| 主权项 |
1. An apparatus for acquiring information about relative movements of portable devices indoors, comprising:
at least one processor and at least one memory including a computer program code, wherein the at least one memory and the computer program code are configured to, with the at least one processor, cause the apparatus at least to: acquire information indicating first indoor magnetic field vectors measured by a first portable device inside a building; generate a first indoor magnetic field sequence, IMFS, on the basis of the first indoor magnetic field vectors; acquire information indicating second indoor magnetic field vectors measured by a second portable device inside the building; generate a second IMFS on the basis of the second indoor magnetic field vectors, wherein the first and the second IMFS s represent at least one of the magnitude and the direction of the Earth's magnetic field; perform a comparison between at least part of the first IMFS and at least part of the second IMFS; and acquire information on the relative movement of the first portable device with respect to the second portable device inside the building on the basis of the comparison result, wherein, for the acquisition of the information on the relative movement, the locations of the first portable device and the second portable device relative to the building are unknown and a magnetic field map of the building is not applied. |
