[NLRS] Broadband over Power Lines (BPL)

[Dr. Gerald N. Johnson, electrical engineer]

I get the feeling lately that the FCC has decided they regulate too much
and that the "entrenched" communicators wouldn't let any new innovation
work that had the remotest possibility of interfering with the existing
communications so the FCC is going hog wild allowing new sources of QRM.
The proponents of this power line networking will claim that since its
in cables (and in big cities in conduit) that it won't be a radiator and
so can run more RF power. The best lobby will be the AM broadcasters
where AM receivers often depend on their connection to the AC line to be
part of their antenna and so any RF applied between 0.54 and 1.7 MHz
will get directly to the BC receiver. That won't help us preserve ham
bands though. We need to show that the radiative properties of typical
residential wiring will cause destructive (not just annoying)
interference to our HF EMERGENCY communications and that any of our
LICENSED HF communications will prevent the network from functioning,
whether in our own house or in the neighborhood.

The FCC has allowed UWB to impact on several of our microwave bands. The
FCC has encouraged spread spectrum to disrupt narrow band communications
on those bands. Both groups proposing those modes claimed they spreading
of their signals would produce little interference to our receivers but
tended to base the state of our art on two decades old technology, not
good GsAs preamps with under 1 dB NF and so the interference from spread
spectrum can easily be 30 dB above our modern threshold on microwaves.
The FCC said "Tough, we can't impede progress."

If the data and spread spectrum signals have controls to avoid strong
signal interference, we may have to stoop to local "beacons" a few KHz
from our receiver frequency to drive away the data to spectrum where it
receives less interference. The automatic avoidance of narrow band
carriers has been proposed from some new spread spectrum modes. I'm sure
we will have to work a great deal harder on receiver input filtering and
handling large undesired broad band signals (as well as that close in
beacon). Right now I don't see the makers of amateur VHF/UHF narrow band
equipment addressing those goals. In my radios they have gotten worse
rather than better over the years. So I'm making my own.

We can and we must file arguments with the FCC though I suspect
sometimes they will be futile. Big money speaks much louder than we.

73, Jerry, K0CQ

-- 
Entire content copyright Dr. Gerald N. Johnson, electrical engineer.
Reproduction by permission only.