Re: Cause of some major X10 problems found

[nobody@xxxxxxxxxxxx (Dave Houston)]

"Robert Green" <ROBERT_GREEN1963@xxxxxxxxx> wrote:

>"Dave Houston" <nobody@xxxxxxxxxxxx> wrote in message
>
><stuff snipped>
>
>> >I seem to recall postings that indicated a device like a noisy PS could
>> >never generate a signal randomly capable of triggering an X-10 device but
>> >your experience seems to indicate that's not so.
>>
>> The probability that a noise source will create valid X-10 PLC codes (1110
>> followed by manchester encoded data synchonized to powerline half-cycles)
>> out of whole cloth is near zero - it ain't gonna happen. However, there
>> are other explanations for the unwanted ONs & OFFs - see the link I cited
>> in my response to Bruce.
>
>Maybe the devices were made by the same 50 monkeys and typewriters that are
>claimed to be able to reproduce the works of Shakespeare if given sufficient
>time.  (-:
>
>There could be a number of reasons for the Stargate not seeing anything. The
>power supplies' noise signal could be too weak to activate anything except
>nearby lights. Certain lights nearby would be affected, but the Stargate
>would not be within range.  Since Bruce uses an XTB, one might suspect that
>weak signals don't propagate far in his house.  There's not enough info to
>know for sure.

The SG uses a TW523 which reports powerline commands on a delayed basis,
after validating them. When transmitting, it reports the first copy of the
code 22 half-cycles later during the transmission of the second copy so it
can send and receive at the same time. A controller using it can detect
collisions by comparing the received copy with the earlier transmitted code.
It only reports valid codes so it does not report anything that doesn't have
valid manchester coding following the 1110.

While there is no way to disprove your wildly imaginative theories, I can
report, based on watching with an oscilloscope, that there was absolutely
nothing on the powerline that in anyway resembled X-10 activity when my
living room lamp would turn off following a manual switching off of the
non-X10 controlled fluorescent in one of my bathrooms. (I have since
replaced the LM14A with an Icon dimmer module and replaced the manual switch
on the bathroom fluorescent with an Icon switch and no longer have any
problem.)

Most of the anecdotal reports are like Bruce's, repeated random ONs of
multiple addresses on multiple housecodes (usually in the middle of the
night) and there are seldom any logged commands (logged commands usually
point to a traceable source). Noise spikes acting directly on the switches
and modules explain these episodes with no need to "monkey" with the laws of
probability.

Ignoring the address, any ON code requires the sequence 0101100110 at the
manchester level. A noise source is not going to generate that sequence
repeatedly. And no X10 PLC code will affect multiple housecodes
simultaneously.