Smartphone-Magnetometers

[Funfinder]

http://www.geotech1.com/forums/showt...tor-Collection

I have posted it here because the apps are all called "metal detectors" and they can detect metal,
at least as long as it is ferrous or magnetic.

But of course they use the smartphones magnetometer which usually works in combination
with the navigation- and GPS-apps so the user sees into which direction he's heading.

[Funfinder]

additional info:


http://www.liv.ac.uk/~cmi/mag/smartphone.html
Using a smartphone to detect shipwrecks

(...) A typical magnetometer is the Asahi Kasei AK8973. This provides output of the magnetic field in 3 orthogonal directions. The data card indicates a sensitivity of 1000nT per least significant bit (8 bit output). Note 1000nT is the same as 1μT (microTesla). (...) the newer AK product range has a resolution of 150nT

The info: Using a smartphone to detect shipwrecks was from 2011, so meanwhile those inbuilt magnetometers are for shure more sensitive than just 1uT.



Here is the mentioned app:
http://ulysse-gizmos.soft112.com/
but whats really would be useful: a magnetical-field-mapping software
which shows after the complete search a field-area with red and blue "hotspots" inclusive coordinates.
Perhaps I'll find something useful but I doubt at the moment there exists already real "treasure-hunting" apps for smartphones!
First some real field tests are needed to see how big has to be the buried iron object so its really detectable by walking over it.



http://en.wikipedia.org/wiki/Magnetometer

Magnetometers can be used as metal detectors: they can detect only magnetic (ferrous) metals, but can detect such metals at a much larger depth than conventional metal detectors; they are capable of detecting large objects, such as cars, at tens of metres, while a metal detector's range is rarely more than 2 metres.

In recent years magnetometers have been miniaturized to the extent that they can be incorporated in integrated circuits at very low cost and are finding increasing use as compasses in consumer devices such as mobile phones and tablet computers.
(...)
Mobile telephones
Many smartphones contain magnetometers; apps exist that serve as compasses. The iPhone 3GS has a magnetometer, a magnetoresistive permalloy sensor, the AN-203 produced by Honeywell.^[21] In 2009, the price of three-axis magnetometers dipped below US $1 per device and dropped rapidly. The use of a three-axis device means that it is not sensitive to the way it is held in orientation or elevation. Hall effect devices are also popular.^[22]


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I found also this:
www.nicap.org/madar/smart_phones/Magnetic_Field_Feature_Analysis_of_SF_Applications _Using_Android_MI_Sensors_2013.pdf

and:
http://stackoverflow.com/questions/1...-android-phone




The main issue is to hold the smartphone exactly in its direction while detecting otherwise the
shown changes don't result from nearby magnetic stuff or iron but just from the directional change.
So an additional hand-held compass should be used or detect only while walking in absolut straight lines.
This only can be prevented if the app calculates the whole 3 axes magnetical-field alltogether so
the then fixed value only changes if a magnetical object or other field disturbance comes closer.


This app seems to combine all 3 orthogonal directions to show the total intensity:

Magnetic Field Detector
https://play.google.com/store/apps/d...detector&hl=en

this one also looks interesting:

Magnetic Field Detector 3D
http://www.downloadandroid.org/downl...ld+detector+3D

[Funfinder]

Perhaps I'll find something useful but I doubt at the moment there exists already real "treasure-hunting" apps for smartphones!

There indeed already exists an android treasure-hunting magnetometer app:
https://play.google.com/store/apps/d...mobyle3d&hl=en

"This free demo of the Rover UC metal detector application uses the internal magnetic field sensors of the Android smart phone to simulate the functionality of the Rove..."

For real use it doesn't works with the smartphones magnetometer but a different one which is connected by bluetooth.


At the moment the situation seems that profi-magnetometers have a sensitivity of 0,001 uT
while those from smartphones meanwhile have around 0,05 uT sensitivity max. which is 50x lower
and so you have to be 50x closer to the treasure until the smartphone is able to detect it.

btw. OKM is a not trusted company because they sell unproven LRL "Bionic" etc. devices.
In earlier times they tried to fool others not to inform them that just gradiometers are built into their devices.
However since 5 years they constructed alot 3D imaging computerized magnetometer treasure-detectors,
some absurd highly overpriced! They work with connected laptop and meanwhile some work just with
connected smartphone.

Anyway, the idea of using the smartphones magnetometer with a colorful 2D or 3 D imaging software is very useful.

We need an app where its possible to enter the lenght and width of the search area or the grid-walking-pattern
so afterwards its possible to see on a picture where exactly on the 10x10m or 20x20m field are magnetical anomalies.

Just by walking around and checking if the total earth magnetical value has changed, outputs not such an useful result
as if you can see afterwards on the slightly changing colors from the drawn magnetical-area-map where are the hotspots
or even if you found some underground structures like ruin-wall-patterns, wells or other interesting visual signs.

Perhaps someone should mail OKM and ask them if they are interesting in modifying their already existing app
so it works as best possible non-demo with the smartphones integrated magnetometer-device.

But even programming this would be no big deal, all what has to be done is recording the magnetometer-output values
each 0,1 seconds and print them onto a mapping area in different colors, depending on the value.
And the middle area of the magnetical field depending on the location has to be detected and adjusted first,
so the picture-drawing sofware knows from where to start with the lower values in blue or the higher ones in red.

btw. for the moment its not that urgent, but if all smartphones in 10 years contains really high sensitive magnetometers
it will became really useful for treasure-hunting for shure!