Detectors for meteorites

[permute]

Basically, I'm a EE by trade. My dad has been wanting to search for meteorites. I figured it would be interesting to design/build some form of metal detector.

I'd also like to make this into something of a development platform. I don't plan to have very much ground penetration. The ground will be a hard clay not far from the surface. Any significant ground penetration will be more for research interests.

Currently, I'm thinking about using either a DE0-NANO or BeagleBone as the core processing platform, and then making an expansion board with the analog and power stages, as well as any display or other peripherals. The DE0 is an FPGA based (cyclone-iv) board, and would win out for raw number crunching, but the BB is an ARM/DSP based board and would win out for complex IO (anything more complex than basic linear/adaptive filtering).

I would like to explore some of the DSP and pattern recognition applications as well. Of course the only downside is that I also don't have any exemplars for meteorites, so I'll probably end up trying to find something that has high iron content to use as an approximation.

Any suggestions?

[Overtheedge]

Magnetite for the irons, but not a clue for stonys. The stonys supposedly run 5-20% Ni-Fe, but is it enough over the background?

From what I understand, your best bet for finding meteorites is to go to a known fall area.

[mario]

Basically, I'm a EE by trade. My dad has been wanting to search for meteorites. I figured it would be interesting to design/build some form of metal detector.

I'd also like to make this into something of a development platform. I don't plan to have very much ground penetration. The ground will be a hard clay not far from the surface. Any significant ground penetration will be more for research interests.

Currently, I'm thinking about using either a DE0-NANO or BeagleBone as the core processing platform, and then making an expansion board with the analog and power stages, as well as any display or other peripherals. The DE0 is an FPGA based (cyclone-iv) board, and would win out for raw number crunching, but the BB is an ARM/DSP based board and would win out for complex IO (anything more complex than basic linear/adaptive filtering).

I would like to explore some of the DSP and pattern recognition applications as well. Of course the only downside is that I also don't have any exemplars for meteorites, so I'll probably end up trying to find something that has high iron content to use as an approximation.

Any suggestions?

I find meteorites all the time.

You don't need a special detector for finding them. Depending on your area, VLF or PI will work just as well. Some people attach a magnet to a stick and use this as a discriminator (discriminates well against lead). Most meteorites have a strong iron content alongside other alloys/minerals so typical discrimination techniques used by commercial detectors will not work. In fact, most meteorites are made out of rock chondrite, so will not be picked by metal detectors even if your coil is on top of them.

You really don't want discrimination.

Most meteorites people find are, at most, 3 inches deep, so you don't need depth either.

The beagle bone is overkill for this project since you don't need DSP unless analyzing analog signals, which you will not do since most variables are already known (example, timings). However, you do need a flexible 16/32bit timer. You will find certain microprocessors with pattern generation capabilities.

In my opinion, make a rectangular coil and retrofit your favorite detector (from the many great projects found on the boards) to your beagle board. When it comes to meteorites, coverage is far more important than depth. Discrimination is useless.

Still, gotta respect the beagle bone. And great project by the way!

Where are you located?

[permute]

I'm in california, but this will be used in southern arizona.

I've been debating about a couple of designs. From my understanding, iron tends to have a grain. Where the orientation of the iron can affect reception. I'm wondering if it makes sense to have two tx/rx coils that are not flat to the ground. the idea being that I don't need deep penetration, but determining orientation might be of use.

There seems to be two main designs -- ones based single frequency, and ones based on pulses. I'm not sure I know what frequency range would be the best choice here.

[6666]

Mario what do you do with your meteorites ?

[nelson]

Hi
In my country we use Delta Pulse PI detector with two coils. One for smallest meteorites and the 1 X 1 meter coil for biggest ones.
The best place to find them is the Atacama desert of Chile.
Regards
Nelson

Basically, I'm a EE by trade. My dad has been wanting to search for meteorites. I figured it would be interesting to design/build some form of metal detector.

I'd also like to make this into something of a development platform. I don't plan to have very much ground penetration. The ground will be a hard clay not far from the surface. Any significant ground penetration will be more for research interests.

Currently, I'm thinking about using either a DE0-NANO or BeagleBone as the core processing platform, and then making an expansion board with the analog and power stages, as well as any display or other peripherals. The DE0 is an FPGA based (cyclone-iv) board, and would win out for raw number crunching, but the BB is an ARM/DSP based board and would win out for complex IO (anything more complex than basic linear/adaptive filtering).

I would like to explore some of the DSP and pattern recognition applications as well. Of course the only downside is that I also don't have any exemplars for meteorites, so I'll probably end up trying to find something that has high iron content to use as an approximation.

Any suggestions?

[mario]

Mario what do you do with your meteorites ?

I save them. I don't see myself parting with them.

I've thought about making jewelry out of them considering my pieces are under an inch. Some of the local gift shops have some really nice jewelry pieces out of meteorites and they do seem to be quiet pricey.

I thought about having them examined, but most of them are distinctly meteorites -just one or two pieces are iffy.

I'll tell you one thing, if you go to Arizona for meteorites, you'll be mainly finding lead -now there's a target worth discriminating against!

[6666]

Thanks mario
thats interesting , here in Oz we have a problem with hot rocks
and I would not even pick one up to look at it
I am becoming interested in meteorites
whats the deal with the lead, bullets ?

[mario]

Thanks mario
thats interesting , here in Oz we have a problem with hot rocks
and I would not even pick one up to look at it
I am becoming interested in meteorites
whats the deal with the lead, bullets ?

Meteorites are easy to over look if you don't have a metal detector. Compared to a hot rock, a meteorite's signal will be distinct and loud instead of it being weak like a deep target.

I remember my first meteorite. I had been prospecting a very clean area without much success when coming across a very loud signal.

Had I not being curious as to the nature of the signal, it's relative strength compared to its type, I probably would have disregarded the meteorite as trash. In the US, collecting meteorites, like gold prospecting, has been made very difficult by private gun owners. They tend to wonder into desert areas and shoot away like morons in spite of it being illegal.

Luckily, I picked my target, and realized, to my delight, that the meteorite had molten into the rock. I continued to search the area and retrieved two more pieces.

By the way, I ran all my meteorite pieces (even the ones that are part rock) under all discrimination settings (with my VLF Tesoro) and still get strong signals regardless of setting.