Acquisition for GPS C/A code and P(Y) code
First Claim
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1. An efficient, data processing minimizing, GPS data acquisition software method comprising the steps of:
- separating first N data points from a received GPS signal into first M subdivisions, a subdivision representing a preselected number of P(Y) data points from said received GPS signal;
dividing second N data points from said locally generated replica P(Y)-code into second M subdivisions, a subdivision representing a preselected number of P(Y) data points from said locally generated replica, said second M subdivisions corresponding with said first M subdivisions from said separating step;
correlating data from said first M subdivisions from said separating step with data from said second M subdivisions from said dividing step, said correlating including the steps of multiplying received P(Y) code with locally generated replica P(Y) code and then performing a summing operation resulting in third M data points;
performing an M-point fast Fourier transform on said third M data points from said multiplying step;
comparing a product from said performing step with a preselected threshold value; and
repeating said correlating step until said preselected threshold from said considering step is satisfied.
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Abstract
An improved global positioning system satellite signal acquisition method. The method of the invention reduces the number of operations in the block correlation used in determining Doppler frequency and time of the received GPS C/A or P(Y) codes. Reducing the number of operations in block correlation increases acquisition speed making it conducive to commercial and military GPS receivers
17 Citations
4 Claims
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1. An efficient, data processing minimizing, GPS data acquisition software method comprising the steps of:
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separating first N data points from a received GPS signal into first M subdivisions, a subdivision representing a preselected number of P(Y) data points from said received GPS signal;
dividing second N data points from said locally generated replica P(Y)-code into second M subdivisions, a subdivision representing a preselected number of P(Y) data points from said locally generated replica, said second M subdivisions corresponding with said first M subdivisions from said separating step;
correlating data from said first M subdivisions from said separating step with data from said second M subdivisions from said dividing step, said correlating including the steps of multiplying received P(Y) code with locally generated replica P(Y) code and then performing a summing operation resulting in third M data points;
performing an M-point fast Fourier transform on said third M data points from said multiplying step;
comparing a product from said performing step with a preselected threshold value; and
repeating said correlating step until said preselected threshold from said considering step is satisfied. - View Dependent Claims (2, 3, 4)
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Specification
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Current AssigneeAir Force Government of The United States of America As Represented By The Secretary
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Original AssigneeUnited States Of America As Represented By The Secretary Of The Air Force
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InventorsLin, David M., Tsui, James B. Y.
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Primary Examiner(s)Phan, Dao
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Application NumberUS09/729,628Publication NumberTime in Patent Office1,226 DaysField of Search342/357.05, 342/357.06, 342/357.12, 342/357.15US Class Current342/357.69CPC Class CodesG01S 19/29 carrier including Doppler, ...G01S 19/32 Multimode operation in a si...H04B 1/70753 Partial phase searchH04B 1/708 Parallel implementationH04L 2027/0065 Frequency error detectors H...
