In article ,
Dan/W4NTI wrote:
It would also seem that the need to "get around" the isolation provided by
the local distribution (120/240) transformers from the HV lines would mean
that filters of some kind would need to bridge lines operating anywhere
from
2.4kv to around 21kv to the low voltage lines into the home. Not a trivial
task to do economically and safely. It seems like there would be potential
(pun intended) to degrade both the reliability and safety of the
electrical
distribution system.
Which is exactly why the FCC didn't authorize the 136 hz sliver band for us,
right?
My recollection is that the FCC turned down the LF allocation,
primarily due to claims by the power companies that even low-power
amateur transmissions could interfere with their existing LF powerline
control systems. It wasn't an issue of bridging past isolation, I
think.
The existing PLC architecture is (I understand from reading elsewhere)
designed to work within the limitations of the power grid... it can
deal with the degree of RF isolation between one section of the grid
and another, and in fact I think it actually depends on this to some
extent to allow for region-limited control.
The power companies' stated concern was that even a relatively
low-power and inefficient amateur LF transmitter (a few watts, on a
short antenna) could create enough low-frequency RF voltage on the
lines to cause their equipment to malfunction (by overdriving and
saturating the RF receiver stages, I imagine).
As the ARRL and others have pointed out, there's a _very_ obvious
disconnect between this claim (which the FCC has accepted), and the
apparent claims of the BPL proponents that BPM systems can co-exist
with amateur-radio and other licensed band users, operating with
*much* higher RF power levels and much more efficient antennas.
--
Dave Platt AE6EO
Hosting the Jade Warrior home page:
http://www.radagast.org/jade-warrior
I do _not_ wish to receive unsolicited commercial email, and I will
boycott any company which has the gall to send me such ads!