Difference between revisions of "Noise Filters and Automatic Gain Control"

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=Related Articles=
=Related Articles=
[http://www.act-solutions.com/uncle.htm Phil Kingery’s series of articles] <BR>
[http://zigbeedomotica.nl/phil-kingery-x10-articles/ Phil Kingery’s series of articles] <BR>
[[Modules Work in Some Locations but not Others]] <BR>
[[Identifying and Troubleshooting Powerline Noise and Control Problems]] <BR>
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[[Fluorescent Lights]]
[[Fluorescent Lights]]
Key Topics: on, off, noise, circuit, phase, coupler
'' Written by [[User:Roger1818|Roger H.]] 14:15, 6 April 2006 (PDT) ''<BR>

Latest revision as of 19:30, 30 November 2015

What is Powerline Noise?

After working with X10 for a while you will no doubt come across someone telling you that you have a noise problem. For many people, their first thought is, "Noise? I don't hear anything." What the person is talking about is electrical noise on the powerline (often called Powerline Noise). Although you cannot hear this type of noise, it really is not all that much different from the type of noise you can hear. At low levels the noise might not cause any problems, but if loud, it might prevent you from hearing what you are listening for. Noise filters attempt to reduce the amount of noise, making it easier for the receiver to hear the signal.

What is Signal Absorption?

Sometimes the device that is causing problems isn't generating too much noise, but instead is absorbing the X10 signal and making it weaker (or be both generating noise and absorbing the X10 signal). This is typically caused by a Noise Trap. Fortunately using a the proper type of noise filter will also resolve this problem, so for the purpose of this article we will lump Powerline Noise and Signal Absorption together as the same problem even though they have their differences.

Common Sources of Powerline Noise


Switching Power Supplies


Transformers have some drawbacks though. If the device needs a lot of power, the transformer needed is big, heavy and expensive. Also they are not very efficient (you will notice that a lot of power supplies will get warm and heat is the product of wasted electricity).


From an X10 perspective, switching power supplies are not as good. Not only are they not inductive in nature, but they will either generate noise on the powerline or have filtering capacitors which suck up the X10 signal. Newer designs are better than some of the older ones and sometimes replacing the powersuply is a better option than using a noise filter (or do both).


Electric Motors


Types of Noise Filters

Noise Traps

A noise trap will attract the noise to it and capture it. This is done by putting a capacitor across the hot and neutral wires. As you may remember from my article on Phase Coupling, capacitors attenuate low frequencies more than high frequencies. Thus very little of the 60Hz AC power will travel through the capacitor. However the higher frequency noise will see an easy return path and will be attracted and dissipated by it.


  1. It captures the noise so that it will not bother anyone else and


Noise Blocks

A noise block will put up a wall to prevent the noise from getting in or out. This is done by putting an inductor in series with the device. You may also remember from my article on Phase Coupling, inductors attenuate high frequencies more than low frequencies. Thus the 60Hz AC power will barely even see the inductor as a bump in the road. However the higher frequency noise will see a big wall preventing it from passing. Thus the noise block will keep the noise on one side of the filter and the X10 signal on the other side.

Not only will a noise block filter noise, but it will provide protection from devices which suck up the X10 signal (such as noise traps). Using a noise block in this situation will prevent the device from weakening the X10 signal.

X10 Noise Filters

You can buy noise blocks for use with X10. These tend to be called X10 noise filters and come in both plug-in (XPPF, 5 amps) and in-line (XPF, 20 amps). The plug-in type are useful when you have something that is plugged into the wall which is causing problems. The in-line filters are useful when the thing that is causing problems does not have a plug, or when a circuit has several devices which produce noise and you do not need to use X10 modules/controllers on that circuit.

Two things to watch out for when using noise filters are:


Whole Home Noise Filters

What if the source of the noise is outside your home? Or what if a neighbor is also using X10 and his powerline signals are coming into your home? In cases like this, you need a whole home noise filter, like our PZZ01. Most whole home noise filters also have a built in passive phase coupler.

This type of filter is installed between the power meter and your main panel. Since you can not easily turn off the power to this line, most people would prefer to leave installation of this to a qualified electrician.

Automatic Gain Control






Related Articles

Phil Kingery’s series of articles
Modules Work in Some Locations but not Others
Identifying and Troubleshooting Powerline Noise and Control Problems
Phase Coupling
Switch Turns On But Not Off
Fluorescent Lights