Re: XTB, reliablity, etc.

["Jeff Volp" <JeffVolp@xxxxxxx>]

First, I want to clear up a misconception.  The X10 signal sent down the
powerline IS essentially RF.  It is a 120KHz carrier that is switched on and
off in 1 mS bursts.  The XTB sends the boosted 120KHz carrier over the
powerline like any other plug-in X10 device.  It does not rely on any RF
transmission through the air.

What you say about the power distribution system being dynamic is very true.
It is also a very complex problem sending 120KHz over wires designed to
carry 60Hz power.  It turns out that the wire lengths and distributed
capacitance in a typical household distribution network can result in a
multiplicity of resonant circuits at 120KHz.  That will cause peaks and
nulls throughout the network even neglecting the impact from various noise
sources and signal suckers.  Any automation system that sends encoded data
over the powerline as an RF carrier must somehow deal with these issues.

The XTB takes a brute force approach, and just pounds out a stronger signal.
It has enough power supply behind it to deal with a few signal suckers.  If
you have a couple of wired X10 sources at the same location, their outputs
can both be boosted by a single plug-in XTB.

There is also the XTB-II, which is designed to be installed adjacent to the
electrical distribution panel to drive both phases directly.  It has
built-in TW523 emulation for a high-end automation controller.  And the new
firmware upgrade includes a repeater function so that all standard X10
signals received by the built-in X10 decoder can be re-transmitted in sync
with the second copy.

To answer your other question regarding monitoring what is plugged in, I
don't do that.  Known problem sources have been isolated with filters.  My
approach has been to insure there is sufficient signal level on all X10
circuits so it doesn't matter what is plugged in - even an occasional signal
sucker.  That works for us because there have been no recognized X10 control
problems in the last several months.

Jeff

<craft.brian@xxxxxxxxx> wrote in message
news:1165002601.106458.163160@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
> I know this topic has been flogged to death, but here goes.
>
> I've had some x10 gear for a few years. As everyone knows, it's not
> very reliable. I've spent some time experimenting and debugging, trying
> to improve the performance. Unfortunately, however much I twiddle with
> filters and what-not, it's never very reliable.
>
> I realized a few months ago exactly why that is. The fundamental
> problem with the notion of fiddling with x10 filters, boosters, and
> meters "until it works" is that it imagines the home power distribution
> network as something that is static, or nearly static. If it's static,
> you identify the noise sources, the signal sinks, and what-not, and you
> compensate. But this doesn't really work.
>
> It doesn't work because the power network changes constantly. As a
> typical American household we have dozens of electronic appliances, and
> things get plugged and unplugged every day. Laptops, shavers, mixers,
> toy ovens, vacuums. Electronic items get purchased and sold regularly.
> Every day, at any moment, in any room, on any circuit with outlets,
> someone may plug in a laptop, or a vacuum, or a boombox, or a baby
> monitor, or who knows what, and abruptly the x10 signal distribution
> has changed. Some light switch stops working. Why? Well.. that could
> take hours to debug. And the solution doesn't generalize. It doesn't
> prevent the NEXT signal failure, when someone plugs something else in
> on a different circuit. It may even depend on permutations, like a
> boombox here and a noisy ballast there. There are literally thousands
> of permutations of things plugged in and things turned on, any number
> of which may disrupt x10 signalling.
>
> SO... my question: To the people who seem to be reasonably successful
> with tweaking this stuff (I'm thinking of Jeff Volp and others), how do
> you deal with this? Do you carefully monitor what gets plugged in? Do
> you live alone, as opposed to in a house with several other people who
> might plug things in? Is there some other secret to tweaking x10 so it
> works even when six different things are plugged in over the course of
> a day?
>
> I just saw the XTB page for the first time, and all the gushing reviews
> about how this solves everything, or nearly everything. On closer
> inspection, though, it seems to more or less confirm that power line
> transmission basically doesn't work. The XTB boosts the power of an RF
> transponder. So to build out with XTB, you basically have to move
> everything to RF. It doesn't help with other x10 signal sources, like
> wired controllers. And, if you have several plug-in x10 signal sources,
> you need an XTB, at $80, for each one. So you really do have to move
> everything to RF, or dump $80 more for every device that's going to
> generate x10 signals (in which case you could spend it on some
> higher-end technology instead of x10).
>
> Unfortunately, RF isn't a great choice for me either, because metal
> lathe in some of the walls leaves RF shadows around the house.
>