1. Home
  2. General Home Automation
  3. X10 RR501 Burst Misalignment

X10 RR501 Burst Misalignment

As first reported here several weeks ago, it appears that the X10 RR501 does not maintain correct registration of its 3-phase bursts. At that time it was just a curiosity, but it has now become a problem when using a gated AGC sample window.

The region just before the zero crossing should be a good place to sample background noise to adjust the X10 sample threshold level. Insteon uses that region, but there should be no X10 transmission there. However, two different RR501 transceivers - Powerhouse and Leviton purchased years apart - occasionally shift their third phase burst into that slot. I captured a scope trace showing that:

formatting link
The scope was line-triggered with zero crossings at dead center, and 8.3 mS on either side. This trace shows the misaligned 3rd phase burst ending only half a millisecond before the next zero crossing. (The bright portion of the trace caught the scope beam writing the phosphor while the camera shutter was open.) Interesting, and possibly related is the missing 3rd phase burst from a prior sweep on the right half of the screen. The rightmost burst is at the next zero crossing.

A Google search has not uncovered this being reported before, and I wonder if anyone else has seen it. Since this occurs on two different units purchased years apart, there may be a gazillion units out there that exhibit this phenomenon. However, since the zero crossing burst IS correctly aligned, perhaps it has never been pursued before.

Jeff

Reply to
Jeff Volp
Loading thread data ...

[ ... ]

Thanks for mentioning that, Jeff. Somehow this kind of deviation from standard doesn't surprise me with X10 gear...

Reply to
Joerg

Just to follow-up on this, looking at that photo again in a dark room I can see two very faint bursts on the right hand side from a prior trace due to phosphor persistence. Referenced to the rightmost zero crossing burst, they were properly positioned.

It is interesting to note that the misalignment agrees exactly with bursts for 50 Hz operation. The start of the third burst would be delayed 6.67 mS after zero crossing rather than 5.55 mS for 60 Hz. Assuming a 1.00 mS bust length, that 1.11 mS delay would shrink the gap between the end of the last burst and the beginning of the next zero crossing burst to .66 mS.

I don't believe the RR501 is supposed to support 50Hz operation, but perhaps it does include code for that timing that is somehow being accessed.

Jeff

Reply to
Jeff Volp

Until 6-7 years ago, when all of their modules and switches were redesigned to meet tighter European emmission and frequency specs, they used the same basic boards and/or circuits and PIC firmware in some of their European devices although I'm not sure about the RR501.

If you have a Kill A Watt, it would be interesting to know the frequency and stability of your 120VAC.

formatting link
snipped-for-privacy@yahoogroups.com

Reply to
Dave Houston

A digital frequency counter pegs it at 60.0 Hz, and it is rock-solid on the scope. The waveform is usually pretty good, with some slight flattening of the peaks, and that little glitch just after the negative-going zero crossing. The 120KHz audio carrier that was coming in over the powerline for a couple of weeks seems to have disappeared.

Jeff

Reply to
Jeff Volp

Hello Jeff,

Look for a family that is buying a little bicycle with training wheels this Christmas. Then you know who it was ;-)

Reply to
Joerg

Cabling-Design.com Forums website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.