[ADXA] BPL info

[LennyK5OVC@wmconnect.com]

received this from Alan-W3BV..=20
=20
California firm develops interference-free BPL technology
 Canadian radio amateurs using the high frequency and VHF spectrum are=20
becoming concerned that proposed broadband over power line (BPL) systems may=
 render=20
the bands unusable due to radiation from the power lines.  Broadcasters and=20
government agencies also fear that BPL radiation, including harmonics, have=20=
the=20
potential to cause interference to VHF TV, FM radio and military and public=20
safety communications in the HF and lower VHF spectrum.  =20
Six weeks or so ago, I read a story that a California company, Corridor=20
Systems, had demonstrated a BPL system that works at 2.4 and 5.3 GHz. The sy=
stem,=20
is designed to provide broadband  (250 MHz) transmission suitable for high=20
speed Internet access, using the existing power distribution system, but whi=
ch=20
does not pose any threat whatever to amateur radio or other users of the rf=20
spectrum.=20
 I tracked down Corridor Systems Chief Technology Officer, a radio amateur,=20
Glenn Elmore N6GN, and he assured me that their BPL technology would not=20
interfere with the HF ham bands. The story below is based on information fou=
nd on=20
the Corridor Systems web site.=20
 Corridor Systems has developed and patented core technology that enables=20
very high capacity, symmetric and full-duplex information transport over a=20
variety of propagation medium types. Power Corridortm is an implementation o=
f this=20
fundamental technology which operates, in part, over a single conductor of a=
n=20
unmodified, existing power line. In Power Corridortm, information-carrying=20
energy is coupled on and off the conductor by identical launch devices at ea=
ch end=20
of conductor segments. This energy, which may extend from VHF through the=20
microwave portions of the spectrum, is launched as a surfacewave mode around=
 the=20
conductor.

Surfacewave transmission on an insulated single conductor was first=20
discovered and presented by Goubau1 in the early 1950's and known as G-Line2=
 after the=20
inventor. The characteristics of surfacewave  propagation, when used with a=20
variety of dielectric types, thickness and specially prepared conductors, ha=
ve=20
been taught and available in reference texts for many years3. Though not wid=
ely=20
utilized in practice, the mode can exhibit extremely low radiation and=20
transmission losses from VHF into the microwave regions.

Corridor Systems has discovered, extended, developed and patented a much mor=
e=20
general surfacewave mode for operation on lines which may be completely=20
uninsulated and which need not have any special surface preparation. Additio=
nally,=20
lines which are much larger in diameter than those of previous work may be=20
utilized. This invention, which makes possible very high rate information=20
transport over existing medium-voltage electric utility power lines, is call=
ed<I=20
style=3D"mso-bidi-font-style: normal"> E-linetm. As with G-line, the vast ma=
jority=20
of energy propagates within a volume located relatively close to the single=20
conductor. In Power Corridortm the diameter of this volume is only a few inc=
hes.=20
Since the energy propagates at very nearly the speed of light, the relative=20
velocity of propagation in this mode is quite close to unity.

Combined with the normal clearances maintained for aerial medium and=20
high-voltage power lines and Corridor System's specially developed and paten=
ted=20
launching devices, E-linetm provides an extremely effective mechanism for th=
e=20
transport of very high speed information over existing power line grids.=20
 Measurements at ground level directly under the power line used during the=20
test showed a maximum radiated power level of less than -10 dBm, 20 dB less=20
than the typical power level from 802.11 based wireless cards.=20
Corridor Systems has tested and demonstrated simultaneous operation of its=20
BPL technology and amateur radio HF communications. Utilizing a 100 watt, 7=20=
MHz,=20
21 MHz and 28 MHz amateur SSB/CW transmitter connected to a dipole antenna=20
located within 20 feet of an operating BPL system, there was not any evidenc=
e=20
whatsoever of the operation of one system in the other. Amateur UHF=20
communications at 446 MHz and at a 25-watt power level were similarly unaffe=
cted and in=20
turn were not detected by the BPL system. Examination of the .1-30 MHz HF=20
spectrum with a quality communications receiver also revealed no evidence of=
 the BPL=20
system.=20
 Glenn also told me that Corridor's demonstration not only used the=20
unlicensed bands, FCC Part 15 in the US, but also simultaneously supported f=
ast scan=20
amateur television with stereo audio under Part 97 of the US Rules. So while=
 the=20
system was being used to support high speed internet traffic it also served=20
as an =E2=80=9Copen band=E2=80=9D for amateur radio uses-- even with one end=
 of the TV link=20
mobile on the roadway near the power lines!=20
 More information and photos can be found at:=20
<A HREF=3D"http://www.corridor.biz/news.htm">http://www.corridor.biz/news.ht=
m</A> and=20
<A HREF=3D"http://www.tvtechnology.com/dlrf/one.php?id=3D259">http://www.tvt=
echnology.com/dlrf/one.php?id=3D259</A>=20







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