Procedure for searching for position determination signals using a plurality of search modes
First Claim
1. 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, andthe third level search is associated with a third integration period that is longer than the second integration period.
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Abstract
A method of and system for searching for position determination signals using a plurality of progressively more sensitive search modes comprising a first level mode, a second mode, and at least one higher level mode. If any of the search window parameters exceed prescribed limits, a first level search is performed, and the search window parameters are refined responsive to the ensuing search results so they are within the prescribed limits. Then, the second level search is performed, and measurements derived from the ensuing search results. If the measurements satisfy selected measurement sufficiency criteria, additional searching within the position fix attempt is avoided. If the measurements do not satisfy the selected measurement sufficiency criteria, a higher level, more sensitive search is performed.
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Citations
26 Claims
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1. 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:
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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. - View Dependent Claims (2, 3, 4, 5, 6)
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7. 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:
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a step for 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; a step for deriving, on the wireless subscriber station, one or more measurements from the ensuing search results; a step for determining, on the wireless subscriber station, whether the measurements satisfy one or more selected measurement sufficiency criteria; a step for 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 a step for 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 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. - View Dependent Claims (8, 9, 10, 11, 12)
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13. A non-transitory memory embodying executable instructions that enable a processor and correlator to:
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perform a first level search associated with a first integration period as part of a position fix attempt; derive one or more measurements from the ensuing search results; determine whether the measurements satisfy one or more selected measurement sufficiency criteria; avoid additional searching within the position fix attempt if the measurements satisfy one or more selected measurement sufficiency criteria; and perform a higher level search beyond the first level search if 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, the third level search is associated with a third integration period that is longer than the second integration period, and the first, second and third integration periods function to provide each of the first, second and third level searches, respectively, with different levels of search sensitivity. - View Dependent Claims (14, 15, 16)
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17. A device including, a processor, a correlator, and a memory, wherein the processor is configured to access software instructions stored in the memory, the processor and correlator in combination for performing the software instructions, the memory embodying executable instructions to:
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perform a first level search associated with a first integration period as part of a position fix attempt; derive one or more measurements from the ensuing search results; determine whether the measurements satisfy one or more selected measurement sufficiency criteria; avoid additional searching within the position fix attempt if the measurements satisfy one or more selected measurement sufficiency criteria; and perform a higher level search beyond the first level search if 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, the third level search is associated with a third integration period that is longer than the second integration period, and the first, second and third integration periods function to provide each of the first, second and third level searches, respectively, with different levels of search sensitivity. - View Dependent Claims (18, 19, 20)
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21. A non-transitory device including memory embodying executable instructions that enable a processor and correlator to search 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, comprising:
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means for performing a first level search associated with a first integration period as part of a position fix attempt; means for deriving one or more measurements from the ensuing search results; means for determining whether the measurements satisfy one or more selected measurement sufficiency criteria; means for avoiding additional searching within the position fix attempt if the measurements satisfy the one or more selected measurement sufficiency criteria; and means for performing a higher level search beyond the first level search if 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. - View Dependent Claims (22, 23, 24, 25, 26)
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Specification