Re: Cause of some major X10 problems found

[nobody@xxxxxxxxxxxx (Dave Houston)]

"Jeff Volp" <JeffVolp@xxxxxxx> wrote:

>"Dave Houston" <nobody@xxxxxxxxxxxx> wrote in message
>news:46e77e9f.1595333671@xxxxxxxxxxxxxxxx
>> "Robert Green" <ROBERT_GREEN1963@xxxxxxxxx> wrote:
>>
>> 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.
>
>It may be near zero, but I have documented on my logic analyzer that it can
>happen.  You may remember an earlier post regarding beating compact
>fluorescent lights producing peaks and valleys similar to a X10
>transmission.  I found that about 2 minutes after I switch on my CFL "noise
>generator" the beat frequency between a couple of the bulbs gets low enough
>that the peaks and valleys occur on alternate half cycles.  If the receiving
>module just happens to catch enough noise 3 times in a row to recognize a
>start pattern, the remainder of the message with alternating 1-0's does get
>through as a valid command.  Even with the enhanced error detection
>requiring complimentary 1-0's, I did capture one squeaking through.

How many valid codes were logged by your Ocelot or Leopard?

If I understand you correctly, the majority of such generated codes would be
M-13 or J-Status Request as they are the only ones that have alternating 1
and 0 manchester patterns. All others will have some 11 or 00 sequences at
the manchester level.