FCC Must Return to BPL Technical Issue

Frank Gentges fgentges at mindspring.com
Tue Apr 29 20:09:49 CDT 2008


The ARRL has posted information on the court review of the FCC and its
decision on BPL.  In particular the US Court of Appeals for the District
of Columbia Circuit today released its decision on the ARRL's Petition
for Review of the FCC's Orders adopting rules governing broadband over
power line (BPL) systems.

We gathered AMRAD members André Kesteloot, Bernie Keiser and myself 
along with Paul Rinaldo and the ARRL counsel, Chris Imlay.  We met at 
the ARRL office to help craft the ARRL submission to the FCC on BPL.

One of the issues we examined was how the signal strength should fall
off as function of distance from a radiating power line.  The AMRAD 
group helped the ARRL develop an argument that it should fall off at a
rate of 20 dB per decade as that more closely represents how a line
source should act.  Key was a drawing showing the line radiating out as 
a horizontal cylinder as opposed to the more familiar sphere.  The FCC 
decided that it should fall off at a rate of 40 dB per decade which 
represents a point source and sphere. After all, that is how
they have always done it.

Now, it looks like our argument of a cylinder as presented by ARRL 
counsel convinced the court it should be reexamined by the FCC.  As the 
ARRL writes:

With regard to the extrapolation factor, the Court ordered: "On remand,
the Commission shall either provide a reasoned justification for
retaining an extrapolation factor of 40 dB per decade for Access BPL
systems sufficient to indicate that it has grappled with the 2005
studies, or adopt another factor and provide a reasoned explanation for
it." The studies in question were conducted by the Office of
Communications, the FCC's counterpart in the United Kingdom, and were
submitted by the ARRL, along with the League's own analysis showing that
an extrapolation factor closer to 20 dB per decade was more appropriate,
as part of the record in its petition for reconsideration of the FCC's
BPL Order. The Court said that the FCC "summarily dismissed" this data
in a manner that "cannot substitute for a reasoned explanation." The
Court also noted that the record in the FCC proceeding included a study
by the National Telecommunications and Information Administration that
"itself casts doubt on the Commission's decision."

We hope the FCC goes back to basics and considers the fundamental
physics involved here.  Using the FCC mandated number, calculations will
underestimate the field strength of the interference.

So much time has expired since our comments went to the FCC on this.  We
are given to wonder how much has been invested in systems based on a
flawed model.  This sunk investment will make it harder to decide on 
changes at this late date.

This seems to vindicate the work done by the assembled AMRAD group. 
AMRAD can make a difference.

Frank K0BRA

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