[RFI] re: BPL

Michael Tope W4EF at dellroy.com
Fri Jun 6 20:37:50 EDT 2003

I think the FCC wants this BPL thing to fly as it falls into their
political paradigm of increased competition and deregulation.
What the amateur community needs to do is make them painfully
aware of the potential for interference to existing spectrum users
so that the proper testing for EMI is done in the various field trials
that  are underway.  The questions that the FCC is posing in their
NOI suggests that the engineers at FCC are aware of the potential
problems and that they want input on how to address these
problems. If the all of the stakeholders in this issue are represented
fairly during the field trials, I think BPL will defeat itself as I think
the operating levels needed for good system performance and the
levels needed for good EMI compatability with licensed services are
mutually exclusive. On the other hand if only the BPL industry conducts
the field trials without independent oversite, they will spin the results
so that EMI issues are understated.

One of the possible achilles heals of this technology is its immunity
to overload from our transmitters. In order to meet part 15 regulations,
BPL systems need to run at very low power spectral densities. They
have trouble with impulse noise, but they get around it because it is
of short duration and they use lots of coding (FEC, interleaving, etc).
On the other hand, what happens when I key up with 1500 watts into
a TH7DX for a 2 minute RTTY transmission when my antenna is 100
feet from an overhead powerline. Will their analog front-ends have
sufficient dynamic range to lock to a signal with a power spectral density
or -100dBm/Hz in the presence of 15KW EIRP signal 100 feet away?
Probably not, BPL modems will have wide open front-ends as they
are designed to look at large portions of HF spectrum at once. They rely on
DSP for filtering. I don't think their ADC's will have enough bits to deal
close proximity to high power transmitters. Filtering this will be tough
as they will need sharp ham band analog notch filters ahead of their
front-ends to deal with this sort of problem. This could get expensive
for BPL operators depending on the radius of suceptibility (area around
offending HF transmitter where BPL hardware is overloaded). Just
one of many potential problems with this technology.

73 de Mike, W4EF..........................................................

> As has been said before, these days, the FCC seems to be following the
money.  If something won't pass the regulations for, e.g., radiation, just
rewrite the rules.  And as far as it being rejected in Japan - so what.
Classic government mentality (is there an oxymoron here?) says not to look
at what
> someone else has done when we have $$ to spend to reinvent the wheel.  And
if they tackled specifically that, it would likely come out square!  Don't
forget what happened with the 220-222MHz debacle - approved by the FCC yet
unproven technology that fell flat on its face despite the warnings.  Did we
> that 2MHz back?  Ha!  Remember, these folks are experts at finding wiggle
room and rationalization.  The real issue here is money; the Physics be
> Many of the services noted below are (generally) limited to metro/suburban
infrastructure.  I live 4 miles from the city line; dialup is it - period.
Perhaps the recent agreement on fiber to the home standards (it's about
time) will have some impact here.  Me - I favor fiber - I worked with it for
> years!
> 73,
> Tom - WA2BPE
> David Jordan wrote:
> > If they can't make it work in japan it's not going to work
> > here...however, the companies have a right to try it and the gov. can't
> > do much more than watch them fail at it...no one here in DC thinks this
> > mode is going to fly...the competition (cable, Satellite, DSL, ISDN, T1,
> > POTS dial-up, wireless 3G, etc.)has a pretty good lock on the market!
> >
> > enjoy,
> > dave
> > wa3gin
> >
> > KA5MGL wrote:
> > > Pardon my naivte here, gang.   Am I correct in thinking the power
companies (or whoever) would need to clean up their systems before it will
reliably *pass* data at BPL speeds?   I'm thinking the bad connections,
loose hardware, weak grounding, etc might be so bad it would hamper their
own intentions.
> > >
> > > Am I far afield on this point?  Just curious.
> > >
> > > 73,
> > > Kelly, KA5MGL
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