[RFI] RE: Broadband over Power Line (BPL) radio interference

Dave Bernstein dave.bernstein at comcast.net
Fri Jul 16 14:55:27 EDT 2004

You cannot purchase extinct species at the store. Their cell lines, their
DNA, the unique enzymes they may have produced -- all are irreversibly

I agree with your characterization of spectrum pollution. However, this
argument is challenging with audiences that aren't already predisposed to
support amateur radio or shortwave listening. Yes, you can convince some
people if you and they are sufficiently patient, but it's a long, hard slog.
And just as many, if not more, will walk away shaking their heads wondering
what you're talking about, or why they should care. Spend the same amount of
time describing BPL's economic challenges and the virtues of WiMAX, and
perhaps newspaper and magazine writers will begin asking hard questions when
they get the next breathless BPL press release.


       Dave, AA6YQ

-----Original Message-----
From: rfi-bounces at contesting.com [mailto:rfi-bounces at contesting.com] On
Behalf Of Ward Silver
Sent: Friday, July 16, 2004 2:05 PM
To: RFI Reflector
Subject: Re: [RFI] RE: Broadband over Power Line (BPL) radio interference

And I can buy fish at the store or bottled water, too.  The point is not
that alternatives are not available.  The point is that a specific
environment (HF spectrum) is in danger of being severely degraded and that
the stress-inducing agent (BPL) is having a measureable effect on
inhabitants of the environment.  Hams, being weak-signal users, are the most
sensitive inhabitants and are showing the most stress when subjected to the

The water quality issue was about a lot more than loss of species, since
pollution in the water was also causing chronic problems at the
top-of-the-food-chain...i.e., us.  Loss of species is an leading indicator
that something a lot more fundamental is wrong.

Once unlicensed garbage fills the airwaves, it has a cumulative effect as
more is added.  All of the over-the-air communications methods, whether
frequency-division or code-division, are degraded by uncorrelated noise.
Some are more tolerant of it than others, but all are degraded. For example,
raise the noise floor power by three dB over a region and the minimum signal
strength at which communications is possible in that region is doubled,
reducing the radius by half over which communications is possible without
changing power, path loss, or protocol.

Furthermore, the ability to withstand degradation from noise is non-linear,
both technically and from a usability perspective.  The tipping point in
usability has already been reached for many urban hams due to Part 15
pollution and susceptibility to interference - even though it's possible to
communicate, they have been driven from the airwaves because it's not
practical to do so within the constraints of return on effort.

BPL exhibits both characteristics of a classic pollution problem - loss of
species (i.e. - hams, SWLs) and general degradation (i.e. - noise floor).

73, Ward N0AX

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