Re: Water heater eating X-10 signal

[nobody@xxxxxxxxxxxx (Dave Houston)]

"Robert Green" <ROBERT_GREEN1963@xxxxxxxxx> wrote:

>> >What would happen if I recorded in MP3 and converted back to WAV format?
>> >would the loss be noticeable?  Disk space wouldn't be as much of an issue
>> >that way.

As I noted earlier, I don't know whether you would lose detail but it's
worth a try. The latest version of LoopRecorder defaults to .WMA which is a
compressed format. Also, you can record the signals in mono which will add
the two channels together but cut the file size in half. This gets the file
down to sizes more easily managed for overnight recording.

>I see.  IIUC, the X-10 signal's frequency (120KHz?) is way outside the
>normal audio range so eventual success is going to depend a lot on the
>characteristics of the sound card and recording software.  Are there any
>electronic tricks that can bring the frequency down?  Halving the playback
>speed would reduce the frequency of a normal audio signal but that wouldn't
>work here because the card may not be able to capture the higher frequency
>to begin with.  No magic frequency divider in a IC package or does that mean
>lots of additional support circuitry and isolation issues?

The noise that I see here turns out to be more complex than I first thought.
There is something on the powerline just before ZC (and after the third X-10
burst) plus the ESM1 is affected by EMI from my Dell CRT monitor. With the
ESM1 plugged into an extension cord that is plugged into a different outlet,
there are no bars until I move it near the monitor and then I see 1 bar. I
don't think this is having any effect on the recorded signal - all of that
noise seems to be related to the mystery 60Hz pulses.

I've added another screenshot to the web page showing the powerline through
the oscilloscope adapter described in Microchip's appnote AN236. It shows
the mystery noise as well as an X-10 signal.

I may play around with a similar circuit fed by a 12VAC wall transformer to
allow soundcard recording with no need for an ESM1. It might make a
worthwhile addition to the troubleshooting arsenal and won't have the
frequency limits of the ESM1.