New detecting method?

[WM6]

Do you mean that if the lower freq. is 9khz and the higher is 10khz then the Tx must be adopted at 9.5Khz?

No, calculated middle frequency will be out of RX antenna resonance. We use real resonate frequency - one of three.

Exactly as J_P explain to you.

[g-sani]

ok I think I got it right this time.

[J_Player]

Yes, but huge changing in propagation (like changing wave polarization etc) are in first line characteristic of very high frequency band as UHF not in VLF/ULF band. By local small transmitter we find some others aspect of problem. We are searching for weak source of reflected signal and at the same time we have in vicinity relative strong source of transmitted signal at the same frequency which cover weak target signal and disturb successive search . This is why I repeated that 0.3W is far enough and even too much for successive search. This is why we need as much as possible directive RX antenna to suppress direct TX signal in combination with some tricks and searching skill.

If we compare UHF and ULF frequency band from reflectivity view UHF are better to detect especially small target in air because of its directivity and worse to detect something underground because of his weak penetration ability, on other side ULF are weak on directivity and so worse to detect something in air but way better to detect something underground because of his excellent penetration ability in soil. Theoretically ULF radar can detect invisible objects (objects behind of hills or behinds of horizon) which UHF radar cannot. This is why ULF can reach targets on unusual way and why we speak about importance of RX sensitivity and Rx antenna directivity.

Hi WM6,
What you say about ULF radar is very interesting. ULF has a very large wavelength (many km) which makes it hard to image any small object from interference/reflection in the way microwave radar can. But the ground penetration is excellent for very large things. If you wanted to use RF to detect things in the ground, then VLF would be more suitable because the wavelength is shorter to allow better resolution of the buried object. As you increase the frequency, the resolution improves but the ground penetration is less. So a treasure hunter is looking for a frequency between the low and high that will have good ground penetration to maybe 1 meter, and good resolution to be able to locate where the anomaly is.

We know geologists use frequencies usually between 10-30KHz to map large rock fractures and ore deposits as well as fault lines. But they cannot find a buried coin 10 cm deep. Their signals are long wavelength that detect up to 25m deep in the ground or more.

But if we raise the frequency to 100 KHz, then the wave becomes shorter and will only penetrate to maybe 10 meters deep. At 250KHz, we expect even less depth, but better resolution of shallow targets.

My question is what is the best frequency you would consider for as treasure hunter who only wants to see to 1-2 meters depth maximum?
From the charts I look at, it seems that this may be very close to the lower AM broadcast band of 550 KHz.

Do you think an AM radio or modified AM radio at below 550 KHz could be used for looking at LF/VLF interference under the ground?
Also, is there a way to use these frequencies as a VLF radar?

Best wishes,
J_P

[WM6]

What you say about ULF radar is very interesting. ULF has a very large wavelength (many km) which makes it hard to image any small object from interference/reflection in the way microwave radar can. But the ground penetration is excellent for very large things. If you wanted to use RF to detect things in the ground, then VLF would be more suitable because the wavelength is shorter to allow better resolution of the buried object. As you increase the frequency, the resolution improves but the ground penetration is less. So a treasure hunter is looking for a frequency between the low and high that will have good ground penetration to maybe 1 meter, and good resolution to be able to locate where the anomaly is.

We know geologists use frequencies usually between 10-30KHz to map large rock fractures and ore deposits as well as fault lines. But they cannot find a buried coin 10 cm deep. Their signals are long wavelength that detect up to 25m deep in the ground or more.

But if we raise the frequency to 100 KHz, then the wave becomes shorter and will only penetrate to maybe 10 meters deep. At 250KHz, we expect even less depth, but better resolution of shallow targets.

My question is what is the best frequency you would consider for as treasure hunter who only wants to see to 1-2 meters depth maximum?
From the charts I look at, it seems that this may be very close to the lower AM broadcast band of 550 KHz.

Do you think an AM radio or modified AM radio at below 550 KHz could be used for looking at LF/VLF interference under the ground?
Also, is there a way to use these frequencies as a VLF radar?

As you say in this field we can find a lot of question and research possibilities that can lead to one of (for amateur) rare ways to get something like real RDL (Reasonable Distance Locator). Principle are simple, realisation not so.

To reach long distances it is allways better to use lower frequencies, because as we go higher more dissipation on earth surface occured. This is not only reason to go at lower frequencies, we amateur are limited by our experimetation to rare authorized frequencies for such experiments or we are out of law. So, for us, relative safe are EM wave experiments inside upper spectrum of audio frequencies, say abuot 20kHz.

