1. A device comprising: a delta range measurement (DRM) module configured to measure a range difference value between a first range value related to a first time instant and a second range value related to a second time instant, wherein the first and second range values indicate spatial relationships between the device and a navigation satellite at respectively the first and second time instants, and wherein the time period between the first time instant and the second time instant is greater than a periodic interval at which a range value is updated; and a filter configured to compute, for a first cycle, a current estimate of a position of the device based at least on the range difference value and an a priori estimate of the position of the device.