Methods are provided for determining a positioning of a portable device including first and second sensor(s) each having a confidence. These methods include: receiving first and second signals from the first and second sensor(s), respectively; generating positional data representing positional conditions of the portable device and including first and second positional data respectively from the first and second signals, by modelling the received signals based on predefined models defining a correspondence between predefined signals and predefined positional data; comparing the first and second positional data to determine a difference between them; adjusting the confidence of the sensors by determining a new confidence depending on a previous confidence and the determined difference between positional data; weighting the generated positional data depending on corresponding confidences; and determining the positioning of the portable device based on the weighted generated positional data. Computer programs and systems suitable for performing such methods are also provided.