BPL at ARRL Hqs
andre.kesteloot at verizon.net
Sat Sep 3 08:58:57 CDT 2005
==>BPL AT HQ: ARRL COOPERATING IN BPL SYSTEM EXPERIMENT
BPL has come to ARRL Headquarters, and preliminary indications are that the
newly installed Motorola Powerline LV system will prove Amateur
Radio-friendly. Motorola approached ARRL last fall seeking input on a BPL
design that could avoid many or most of the interference problems that have
plagued some other BPL systems. This past May, Motorola introduced its
Powerline LV wireless-to-low voltage BPL solution at the United Telecom
Council's "Telecom 2005." The ARRL said at the time that it was "encouraged"
by Motorola's approach but reserved judgment until it had the chance to see
a system up close. A Motorola Powerline LV system was put into operation at
Maxim Memorial Station W1AW in late August.
"Theory is great, but the final proof is in how things work out in
practice," says ARRL Laboratory Manager Ed Hare, W1RFI, who's been working
with Motorola Principal Staff Engineer Dick Illman, AH6EZ.
Motorola says its Powerline LV system, which unites its Canopy wireless
broadband Internet platform with enhanced ham band-notching HomePlug
technology, drastically reduces the potential for widespread BPL
interference. Illman says it does this by restricting the application of
high-frequency RF to low-voltage (220 V ac) power lines instead of to
medium-voltage wires that line many residential streets.
In addition, Motorola took the HomePlug modem concept to the next step by
adding tunable hardware filters to deepen the notches and improve the
immunity of the system to nearby ham transmitters.
At ARRL, a Motorola Canopy wireless link was set up between ARRL
Headquarters and W1AW across the parking lot. The system's connected into
the League's local area network on the Headquarters side and into a 220 V ac
power drop on the W1AW end. Hare and Illman then spent several days checking
whether the system affected reception on the Amateur Radio bands at W1AW.
"Although more testing needs to be done over the coming weeks, the initial
results for Amateur Radio were positive," Hare said. "While it would be hard
to envision a BPL system closer to more antennas and receivers, we found
only a few dB of BPL noise on one ham band using the highest-gain antenna at
W1AW aimed right at the W1AW building."
Hare and Illman also looked into the Powerline LV system's immunity to the
interference from nearby transmitters. As they were testing the system, Hare
recounts, W1AW fired up its bulletin transmissions, putting out with more
than 1000 W simultaneously on seven bands.
"I could hardly imagine a more difficult environment, with part of the
BPL-system wiring 30 feet from W1AW's antennas," Hare remarked, "but the
system continued as if the station wasn't even on the air."
Hare says that based on what he's seen so far, Amateur Radio operators
should be able to operate fixed and mobile in close proximity to a Motorola
Powerline LV installation. The Powerline LV system will remain at ARRL while
Hare continues to test the system.
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