Indoor positioning via magnetic field measurement: This method of positioning makes use of the earth’s magnetic field. It takes advantage of the fact that modern buildings have a specific magnetic fingerprint, which results from the interaction of the earth’s magnetic field with the building materials used and the architectural conditions. The more steel used in the building, the better for this positioning solution. What proves to be annoying when positioning via radio signals makes positioning possible in this case. The steel provides the characteristic disturbances of the earth’s magnetic field. A positioning with an accuracy of one to two meters should be possible with the help of the compass integrated in modern smartphones.
no infrastructure required
Other systems are now more accurate
Very few providers
These systems are also called Magnetic Indoor Local Positioning System (MILPS). In addition, there are commercial systems in which an electromagnetic field is artificially generated. These enable very precise motion tracking. They are not used for commercial location-based services, but in medical and military simulators. This paragraph therefore only refers to systems that use the earth’s magnetic field.
Disadvantages of the technology are that the magnetic field of the building has to be mapped in advance and that the magnetic field of the earth is variable. The map of the magnetic field must therefore be updated regularly – in practice approx. every three months. To do this, the building must be completely expired and “scanned” manually. This makes the “installation” especially for large building complexes very complex. There are few companies that specialize in positioning via magnetic field as stand-alone technology. The technology can also be combined with WLAN or beacon technology. Even the Finnish market leader IndoorAtlas now recommends combining the technology with Beacons. However, this also makes the system less flexible. If a beacon is moved or should change its location, either the beacon has to be reconfigured or a new card has to be installed.