An item on the American Radio Relay League Web site, ARRL Repeats Call for Shutdown of Arizona BPL Field Trial, shows a plot of the measured noise level taken from Electronic Broadband LLC's FCC-required six month report on its Broadband over Power Line (BPL) system. The plot shows that at some frequencies, the noise level dropped 30 dB when the BPL system was turned on.
ARRL General Counsel Chris Imlay, W3KD, wrote in a cover letter to accompany the ARRL's technical analysis, "To be blunt, as can be easily determined from the EB report itself, one of two things occurred: either (1) EB altered the data to suit its false conclusion that the system is operating in accordance with FCC rules; or (2) its technical consultants were not qualified to conduct the tests and glaringly misinterpreted, among other things, the source of noise generated internally in their own test equipment."
Examining the plot, one explanation of how turning on the BPL system could have the impossible effect of dropping the noise level was that the analyzer's sensitivity was reduced by 30 dB for the measurements with the BPL system turned on. As the ARRL notes in its technical analysis, "It is not possible that turning on a BPL signal would decrease the ambient-noise levels by 30 dB. If the BPL data were increased by 30 dB to match up the ambient-noise levels, the BPL signal would exceed the FCC Part 15 emissions limits."
Other figures in the ARRL technical analysis demonstrate that Electronic Broadband LLC's own measurements in the low-VHF public safety band show "this system exceeds the Part 15 emissions limits by approximately 19 to 28.5 dB on these frequencies."
It will be interesting to see how the FCC responds to the ARRL request and how long it takes. As reported in last week's RF Report, the FCC Report and Order authorizing BPL clearly stated that BPL systems would not be allowed to cause unacceptable interference to licensed services. Several FCC Commissioners' comments stated licensed services had to be protected from interference. The first Amateur Radio complaint was filed in June. In August, the ARRL asked the FCC to shut down the system.
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