Spectrum Analyzer

The electrical pollution at a power receptical in a home can be measured with a spectrum analyzer. These are expensive instruments (over $10,000) and are not simple to use.

The spectrum analyzer displays indicate that the pollution is mainly in the frequency range of 10 kHz to 50 kHz and is pulsed. They also indicate the change in level of pollution with time of day due to the variation in pollution from the utility with the variation of load on the utility. Also shown is the decrease in the level of pollution with one 20 µF capacitor plugged into the power receptical.

Dr. Martin Graham, Professor Emeritus at University of California in Berkeley, obtained the spectra shown below using a spectrum analyzer. They illustrate the above points.

The wideband noise shown in the spectrums is amplitude modulated at 120 pulses per second.
The pulses are about 400 microseconds wide.

Pollution at a 120 volt residential outlet

Pollution at a 120 volt residential outlet