Patent ID: 8473205

Claim:
A method of searching for position determination signals using a plurality of progressively more sensitive search modes with sensitivity levels that are characterized by their respective integration periods and which plurality comprises, in order of increasing sensitivity, a first level mode, a second level mode, and a third level mode, the method comprising: performing, on a wireless subscriber station, a first level search associated with a first integration period as part of a position fix attempt of the wireless subscriber station; deriving, on the wireless subscriber station, one or more measurements from the ensuing search results; determining, on the wireless subscriber station, whether the measurements satisfy one or more selected measurement sufficiency criteria; avoiding additional searching within the position fix attempt if the wireless subscriber station determines that the measurements satisfy the one or more selected measurement sufficiency criteria; and performing, on the wireless subscriber station, a higher level search beyond the first level search if the wireless subscriber station determines that the measurements do not satisfy the one or more selected measurement sufficiency criteria, wherein: the higher level search is a second level search if a number of space vehicles in a first set exceeds a threshold number or an estimated time to perform a third level search on a number of space vehicles in a second set exceeds a maximum time remaining in the position fix attempt, the higher level search is the third level search if the number of space vehicles in the first set does not exceed the threshold number and the estimated time to perform the third level search on the number of space vehicles in the second set does not exceed the maximum time remaining in the position fix attempt, the second level search is associated with a second integration period that is longer than the first integration period, and the third level search is associated with a third integration period that is longer than the second integration period.