A method for determining a position of an object having a Global Navigation Satellite System (GNSS) receiver, the method comprising the steps of: - receiving signals by the GNSS receiver which are transmitted by GNSS transmitters (GNSS E1 to GNSS En) positioned on board of satellites (SAT 1 to SAT n) which are positioned in a view of the object; - updating service data in the object, the service data being provided by a GNSS service provider and including: satellite clock data indicating internal clocks of the satellites (SAT 1 to SAT n); satellite orbit data indicating positions of the satellites (SAT 1 to SAT n); satellite delay code bias data relating to delay code biases of the GNSS.transmitters (GNSS E1 to GNSS En); and ionospheric model data indicating a state of an ionosphere; - determining, based on the ionospheric model data, ionospheric delay data indicating corrections relating to delays of the signals, the delays of the signals resulting from a passage of the signals through the ionosphere between transmission of the signals from the GNSS transmitters (GNSS E1 to GNSS En) and reception of the signals by the GNSS receiver (SUR GNSS); - obtaining code observation data from the signals, the code observation data relating to data transmitted with the signals and comprising code observables relating to data transmitted with the signals; - obtaining carrier phase observation data from the signals, the carrier phase observation data relating to carrier phases of the signals and comprising carrier phase observables relating to the carrier phase of the signals; and - determining a position of the object based on the satellite clock data, the satellite orbit data, the satellite delay code bias data, the determined ionospheric delay data, the code observation data obtained from the signals and the carrier phase observation data obtained from the signals, wherein all code observables and all carrier phase observables involved in the step of determining the position of the object are processed in an undifferenced mode, characterized in that in the step of determining the position of the object at least one linear combination of observables which is not ionospheric free, and additionally a linear combination of observables which is ionospheric-free are processed. - receiving signals by the GNSS receiver which are transmitted by GNSS transmitters (GNSS E1 to GNSS En) positioned on board of satellites (SAT 1 to SAT n) which are positioned in a view of the object; - updating service data in the object, the service data being provided by a GNSS service provider and including: satellite clock data indicating internal clocks of the satellites (SAT 1 to SAT n); satellite orbit data indicating positions of the satellites (SAT 1 to SAT n); satellite delay code bias data relating to delay code biases of the GNSS.transmitters (GNSS E1 to GNSS En); and ionospheric model data indicating a state of an ionosphere; satellite clock data indicating internal clocks of the satellites (SAT 1 to SAT n); satellite orbit data indicating positions of the satellites (SAT 1 to SAT n); satellite delay code bias data relating to delay code biases of the GNSS.transmitters (GNSS E1 to GNSS En); and ionospheric model data indicating a state of an ionosphere; - determining, based on the ionospheric model data, ionospheric delay data indicating corrections relating to delays of the signals, the delays of the signals resulting from a passage of the signals through the ionosphere between transmission of the signals from the GNSS transmitters (GNSS E1 to GNSS En) and reception of the signals by the GNSS receiver (SUR GNSS); - obtaining code observation data from the signals, the code observation data relating to data transmitted with the signals and comprising code observables relating to data transmitted with the signals; - obtaining carrier phase observation data from the signals, the carrier phase observation data relating to carrier phases of the signals and comprising carrier phase observables relating to the carrier phase of the signals; and - determining a position of the object based on the satellite clock data, the satellite orbit data, the satellite delay code bias data, the determined ionospheric delay data, the code observation data obtained from the signals and the carrier phase observation data obtained from the signals,