3kHz – 30kHz / 30Hz – 3kHz / 30 – 300Hz / 3 – 30Hz
A word of caution!
I have made one or two interesting observations in the SIGINT pages here and I hope these will stimulate a much wider discussion: the natural frequency spectrum of the Earth’s geomagnetic field spans from d.c. to just above 30Hz. Within this range there is the stronger d.c. component with micropulsations which peak in the range between 7 and 10Hz.
Brain waves encompass four distinct ranges: the frequency of beta waves ranges from 15 to 40Hz, whilst alpha waves have a frequency span of 9 to 14Hz. Theta waves span 5 to 8Hz whereas delta waves span 1.5 to 4Hz usually around 2 to 3Hz.
It seems highly unlikely that artificially generating these frequencies locally, (such as with a.c. power lines or worse still a.c. power lines with BPL signals superimposed on them) will not affect living creatures in some way or another! Those of you who advocate the use of “homeplug” type devices for introducing broadband signals around a home network should beware you are not unwittingly subjecting yourselves and your families to potentially harmful fields! Read “Cross Currents” by Dr Robert Becker then tell me you still want anything to do with BPL!!
Very Low Frequency radio amateur experimentation has taken place in the band 8.97kHz to 9.1kHz.
This is a very interesting area of radio frequency to explore and there are some fascinating naturally-occurring artefacts to “hear” especially at even lower frequencies. Radio amateur Stephen McGreevy N6NKS is a very keen enthusiast.
The N A S A INSPIRE programme has delivered some amazing results and one of my favourite sites is well worth visiting.