US6493380B1 — System and method for estimating signal time of a…

Claim 1

Independent Claim 88 words

A method for estimating a time delay, the method comprising the steps of: a. estimating a channel spectrum from a received signal and a known reference signal; b. formulating a unique data matrix using the estimated channel spectrum; and c. determining a time delay estimate using the data matrix, wherein step (a) comprises the steps of a. estimating a baseband channel response using the received signal and the known reference signal; and b. estimating the continuous channel spectrum using a Discrete Fourier Transform of the baseband channel response.

Claim 2

Independent Claim 88 words

A method for estimating a time delay, the method comprising the steps of: a. estimating a channel spectrum from a received signal and a known reference signal; b. formulating a unique data matrix using the estimated channel spectrum; and c. determining a time delay estimate using the data matrix, wherein step (a) comprises the steps of a. estimating a baseband channel response using the received signal and the known reference signal; and b. estimating the continuous channel spectrum using a Discrete Fourier Transform of the baseband channel response.

Claim 3

Independent Claim 78 words

A method for estimating a time delay, the method comprising the steps of: a. estimating a channel spectrum from a received signal and a known reference signal; b. formulating a unique data matrix using the estimated channel spectrum; and c. determining a time delay estimate using the data matrix, wherein step (b) comprises the step of constructing a signal space using the estimated channel spectrum and one slot so that the signal space includes delay and multipath information.

Claim 4

Independent Claim 78 words

A method for estimating a time delay, the method comprising the steps of: a. estimating a channel spectrum from a received signal and a known reference signal; b. formulating a unique data matrix using the estimated channel spectrum; and c. determining a time delay estimate using the data matrix, wherein step (b) comprises the step of constructing a signal space using the estimated channel spectrum and one slot so that the signal space includes delay and multipath information.

Claim 5

Dependent Claim 22 words

The method recited in claim 2 wherein step (a) comprises the step of representing the signal space as a Hermitian Toeplitz matrix.

Claim 6

Independent Claim 138 words

A method for estimating a time delay, the method comprising the steps of: a. estimating a channel spectrum from a received signal and a known reference signal; b. formulating a unique data matrix using the estimated channel spectrum; and c. determining a time delay estimate using the data matrix, wherein step (c) comprises the steps of a. performing singular value decomposition on the data matrix; b. detecting automatically, based on the singular value decomposition results, the number of physical paths; c. determining a noise space using the number of physical paths; d. determining a projection polynomial using the noise space; e. determining at least one root pair by solving the projection polynomial; f. mapping the roots to determine a rough time delay estimate; and g. estimating the time delay by removing bias in the rough time delay estimate.

Claim 7

Independent Claim 138 words

A method for estimating a time delay, the method comprising the steps of: a. estimating a channel spectrum from a received signal and a known reference signal; b. formulating a unique data matrix using the estimated channel spectrum; and c. determining a time delay estimate using the data matrix, wherein step (c) comprises the steps of a. performing singular value decomposition on the data matrix; b. detecting automatically, based on the singular value decomposition results, the number of physical paths; c. determining a noise space using the number of physical paths; d. determining a projection polynomial using the noise space; e. determining at least one root pair by solving the projection polynomial; f. mapping the roots to determine a rough time delay estimate; and g. estimating the time delay by removing bias in the rough time delay estimate.

Claim 8

Dependent Claim 21 words

The method recited in claim 4 wherein step (e) comprises the step of solving the projection polynomial using Kuhn's sandwich method.

Claim 9

Dependent Claim 107 words

The method recited in claim 4 wherein step (f) comprises the steps of: a. for each root pair, selecting the constituent root closest to the unit circle when plotted on the complex plane; b. for each constituent root selected, determining a delay according to the formula: τ = min [  arctan  Re ( r M + 1 - i ) im ( r M + 1 - i )  2   π   Δ ] for each physical path i, where τ=TOAF, r=roots, Re=real part, im=imaginary and Δ is predetermined; c. determining the rough time delay estimate by selecting the shortest delay.

Claim 10

Dependent Claim 31 words

The method recited in claim 4 wherein step (g) comprises the step of determining the time delay estimate by modifying the rough time delay using a predetermined, empirical multipath compensation factor.

