New detecting method?

[Seden]

Ground probes = more effective

JP,

In the reports I've read from the Amatuer Op's in Europe operating at 73K.C.'s, a ground rod as short as 18" seems to work out well and you can resonate and impedance match a ground antenna by the way. A Google search using 73khz amatuer band will get you lot's of hits.

For a permanent home setup I much prefer the 8' copper rods used for grounding home electrical systems to give me more cross sectional area which decreases the resistance obviously and less susceptible to variations in soil conductivity via drying out in the summer heat.

Works for me.

Randy

[WM6]

seems to work out well and you can resonate and impedance match a ground antenna by the way.

Randy, those "impedance match" work with resistive component of soil. Nothing to do with resonance of antenna (Q are practically nonexistent). This is only additional antenna load that maybe help to not burn TX output transistor.

[Seden]

Ground Antenna

WM6,

You may be right as so far I have never made one, just read about the Amatuer's experiences.

Well then it's top loaded vertical with MANY ground radials and a large capacity hat. Yeah it can be done in the field with some guy wires,maybe buy the portible antenna setup the military uses that are sold to Amatuer Ops for field day operation.

Randy-WD6ELU

[mikebg]

Hi Geo.
It looks like a mini two-box.
And I think the 2 antennas with a vertical magnetic polarity, the land
component preferably disperses component magnetic field the electromagnetic field.
Maybe someone is thinking of something better than the ferites
antenna.
Vy 73 Chris

Chris, this is done 50 years ago for prospecting. For induction balance and to suppress GND signal from soil surface, ferrite rods are not exactly perpendicular.

[Geo]

Hi Geo.
Forgive my English, I have different translators, none technical.
To new idea the best magnetic aerial is needed to Tx, for good irradiating the area. Best if only the entire energy went to one's grave as the magnetic component, Tx Energy radiated by the area is completely unnecessary and harmful.
I am looking for something better than the ferrite vertical antenna in my memory and good books. I want energy fields 10 - 100 miliwat of the radiation. And ferrite will already be then too weak.
He is staying to bury to the earth frame antenna. Other idea of the antenna, can stick 2 probes to the earth, and made Tx in the B class push-pull. GND connect with 3rd probe.
A few attempts I will make in spring.
Best regards Chris.

Hi Chris.
The idea of the probes to the ground is not good if you want to use the detector as mobile detector and not as "constant".
For vertical antenna a simple spiral antenna is a good solution. I worked with a similar one

Regards

[WM6]

Chris, this is done 50 years ago for prospecting. For induction balance and to suppress GND signal from soil surface, ferrite rods are not exactly perpendicular.

Hi mikebg, those are aldest model, newest are some different:

"Transmitter and receiver dipole orientations of the EM38-DD and DUALEM-1S (instruments are oriented parallel to the surface). The loops of wire form a solenoid and a dipole is created when current passes through the wire. The EM38-DD (top) has its transmitter and receiver dipoles oriented in horizontal–horizontal (H–H) and vertical–vertical (V–V) modes. The DUALEM-1S (bottom) also uses a V–V and a vertical–horizontal (V–H) mode for the dipoles in its transmitter and receiver."

The 4 most common types of EMI instruments, are the EM38, EM31, EM34 and EM39. Although they all operate the same, they vary in the depth to which they read within the soil profile. All operate in both the vertical and horizontal mode (this determines the depth to which they read). A summary of this is given below:

EM38 - vertical mode (1.5m) horizontal mode (0.7m)
EM31 - vertical mode (6.0m) horizontal mode (3.0m)
EM34 - 6.0m to 60.0m
EM39 - used for logging down boreholes.

These depths are only indicative, as the depth of penetration of the electrical signal will be determined by the uniformity, or non-uniformity, of the soil. If the soil is very conductive near the surface then the signal will be dissipated and will not read to a greater depth.

[Krzysztof]

Inventors hello to all.
My humble figure.
Sed.Probes the ground in a triangle to have a concentric radiation underground.
Geo. I think that each antenna will sow the ground surface wave. Im only interested in measuring the electromagnetic wave Reflected from the underground treasure with a very sensitive receiver. Narrowband = 100Hz max. Low noise. Sensitive = 1mikroVolt. There may be a vertical antenna ferite.
Micebg. I know the history of art, now I go to do already without fear.Do private mini-VLF radio station located in a fixed location and look at neighborhood.
I look forward to constructive criticism.
Best regards

[Geo]

Hi Chris
I agree that the treasure will influence the radiated energy (it will grow her or it will minimize). This will become perceptible with receiver above the treasure. However how we will take a "line" with the receiver from the point where we found itself, up to the point of treasure???

