On Wed, 30 Mar 2005 08:31:08 -0500, Albert wrote:
Last night, I looked at the signal using spectrum lab's vlf receiver
program. When I zoomed in on the transmitters signal, I noticed that
there were sidebands occurring every 15 hz. I will post another
message with more details.

Hi Albert,

This could be an ID modulation to serve the receiver's logic. In
other words, correction is based upon both signal strength AND
modulation.

Thus the received signal strength has to fall to a certain level that
is still above noise level (not complete drop-off) to insure that
corrections are not applied due to power failure at the transmitter
(and to allow registration at power-up).

VLF is used because the signal penetrates the ground better,

This was what I described as the subterranean communications channel
used in the trenches of WWI. I would still suggest a power boost over
building a ground dipole. The design of the amp is trivial, and kits
are available to do the job for less than $20.

73's
Richard Clark, KB7QHC