Claim 11

Independent Claim 72 words

A method for estimating a time delay, the method comprising the steps of: a. estimating a channel spectrum from a received signal and a known reference signal; b. formulating a unique data matrix using the estimated channel spectrum; and c. determining a time delay estimate using the data matrix, wherein the known reference signal in step (a) is a shortened burst or sync word in norm burst in an IS- 136 system.

Claim 12

Independent Claim 72 words

A method for estimating a time delay, the method comprising the steps of: a. estimating a channel spectrum from a received signal and a known reference signal; b. formulating a unique data matrix using the estimated channel spectrum; and c. determining a time delay estimate using the data matrix, wherein the known reference signal in step (a) is a shortened burst or sync word in norm burst in an IS- 136 system.

Claim 13

Independent Claim 149 words

A method for estimating a time of arrival, the method comprising the steps of: a. matched filtering an input signal to produce a matched filtered signal; b. buffering the matched filtered signal and adding global positioning system time stamps to produce a buffered signal; c. compensating for the carrier offset in the buffered signal to produce a received signal; d. determining the start of a shortened burst signal in the received signal using a framer; e. at the start of the shortened burst, determining the inter-symbol delay by framing the shortened burst; f. at the start of the shortened burst, estimating a channel response using the received signal and a known reference signal; g. formulating a data matrix using the estimated channel spectrum; h. determining an intra-symbol delay estimate using the data matrix; and j. determining a time of arrival by adding the inter-symbol delay and the intra-symbol delay.

Claim 14

Independent Claim 149 words

A method for estimating a time of arrival, the method comprising the steps of: a. matched filtering an input signal to produce a matched filtered signal; b. buffering the matched filtered signal and adding global positioning system time stamps to produce a buffered signal; c. compensating for the carrier offset in the buffered signal to produce a received signal; d. determining the start of a shortened burst signal in the received signal using a framer; e. at the start of the shortened burst, determining the inter-symbol delay by framing the shortened burst; f. at the start of the shortened burst, estimating a channel response using the received signal and a known reference signal; g. formulating a data matrix using the estimated channel spectrum; h. determining an intra-symbol delay estimate using the data matrix; and j. determining a time of arrival by adding the inter-symbol delay and the intra-symbol delay.

Claim 15

Dependent Claim 44 words

The method recited in claim 9 wherein step (f) comprises the steps of a. estimating a baseband channel response using the received signal and the known reference signal; b. estimating the continuous channel spectrum using a Discrete Fourier Transform of the baseband channel response.

Claim 16

Dependent Claim 35 words

The method recited in claim 9 wherein step (g) comprises the step of constructing a signal space using the estimated channel spectrum and one slot so that the signal space includes delay and multipath information.

Claim 17

Dependent Claim 22 words

The method recited in claim 9 wherein step (a) comprises the step of representing the signal space as a Hermitian Toeplitz matrix.

Claim 18

Dependent Claim 95 words

The method recited in claim 9 wherein step (h) comprises the steps of a. performing singular value decomposition on the data matrix; b. detecting automatically, based on the singular value decomposition results, the number of physical paths; c. determining a noise space using the number of physical paths; d. determining a projection polynomial using the noise space; e. determining a least one root pair by solving the projection polynomial; f. mapping the roots to determine a rough intra-symbol delay estimate; and g. estimating the intra-symbol delay by removing bias in the rough intra-symbol delay estimate.

Claim 19

Dependent Claim 21 words

The method recited in claim 13 wherein step (e) comprises the step of solving the projection polynomial using Kuhn's sandwich method.

Claim 20

Dependent Claim 107 words

The method recited in claim 13 wherein step (f) comprises the steps of: a. for each root pair, selecting the constituent root closest to the unit circle when plotted on the complex plane; b. for each constituent root selected, determine a delay according to the formula: τ = min [  arctan  Re ( r M + 1 - i ) im ( r M + 1 - i )  2   π   Δ ] for each physical path i, where τ=TOAf, r=roots, Re=real part, im=imaginary and Δ is predetermined. c. determine the rough intra-symbol delay estimate by selecting the shortest delay.

Claim 21

Dependent Claim 31 words

The method recited in claim 13 wherein step (g) comprises the step of determining the intra-symbol delay estimate by modifying the rough intra-symbol delay using a predetermined, empirical multipath compensation factor.

