LOW FREQUENCY MAGNETIC RADIO
PictureRadiolocating an autonomous vehicle under sea ice in Antarctica
 
 Theory, practice, advice, radio kits and circuit boards, volunteer and commercial services, and other cave related electronic stuff.
My old website http://radiolocation.tripod.com is no longer maintained but has useful information not given here.  More information will be added here from time to time.
This site was last updated on April 11, 2022.
For the latest information click on the links below:

The Ultraphone, a high performance single wire telephone for expedition use. They are in use on Bill Stone's Cheve Mexico expedition Jan-April 2021.  I plan to offer PC boards and possibly kits later this year.
The Basic-2, a simple, low cost, 1750Hz thru-the Earth radiolocation and 2-way morse code communication radio for beginners or demonstrations.  A complete kit (except for the loop antenna) is available.


The Double-Quadrature (DQ) 3496Hz receiver.  These are the most sensitive radiolocation receivers available.
Circuit boards and certain hard to find parts are available.

The Class-E 3496Hz underground Radiobeacon for use with the DQ receiver.  This simple and efficient design can be easily adapted to large and small loop antennas and multiple power levels.  Circuit boards and certain
hard to find parts are available.

Thru-the-Earth low frequency single-sideband voice communications using a transverter with portable HF Ham Radios.

Technical articles detailing experiments in thru-the-earth text and voice communications, cave surveying, and other electronic topics of interest to underground explorers.  Some are derived from PowerPoint presentations given at the annual National Speleological Society annual convention.