US5504318A — Analog waveform decoder using peak locations

Claim 1

Independent Claim 82 words

A method for decoding an analog waveform representative of information contained in a symbol, comprising the steps of: storing a group of reference values corresponding to each symbol from an alphabet of possible symbols; processing said analog waveform to find the locations of extrema in said waveform; forming feature values from said extrema locations; decoding said waveform by comparing said feature values to at least two groups of reference values to produce a signal indicative of the information contained in the symbol.

Claim 2

Independent Claim 82 words

A method for decoding an analog waveform representative of information contained in a symbol, comprising the steps of: storing a group of reference values corresponding to each symbol from an alphabet of possible symbols; processing said analog waveform to find the locations of extrema in said waveform; forming feature values from said extrema locations; decoding said waveform by comparing said feature values to at least two groups of reference values to produce a signal indicative of the information contained in the symbol.

Claim 3

Dependent Claim 31 words

The method of claim 1, further comprising determining boundaries of said analog waveform to identify a decodable portion of said waveform, and subsequently processing only said decodable portion of said waveform.

Claim 4

Dependent Claim 55 words

The method of claim 1, further comprising storing a reference array corresponding to each group of reference values representative of information contained in a symbol from an alphabet of possible symbols, and forming a feature array from said extrema locations, wherein said decoding step comprises comparing said feature array to at least two reference arrays.

Claim 5

Dependent Claim 51 words

The method of claim 3, wherein said processing comprises calculating the distances between extrema in said analog waveform and storing said distances as elements in said feature array, wherein elements of each reference array for a symbol correspond to the distances between extrema in the analog waveform representative of the symbol.

Claim 6

Dependent Claim 16 words

The method of claim 4, further comprising normalizing each said reference array and said feature array.

Claim 7

Dependent Claim 22 words

The method of claim 5, wherein said decoding comprises calculating a distance metric from said feature array and one said reference array.

Claim 8

Dependent Claim 36 words

The method of claim 6, wherein said decoding further comprises matching said feature array to a reference array based on how close the feature array is to the reference array in terms of said distance metric.

Claim 9

Dependent Claim 35 words

The method of claim 7, wherein said decoding comprises matching a feature array to two reference arrays if a distance defined by said distance metric to both of said two reference arrays is substantially identical.

Claim 10

Dependent Claim 43 words

The method of claim 7, wherein said decoding comprises matching said feature to either a reference array or labeling said feature array as unclassified, and wherein said distance metric contains a threshold controlling a rate at which feature arrays are labeled as unclassified.

Claim 11

Dependent Claim 52 words

The method of claim 9, wherein said decoding comprises matching said feature array to either one reference array, to two reference arrays, or labeling said feature array as unclassified, and wherein said distance metric contains a second threshold that controls a level of confidence in a match to only one reference array.

Claim 12

Dependent Claim 22 words

The method of claim 3, wherein said step of storing comprises storing at least one said reference array in a training sequence.

Claim 13

Dependent Claim 23 words

The method of claim 3, wherein said step of storing comprises storing at least one said reference array directly from a known symbology.

Claim 14

Dependent Claim 24 words

The method of claim 1, wherein said processing comprises deblurring the analog waveform to produce an estimator function used in finding the extrema locations.

Claim 15

Dependent Claim 30 words

The method of claim 13, wherein said analog waveform is the convolution of a symbol pattern with a second function, and said deblurring is performed by deconvolving said analog waveform.

Claim 16

Dependent Claim 16 words

The method of claim 14, wherein said deblurring comprises a partial deconvolution of said analog waveform.

Claim 17

Dependent Claim 17 words

The method of claim 14, further comprising estimating said second function from said analog waveform before deconvolving.

Claim 18

Dependent Claim 21 words

The method of claim 16, wherein said estimation comprises estimating a standard deviation of said second function from said analog waveform.

Claim 19

Dependent Claim 20 words

The method of claim 13, wherein said processing comprises finding a zero crossing of a derivative of said estimator function.

Claim 20

Dependent Claim 42 words

The method of claim 18, wherein said processing comprises removing noise prior to finding the extrema locations, wherein the noise removal comprises establishing a threshold, and removing all extrema in the derivative of said estimator function with magnitude less than said threshold.

Claim 21

Dependent Claim 23 words

The method of claim 19, further comprising forming a histogram of extrema magnitudes and choosing the threshold at a trough in the histogram.

Claim 22

Dependent Claim 34 words

The method of claim 19, further comprising estimating a standard deviation of noise in the derivative of the estimator function, and choosing a threshold above or equal to said standard deviation of the noise.

