The invention concerns a device (1) comprising means (2) for emitting periodically position data, means (3) for emitting inertial data, means (4) for determining the position of the mobile object upon each position data emission based thereon, and means (5) for determining the position of the mobile object between two successive emissions of position data, the time interval between two successive emissions being divided into time ranges of equal duration separated by intermediate times, the latter means (5) determining for each current intermediate time the position of the mobile object, based on its position at the preceding intermediate time and based on its movement during the time range delimited by the current and preceding intermediate times, movement which is calculated by means of the inertial date.