Re: XTB-II Options

["Robert Green" <ROBERT_GREEN1963@xxxxxxxxx>]

"Dan Lanciani" <ddl@danlan.*com> wrote in message

<stuff snipped>

> I suspect that it's also fairly easy to fool yourself as I once did when I
thought I
> could get multiple RF->powerline transceivers to coexist.

That's what I thought and was the issue that first brought me to CHA.

> With two transmitters and a receiver plugged into a power strip you may
> well never see a problem (I didn't.)

My experience is that when the transmitters were very close or very remote,
there wasn't much problem but if the transmitters were just close enough so
that their transmissions would both arrive at a receiver at different
strengths, particularly marginal ones, the fun began.   Things actually got
infinitely worse when I add a Decora AHT to the mix since it seemed to have
either collision avoidance or a transmission pattern somehow different
enough from the TM-751's that there were issues.  It caused a terribly
frustrating problem with the Hawkeye controlled bathroom light turning on
and then off about one second later.  Boy, did THAT have low SAF!  The
Decora is now removed and the occasional bathroom light instant turning off
problem is thankfully gone with it.

As I understand it, there's no guarantee that each TM-751 will begin
receiving an RF command and begin transmitting to the powerline absolutely
simultaneously.  Judging by what the Monterey showed, one or the other units
would begin early, resulting in collisions at a point in the house where
both signals were received.  I suppose that's due to long button presses,
marginal RF reception and human body interference because it was sensitive
to people moving around.

I assume that if the second TM-751 was even one half cycle off in hitting
the powerline, the two transmissions would "step on" each other.  Since the
problem seemed to get worse when my wife was home and moving around the
house (perhaps blocking good reception at the second transmitter momentarily
or maybe emitting anti-proton beams) it had to be fixed.  I doubt if two
transmitters on the same strip would be subject to that kind of problem -
they would see the RF command virtually simultaneously every time.

Thank God for the XTB - now I don't need to use TM-751 as a poor man's
repeater - the XTB signal is strong enough to couple the phases at the power
pole, or at least that's the conclusion Jeff and I came to.

I have a TM-751 for each housecode I use and they are all routed through
XTB's for amplification.  The TM's are located nearest to where they will be
receiving RF.  The one for the driveway is concealed along the top edge of
the living room window and oriented horizontally.  It *mostly* covers the
driveway.  (-:  Every once in a while, nothing I do will activate the porch
light from 50 feet but it always happens in bad weather so I've been
reluctant to debug it.  I just activate the keyfob a little closer to the
house.  We have good streetlights so it's not an issue.  Other TM's are
placed accordingly and it's very rare now that I see the dreaded "BSC/BBK"
codes on the Monterey analyzer that indicate a collision or otherwise failed
transmission.

Say, did you ever set up your mast mounted WiFi-finder cam?

--
Bobby G.