Claim 23

Dependent Claim 49 words

The method of claim 21, further comprising estimating a standard deviation of noise in the derivative of the estimator function, and choosing the threshold as the standard deviation if said standard deviation coincides with a trough in said histogram, otherwise choosing a second trough greater than said standard deviation.

Claim 24

Dependent Claim 25 words

The method of claim 21 or 22 wherein said standard deviation is estimated from a root mean square of the derivative of the estimator function.

Claim 25

Dependent Claim 44 words

The method of claim 18, wherein said step of processing includes sampling and interpolating said analog waveform prior to finding said extrema locations, and wherein said processing is repeated if said waveform is unsuccessfully decoded to further smooth the waveform in a second interpolation.

Claim 26

Dependent Claim 19 words

The method of claim 1, wherein said processing comprises finding zero crossings of a derivative of said analog waveform.

Claim 27

Dependent Claim 29 words

The method of claim 25 or 18, wherein said processing further comprises passing said analog waveform through a low pass filter before taking said derivative to further reduce noise.

Claim 28

Dependent Claim 26 words

Claim 26, wherein the cutoff frequency of said low pass filter is chosen as half the inverse of the smallest extrema width in the analog waveform.

Claim 29

Dependent Claim 42 words

The method of claim 25, wherein said processing comprises removing noise prior to finding the extrema locations, wherein the noise removal comprises establishing a threshold, and removing all extrema in the derivative of said analog waveform with magnitude less than said threshold.

Claim 30

Dependent Claim 23 words

The method of claim 28, further comprising forming a histogram of extrema magnitudes and choosing the threshold at a trough in the histogram.

Claim 31

Dependent Claim 49 words

The method of claim 29, further comprising estimating a standard deviation of noise in the derivative of the analog waveform, and choosing the threshold as the standard deviation if said standard deviation coincides with a trough in said histogram, otherwise choosing a second trough greater than said standard deviation.

Claim 32

Dependent Claim 34 words

The method of claim 28, further comprising estimating a standard deviation of noise in the derivative of the analog waveform, and choosing a threshold above or equal to said standard deviation of the noise.

Claim 33

Dependent Claim 25 words

The method of claim 31 or 30 wherein said standard deviation is estimated from a root mean square of the derivative of the analog waveform.

Claim 34

Dependent Claim 17 words

The method of claim 1, wherein said processing comprises removing noise prior to finding the extrema locations.

Claim 35

Dependent Claim 42 words

The method of claim 1, wherein said processing includes sampling and interpolating said analog waveform, prior to finding said extrema locations, and wherein said processing is repeated if said waveform is unsuccessfully decoded to further smooth the waveform in a second interpolation.

Claim 36

Independent Claim 174 words

A method for decoding an analog waveform representative of information contained in a symbol comprising the steps of: storing a reference array corresponding to each symbol from an alphabet of possible symbols, wherein the elements of each reference array for a symbol correspond to the distances between extrema in the analog waveform representative of the symbol; determining boundaries of said analog waveform to identify a decodable portion of said waveform, processing said decodable portion to find locations of extrema in said decodable portion of said waveform, comprising deblurring the analog waveform to find an estimator function, taking a derivative of the estimator function, removing noise from the derivative of the estimator function, finding the extrema locations from the zero crossings of the estimator function; forming a feature array from said extrema locations by calculating the distances between said extrema, assigning said distances to elements of said feature array; and decoding said waveform by comparing said feature array to each said reference array to produce a signal indicative of the information contained in the symbol.

Claim 37

Independent Claim 174 words

A method for decoding an analog waveform representative of information contained in a symbol comprising the steps of: storing a reference array corresponding to each symbol from an alphabet of possible symbols, wherein the elements of each reference array for a symbol correspond to the distances between extrema in the analog waveform representative of the symbol; determining boundaries of said analog waveform to identify a decodable portion of said waveform, processing said decodable portion to find locations of extrema in said decodable portion of said waveform, comprising deblurring the analog waveform to find an estimator function, taking a derivative of the estimator function, removing noise from the derivative of the estimator function, finding the extrema locations from the zero crossings of the estimator function; forming a feature array from said extrema locations by calculating the distances between said extrema, assigning said distances to elements of said feature array; and decoding said waveform by comparing said feature array to each said reference array to produce a signal indicative of the information contained in the symbol.

Claim 38

Dependent Claim 103 words

An analog waveform decoder that operates upon an analog waveform representative of a symbol for decoding information in said symbol, said analog waveform decoder comprising: a memory holding reference values, each group of reference values corresponding to a symbol from an alphabet of possible symbols; a processor for analyzing said analog waveform to find locations of extrema in said waveform, said processor producing feature values for said waveform from said extrema locations, wherein said processor decodes said waveform by comparing said feature values to at least two groups of reference values to produce a signal indicative of the information contained in the symbol.

