Unbiased code phase estimator for mitigating multipath in GPS
First Claim
1. A method of measuring the phase of a pseudorandom (PN) sequence of chips, each chip having a polarity that is either positive or negative, and having a time duration, Tchip, the method comprising:
- generating a reference model exhibiting a reference phase, said reference phase adjustable to facilitate alignment with said phase of said pseudorandom sequence;
establishing a plurality of pulsed-windows over which a plurality of samples of said pseudorandom sequence are collected for a selected accumulation internal;
accumulating said plurality of samples for each pulsed window of said plurality of pulsed windows to form a plurality of accumulated sums;
compensating each accumulated sum to form at least one compensated sum, if a number of level transitions and non-transitions of said pseudorandom sequence is not equal; and
combining said compensated sum to determine a phase error from said plurality of compensated sums, said phase error corresponding to a phase difference between said reference phase and said phase of said pseudorandom sequence.
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Abstract
A method of measuring phase of a pseudorandom (PN) sequence of chips, the method includes: generating a reference model exhibiting a reference phase, the reference phase adjustable to facilitate alignment with the phase of the pseudorandom sequence; establishing a plurality of pulsed-windows over which a plurality of samples of the pseudorandom sequence are collected for a selected accumulation interval; and accumulating the plurality of samples for each pulsed-window of the plurality of pulsed windows to form a plurality of accumulated sums. The method also includes: compensating each accumulated sum to form at least one compensated sum, if a number of level transitions and non-transitions of the pseudorandom sequence is not equal; and combining the compensated sum to determine a phase error from the plurality of compensated sums, the phase error corresponding to a phase difference between the reference phase and the phase of the pseudorandom sequence.
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Citations
23 Claims
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1. A method of measuring the phase of a pseudorandom (PN) sequence of chips, each chip having a polarity that is either positive or negative, and having a time duration, Tchip, the method comprising:
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generating a reference model exhibiting a reference phase, said reference phase adjustable to facilitate alignment with said phase of said pseudorandom sequence;
establishing a plurality of pulsed-windows over which a plurality of samples of said pseudorandom sequence are collected for a selected accumulation internal;
accumulating said plurality of samples for each pulsed window of said plurality of pulsed windows to form a plurality of accumulated sums;
compensating each accumulated sum to form at least one compensated sum, if a number of level transitions and non-transitions of said pseudorandom sequence is not equal; and
combining said compensated sum to determine a phase error from said plurality of compensated sums, said phase error corresponding to a phase difference between said reference phase and said phase of said pseudorandom sequence. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17)
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18. A method of measuring the phase of a pseudorandom (PN) sequence of chips, each chip having a polarity that is either positive or negative, and having a time duration, Tchip, the method comprising:
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generating a reference model exhibiting a reference phase, said reference phase adjustable to facilitate alignment with said phase of said pseudorandom sequence;
establishing a pulsed-window over which a plurality of samples of said pseudorandom sequence are collected for a selected accumulation interval;
accumulating said plurality of samples for each pulsed-window to form at least one accumulated sum;
combining said at least one accumulated sum to determine a phase error, said phase error corresponding to a phase difference between said reference phase and said phase of said pseudorandom sequence; and
normalizing said phase error by dividing said at least one accumulated sum, by a second summation taken only over pulsed windows that are based on a number of polarity transitions of said pseudorandom sequence. - View Dependent Claims (19)
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20. A system for measuring the phase of a pseudorandom (PN) sequence of chips, each chip having a polarity that is either positive or negative, and having a time duration, Tchip, the system comprising:
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a means for generating a reference model exhibiting a reference phase, said reference phase adjustable to facilitate alignment with said phase of said pseudorandom sequence;
a means for establishing a plurality of pulsed-windows over which a plurality of samples of said pseudorandom sequence are collected for a selected accumulation interval;
a means for accumulating said plurality of samples for each pulsed window of said plurality of pulsed windows to form a plurality of accumulated sums;
compensating each accumulated sum to form at least one compensated sum, if a number of level transitions and non-transitions of said pseudorandom sequence is not equal; and
a means for combining said compensated sum to determine a phase error from said plurality of compensated sums, said phase error corresponding to a phase difference between said reference phase and said phase of said pseudorandom sequence. - View Dependent Claims (21)
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22. A storage medium encoded with a machine-readable computer program code for measuring the phase of a pseudorandom (PN) sequence of chips, each chip having a polarity that is either positive or negative, and having a time duration, Tchip, said storage medium including instructions for causing controller to implement a method comprising:
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generating a reference model exhibiting a reference phase, said reference phase adjustable to facilitate alignment with said phase of said pseudorandom sequence;
establishing a plurality of pulsed-windows over which a plurality of samples of said pseudorandom sequence are collected for a selected accumulation interval;
accumulating said plurality of samples for each pulsed window of said plurality of pulsed windows to form a plurality of accumulated sums;
compensating each accumulated sum to form at least one compensated sum, if a number of level transitions and non-transitions of said pseudorandom sequence is not equal; and
combining said compensated sum to determine a phase error from said plurality of compensated sums, said phase error corresponding to a phase difference between said reference phase and said phase of said pseudorandom sequence.
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23. A computer data signal embodied in a carrier wave for measuring the phase of a pseudorandom (PN) sequence of chips, each chip having a polarity that is either positive or negative, and having a time during, Tchip, said data signal comprising code configured to cause a controller to implement a method comprising:
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generating a reference model exhibiting a reference phase, said reference phase adjustable to facilitate alignment with said phase of said pseudorandom sequence;
establishing a plurality of pulsed-windows over which a plurality of samples of said pseudorandom sequence are collected for a selected accumulation interval;
accumulating said plurality of samples for each pulsed window of said plurality of pulsed windows to form a plurality of accumulated sums;
compensating each accumulated sum to form at least one compensated sum, if a number of level transitions and non-transitions of said pseudorandom sequence is not equal; and
combining said compensated sum to determine a phase error from said plurality of compensated sums, said phase error corresponding to a phase difference between said reference phase and said phase of said pseudorandom sequence.
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Specification