Regards

[Krzysztof]

Hi Geo.
It does not interest line of completely.
I. it touches it only Tx as lighting lamp Signal grows over purpose according to statistic schedule Gaus. Good narrow receiver wanted only.
It touches it technical colleges it LRL but it not twig, I am technocrat only.

Best regards Chris

[mikebg]

WM6,
The device in posting # 64 is model APEX MKI. It is like Geonics
EM15, designed by Vaino Ronka.
Chris,
1. Target signal at metal detecting seems as modulated TX signal with frequency spectrum from 0,1Hz to maximum 6Hz. That means we need RX having bandwidth no more than 12Hz. More bandwidth means more noise. There are sensitive metal detectors operating with bandwidth 4Hz only. We need automatic digital filtering to achieve stabile narrow band receiving. Bandwidth 100Hz means 5 times more noise relative to bandwidth 4 Hz.
2. The modulation index of target signal is very small because RX receives two large signals AIR and GND having the same frequency. If you wish to detect target signal 1uV, but AIR and GND signals are 10mV, then the modulation index is 0.0001. We need suitable automation to increase the modulation index by suppressing AIR and GND signals. However if you swing search head one or two times pro seconde, the GND signal will be modulated by frequency 1 or 2Hz. This is in target spectrum.
3. We need reference signal for synchronous demodulation. For example, Vaino Ronka uses AIR signal from second RX antenna as reference signal. To demodulate weak signals,we should use GND signal as reference.
4. Your TX antenna is absolutely inefficient becase has only one small turn. Read for TX antennas and loop used in metal detecting in site www.geonics.com

[WM6]

The device in posting # 64 is model APEX MKI. It is like Geonics EM15, designed by Vaino Ronka.

Thank you mikebg, APEX is not known to me. I think it was EM15.

However if you swing search head one or two times pro seconde, the GND signal will be modulated by frequency 1 or 2Hz. This is in target spectrum.

Not only ULF modulation because of swinging, but because of handshaking too, a lot of parasitic modulations that suppress target signal.

[Seden]

New detecting method?

Chris,

Go to Google and type in TURAM system. In this you transmit the signal into the ground via ground rods and you have 2 separate coils for the receiver that goes into a phase detector. The coils are separated just like a two box detector and so when you the lead coil passes over the ore body or treasure chest you will get a phase difference. This saves having to have to separate receivers,one to get the air signal for reference and the other for the ground signal. The air signal is ALWAYS the reference as the ground signal is where you are looking for a change due to whatever's buried that's big enough to change the phase in the ground signal.

Randy

[Krzysztof]

Hi Mikebg.
You are absolutely right. I have past experience in the construction of an amateur on the 4MHz filter ladder with 100Hz bandwidth and less. At 32kHz easily get smaller bandwidth, the more crystals are exactly the same watch. What about modulation A2 ?
Vaino Ronk AIR uses second RX signal from antenna as reference signal , a brilliant idea + todays software that gives a strong instrument.
I hoped to check the simplest method. Lighting treasure chest only to the GND, a simple receiver - preferably with a vertical antenna ferite. Then I have a minimum of receipt by the AIR and directional reception of the order. SPECTRUM LAB is the program straight from the VLF.
Ideally, it was simple, easy and fun, small and cheap. Perpetium mobile not yet.
Is this a useful?
http://www.stormwise.com/page28.htm
Best regards

[Krzysztof]

Hi Seden.
Do you have a good illustrated examples to seek treasures TURAM system? With Google is a lot of rubbish and a narrow scientific publications for money.
Turam is perfect for the geology of ore. Engineering phase is interesting that the resolution can be obtained. There is a lot of redundant data - You will need a smart program.
If it were available for advanced amateurs will be interesting to face this.
It affects everything VLF, I found something similar:
http://www.eos.ubc.ca/ubcgif/iag/fou.../vlf-notes.htm
Consider the last sentence!
Best regards. Chris

[Seden]

TURAM system

Chris,

That was an excellent article on the VLF system and yes the last sentence was interesting. So now we're back to an inductive antenna if I read that correctly. In "Mining Geophysics" TURAM is used strictly for Ore bodies but that's what the book is all about.

As I mentioned earlier in this book a HORIZONTAL ~24" Ferrite bar mounted on a tripod as well as a 15'per side wire loop were used for VLF type of exploration. I would try the large diameter 24" ferrite as they can handle some wattage (as I have experimented on 183.5 K.C. with successfully). The ferrite bars are not prone to saturation as easily as a ferrite torroid which can be verified with the formulas.

For the reference signal here in the US I would use the little 400 MHZ transmitter-receiver boards that are so inexpensive.

Randy