A set of device parameters consisting of clock bias and position of a mobile device is determined without previous knowledge of the week number (WN) in that solutions of a set of equations derived from a least squares type weight function involving pseudoranges related to the device parameters via basic equations are attempted with a time of week (TOW) extracted from satellite signals and various week number candidates. A solution algorithm which iteratively solves the set of equations is used, each iteration step involving a linearization of the latter and resulting in corrections of the device parameters. After elimination of week numbers where the solution algorithm does not yield a solution a valid week number is selected from the remaining week numbers in that a deviation value is determined which reflects differential terms, i.e., differences between pseudorange values as measured and as derived from the set of device parameters according to the solution, e.g., by evaluation of the weight function. The week number yielding the smallest deviation value is selected. If the week number is confirmed by various checks the device parameters according to the corresponding solution are used, e.g., displayed, by the mobile device.