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

Ward Silver hwardsil at centurytel.net
Fri Jul 16 14:04:53 EDT 2004

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

----- Original Message ----- 
From: "Dave Bernstein" <dave.bernstein at comcast.net>
To: "'Ward Silver'" <hwardsil at centurytel.net>; <rfi at contesting.com>
Sent: Friday, July 16, 2004 10:44 AM
Subject: RE: [RFI] RE: Broadband over Power Line (BPL) radio interference

> Unfortunately, your analogy does not survive close inspection. There is no
> way to compensate for the loss of a species; if you lose access to HF,
> however, you can chat with your VK friends using voice over internet
> You have lost a mode of communication, not the ability to communicate.
> Please keep in mind that I do not support the allocation of amateur
> to BPL. My point is that some arguments against BPL are counterproductive,
> and should be abandoned in favor of those that are more effective.
>     73,
>         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 10:37 AM
> To: rfi at contesting.com
> Subject: [RFI] RE: Broadband over Power Line (BPL) radio interference
> > If I say "you can't have cheap broadband access because I want to be
> > able
> to
> > chat on the radio with my friends in Australia each evening", then I'm
> > arguing that my self-interest is more important than your
> > self-interest.
> You
> > are of course free to disagree, self-interest being entirely
> > subjective.
> If
> > enough of a majority decides they prefer cheap broadband access over
> > hams continuing to do their thing, then the hams will lose. Actually,
> > all
> that's
> > required for hams to lose is the belief by politicians and bureaucrats
> that
> > a majority won't strenuously object.
> My response to this argument has been to say that hams are acting as
> "canaries in the coal mine", tipping off the public and corporations to
> problems of this technology before it becomes pervasive enough to do real
> harm.  Just as the sport fishermen and duck hunters helped raise awareness
> about water pollution a generation ago, we are doing the same for spectrum
> pollution.  Whether or not amateur radio and sport fishing are critical to
> society is not the point, but irreversible and needless loss of spectrum
> used by important services certainly is.
> 73, Ward N0AX
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