Claim 39

Dependent Claim 103 words

An analog waveform decoder that operates upon an analog waveform representative of a symbol for decoding information in said symbol, said analog waveform decoder comprising: a memory holding reference values, each group of reference values corresponding to a symbol from an alphabet of possible symbols; a processor for analyzing said analog waveform to find locations of extrema in said waveform, said processor producing feature values for said waveform from said extrema locations, wherein said processor decodes said waveform by comparing said feature values to at least two groups of reference values to produce a signal indicative of the information contained in the symbol.

Claim 40

Dependent Claim 32 words

The decoder of claim 36, wherein said processor determines boundaries of said analog waveform to identify a decodable portion of said waveform, and subsequently analyzes only said decodable portion of said waveform.

Claim 41

Dependent Claim 61 words

The method of claim 36 further comprising a memory holding reference arrays, each reference array corresponding to a group of reference values representative of information contained in a symbol from an alphabet of possible symbols, wherein said processor forms a feature array from said extrema locations and decodes said waveform by comparing said feature array to at least two reference arrays.

Claim 42

Dependent Claim 50 words

The decoder of claim 38 wherein said processor calculates the distances between extrema in said analog waveform and stores said distances as elements in said feature array, wherein elements of each reference array for a symbol correspond to the distances between extrema in the analog waveform representative of the symbol.

Claim 43

Dependent Claim 16 words

The decoder of claim 39, wherein said feature array and each said reference array are normalized.

Claim 44

Dependent Claim 25 words

The decoder of claim 40, wherein said processor decodes said waveform by calculating a distance metric from said feature array and one said reference array.

Claim 45

Dependent Claim 38 words

The decoder of claim 41, wherein said processor decodes said waveform by matching said feature array to a reference array based on how close said feature array is to said reference array in terms of said distance metric.

Claim 46

Dependent Claim 47 words

The decoder of claim 42, wherein said processor matches said feature array to two reference arrays if a distance defined by said distance metric to both of said two reference arrays is substantially identical and said distance is smaller than a distance to any other reference array.

Claim 47

Dependent Claim 43 words

The decoder of claim 42, wherein said processor matches said feature array either to a reference array or labels said feature array as unclassified, and wherein said distance metric contains a threshold controlling a rate at which feature arrays are labeled as unclassified.

Claim 48

Dependent Claim 51 words

The decoder of claim 44, wherein said processor matches said feature array to either one reference array, to two reference arrays, or labels said feature array as unclassified, and wherein said distance metric contains a second threshold that controls a level of confidence in a match to only one reference array.

Claim 49

Dependent Claim 13 words

The decoder of claim 39, wherein said processor partially deconvolves said analog waveform.

Claim 50

Dependent Claim 18 words

The method of claim 46, wherein said processor estimates said second function from said analog waveform before deconvolving.

Claim 51

Dependent Claim 25 words

The decoder of claim 47, wherein said processor estimates said second function by estimating a standard deviation of said second function from said analog waveform.

Claim 52

Dependent Claim 20 words

The decoder of claim 38 wherein said reference storage comprises at least one reference array stored in a training sequence.

Claim 53

Dependent Claim 22 words

The decoder of claim 38 wherein said reference storage comprises at least one said reference array stored directly from a known symbology.

Claim 54

Dependent Claim 23 words

The decoder of claim 36, wherein said processor deblurs the analog waveform to produce an estimator function used in finding the extrema locations.

Claim 55

Dependent Claim 32 words

The decoder of claim 51, wherein said analog waveform is the convolution of a symbol pattern with a second function, and said processor deblurs said analog waveform by deconvolving said analog waveform.

Claim 56

Dependent Claim 23 words

The decoder of claim 51 wherein said processor finds a zero crossing of a derivative of said estimator function to locate said extrema.

Claim 57

Dependent Claim 47 words

The method of claim 53, wherein said processor removes noise from said analog waveform prior to finding the extrema locations, wherein the processor removes the noise by establishing a threshold, and removing all extrema in the derivative of said estimator function with magnitude less than said threshold.

Claim 58

Dependent Claim 24 words

The method of claim 54, wherein said processor forms a histogram of extrema magnitudes and chooses the threshold at a trough in the histogram.

Claim 59

Dependent Claim 35 words

The decoder of claim 54, wherein said processor estimates a standard deviation of noise in the derivative of the estimator function, and chooses a threshold above or equal to said standard deviation of the noise.

Claim 60

Dependent Claim 51 words

The decoder of claim 56, wherein said processor estimates a standard deviation of noise in the derivative of the estimator function, and chooses the threshold as the standard deviation if said standard deviation coincides with a trough in said histogram, and otherwise chooses a second trough greater than said standard deviation.

