Systems and methods to determine a location of a mobile device by combining a radio frequency navigation system and an inertial navigation system, where the radio frequency navigation system determines a location of the mobile device in reference to a map of radio frequency signals and the inertial navigation system based on dead reckoning the position of the mobile device based on measurements from motion sensors. When a set of successive locations determined by the radio frequency navigation system is found to have a predetermined pattern (e.g., within a minimum distance from each other, or separated by more than a maximum distance), the mobile device discards the location results from the radio frequency navigation system for the period of time, in favor of the location results from the inertial navigation system.