Model Forum / Radio Controlled / Air Models / April 2004

I am right with you there, Ed. Japan is a very regulated society. The
USA is, so far, much less so. The Japanese may putup with restrictions
that the US citizens would not. I say teh stuff has not got the quality
to be useable except in teh last few miles to teh consumer, same as
ADSL. That is already infesting telephone lines with leaky radiation.

I'd like to know exactly where, and at what power leles and bandwidth
this is all supposed to work. All my dealings wit ythis sort of thing
give at best a few miles as te absolute maxium range of unshielded
broadband wires, with tight bean microwave being the next useable step
up with 10-20 mile ranges, or more, and optical fibre being the ultimate
medium of choice for 100km + .

If it does come in it will render the whole SW band unuseable: we will
just end up with Ghz band models. Arguably that in itself is not a huge
issue, but I worry about spectral polloution for those - CIA etc - who
regularly scan the global shortwaves for intelligence, and there are
other scientific and miltary uses of that band as well, that would be
severely compromised.

f.ck off noddy.

Is that typed clear enough for you?

Commie bastard.

You should have kept your politcs out of it. You lost me as soon as you
started your ignorant political rant.

As usual, I agree with you, Fred.

I just thought it would make the troops feel better, when, in the following
years, they look at a picture of a once loved and enjoyed R/C model, they
know that they at least tried to stand in the way of the tsunami that is
approaching. At least they could say they tried to make a difference in
preserving their hobby.

Ed Cregger

That is incorrect, for at least two reasons :

1) R/C does use the 27 mhz band, even today.  So does CB.  I believe
channel 6 is shared with one of the CB channels, but even the other
five channels are very close to the CB channels and could be affected
by a CBer close by -- especially if he's (illegally) using more than 4
watts.  Also, some CBers transmit slightly outside of the CB band
(freebanders) -- including directly on the frequencies used by R/C.
Yes, it's illegal, but it happens.

(Of course, you're concentrating on the 72 mhz band, but remember that
it's not the only R/C band.)

2) Cell phones usually use bands far removed from the 72 mhz band we
normally use, so they're normally not a big problem.  But even so, a
cell phone tower *could* certainly interfere with your plane -- either
via intermod, or by desensitizing your receiver to the point where it
can't hear your transmitter anymore.  Fortunately, this is only likely
when your plane is much closer to the cell phone tower than your
transmitter.

Of course, a pager tower that's using the 72 mhz band is a much larger
concern than a cell phone tower at 800 (or more) mhz -- but even so,
the cell phone tower may be a problem under certain conditions.

None of this is rocket science -- this stuff has been understood for
decades, and certainly people considered it long before the 72 mhz
band was allocated to R/C.

As for BPL, it's a disaster for ham radio (at least DXing) and
shortwave listening -- that's well understood.  For us, the problem is
a lot more vague.

We don't normally deal with the extremely weak signals that hams do --
our receivers aren't actually that good at picking up weak signals.
As long as our transmitter's signal is a good deal stronger than the
signal received from other sources (including BPL) we're usually good.
As I understand it, the signal generated by BPL isn't going to be that
strong -- yes, stonger than a guy in Europe transmitting with 100
watts, but not as strong as your 1 watt transmitter only a few hundred
feet away.  Hopefully, BPL won't do anything more than reduce our
effective range by a small amount, and create some `don't fly there'
zones around power lines.  But certainly, the AMA should try and
quantify the danger more carefully, and join the ARRL in fighting
against BPL.  BPL is likely to be a problem for us, but it's not
certain how large the problem will be.

As for interfering with GPS (as another poster suggested), GPS uses
signals around 1200, 1600 and 2200 mhz.  These are so far removed from
the 2-80 mhz signals that BPL creates that they should be safe except
under some extreme conditions, like being 10 feet away from a power or
something (and if your plane is is that close, you've got bigger
problems than a useless GPS.)  I'd be much more concerned about
intereference with the 118 - 134 mhz air band.

Er...haven't you missed a 'not' out there somewhere?

Nothing new there, then.

I sympathise. I live in one of the few parts of England that, until a
few months ago, was still suitable for putting up an astropnomiacl
telescoe and being actually able to see stars, rather than a haze of
orange light spread uniformly acrssoss the sky.

Until some merchant banker decided to 'upgrade' an old cottage to
resemble a hollywood shag pad and create something akin to a supermarket
car park in front of it, complete with floodlights.

If you happen to be visting with a silenced subsonic rifle, there is
excellent shooting to be had nearby...rabbits as well :)

I would not worry TOO much. I have dome a few cost studies

as part time consultant to a small UK broadband company.

The domianmnt cost to providing broadband is teh lats mile circuit and
associated equipment. ADSL and cable works because the phonelines are
there, but still need a piece of termination equipment per subscriber.
Power companies ar faced with diminishing margins, not onl because they
have ripped off most of them into directors pockes, but because there is
an impending energy crisis, made rather worse by the ecent actiuons in
teh middle east.

Leveraging installed badse of power wires looks superficially
attractive, but actually there is a beter way to get broadband to usrs,
and that is distrubuted microwaves: Technology and the 5Ghz spectrum are
JUST becoming avaialable. Cel phone towers that already exist are
suitable co-location points and already have data power and masts
avialable. The total available bandwith theoteically exceeds that
aviailable to any wired technology, apart from very very high quality
cable, and there is only a single piece of kit needed to serve multiple
subscribers.

Its likely that most rural broadband needs will be met by this
technology in a few years, and power line transmission will be stillborn.

Going back in time, does anyone remember when Loran "A" was introduced?

This navigation service, for all intents and purposes, rendered the former
160meter ham band useless.

Mike

They were running quite heavily in the Denver and Chicago market (I have
satellite).  Start with a little kid with a plastic model and then goes
through the kid's life where he is eventually shown flying an R/C.  The
caption then says something like "We've been looking for you" and shows a
Predator drone and it's pilot sitting at a console.

Pretty cool ad.

Don

I recall that there was a statement saying that they would not be
allowed to cause HARMFULL interferance.  That means that there would
be a low level of interferance.  This statement is used often in part
15.  I don't think coax would work for powerline shielding, lines
would get too hot for the insulation.  In fact there would probably
have to be an air gap and some sort of ventalation.  Not sure but I
wouldn't think it would have to almost completly get rid of
interferance as coax does.