Outlier-tolerant navigation satellite system positioning method and system

System comprising at least one of a navigation satellite system receiver, hereinafter abbreviated as “NSS receiver”, and a processing entity capable of receiving data from the NSS receiver, for estimating parameters useful to determine a position, the NSS receiver being configured to observe a NSS signal from each of a plurality of NSS satellites over multiple epochs,

• the system being configured for receiving input data comprising at least one of:
• NSS signals observed by the NSS receiver, and information derived from said NSS signals;
• and
• the system is configured to operate a first filter, hereinafter referred to as “robustifier”, and a second filter, hereinafter referred to as “main estimator”, wherein the robustifier and the main estimator are configured so that, in operation:
• each of the robustifier and main estimator uses state variables, and computes the values of their respective state variables at least based on the received input data;
• the robustifier identifies, within the received input data, any measurement that does not match a stochastic model assigned thereto;
• for each measurement identified by the robustifier as not matching its stochastic model, at least one of the following applies:
• the robustifier rejects the measurement, and the main estimator does not use the rejected measurement;
• the robustifier adjusts the stochastic model assigned to the measurement, and the main estimator uses the adjusted stochastic model;
• and
• the robustifier corrects the measurement, and the main estimator uses the corrected measurement;
• and
• the robustifier uses fewer state variables than the main estimator.