Patent attributes
A system detects slowly diverging navigational signals by updating the current location from purely internal navigational aids for a period of time. The updated location compared to a continuously corrected current location; if the comparison indicates a deviation outside an expected boundary threshold, the external source is excluded from further measurements. Multiple monitoring elements may be staggered such that one or more monitoring elements are always sequestered for future comparisons. The multiple monitoring elements may monitor different external sources with different weights to identify a specific faulty external source.