Re: Test results
>From cplyler-at-i-america-dot-netSun Aug 11 22:47:40 1996
>From:Charlie Plyler <cplyler-at-i-america-dot-net
To: Tesla List <tesla-at-poodle.pupman-dot-com>
Subject: Re Test results
>>From jim.fosse-at-bdt-dot-comTue Aug 13 11:44:45 1996
>Date: Tue, 13 Aug 1996 04:21:50 GMT
>From: Jim Fosse <jim.fosse-at-bdt-dot-com>
>Subject: Re: Test results
>> You've perked my interest,
>>The distance between our transmit and receive antenna array is 1.5 miles.
>>By using an array of copper ground rods spaced 1000 ft. from another, we
>>were able to obtain a dc resistance of 50 ohms between the two.
>>Then we injected a 7hz sine wave into the earth at various signal levels.
>That looks like a great ground substrate. Just for grins, I measured
>my ground: 2 8' rods ~45' apart: 10 ohms, but my brackish water table
>is only 12' down. Do you know what level your water table is?
>>At the receive site, (1.5 mi distant) we recovered the transmitted signal
>>after using standard low pass filters. After amplification the signal
>>was recorded and analyzed.
>What was the gain? You recorded 2.5 or 5 volts in the spectrum
>analyser, divide by the gain to get the picked up signal level.
>>All input signals were transmitted from the signal source at 7 hz into
>>a 50 ohm resistance.
>Was this the 50 ohms of your ground array or an additional 50 ohms
>series resistance? Did you drive the ground rods in a balanced or
>Have you considered running a sweep, with your signal generator, to
>see what the earth's transfer curve is?
>It took me awhile to find the marks in the gifs: T-0 came through as
>img-gif0, T-1 as img-gifb, T-2 as img-gifc, 5V spectrum as img-gifa,
>and the 2.5V spectrum as img-gifd.
>Those were some well done screen captures of your spectrum analyser
>output. What program/hardware did you use for the spectrum analyser?
You've perked my interest as well. Those spectrum analyzer screen
grabs were beautiful. Since it appears that you've got some pretty
nifty test equipment at you disposal, I second Jim's suggestion that
you attempt to send a swept frequency chirp through the medium under
test to try to establish that at a short distance at least, is there
any frequency preference curve.
I would like to suggest another, more ambitious experiment. Not
unlike an amateur radio operator attempting to obtain a faint echo of
a transmitted radio wave pulse back from the moon, have you
considered transmitting a short tone burst pulse of considerable
power into the earth through your ground rods, and then immediately
after transmission, connecting the rods through a TR
(transmit/receive) switch hooking up to a sensitive receiver and
chart recorder employing a narrow band pass filter set to the transmitter
frequency, in an attempt to measure backscatter from, nearby geological
subterranean strata and techtonics, and hopefully long route passes around the
crust of the planet, or perhaps lensed or otherwise reflex action through the core
of the earth and back. Your weak echoes, if present would be identifiable
at least by their fixed, repeatable time delay compared to your TX pulse. You
might try this experiment initially at your 7 Hz, and if successful
in receiving returns, you could then employ a chirp as suggested by
The experiment that begs to be tried using an actual Tesla coil if
the earth can be found to be a resonant (echo producing) ground counterpoise
over a narrow frequency window which may be measureable with modern
equipment will be obvious.