"Telamon" wrote in message
...

No it just that since the data is sent without a clock the data stream
regardless of the encoding need fast and precise (low jitter) edge
times. Faster edges provide more timing margin. Fast edges have most
of
the energy in the odd harmonics 1, 3, 5, 7 etc. Most of the energy is
in
the lowest odd harmonics 1, 3 and 5 being the most important. This
explanation only makes sense for a single carrier two level scheme.

Let's say one of the BPL carriers is at 10 Mhz. Let's say it's
modulated at 10 khz. If you're saying the modulation is making a
channel which covers something like 9.960 Mhz to 10.040 Mhz, that sounds
OK to me.

If you're saying the modulation creates harmonics at 20, 30, 40 Mhz, I
can't see how.


I do
not know what BPL employs but I expect a high frequency scheme be used
to reduce the coupling requirements across transformers in the power
system.

--
Telamon
Ventura, California

Power pole transformers should have a nice grounded copper
electrostactic shield between the primary and secondary windings. This
reduces capacitive coupling between the windings to almost zero. The
BPL company will have to bypass the shield with some sort of bandpass
coupling. I suppose something as simple as a capacitor would do the
job, but they probably have something more elaborate.

Maybe they're using a small ferrite transformer with enough insulation
to withstand the full primary voltage. Bypassing the power
transformer's internal shield would be a lightning hazard.

Frank Dresser