[NLRS] six meter au. & Broadband over Power Lines (BPL)

[Dr. Gerald N. Johnson, electrical engineer]

But is it not true that if the PLC is bothered by outside low power
signals it should be radiating and thus require (in the USA) an FCC
license? How does it handle being in the vicinity of Jim Creek
Washington or Cutler Maine with Megawatt transmitters on VLF or near
Loran-C transmitters on 100 Khz with Megawatt peaks? If its truly wire
only and not radiating in the VLF spectrum (and I've never noticed it
there, all signals I hear at VLF are true radio stations and I'm just a
half mile from a long 115 KV line that runs across Iowa, though that
utility and transmission coop does own microwave) then it should not be
affected by receiving outside VLF signals.

Still the power companies have made the of the responses opposing
creation of a VLF amateur band in the USA. Here amateur radio is a
SERVICE, not a hobby, and that service includes emergency communications
as well as experimenting with propagation and equipment and learning so
that there is a cache of technical persons should the national need
arise again.

The proposal that the FCC just posted for comment is to allow several
watts of power at HF frequencies be applied to domestic (and I suppose
industrial) distribution lines within homes or buildings for use as
wired networks not requiring additional wires. Watts are required and
the radiation exceeds present FCC part 15 regulations on non intentional
radiators because certain loads create a lot of hash on the wiring in
residences and industrial buildings. Primarily lamp dimmers, fluorescent
lamps, and switching power supplies. The problem these pose is that the
radiated data is likely to swamp ordinary strength signals on HF amateur
bands (as well as MF and SW broadcast bands) and that the house wiring
has the opportunity to act as a receiving antenna to let licensed
amateur radio transmissions interfere with the data transmission.
Previous equipment proposed and sold for such purposes HAS shown both
properties, being a source on interference to radio reception and being
bothered by amateur transmissions. Those have only been kept working by
using frequencies that avoid ham bands. If we add a band about 5 MHz
that gets more difficult to select an operating frequency outside ham
bands while still handling a few megabits data rate. Relaxing the
radiation limits of FCC part 15 just makes it more likely that use of
such devices can prevent using HF amateur equipment at home.

73, Jerry, K0CQ
-- 
Entire content copyright Dr. Gerald N. Johnson, electrical engineer.
Reproduction by permission only.