Reducing and sharing computations for GPS signal processing
First Claim
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1. A method of processing a Global Positioning System (GPS) signal, comprising:
- transforming a time domain GPS signal extending over a plurality of milliseconds to a frequency domain GPS signal, wherein the frequency domain GPS signal has a frequency bin spacing of an inverse of the plurality of milliseconds; and
correlating the frequency domain GPS signal with a frequency domain pseudorandom noise (PRN) signal at a plurality of frequencies, said correlating comprising;
performing a circular shift on the frequency domain GPS signal by an amount corresponding to one of the plurality of frequencies;
downsampling the shifted frequency domain GPS signal to produce a shifted and downsampled frequency domain GPS signal that has the same frequency bin spacing as a frequency bin spacing of the frequency domain PRN signal;
multiplying the shifted and downsampled frequency domain GPS signal by the frequency domain PRN signal to produce a frequency domain correlated signal; and
transforming the frequency domain correlated signal into a time domain correlated signal extending over a single millisecond.
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Abstract
Methods and systems for processing a Global Positioning System (GPS) signal are provided. A method includes: transforming a time domain GPS signal to a frequency domain GPS signal; storing a frequency domain pseudorandom noise (PRN) signal; correlating the frequency domain GPS signal with the PRN signal at a plurality of frequencies, said correlating including: shifting the frequency domain GPS signal by an amount corresponding to one of the plurality of frequencies; downsampling the shifted frequency domain GPS signal; and multiplying the shifted frequency domain GPS signal by the stored frequency domain PRN signal to produce a correlated signal.
25 Citations
16 Claims
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1. A method of processing a Global Positioning System (GPS) signal, comprising:
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transforming a time domain GPS signal extending over a plurality of milliseconds to a frequency domain GPS signal, wherein the frequency domain GPS signal has a frequency bin spacing of an inverse of the plurality of milliseconds; and correlating the frequency domain GPS signal with a frequency domain pseudorandom noise (PRN) signal at a plurality of frequencies, said correlating comprising; performing a circular shift on the frequency domain GPS signal by an amount corresponding to one of the plurality of frequencies; downsampling the shifted frequency domain GPS signal to produce a shifted and downsampled frequency domain GPS signal that has the same frequency bin spacing as a frequency bin spacing of the frequency domain PRN signal; multiplying the shifted and downsampled frequency domain GPS signal by the frequency domain PRN signal to produce a frequency domain correlated signal; and transforming the frequency domain correlated signal into a time domain correlated signal extending over a single millisecond. - View Dependent Claims (2, 3, 4, 5)
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6. A receiver for processing a GPS signal, comprising:
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a memory for storing a frequency domain GPS signal and a frequency domain pseudorandom noise (PRN) signal; and a processor configured to; transform a time domain GPS signal extending over a plurality of milliseconds to a frequency domain GPS signal and store the frequency domain GPS signal in the memory, wherein the frequency domain GPS signal has a frequency bin spacing of an inverse of the plurality of milliseconds; and correlate the frequency domain signal with the PRN signal at a plurality of frequencies, said correlating comprising; performing a circular shift on the frequency domain GPS signal by an amount corresponding to one of the plurality of frequencies; downsampling the shifted frequency domain GPS signal to produce a shifted and downsampled frequency domain GPS signal that has the same frequency bin spacing as a frequency bin spacing of the stored frequency domain PRN signal; multiplying the shifted and downsampled frequency domain GPS signal by the stored frequency domain PRN signal to produce a correlated frequency domain signal; and transforming the correlated frequency domain signal into a correlated time domain signal extending over a single millisecond. - View Dependent Claims (7, 8, 9, 10, 11)
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12. A method of processing a Global Positioning System (GPS) signal extending over a plurality of K milliseconds, wherein K is a positive integer, comprising:
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producing a frequency domain representation of the GPS signal, the frequency domain GPS signal comprising a plurality of frequency bins having a bin frequency spacing of fb, wherein fb is an inverse of K milliseconds; and correlating the GPS signal with a pseudorandom noise (PRN) signal at a plurality of M mixing frequencies with a mixing frequency spacing of fM=K×
fb, said correlating comprising for each mixing frequency;performing a circular shift on the frequency domain GPS signal by K×
S samples, wherein S is an integer ranging from 0 to (M−
1) to obtain a frequency domain shifted signal shifted by S×
fM;downsampling the frequency domain shifted signal by K to produce a downsampled frequency domain shifted signal; multiplying the downsampled frequency domain shifted signal with a frequency domain representation of the PRN signal to produce a frequency domain correlated signal; and transforming the frequency domain correlated signal into a time domain signal extending over a single millisecond. - View Dependent Claims (13, 14, 15, 16)
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Specification