A navigation system with resume logic and mode logic provides as an output
an accurate navigation solution using multiple RF sensors. The resume
logic determines which sensors are currently providing good data to the
navigation system. The mode logic selects an operating mode of the
navigation system and selects which data to use for calculating
corrections to the navigation solution. The mode logic makes the
selections based on the results of the resume logic. The resume logic
continues to test data from the sensors. If a sensor that has previously
provided erroneous data starts providing good data, the mode logic will
automatically select that data for use in calculating the corrections to
the navigation solution. The tracking of RF transmitters by the multiple
RF sensors is controlled using a plurality of available inertial and
non-inertial sensors.