General Home Automation X10 signal levels

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Subject Author Date
X10 signal levels George Pontis 07-28-05
Posted by George Pontis on July 28, 2005, 2:05 pm
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While debugging an X10 problem recently I paid some attention to signal levels.
I
have a Monterey Instruments powerline signal analyzer connected to a power strip
that has an appliance module. Under some conditions, the module will not
recognize
the X10 command. In practice the problematic conditions are when I turn on
either
some fluorescent lights, or a Sony TV. Both reduce the signal level to about
..26-.29 volts, as displayed by the analyzer. I also checked the noise level
using
the analyzer, and it remains low (less than 20mv) all the time.

It seems to me that a quarter of a volt is plenty of signal for an X10 device to
recognize. In practice, I see reliable operation with a PowerHouse AM466 and the
Appliancelinc 2002SHL. An X10 Pro appliance module and some Honeywell modules do
not recognize the signal. I also tried sending from a different transmitter
(CM11A), lest the frequency be in error. Though the signal levels were even
lower,
in the low 100mV range, the appliancelinc and AM466 still responded.

What are reasonable signal levels for reliable X10 with the better switches and
modules ?


Posted by on July 28, 2005, 11:12 pm
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I have found that when I get less than about 1.5 volts, things get
unreliable.

FYI: APC Powerbars will also drop the volts on outlets that are further
away from the circuit breaker feeding the circuit the APC power bar is
plugged into.

i.e.: breaker--->1stOutletonCircuit--->nextOutletONWall
        5volts         |         2-3v on next oulet
                        |
                        V
                 APC Powerbar
                 4v on APC plugs

Sorry for the crude drawing.

Using the X10pro filters solves the issue:
http://www.x10.com/pro/automation/xppf.htm

JR


> While debugging an X10 problem recently I paid some attention to signal
> levels. I have a Monterey Instruments powerline signal analyzer
> connected to a power strip that has an appliance module. Under some
> conditions, the module will not recognize the X10 command. In practice
> the problematic conditions are when I turn on either some fluorescent
> lights, or a Sony TV. Both reduce the signal level to about .26-.29
> volts, as displayed by the analyzer. I also checked the noise level
> using the analyzer, and it remains low (less than 20mv) all the time.
5~>
> It seems to me that a quarter of a volt is plenty of signal for an X10
> device to recognize. In practice, I see reliable operation with a
> PowerHouse AM466 and the Appliancelinc 2002SHL. An X10 Pro appliance
> module and some Honeywell modules do not recognize the signal. I also
> tried sending from a different transmitter (CM11A), lest the frequency
> be in error. Though the signal levels were even lower, in the low 100mV
> range, the appliancelinc and AM466 still responded.
>
> What are reasonable signal levels for reliable X10 with the better switches and
> modules ?
>


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