In article , "Ryan, KC8PMX"
writes:

I definitely am not an expert in any way, shape or form about this whole BPL
thing, but to me logic would dictate that if these BPL lines are going to be
emanating a ton of intereference, would they not also be prone to
interference coming in???

Not necessarily. It depends on the format of the wideband information
and whatever is used, if any, for error detection/correction, and whether
or not that detection/correction is in the "up" or "down" direction along
the lines.

The problem in trying to decide anything about BPL is that NONE of
the proponents are revealing anything about the technical characteristics
of their various systems. None of us know the "weight" of the "ton of
interference," not even the ARRL Lab.

Seems to me that would create problems with connections and the quality of
transfer rates.

Ordinarily, with simple systems, yes.

Case in point against: We (wife and self) decided on the digital cable TV
service from our cable TV provider, main point being the larger number
of non-fee channels available plus other services. That digital TV service
provides "up" (to the head-end) communications through the supplied
cable set-top box, used mainly for pay-per-view requests and the like.
The analog TV service from the same provider requires telephone contact
(tone-dial entry). Minor point, but the analog TV distribution is one-way
and IS subject to external RFI affecting the signal.

The digital TV distribution is very nearly interference-free on all channels
and there are many more of those available in the same bandspace than
can be had via analog TV distribution. The digital TV formatting is the
major key in being interference-free...as well as holding video and audio
quality consistent regardless of signal strength.

I don't know for sure whether the digital TV format includes any error-
correction capabilities in our particular TV cable provider but I suspect
it does based on general electronics trade information of the past.

"Broadband over Power Lines" is such a general term that no clue can
be derived from the name or the bandwidth of the "broadband" part.

If the BPL was carrying just a single Internet provider, then the bandwidth
could be considerably smaller than the 78 MHz bandwidth referred to on
03-104, even for 1.54 MHz "T1" or equivalent digital service...in both "up"
and "down" directions operating equivalent to full duplex.

Irrespective of the bandwidth, there's no information on the lines' RF
levels from various BPL proponents. Only one BPL system was
indicated as wanting "Part 15" incidental radiation levels much higher
than existing regulations. That still doesn't give any indication on what
the BPL distribution system line levels are.

Line levels of RF are important in considering the BPL coupling systems
to provide subscriber drops...but there is NO information on what any of
them use for couplers. We don't know for sure if they are really using the
"MV" (4 to 12 KVAC, depending on locality) lines as long distribution lines.
Those MV lines have finite lengths and we don't know if the BPL system
provides any sort of terminations at RF of those ends. If there is no
termination, then the lines will radiate as indicated in the ARRL model.
Those MV lines can radiate even if terminated, although such radiation
at HF will be lower.

MV lines were NEVER characterized, standardized, or municipally-coded
as RF transmission lines, not even in the National Electrical Code
documents. Their lengths and wire spacings (especially above ground)
vary considerably. They work very fine at 60 Hz, dependable and
reliable as they are, whether elevated or underground.

There are no details sufficient for any sort of real technical evaluation so
all of it is a big guessing game at this point. The only true reports are
the radio observations done at the BPL test sites, not done with
calibrated field strength meters/receivers.

LHA