pending compliance determinations and a demonstration that the system can operate without causing harmful interference." It also demanded that the FCC rescind Ambient's Part 5 experimental authorization and "determine other appropriate sanctions" against the company. A copy of the ARRL's January 7 letter to the FCC is on the ARRL Web site <http://www.arrl.org/news/stories/2005/01/11/2/BPL-BCM-ARRLresponse2Ambien t0105.pdf>. For more information on BPL, visit the "Broadband Over Power Line (BPL) and Amateur Radio" page on the ARRL Web site <http://www.arrl.org/bpl/>. Material from The ARRL Letter may be republished or reproduced in whole or in part in any form without additional permission. Credit must be given to The ARRL Letter and The American Radio Relay League.