Patent ID: 8510077

Claim:
A method of implementing a positioning system, the method comprising: implementing a buffer configured to store a buffer record for each of a plurality of position fixes determined by a positioning system receiver; implementing a database configured to store a database record for each of a plurality of threshold positions; receiving zero or more positioning signals from a plurality of navigational satellites; accumulating, in the buffer, a plurality of buffer records, wherein each buffer record is for a corresponding one of the plurality of position fixes determined by the positioning system receiver; identifying a first threshold position near an area in which a degradation event occurs; recording the first threshold position in a first database record of the database; identifying a second threshold position near the area, the second threshold position i) indicated by one of the plurality of position fixes outside of the area, and ii) proximate to a position at which the degradation event ends; and recording the second threshold position in a second database record of the database, the second database record stored in a memory location determinable from the first database record, the first database record stored in a memory location determinable from the second database record.