A detection system (100, 150) for qualitative or quantitative detection of a magnetic field property of a modulated magnetic field is described. The modulated magnetic field may e.g. stem from an adjacent electrical current (Iadj) or magnetic particles. The detection system (100, 150) comprises at least one magneto resistive sensor element (102), a current controller (104) for providing a sensing current (Isense) flowing through the magnetic sensor element (102) and a controlling means (108). The controlling means (108) is adapted for deriving at a first frequency f1 a temperature-related parameter of the at least one magneto resistive sensor. The controlling means (108) furthermore is adapted for deriving a qualitative or quantitative characteristic of the adjacent electrical current (Iadj) or magnetic particles, taking into account the derived temperature-related parameter. This second frequency (f1) is different from the first frequency (f1}). The invention also relates to a corresponding method.