A method of processing a first set of GNSS signal data derived from at least three carriers of navigation system signals of a first group of transmitters and a second set of GNSS signal data derived from two carriers of navigation system signals of a second group of transmitters, comprising a. applying to the first set of GNSS signal data and the second set of GNSS signal data a geometry filter process using a geometry carrier-phase combination to obtain an array of ambiguity estimates for the geometry carrier-phase combination and associated statistical information; b. applying to the first set of GNSS signal data a first bank of ionosphere filters using a geometry-free ionosphere carrier-phase combination to obtain an array of ambiguity estimates for the ionosphere carrier-phase combination of the first bank of ionosphere filters and associated statistical information; c. applying to the first set of GNSS signal data at least one bank of filters using a geometry-free and ionosphere-free carrier-phase combination to obtain an array of ambiguity estimates for the geometry-free and ionosphere-free carrier-phase combination and associated statistical information; d. applying to the first set of GNSS signal data at least one first code filter using a plurality of geometry-free code-carrier combinations to obtain an array of ambiguity estimates for the code-carrier combinations of the at least one first code filter and associated statistical information; e. applying to the second set of GNSS signal data a second bank of ionosphere filters using a geometry-free ionosphere carrier-phase combination to obtain an array of ambiguity estimates for the ionosphere carrier-phase combination of the second bank of ionosphere filters and associated statistical information; f. applying to the second set of GNSS signal data at least one second code filter using a plurality of geometry-free and ionosphere-free code-carrier combinations to obtain an array of ambiguity estimates for the code-carrier combinations of the at least one second code filter and associated statistical information; and g. combining the arrays of a., b., c., d., e. and f. to obtain a combined array of ambiguity estimates for all carrier phase combinations and associated statistical information. a. applying to the first set of GNSS signal data and the second set of GNSS signal data a geometry filter process using a geometry carrier-phase combination to obtain an array of ambiguity estimates for the geometry carrier-phase combination and associated statistical information; b. applying to the first set of GNSS signal data a first bank of ionosphere filters using a geometry-free ionosphere carrier-phase combination to obtain an array of ambiguity estimates for the ionosphere carrier-phase combination of the first bank of ionosphere filters and associated statistical information; c. applying to the first set of GNSS signal data at least one bank of filters using a geometry-free and ionosphere-free carrier-phase combination to obtain an array of ambiguity estimates for the geometry-free and ionosphere-free carrier-phase combination and associated statistical information; d. applying to the first set of GNSS signal data at least one first code filter using a plurality of geometry-free code-carrier combinations to obtain an array of ambiguity estimates for the code-carrier combinations of the at least one first code filter and associated statistical information; e. applying to the second set of GNSS signal data a second bank of ionosphere filters using a geometry-free ionosphere carrier-phase combination to obtain an array of ambiguity estimates for the ionosphere carrier-phase combination of the second bank of ionosphere filters and associated statistical information; f. applying to the second set of GNSS signal data at least one second code filter using a plurality of geometry-free and ionosphere-free code-carrier combinations to obtain an array of ambiguity estimates for the code-carrier combinations of the at least one second code filter and associated statistical information; and g. combining the arrays of a., b., c., d., e. and f. to obtain a combined array of ambiguity estimates for all carrier phase combinations and associated statistical information.