[geeks] can't wait for Vista

[Geoffrey S. Mendelson]

On Tue, Nov 07, 2006 at 12:17:15PM -0600, Bill Bradford wrote:
> On Tue, Nov 07, 2006 at 07:58:38PM +0200, Geoffrey S. Mendelson wrote:
> >The Current Communications (Google) system does this by turning off usage of a 
> > specific freqeuncy. If someone complains, they turn it off. 
> 
> And what's wrong with that?  The interference goes away when they stop
> using a certain frequency, no?

Yes, but there are two problems with that. 

The first is that there are too many users to turn off all of the frequencies
involved. Eventualy they will have to stop operating on every frequency.

The second is that once you get beyond ground waves, radio waves travel
for a distance beyond line of sight along the ground, they also bounce,
you can't tell where it came from. Since most people have never heard a 
BPL signal, they can't differentiate it from any other man made noise.
 
> > In Austrialia, a test was conducted near a coastal radio station and it
> > prevented ships from communicating with it. 
> 
> A *test*.  Obbivously the test didn't go well.  Was the test discontinued
> once it was shown that it interfered with the coastal station?

AFIK, they dropped BPL entirely. 

> What does that have to do with the discussion?  I pointed out that I have
> an amateur radio license to show that I view the issue from both sides.

Simple, experience. If you are a regular HF operator you will understand
the mess the bands are in already. You also have a good working experience
with harmonics (radiating on multiples of the actual frequency), 
intermodulation, where two signals mix and form a third, and world wide
propigation, all things you never see on VHF, even with a high powered
weak signal station. 

You may have exeperinced working a station thousands of miles away with
a few milliwats of power, or the inability to determine a station's location
except by it's call sign. Often HF signals come from the direct path, some times
they come from around the other side of the world, and sometimes they 
just randomly pop up.

You would understand from experience that you could be listening to two 
stations working each other, while you hear a third that neither of them
can, or that you can hear someone working a station you can't hear.

Radio signals behave very differently onHF than they do on VHF. HF
operators act differently than VHF operators. In general, VHF operators
tend to be calmer and more friendly than HF operators, but they can
afford to be, there is no competition for frequencies beyond line of
sight most of the time and the bands are much wider. The U.S. 6 meter or
2 meter band is almost as wide as all of the HF bands combined.
 
> I'm not denying that yes, BPL can cause interference.  However, I've not
> seen any evidence that there have been any permanent (non-test) BPL setups
> that continued spewing interference willy-nilly into the environment 
> around them once the interference was documented, or that people running 
> said TEST rollouts (note the word TEST) didn't care about any interference
> they caused.

I won't argue with that. I can't say what you have or have not seen. If you
want more information, go to the ARRL web page, or if you are a member,
contact Ed Hare directly.
 
> I suppose you hate spark-gap transmitters, too. 8-)

No, I have one hooked up to my difference engine and run packet 
at 1 bit per second. :-)

There really is nothing wrong with a tuned spark gap transmitter. They put
out a wide signal, but not much wider than AM signals which are still used on
some of the HF bands. While they were obsolete by the 1920's they were still
in use until the the 1950's.

Geoff.
-- 
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