Science Sunday: Using Magnetic Sensors for Global Positioning.

earth_magnetic_poleIf birds do it, and even hamsters do it, I am sure we can figure out a way to do it too; I am of course, referring to the use of magnetic sense to navigate on a long journey.

The method is called Magnetic Global positioning. The idea is simple; the earth is like a giant bar magnet placed along the it’s axis. All we need to do is to take precise measurements of the earth’s magnetic field around the globe and then when you want to find out where you are, just check the magnetic field of that location!

Where do you get the magnetic field data around the globe? Well, it turns out that the United States Geological Survey has already done the work. It has tabulated the Earth’s mean field and its inclination at many points over much of the Earth’s surface.

To measure small magnetic fields, we simply rely on the two guys who just won noble prize in physics for discovering Giant Magnetoresistance Effect. They showed that for certain materials, a small change in a magnetic field makes a large change in the associated electric field. In fact, your hard drive and the IPods , work the same way too!

So to find your location, you measure the magnetic field and its inclination , and compare it with the known value and you know exactly where you are! No satellite needed.


Although less accurate than satellite GPS, the new sensor’s use of the magnetic field means it is more reliable in certain situations. For example, in remote areas that have no satellite reception, or in bad weather conditions where the connection is temporarily lost.

The accuracy of the positioning accuracy is dependent on the accuracy of the magnetic data for a location and that can be significantly improved. The next time when Google or Amazon is doing a “street view” perhaps they can carry a magnetic sensor with them too!

I am not even suggesting that we use it instead of GPS, we might want to consider using it in conjunction with the GPS . In downtown areas where the tall buildings are blocking access to the GPS satellite, the magnetic positioning will take over. The magnetic position can also be used indoors, like in a parking structure or a building.

Via NewScientist

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