[mythtv-users] Power Line Network Connections and Myth ?

Craig Huff huffcslists at gmail.com
Thu Sep 30 02:01:09 UTC 2010


OK, so I bit the bullet and bought some of these to see what they'd do
for my problem.

(To recap _my_ problem, I have a frontend that I was trying to work
with via WiFi.  It was barely adequate during the daytime when no one
in the neighborhood, including my wife, was doing anything with WiFi,
but once the evening came, there were all sorts of dropped frames and
finally lost connections, so it was impossible to watch a single
recording.  This is all SD video since I have spent all my $$$ on
MythTV instead of new TV displays ;-)).

In any case, (based on an earlier message in this thread, I believe) I
installed iperf and jperf on my combination BE/FE, an FE that is on
10/100base-T, and the problem child struggling with WiFi.

As a baseline, I found that the bandwidth to the 10/100Base-T FE was
upwards of 95Mbps while the bandwidth to the WiFi unit (under evening
--bad-- conditions) was around 6-7Mbps.  I was shocked that I could
even get the poor performance I was getting with 6-7Mbps!

Went to NewEgg and ordered these:
http://www.newegg.com/Product/Product.aspx?Item=N82E16833122360

(Pardon the /lecture mode, but some folks may not know the following.)
/lecture mode on
While waiting for them to come in, I did a little research in the
basement at the power panel.  Most homes built in the US in the last
40+ years use circuit breaker panels instead of fuses (with the
exception of cut-off boxes outdoors next to major items like an air
conditioner compressor or an above-ground pool filtration pump).  The
standard circuit breaker box is laid out with breakers in two columns
on the left and right.  One might think that those on the left were on
one half of the split 220 service (220 is the nominal service voltage,
 some power companies may only supply 200V and others may supply 240V
or more) and those on the right were on the other half of the split
220 service.  One would be wrong!  If you look closely, you most
likely will find one or more double-wide circuit breakers that support
things like a 220V electric dryer, 220V oven, etc.  The breakers from
top to bottom on one side of the panel alternate between one side of
the split 220 service and the other.  Thus the odd ones counting from
one end are on one side of the split 220 service and the even ones are
on the other.  To get ones on the same side of the split for use with
the above powerline ethernet devices, they must be on circuits that
are an even number of breakers apart on one side of the circuit
breaker panel.  I can't be sure that there is a consistent pattern
transitioning from one side of the circuit breaker panel to the other,
so all bets are off without further research there.
/lecture mode off

I was fortunate in that the circuit serving the "office" was two
breakers away from the one serving the WiFi FE location and on the
same side of the circuit breaker ;-).  OTOH, both outlets are on the
second floor and the circuit breaker box is in the basement, so the
distance between the outlets may be 20 feet "as the crow flies", but
it's about 80 feet following the power lines down and back up.

So... After all that, the net result was nowhere near 200Mbps, or
100Mbps, but rather around 14Mbps.  Casual testing post-install
indicates it may be "good enough" for my SD use, but it is still a far
cry from the performance over a CAT-5 drop.

YMMV!

Craig.


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