XTB-ANR  X10 Active Noise Reducer
by JV Digital Engineering

Revised 11/20/11

Our electrical systems have become vastly more complex since the 70's when the X10 protocol was developed.  We now have to deal with all sorts of devices that load down X10 signal levels and generate electrical noise that prevents X10 modules from properly decoding commands.  Many of us are using signal boosters to provide adequate signal levels, but the noise problem can be more difficult to resolve.

X10 commands are sent as a series of signal bursts coupled to the powerline.   Presence of a burst signifies a logic "1", and absence a logic "0".  Noise near the X10 carrier frequency can fill in those blank frames, making it impossible for a receiving module to decode the command unless it includes AGC to raise its detection threshold above the background noise level.  Until now, we were pretty much forced to isolate noise sources from the powerline with X10 filters.  Like the XTBR and XTB-IIR do for signal levels, the Active Noise Reducer provides an alternate way to deal with powerline noise.

XTB-232_description_pcb.jpg

The XTB-ANR severely attenuates all powerline noise, even noise inside the X10 band, but lets X10 signals pass through.  While normally attenuating noise in the X10 transmit windows, it constantly monitors the powerline looking for X10 signals that rise above the background noise level, and switches off the attenuator during the zero-crossing transmit window when it detects such a signal.  That acts like AGC for those X10 devices with fixed detection thresholds, allowing them to detect X10 signals that would normally have been totally blocked by powerline noise.

The XTB-ANR can be used in combined X10/Insteon systems.  There is a small jumper inside the unit labeled TP/INST that must be removed to enable Insteon compatibility.  When the Insteon mode is enabled, the XTB-ANR turns off the attenuator at the beginning of the Insteon transmit window.  If a signal near 131KHz switches on at that point, the attenuator remains off throughout the Insteon window.  Because the second half of the Insteon window overlaps the X10 transmit window, and there are some noise sources that may be recognized as an Insteon transmission, the Insteon compatibility mode should be disabled if not needed.

The LED normally glows dimly whenever the XTB-ANR is plugged in to indicate it is active and monitoring the powerline.  It will flash brightly when the attenuator switches off to allow an X10 or Insteon signal to pass.  That gives an indication of how X10 signals are propagating though the system.

The XTB-ANR will attenuate any noise on the circuit it is plugged into.  If X10 devices are on both phases, plugging an XTB-ANR into a circuit on each phase near the distribution panel will reduce all noise levels throughout the home, including noise coming in over the utility feed.  If there is a known serious noise source, best results may be obtained with the XTB-ANR plugged directly into that circuit between the noise source and the distribution panel.  Since the XTB-ANR has little effect on X10 signals, several can be installed at strategic locations to address particularly noisy installations.

Combining the XTB-ANR to combat noise with the XTBR or XTB-IIR to boost signal levels should solve the major problems we face with our X10 systems today.

Click here for prices and ordering information for the XTB-ANR and related products.

Please contact me if you have any questions at: jeff@jvde.us
If you don't receive a response within 24 hours, try: xtbjeff@gmail.com

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