X-10 RF troubleshooting

For a while last night, I thought Bill K. might be right - X10 is junk! (*(_*#^&^^ rotten stinkin' JUNK!!!!!

In the last few days I noticed, in this sequence:

The light on my RF-sensing pen started to flicker constantly, not in its usual random pattern. This was promotional item I got at some show that lights a diode whenever it detects cellphone EMF nearby to let you know your cellphone is ringing by eye.

Then, the Powermid IR unit in the LR would not control the AV stack but direct control and control of the AV gear from the kitchen was still possible.

Finally, almost everything stopped working, especially RF remotes. Local control was still available, and close-by controllers worked close-by modules. The Monterey showed a steady stream of P1 OFF's - P is the code for all the PalmPads.

So while other people were hunting Easter eggs, I lashed my ESM-1 to a TM751 and plugged them into a long extension cord and began hunting for stuck transmitters. The ESM1 varied wildly as I moved about the house and changed the orientation of the antenna relative to the case. I finally found the problem - out of the corner of my eye I saw a blinking red LED when I turned the lights out. The ESM-1/TM751 combo had led me to that area, but not right to that spot. It was the same as before - a stinkin' &&^$# PalmPad got wedged under a keyboard in the PC room. I had previously searched that area pretty closely using the AM radio technique and found nothing, FWIW.

I thought that the PLC signal strength might be affected by the RF signal strength, but that turned out not to be the case. I think with the TM-751 sitting so close to the ESM-1 on the extension cord (they're back to back, connected by rubber bands to hold the meter head in place) I was seeing some sort of inductive coupling.

But I also noticed something much more interesting. When hunting a known test item in a known test location I found that I could use doorways to form collimating slits. The walls are old lead-based paint over wire lathe plaster -- :-( -- RF barely penetrates. But when I position the Palmpad somewhere where it's visible to the naked eye, the ESM-1 clearly indicates any deviance from that line of sight. As soon as there's a wall between the TM-751 and the Palmpad, the signal vanishes.

This is at least the third or fourth time there's been a "stuck" transmitter button. The ESM-1 is useful in tracking down the stuck Maxicontroller keys - the closer you get, the higher the signal level - but so far tracking down the RF "stuckees" has been rather more difficult. It would be nice if I could build a cheap X-10 RF signal strength tracker. Even a simple direction finder would be nice. I guess I can find an old coffee can and run some tests. Problem is, we don't drink coffee anymore!

-- Bobby G.

Reply to
Robert Green
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Reply to
Dave Houston

Stop reading my mind!!! :-) I just sat down to write and ask if the BX24-AHT could be modified to show a "good X-10 signal received" via an LED output.

By ADC I assume you mean Analog to Digital converter. I'm afraid although I can follow the concepts, translating that into a circuit diagram is beyond my skills. It may be that the RF sensing pen I wrote about could be up to the task of finding a stuck ON unit if I'm able to mount it in a can and operate it directionally. I really surprised that there isn't a low cost COTS solution to this problem. I am going to mount the TM751/ESM-1 combo inside an old 12" parabolic lamp reflector. That should give me some feeling for whether a battery operated unit would work well.

I don't think that I could design something even that simple, Dave. :-( If the reflector works, I'll be happy enough.

Let me know if you'll still be able to incorporate the RatShack wireless thermometers in your new device. I'll ship them out whenever you need them.

-- Bobby G.

Reply to
Robert Green

Yes, the BX24-AHT already gives an RSSI measurement - it's the [bracketed] number in the RF output. It could control an LED but that would be such heavy overkill as to border on being criminally insane. ;)

It would be possible to write a simple program for the BX-24 or ZX-24 to do this and you could download it instead of the normal program then switch back when finished. The users manual for the BasicX and ZBasic languages can be downloaded from their respective web sites. Look at the "GetADC" and "PutDAC" procedures. I think they even have simple schematics for "PutDAC" in some app notes on the BasicX site. The BX24-AHT is not, however, amenable to being battery powered.

A PIC12F675 makes more sense at ~$1.25 vs $40-60 for the BX-24 or ZX-24 although there are no free Basic language compilers for PICs. I will try to remember to create a PIC program for this and send you a vector board circuit when I get to the wireless thermometers.

I've been struggl>> You could do this inexpensively by using an 8-pin PIC with ADC (e.g.

Reply to
Dave Houston

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