[Milsurplus] A New Concept: Virtual Spectrum

[aGEnuine Ham]

William and group:

Apples and oranges.

Carrier Current signalling has been in use on the power grid for as long
as there has been a power grid.  BUT ONLY ON THE TRANSMISION LINES.  One
of the more lucid descriptions is Chapter 14of the "Communication Systems
Handbook" by Hamsher, McGraw Hill, 1967.  Chapter 14 is written by a
couple of TVA engineers.  Wherein it describes the use on transmission
lines because they rarely change, while difficult to impossible to
implement reliably on distribution lines because of major impedance
shifts hour to hour, day to day, from one construction addition to the
next, and so on.  BPL is on distribution lines, and is on HF.  Carrier
current is on transmission lines, and LF to low MF.  They avoided HF for
CC, because tests showed radiation to be unacceptable.  Not only because
of the radiation effects, but because all the signal was gone by the time
it reached the other end. And, the impedance variations were difficult
enough to tune out at LF, impossible at HF.   Since few non-professionals
are really conversant with the details of the electric powerline grid
structure, this distinction is one of many misunderstandings about BPL
vs. CC and other systems.  

73,
George
W5VPQ

On Mon, 13 Oct 2003 23:47:57 -0400 (EDT) William Donzelli
<aw288@osfn.org> writes:
> > Guy there writes as tho BPL is a fait accompli.  Watch for it 
> everywhere
> > in a year.
> 
> And when every house gets fibre or digital cable, cash in on the 
> mounds of 
> BPL equipment in the scrapyards. Just like broadcast HDTV.
> 
> The concept of using the power grid for data transmission is older 
> than 
> most people think. Westinghouse was making power line data equipment 
> back 
> in the 1930s, for sending messages between the power stations. 
> 
> Marty, received the SPARC the other day...thanks!
> 
> William Donzelli
> aw288@osfn.org
> _______________________________________________
> Milsurplus mailing list
> Milsurplus@mailman.qth.net
> http://mailman.qth.net/mailman/listinfo/milsurplus
> 


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