Re: Need help with PLC noise problems in a Manhattan (New York City) apartment

["tparent" <tparent@xxxxxxxxxx>]

If you are fully insulated from "external" noise or unsollicited X10
(neightbour RF or PLC), I discovered in my case that most of my noise
problem are coming from fluorescent bulb.

Like already explained, I'm talking about interference meaning that one
specific X10 command become an unpredictable result (issuing D10 ON,
result is D10 ON and D12 OFF at the same time). Sometime X10 device are
triggered without any issued X10 command (often lamp module).

These kind of strange behaviour is not detectable by computer interface
or dumpable through PC software.

Most of the time, "uncontrollable device" are basic X10 type (LM465,
AM..), but it's not systematic (less often Smarthome or ADS could be
hit).

After hours trying to guess what really happens with a digital
oscilloscope, I have the following feeling (I'm not a pro, just an
enthusiast) :
- Fluorescent bulb generate at zero crossing a current spike around
0.3V.
- This spike doesn't seems to be 120khz but are not filtered by LM465
electronic (as a consequence, spike is 'readable" on chip pin 1. In
specific condition (were the signal parasite match with X10 command,
the original command is tampered by fluorescent bulb spike".
-by the fact that spike are "low current", they are unable to be spread
on whole installation (attenuation will kill il before reaching
distribution panel).

On the basis of my test, I believe that basic X10 module doesn't
"stricto sensu" follow X10 protocol for the following reasons :
- they are not waiting the expected delay with 120khz on the line to
consider the signal valid (spike is enough to be considered valid).
-they are not matching the first and second copy of the X10 command
(only one is analysed and interpreted). In one of my room, two module
on the same address are triggered with a delay between the two. My
explanation is, the first one is on "good line" the second on a line
which require "signal repeater" to be listenable. First is directly
triggered on the first copy of X10, second is triggered by the signal
repeater amplified command with small delay.

It's very difficult to provide solution (excluding removing all
Fluorescent bulb).
Just few good practice :
- Plug your "X10 sending" device on a dedicate line directly wired to
the distribution panel.
- If it happens with one fluorescent bulb brand, try another one. On
basis of scope analysis, they are all noisy but some are producing
twice time bigger interference than others.
- replace "basic X10" by more reliable.

Hope it helps
(happy to be back "on the X10 battlefield",discovered that my new ISP
is not forwarding my replies on usenet since 6 month).

Thierry

Dave Houston wrote:
> Any RF system is likely to be problematic in a densely inhabited urban
> environment.
>
> My mystery signal disappeared after being here 24/7 for about a week.
>
> "Robert Green" <ROBERT_GREEN1963@xxxxxxxxx> wrote:
>
> >If I were in your shoes, I would look to an RF solution that didn't care a
> >whit how dirty the powerline was.  We've recently seen a "2 apartments
> >combined" scenario stump our resident X-10 expert, who was armed with both
> >an oscilloscope and a million man-ours of X-10 experience.  That doesn't
> >bode well for you.