For "about 20 kHz" frequencies we need only weak transmitter to reach huge distance because of very low surface dissipation. On other side weak transmitter do not push our very weak tracked signals "back to underground" from our antenna and cover it and false its direction by its own signal strenght. Distance propagation of those wavelenght not mean that we can detect something at miles and kilometers, as babbling scammers propaganda. No, we can discuss only about meters, provided that we build our devices so, that it is possible. Nor detection of single coin from distance of a meter or so is impossible under some circumstances (at first of coin orientation against directed Rx antenna). But at first we can locate by this method different underground metalic deposits and not small golden nuggets.

Additional hint: such "about 20 kHz" weak transmitter equipped with well build and tunned stacked vertical antenna we can put even in our backyard and search in circle on radiated terrain kilometers away from home equipped only with a receiver. In this case transmitter have to be weak as discussed yet and well adjusted to antenna to prevent disturb our neighbors by radiated harmonic interferences.

In general VLF wave are not less reflective from the same target (if we neglect diffraction) as UHF wave but are more dispersive in reflection so we get by multiple factor weaker signal from VLF reflection as by same ULF propagation. Reason more for sensitive receiver and extremly directive Rx antenna.

[Krzysztof]

Hi, WM6, J_player.
I have some ideas for discussion:
1. Tx antenna should be the characteristics of a vertical magnetic. For example, a low power 10mW may be an antenna coil structure feryt of basketball (max Q) upright position (at the high power nature ferytu turn into a piece of wire). Maybe some other magnetic antenna Slit (but size - it could be a bad idea) . I think that 1/4 lambda antenna or coil, has a large vertical leaf levels of radiation, and we do not want to receive the signal reflected from the surface only goal.
2. Can benefit from the popular timers 36kHz quartz and pure analog generator to minimize the distortion and
harmonics. Rx side, you can think of crystal ladder filter with the same X-tals
3. I think that AM 500 kHz bandwidth makes for great Skin effect (more superficial than deep). In addition, A3 gives random modulation signal strength at measurement. Any modulation of A1, A2, A3, A3A is amplitude modulation, which forces a large measure of time - averaging.
4. How about an antenna Tx / Rx Framework 1m x 1m placed horizontally 20cm above ground level to eliminate the capacity of the soil (detuning) and reduced mutual visibility (direct reception)
5. Do you not think that we are moving close to the technology 50 years ago and described by Mikebg in this forum?
Vy 73 Chris

[WM6]

Hi Krzysztof,

thanks, I think your ideas are worth to be seen.

Can you go a little further according your ideas and post here some graphic presentation of your ideas and maybe some schematic or diagrams?

Yes, we are talking about an old radio communication technology as mikebg rediscover it too, but if it work all is ok.

It work if proper builded and used, and, as we can see, even used by modern army in different way.

[Geo]

Hi, WM6, J_player.
I have some ideas for discussion:
1. Tx antenna should be the characteristics of a vertical magnetic. For example, a low power 10mW may be an antenna coil structure feryt of basketball (max Q) upright position (at the high power nature ferytu turn into a piece of wire). Maybe some other magnetic antenna Slit (but size - it could be a bad idea) . I think that 1/4 lambda antenna or coil, has a large vertical leaf levels of radiation, and we do not want to receive the signal reflected from the surface only goal.
2. Can benefit from the popular timers 36kHz quartz and pure analog generator to minimize the distortion and
harmonics. Rx side, you can think of crystal ladder filter with the same X-tals
3. I think that AM 500 kHz bandwidth makes for great Skin effect (more superficial than deep). In addition, A3 gives random modulation signal strength at measurement. Any modulation of A1, A2, A3, A3A is amplitude modulation, which forces a large measure of time - averaging.
4. How about an antenna Tx / Rx Framework 1m x 1m placed horizontally 20cm above ground level to eliminate the capacity of the soil (detuning) and reduced mutual visibility (direct reception)
5. Do you not think that we are moving close to the technology 50 years ago and described by Mikebg in this forum?
Vy 73 Chris

Hi Chris.
Do you mean something like the photo???

Regards

[Krzysztof]

Hi all.
Modest note attached.

Unchecked idea is to use my Fluxgate magnetometer as an Rx!
Always treated the VLF and the other as EMI, now you look at it differently.
Tx antenna gives the issue a magnetic field, propagated in the ground, when it is sufficiently stronger than the earths magnetic field in conjunction with GPS and "Vumate" or "Snuffler" we are better than many well-known German company.
Who else will join the storm drain?
Vy 73 Chris

[Krzysztof]

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

[WM6]

Hi Geo,

you are main developer here. Are you done some test?


Yes Krzysztof, it is more clear to me now, what you suggest.
Except draving Ad.4: did you imagine RX or TX coils as a fixed scaning or mobile?

