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Author Topic: JV Digital Engineering  (Read 17248 times)

Duck69

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JV Digital Engineering
« on: March 27, 2010, 10:53:06 PM »

As is said. A picture is worth a thousand words.
« Last Edit: March 28, 2010, 07:53:10 AM by Duck69 »
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Brian H

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Re: JV Digital Engineering
« Reply #1 on: March 28, 2010, 06:49:05 AM »

I agree 100%
My XTB-IIR blasts X10 signals all over my home.
MY XTBM has also been a valuable tool in finding signal suckers and noise makers. If I pick an outlet where the signal is about 9.85 [just below full scale 9.99]. I can plug in devices and see how much that outlet drops with the device connected. It found my $79.99 EarthLED EvoLux S LED light bulb was both a noise maker and signal sucker. Signal dropped to 6.66 volts signal and 0.99 volts noise with the bulb in the circuit.  ???  ::)

I paid the early adopter price for the EvoLux S as it is now $49.99  B:(
« Last Edit: March 28, 2010, 07:30:48 AM by Brian H »
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JeffVolp

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Re: JV Digital Engineering
« Reply #2 on: March 28, 2010, 12:08:03 PM »

Thank you for the feedback.

The worst noise source I ran across is a Lumoform 120V 4W LED light.  Even with the powerful XTB signals, I was having problems with Leviton switches on one circuit.  That was before I developed the XTBM, so it took some trial and error to trace the problem to the Lumoform LED.  It was generating so much noise that it even blocked the Leviton switches (which incorporate gated AGC) from receiving commands.  That bulb radiates a VERY strong signal near 120KHz onto the powerline.  I am afraid that as LED bulbs become more widespread, this will be the next problem we will have to deal with.

Jeff
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Brian H

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Re: JV Digital Engineering
« Reply #3 on: March 28, 2010, 12:38:04 PM »

Mine must be out of the frequency counters range.
Shows high noise at around .99 volts but no frequency display.
I would guess it alo may fool some AGC circuits in modules.
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JeffVolp

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Re: JV Digital Engineering
« Reply #4 on: March 28, 2010, 02:37:48 PM »


Checking the Lumoform 120V 4W LED bulb with the XTBM, it started with a frequency < 100KHz, and the noise level at .99.  Since the readout saturates at .99, it could have been significantly higher.  After a few minutes, the noise level dropped down to about .95, and the XTBM began displaying a series of random X10 commands.  Since they are error-checked before being displayed, the Lumoform was doing a pretty good job emulating X10 commands.  As the bulb continued to warm up, the XTBM displayed an unstable frequency varying over the 110KHz to 130KHz range.  This is one nasty device, but its effects are blocked by a XPPF filter.

Jeff
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Brian H

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Re: JV Digital Engineering
« Reply #5 on: April 05, 2010, 02:58:44 PM »

I noticed something today. Had the EvoLux running and was in the cellar. I saw the XTB-IIRs LED randomly flickering. Turned off the bulb flicker went away. XTBM in the XTB-IIRs outlet showed the .99 V noise and warning. ESM1 in outlet showed no bars of noise or valid X10 messages.
I may try my TesterLinc in it just for giggles. ;D
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JeffVolp

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Re: JV Digital Engineering
« Reply #6 on: April 05, 2010, 03:54:57 PM »

The XTB-IIR LED will flicker whenever it thinks it is receiving a X10 "1" bit.  It will not re-transmit that until the entire message has been received and error checked.

Normally the detection threshold is set above the background noise level, but some noise can just slip under the bar.  The background noise is sampled on either side of the X10 detection window so it will ignore valid X10 signals.  If the noise peaks are higher in the X10 reception window than outside, the detection threshold may not be set high enough to ignore it.  In that case it will rely on error checking to reject the noise "bits".

Noise high enough to register random "1" bits may corrupt valid incoming X10 commands.  .99 is one heck of a lot of noise.  X10 modules without AGC can begin to have trouble when the noise gets above .05Vpp.

Jeff
« Last Edit: April 05, 2010, 03:58:29 PM by JeffVolp »
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