Patent ID: 8866674

Claim:
An apparatus for updating a reference database comprising reference measurement packets associated with geographical reference positions, which comprise reference transmitter identifications of radio transmitters receivable at the reference position at the reference times, determined at the respective geographical reference positions at reference times, comprising: a determiner for determining a current measurement packet at a current geographical position at a current time, wherein the current measurement packet comprises transmitter identifications of radio transmitters receivable at the current geographical position at the current time; a selector for selecting an amount of reference measurement packets exceeding a predetermined measure of correspondence to the current measurement packet, wherein the amount of selected reference measurement packets comprises a reference measurement packet or a plurality of reference measurement packets; a storer for storing that is implemented to store transmitter identifications received prior to the current time and after a last update of the reference database in an amount of previously received radio transmitters; a determiner for determining a transmitter identification comprised in the amount of selected reference measurement packets and not comprised in the current measurement packet; and a generator for generating an experience message with respect to the determined transmitter identification, wherein the generator for generating the experience message is adapted to store the determined transmitter identification in an amount of transmitter identifications to be potentially removed, when the determined transmitter identification is not stored in the amount of previously received radio transmitters stored by the storer.