Coding in a wide area positioning system (WAPS)
First Claim
1. A positioning system, comprising at least one processor that:
- determines an estimated position of a receiver using positioning signals acquired from a plurality of transmitters,wherein at least a first portion of a first acquired positioning signal is modulated in accordance with a first pseudorandom sequence,wherein at least a second portion of a second acquired positioning signal is modulated in accordance with a second pseudorandom sequence,wherein at least a third portion of a third acquired positioning signal is modulated in accordance with a third pseudorandom sequence,wherein the first, second and third pseudorandom sequences are members of a subset of at least three pseudorandom sequences from a set of pseudorandom sequences,wherein a maximum magnitude of a cross-correlation function between any two sequences of the set of pseudorandom sequences is below a specified threshold,wherein all magnitudes of an autocorrelation function corresponding to the members of the subset, within a specified region adjacent to a peak of the autocorrelation function, are equal to or less than a prescribed value, andwherein two or more magnitudes of the autocorrelation function, outside of the specified region, are greater than the prescribed value.
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Accused Products
Abstract
Embodiments describe determining position by selecting a set of digital pseudorandom sequences. The magnitudes of the cross-correlation between any two sequences of the chosen set are below a specified threshold. A subset of digital pseudorandom sequences are selected from the set such that the magnitudes of the autocorrelation function of each member of the subset, within a specified region adjacent to the peak of the autocorrelation function, are equal to or less than a prescribed value. Each transmitter transmits a positioning signal, and at least a portion of the positioning signal is modulated with at least one member of the subset. At least two transmitters of the plurality of transmitters modulate respective positioning signals with different members of the subset of digital pseudorandom sequences.
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Citations
43 Claims
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1. A positioning system, comprising at least one processor that:
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determines an estimated position of a receiver using positioning signals acquired from a plurality of transmitters, wherein at least a first portion of a first acquired positioning signal is modulated in accordance with a first pseudorandom sequence, wherein at least a second portion of a second acquired positioning signal is modulated in accordance with a second pseudorandom sequence, wherein at least a third portion of a third acquired positioning signal is modulated in accordance with a third pseudorandom sequence, wherein the first, second and third pseudorandom sequences are members of a subset of at least three pseudorandom sequences from a set of pseudorandom sequences, wherein a maximum magnitude of a cross-correlation function between any two sequences of the set of pseudorandom sequences is below a specified threshold, wherein all magnitudes of an autocorrelation function corresponding to the members of the subset, within a specified region adjacent to a peak of the autocorrelation function, are equal to or less than a prescribed value, and wherein two or more magnitudes of the autocorrelation function, outside of the specified region, are greater than the prescribed value. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23)
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24. A method for determining an estimated position of a receiver, the method comprising:
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determining an estimated position of a receiver using positioning signals acquired from a plurality of transmitters, wherein at least a first portion of a first acquired positioning signal is modulated in accordance with a first pseudorandom sequence, wherein at least a second portion of a second acquired positioning signal is modulated in accordance with a second pseudorandom sequence, wherein at least a third portion of a third acquired positioning signal is modulated in accordance with a third pseudorandom sequence, wherein the first, second and third pseudorandom sequences are members of a subset of at least three pseudorandom sequences from a set of pseudorandom sequences, wherein a maximum magnitude of a cross-correlation function between any two sequences of the set of pseudorandom sequences is below a specified threshold, wherein all magnitudes of an autocorrelation function corresponding to the members of the subset, within a specified region adjacent to a peak of the autocorrelation function, are equal to or less than a prescribed value, and wherein two or more magnitudes of the autocorrelation function, outside of the specified region, are greater than the prescribed value. - View Dependent Claims (25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43)
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Specification