[g-sani]

It seems to me that many of you here know the tips to build an LRL using rf (Tx and a Receiver to go on target)
This theory is already proved that it works and all you electronics should have one ready in your home for your treasure hunting expeditions.
Instead of that you are looking for other ways of building LRLs when you never had any treasure discovered yet.
Forgive me but I don't understand you.
I remember Esteban said that it is working and I think also he put a very old pfoto somewhere of people using it back in the late '30s.
Well I will put it down again.
I used to owe once something like that and I said it before in some other thread that it was working allright.Some people don't believe me but what can I do about that.
I said to Geo that sometime I will give him the Rx(which I still have) to see if we can make a suitable Tx so to make it work again.
You see we placed it once underneath a tree and we took the Rx and went a bit far from the transmiter while trying to spot a target.It was raining heavily some hours before and water drops was coming down from the leaves.The result was a short circuit at the Tx and it stopped working.We sent it for service but...
They sent us a different LRL back telling us that they could not repair the Tx.I loved that LRL and I was upset when we received back a different one.
Anyway, this one works as well but now you have to be a bit of a dowser to go on target.
To tell you the truth I wouldn't mind of paying some money again for such an LRL and if anybody knows anything in the market please let me know.
Does anybody knows if MAGNACAST™ 5000 FORWARD GAUSS Metal Detector™ works on the same principle?

http://www.vernellelectronics.com/productinfo.htm#5000

[mikebg]

AL 707 and AL718

AL707 and AL718 are very primitive and imperfect compared to EM16 of Geonics, because they have no a second ferrite rod antenna for reference signal. The operating principle of EM16 is described in patent US3500175.

[WM6]

When, in disgrace with fortune and men's eyes

Instead of that you are looking for other ways of building LRLs when you never had any treasure discovered yet.
Forgive me but I don't understand you.

When, in disgrace with fortune and men's eyes,
I all alone beweep my outcast state
And trouble deaf heaven with my bootless cries
And look upon myself and curse my fate,
Wishing me like to one more rich in hope,
Featured like him, like him with friends possess'd,
Desiring this man's art and that man's scope,
With what I most enjoy contented least;
Yet in these thoughts myself almost despising,
Haply I think on thee, and then my state,
Like to the lark at break of day arising
From sullen earth, sings hymns at heaven's gate;
For thy sweet LRL remember'd such wealth brings
That then I scorn to change my state with kings.

Willy Shake (S.29)

[Seden]

MikeBG,

This is true. What I would rather use is an active antenna to pick up the reference signal and compare the phase of the ref. signal with the signal from the horizontal loop over the treasure or ore. Another idea that I've seen in Magnetotelluric patents is to observe spectrum in the audio range when you are over ore deposits. For treasure you would use higher frequencies to see the smaller objects. In lieu of that you could use a white noise generator to do the same with much better S/N for the same spectrum signature of different metals or ores.

Randy

[Krzysztof]

Hi of all.
I don't think so , that we're to clear forums as well bids of unfamiliar utilization present techniques not abnegating sie the old man vets. Yourselves ain't dowser , Respect those regular people whereas not swindler.
I not know gold gun , I think not , everybody they've entrance into nich as well wherefore bids of unfamiliar coinage DIY.
J_Player g_Sani.
To be sure best antenna is not they've big storing magnetically clearing switch pawn as well least radiation electricians over world ; 60 years before the communication was done ex antenna underground on figures 2 probes tributary margin ex generator engine-room undersized frequency communication (besieged troops ).
Wherefore coinage ex signal electric ex generator Tx until world is not worst.
J_Player.
Zone LF this dubious coinage. Exemplary transmitter Monte Carlo (225kHz, 200kW) premises (interference) transmitter Warsaw (227kHz, 1MW) heard on Nand France free past distances upwards of 1000km to automotive receiver wireless.
Wave worldly-minded superficial is not large what prompts breaking signal aims.
Yesterday wrong frequency quartz ex timepieces duty be 32768Hz.
I don't think so , that Tx generator to quartz 32kHz at least on often Tx clearing us ex the rubs and worries of life of stability.
WM6.
Account spool Rx clear mobil until scaning. Spool blanket 1m x 1m will correspondent , not refutes of utilization spools on the lines of MD average 30 - 40 cm , whereas depths yet never mind.
Receiver tenderheartedness 1 mikroVolt ex strait zones ex such quartz on strained serial duty be gross on hand.
Yourselves deal to spring coinage ex Rx on figures gradiometers fluxgate ( tenderheartedness some nT/m )- this so-so promisingly.
At least once EMI will be utilization.
Bids until tendering your coinage.
Best regards. Vy 73! Chris.