Claim 61

Dependent Claim 26 words

The decoder of claim 56 or 57 wherein said processor estimates said standard deviation from a root mean square of the derivative of the estimator function.

Claim 62

Dependent Claim 46 words

The decoder of claim 53 wherein processor samples and interpolates said analog waveform prior to finding said extrema locations, and wherein said processor interpolates said waveform a second time to further smooth the waveform before reprocessing if said waveform is unsuccessfully decoded in a first analysis.

Claim 63

Dependent Claim 25 words

The decoder of claim 36, wherein said processor finds zero crossings of a derivative of said analog waveform to locate the extrema of said waveform.

Claim 64

Dependent Claim 40 words

The decoder of claim 60, wherein said processor removes noise from said waveform prior to finding the extrema locations by establishing a threshold, and removing all extrema in the derivative of said analog waveform with magnitude less than said threshold.

Claim 65

Dependent Claim 24 words

The decoder of claim 61, wherein said processor forms a histogram of extrema magnitudes and chooses the threshold at a trough in the histogram.

Claim 66

Dependent Claim 35 words

The decoder of claim 62, wherein said processor estimates a standard deviation of noise in the derivative of the analog waveform, and chooses a threshold above or equal to said standard deviation of the noise.

Claim 67

Dependent Claim 34 words

The decoder of claim 60 or 63, wherein said decoder further comprises a low pass filter that filters said analog waveform before said processor takes said derivative of said waveform to further reduce noise.

Claim 68

Dependent Claim 26 words

The decoder of claim 64, wherein a cutoff frequency of said low pass filter half an inverse of the smallest extrema width in the analog waveform.

Claim 69

Dependent Claim 51 words

The decoder of claim 62, wherein said processor estimates a standard deviation of noise in the derivative of the analog waveform, and chooses the threshold as the standard deviation if said standard deviation coincides with a trough in said histogram, and otherwise chooses a second trough greater than said standard deviation.

Claim 70

Dependent Claim 26 words

The decoder of claim 63 or 66 wherein said processor estimates said standard deviation from a root mean square of the derivative of the analog waveform.

Claim 71

Dependent Claim 19 words

The decoder of claim 36, wherein said processor removes noise from said waveform prior to finding the extrema locations.

Claim 72

Dependent Claim 47 words

The decoder of claim 36, wherein said processor samples and interpolates said analog waveform prior to finding said extrema locations, and wherein said processor interpolates said waveform a second time to further smooth the waveform before reprocessing if said waveform is unsuccessfully decoded in a first analysis.

Claim 73

Dependent Claim 189 words

An analog waveform decoder that operates directly on an analog waveform representative of a symbol, for decoding information in said symbol, said decoder comprising: reference storage for storing a reference array corresponding to each symbol from an alphabet of possible symbols, wherein the elements of each reference array for a symbol correspond to the distances between extrema in the analog waveform representative of the symbol; a processor for determining boundaries of said analog waveform to identify a decodable portion of said waveform, and processing said decodable portion to find locations of extrema in said decodable portion of said waveform, said processing comprising deblurring the analog waveform to find an estimator function, taking a derivative of the estimator function, removing noise from the derivative of the estimator function, finding the extrema locations from the zero crossings of the estimator function; forming a feature array from said extrema locations by calculating the distances between said extrema, assigning said distances to elements of said feature array; and decoding said waveform by comparing said feature array to each said reference array to produce a signal indicative of the information contained in the symbol.

Claim 74

Dependent Claim 189 words

An analog waveform decoder that operates directly on an analog waveform representative of a symbol, for decoding information in said symbol, said decoder comprising: reference storage for storing a reference array corresponding to each symbol from an alphabet of possible symbols, wherein the elements of each reference array for a symbol correspond to the distances between extrema in the analog waveform representative of the symbol; a processor for determining boundaries of said analog waveform to identify a decodable portion of said waveform, and processing said decodable portion to find locations of extrema in said decodable portion of said waveform, said processing comprising deblurring the analog waveform to find an estimator function, taking a derivative of the estimator function, removing noise from the derivative of the estimator function, finding the extrema locations from the zero crossings of the estimator function; forming a feature array from said extrema locations by calculating the distances between said extrema, assigning said distances to elements of said feature array; and decoding said waveform by comparing said feature array to each said reference array to produce a signal indicative of the information contained in the symbol.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1999-04-02	1999-10-02	2000-04-02	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	2003-04-02	2003-10-02	2004-04-02	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	2007-04-02	2007-10-02	2008-04-02	$7700.00	Window Closed / Lapsed

Analog waveform decoder using peak locations

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