Re: Test results
At 12:25 8/13/96 -0600, you wrote:
> 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?
One end of the array is at the water table level in a swamp and the other
end rises to a height of 55 feet. This end has soil approx 15 feet deep on
granite bedrock. The other site 1.5 miles away is similar in that one end
is located in a swamp, however the other array is installed in sedentary
material with bedrock 300 feet deep.
>>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.
The gain for this particular test was 240. As you can see the received
signal before amplification with 20 volts PTP transmitted translates
to approx 2 mv PTP at the detector. At 10 volts PTP the detected signal
was approx 1 mv PTP.
>>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
This 50 ohm resistance is the ground load, and I drove the array in
a balanced configuration.
>have you considered running a sweep, with your signal generator, to
>see what the earth's transfer curve is?
We are in the process of doing that measurement. As soon as the tests
are conclusive I will forward the results to you.
>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.
The next time I will send the pics in jpeg format to Chip. This may
cure that problem.
>Those were some well done screen captures of your spectrum analyser
>output. What program/hardware did you use for the spectrum analyser?
Thanks very much for the compliment. The scope, analyzer is interfaced
to my PC with a device called Handyscope. It is manufactured in
Holland by Tie-Pie Industries. I will be glad to send to you the cost
of the unit,and the address of Tie-Pie, which is complete with software,
by private email. I,m not sure of Chip's policy on this subject.
We are almost ready for testing using a Tesla coil to generate ELF
pulses and I beleive this may get interesting. Time will tell.