Method and apparatus for performing frequency synchronization
First Claim
Patent Images
1. A method comprising:
- forming a sequence of correlation values from a plurality of correlations performed over a period less than a repeating period of a code; and
analyzing the sequence of correlation values to estimate a frequency that is used to receive a signal comprising the code, wherein analyzing the sequence of correlation values comprises;
hypothesizing a plurality of possible frequencies;
determining a quantity indicative of a power in the sequence of correlation values at each of the plurality of possible frequencies; and
estimating the frequency as a function of the quantity.
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Abstract
A method and apparatus for performing frequency analysis of sub-epoch correlations to estimate an unknown frequency of a received signal is provided. The method includes forming a sequence of correlation values from a plurality of correlations performed over a period less than a repeating period of a code, and analyzing the sequence of correlation values to estimate the frequency that is used to receive a signal comprising the code.
7 Citations
29 Claims
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1. A method comprising:
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forming a sequence of correlation values from a plurality of correlations performed over a period less than a repeating period of a code; and analyzing the sequence of correlation values to estimate a frequency that is used to receive a signal comprising the code, wherein analyzing the sequence of correlation values comprises; hypothesizing a plurality of possible frequencies; determining a quantity indicative of a power in the sequence of correlation values at each of the plurality of possible frequencies; and estimating the frequency as a function of the quantity. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. An apparatus comprising:
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a memory for storing a sequence of correlation values produced over a period less than a repeating period of a code; a processor for accessing the sequence of correlation values from the memory and processing the values to produce a frequency estimate that is used to receive a signal comprising the code, wherein the processor hypothesizes a plurality of possible frequencies, determines a quantity indicative of a power in the sequence of correlation values at each of the plurality of possible frequencies and estimates the frequency as a function of the quantity. - View Dependent Claims (9, 10, 11, 12, 13, 14)
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15. A GNSS receiver comprising:
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a tuner comprising a numerically controlled oscillator for adjusting an intermediate frequency; a GNSS signal convolution processor, coupled to the tuner, for producing a sequence of correlation values, where the sequence of correlation values are produced over a period less than a repeating period of a code; a correlation history memory, coupled to the convolution processor, for storing the sequence of correlation values; a processor, coupled to the correlation history memory, for analyzing a power of the correlation values and controlling a frequency of the numerically controlled oscillator, wherein the processor hypothesizes a plurality of possible frequencies, determines a quantity indicative of a power in the sequence of correlation values at each of the plurality of possible frequencies and estimates the frequency as a function of the quantity. - View Dependent Claims (16)
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17. A method comprising:
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forming a sequence of correlation values from a plurality of correlations performed over a period less than a repeating period of a code; analyzing the sequence of correlation values to estimate a frequency that is used to receive a signal comprising the code; compensating the sequence of correlation values based on the frequency to form a frequency-compensated sequence of correlation values; and accumulating the frequency-compensated sequence of correlation values to form a second sequence of correlation values that form a correlation vector. - View Dependent Claims (18, 19, 20, 21, 22)
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23. An apparatus comprising:
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a memory for storing a sequence of correlation values produced over a period less than a repeating period of a code; a mixer for compensating the sequence of correlation values with each of the plurality of possible frequencies to form frequency-compensated correlation values; a second mixer for compensating the sequence of correlation values based on the frequency to form a frequency-compensated sequence of correlation values; an accumulator for accumulating the frequency-compensated sequence of correlation values to form a second sequence of correlation values; a processor for accessing the sequence of correlation values from the memory and processing the values to produce a frequency estimate that is used to receive a signal comprising the code; and an absolute value circuit for determining power of each of the second sequence of correlation values. - View Dependent Claims (24, 25, 26, 27)
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28. A GNSS receiver comprising:
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a tuner comprising a numerically controlled oscillator for adjusting an intermediate frequency; a GNSS signal convolution processor, coupled to the tuner, for producing a sequence of correlation values, where the sequence of correlation values are produced over a period less than a repeating period of a code; a correlation history memory, coupled to the convolution processor, for storing the sequence of correlation values; a processor, coupled to the correlation history memory, for analyzing a power of the correlation values and controlling a frequency of the numerically controlled oscillator; a mixer for compensating the sequence of correlation values with each of the plurality of possible frequencies to form frequency-compensated correlation values; an accumulator for accumulating the frequency-compensated sequence of correlation values to form a second sequence of correlation values; and an absolute value circuit for determining power of each of the second sequence of correlation values. - View Dependent Claims (29)
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Specification