Claim 22

Independent Claim 95 words

A system for estimating a time delay, the system comprising: a. a channel spectrum estimator for estimating a channel spectrum from a received signal and a known reference signal; b. means for extracting a virtual array structure from the estimated channel spectrum; and c. means for determining the time delay using the virtual array structure, wherein the extracting means comprises means for formulating a data matrix representing a signal space, the formulating means using the estimated channel spectrum and one slot so that the data matrix representing the signal space includes delay and multipath information.

Claim 23

Independent Claim 95 words

A system for estimating a time delay, the system comprising: a. a channel spectrum estimator for estimating a channel spectrum from a received signal and a known reference signal; b. means for extracting a virtual array structure from the estimated channel spectrum; and c. means for determining the time delay using the virtual array structure, wherein the extracting means comprises means for formulating a data matrix representing a signal space, the formulating means using the estimated channel spectrum and one slot so that the data matrix representing the signal space includes delay and multipath information.

Claim 24

Independent Claim 156 words

A system for estimating a time delay, the system comprising: a. a channel spectrum estimator for estimating a channel spectrum from a received signal and a known reference signal; b. means for extracting a virtual array structure from the estimated channel spectrum; and c. means for determining the time delay using the virtual array structure, wherein the determining means comprises: a. means for performing singular value decomposition on the data matrix; b. means for detecting automatically, based on the singular value decomposition results, the number of physical paths; c. means for determining a noise space using the number of physical paths; d. means for determining a projection polynomial using the noise space; e. means for determining at least one root pair by solving the projection polynomial; f. means for mapping the roots to determine a rough intra-symbol delay estimate; and g. means for estimating the intra-symbol delay by removing bias in the rough time delay estimate.

Claim 25

Independent Claim 156 words

A system for estimating a time delay, the system comprising: a. a channel spectrum estimator for estimating a channel spectrum from a received signal and a known reference signal; b. means for extracting a virtual array structure from the estimated channel spectrum; and c. means for determining the time delay using the virtual array structure, wherein the determining means comprises: a. means for performing singular value decomposition on the data matrix; b. means for detecting automatically, based on the singular value decomposition results, the number of physical paths; c. means for determining a noise space using the number of physical paths; d. means for determining a projection polynomial using the noise space; e. means for determining at least one root pair by solving the projection polynomial; f. means for mapping the roots to determine a rough intra-symbol delay estimate; and g. means for estimating the intra-symbol delay by removing bias in the rough time delay estimate.

Claim 26

Dependent Claim 141 words

The system recited in claim 18 , a. wherein the mapping means comprises: i. means for selecting, for each root pair, the constituent root closest to the unit circle when plotted on the complex plane; ii. means for determining, for each constituent root selected, a delay according to the formula: τ = min [  arctan  Re ( r M + 1 - i ) im ( r M + 1 - i )  2   π   Δ ] for each physical path i, where τ=TOAF, r=roots, Re=real part, im=imaginary and Δ is predetermined. iii. means for determining the rough time delay estimate by selecting the shortest delay; and b. wherein the estimating means comprises: i. means for determining the time delay estimate by modifying the rough time delay using a predetermined, empirical multipath compensation factor.

Claim 27

Dependent Claim 15 words

The system recited in claim 19 , wherein the time delay is an intra-symbol delay.

Claim 28

Dependent Claim 39 words

The system recited in claim 20 further comprising: a. a framer for estimating a inter-symbol delay using the received signal; and b. a summer for combining the inter-symbol-delay and the intrasymbol delay to produce a time of arrival estimate.

Claim 29

Dependent Claim 74 words

The system recited in claim 21 , the system further comprising: a. a matched filter for matched filtering an input signal to produce a filtered signal; b. a data buffer for buffering the filtered signal and for adding a global positioning system time stamp to the filtered signal to produce a buffered signal; and c. a carrier frequency offset compensator for compensating for carrier offset in the buffered signal to produce the received signal.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	2005-12-09	2006-06-10	2006-12-10	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	2009-12-09	2010-06-10	2010-12-10	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	2013-12-09	2014-06-10	2014-12-10	$7700.00	Window Closed / Lapsed

System and method for estimating signal time of arrival

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