Andre Kesteloot andre.kesteloot at
Sat Jul 22 08:48:31 CDT 2006


A Manassas, Virginia, radio amateur who has complained of BPL interference
to his mobile operation has taken issue with how FCC-mandated interference
testing was performed. Dwight Agnew, AI4II, told the FCC July 20 that a
testing review, carried out July 14 by Columbia Telecommunications Corp
(CTC), "did not represent the Manassas BPL system at peak system loading,"
as the FCC had required.

"The BPL folks' unwillingness to bring the system to peak traffic load
further illustrates a lack of openness and cooperation," Agnew wrote the
FCC's Spectrum Enforcement Division. "It's ludicrous that a system operator
would not keep track of system loading and deny the existence of any such
reporting mechanism." Objective interference testing is impossible unless
the system is loaded at peak levels, Agnew asserted.

Responding in March to Agnew's interference complaint, FCC Spectrum
Enforcement Division Chief Joseph Casey called on system operator COMTek and
the City of Manassas to take measurements at locations Agnew cited in his
complaint "during the hours of peak usage of the system by BPL customers."
He reiterated that directive in June.

Working with CTC's Lee Afflerbach, W3BRH, Agnew and other Manassas radio
amateurs on July 14 reviewed testing done earlier by Product Safety
Engineering (PSE) on behalf of COMTek and the city, which owns the power
grid. The latest PSE testing responded to Casey's June 16 request. He'd
ordered the city and COMTek to provide a detailed report on actions taken
and progress made in resolving the interference complaint or reducing the
emissions in the area referenced in Agnew's complaint to 20 dB below the
Part 15 limit.

In its reply to the FCC July 17, COMTek said remedial actions it and the
city took "have successfully resolved Mr Agnew's complaint." Local radio
amateurs did not witness the actual system testing.

CTC reviewed the earlier test results at three BPL system test points picked
by Agnew and the other radio amateurs. CTC subsequently reported in part,
that while the BPL signal "was perceptible in at least one test location"
the "very low amplitude BPL signal" did not impair reception of desired
communications. BPL signals within the ham bands "were substantially
attenuated" from BPL signals outside the ham bands, the report said.

The CTC report, which Manassas supplied to the FCC as a supplement to the
PSE testing analysis, suggested that some interference radio amateurs have
attributed to BPL "may in fact originate from other sources." Afflerbach
recommended that the Manassas radio amateurs employ "proven modern receiver
technology" such as filters and noise-suppression to minimize the effects of
interference, "including any from BPL transmission."

PSE said in its report that Agnew confirmed "subjectively" that the remedial
actions COMTek and the city had taken had "eliminated the BPL interference
completely or reduced them [sic] to acceptable levels."

Agnew said in his letter this week that monitoring un-notched BPL signals on
8 MHz indicated that system traffic during the post-testing review "was very
low and did not represent peak or even normal system usage."

George Tarnovsky, K4GVT, one of the hams witnessing the post-testing review,
told ARRL that the interference "was right back" the day after CTC conducted
its interference review.

"They're trying to discredit the ham radio community," he charged, referring
to COMTek and the City of Manassas. "When the system is active, you'll hear
it." Tarnovsky says the post-testing review indicated to him that the BPL
system had not been tested at peak loading.

Agnew told the FCC that further testing without the system at peak loading
would be a waste of time. "If the BPL folks are unwilling to share the peak
loading data with us, I would like to recommend future testing of the
Manassas BPL system be conducted by the FCC." To date, the Commission has
not done any testing of the Manassas BPL system.

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