US4958361A
Expired / Lapsed
US
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Edge effect reduction by smoothing in digital receivers
Assignee: Raytheon Co
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Filing: 1988-04-22
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Granted: 1990-09-18
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Expires: 2008-04-22
Abstract
Abstract A method for reducing interchannel noise or spectral splatter in fast fourier transform processing of digital data. Data is buffered and processed along two paths. During processing along the first path, a sharp discontinous edge is detected. Weights are applied to data samples around the edge to smooth the discontinuity. When the edge is processed by fourier transform methods, the sharp edge no longer causes broad band interchannel noise.
Inventors
- 👤 Robert A. Rosen
- 👤 Kapriel A. Krikorian
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 06:35
CPC Classifications
H; H03; H03H; H03H17/00; H03H17/02
Claims Analysis
Total Claims: 25
Claim 1
Independent Claim
80 words
A method for reducing spectral splatter in a signal processor comprising: processing digital data along two paths; along the first of said two paths determining when said data comprises an edge; and when said edge is determined in said first path, applying weights to said edge in said second path, said weights, when applied to said edge, tending to reduce said spectral splatter and tending to limit said edge to a narrow bandwidth when the weighted edge is spectrally analyzed.
Claim 2
Independent Claim
80 words
A method for reducing spectral splatter in a signal processor comprising: processing digital data along two paths; along the first of said two paths determining when said data comprises an edge; and when said edge is determined in said first path, applying weights to said edge in said second path, said weights, when applied to said edge, tending to reduce said spectral splatter and tending to limit said edge to a narrow bandwidth when the weighted edge is spectrally analyzed.
Claim 3
Independent Claim
124 words
A method for reducing spectral splatter in a signal receiver comprising the steps of: receiving signal data in digital form; processing said data along two paths; along the first of said paths, converting said digital data to real-valued data; determining when a series of said real-valued data comprise an edge; along the second of said paths, delay buffering said digital data; along the second of said paths, determining the weighting values for applying to said detected edges; and in said second of said paths, applying said weighting values to said detected edges while said digital data traverses said second path, said weighting values, when applied to said edge, tending to reduce said spectral splatter and tending to limit said edge to a narrow bandwidth.
Claim 4
Independent Claim
124 words
A method for reducing spectral splatter in a signal receiver comprising the steps of: receiving signal data in digital form; processing said data along two paths; along the first of said paths, converting said digital data to real-valued data; determining when a series of said real-valued data comprise an edge; along the second of said paths, delay buffering said digital data; along the second of said paths, determining the weighting values for applying to said detected edges; and in said second of said paths, applying said weighting values to said detected edges while said digital data traverses said second path, said weighting values, when applied to said edge, tending to reduce said spectral splatter and tending to limit said edge to a narrow bandwidth.
Claim 5
Dependent Claim
30 words
A method for reducing spectral splatter as claimed in claim 2 further comprising: selecting said weighting values so as to reduce said spectral splatter when said data is spectrally analyzed.
Claim 6
Dependent Claim
13 words
Method as claimed in claim 2 further comprising receiving signals comprising electromagnetic waves.
Claim 7
Dependent Claim
16 words
Method as claimed in claim 2 further comprising converting received analog signal data into digital form.
Claim 8
Dependent Claim
18 words
Method as claimed in claim 2 further comprising processing said weighted data by performing a Fast Fourier Transform.
Claim 9
Dependent Claim
100 words
Method as claimed in claim 2 wherein determining when a series of said real-valued data comprise an edge includes: calculating b j 's from said real-valued data labeled a j ; and determining when one of said b j 's is greater than its two nearest neighbors, b j-1 and b j+1 , and is greater than a threshold value t j such that a j comprises an edge, wherein b j is the weighted offset value at data point j for which an edge test is performed, and a j is the magnitude of the data at point j.
Claim 10
Dependent Claim
64 words
Method as claimed in claim 7 wherein calculating b j includes: calculating a first sum of 2m+1 said a j 's around a j+n ; calculating a second sum of 2m+1 said a j 's around a j-n ; and subtracting said second sum from said first sum, wherein m is defined as the summation bound for calculated weighted offset values b j .
Claim 11
Dependent Claim
97 words
Method as claimed in claim 7 further comprising forming a threshold value t j by: calculating a first sum of 2m+1 said a j 's around a j+n ; calculating a second sum of 2m+1 said a j 's around a j-n ; and letting t j equal a number S times the minimum of said first sum of said second sum, wherein m is defined as the summation bound for calculated weighted offset values b j , n is defined as an offset value, and S is defined as the relative sensitivity for thresholding said edge.
Claim 12
Independent Claim
100 words
An apparatus for reducing spectral splatter in a signal receiver comprising: means for receiving signal data in digital form; means for converting said data into real-valued data; means for determining when a series of said real-valued data comprise an edge; means for delaying a second set of said signal data until said converting means and said determining means have finished processing said signal data; and means for applying weighting values to said edges in said second set of said signal data, said weighting values tending to reduce said spectral splatter and tending to limit said edge to a narrow bandwidth.
Claim 13
Independent Claim
100 words
An apparatus for reducing spectral splatter in a signal receiver comprising: means for receiving signal data in digital form; means for converting said data into real-valued data; means for determining when a series of said real-valued data comprise an edge; means for delaying a second set of said signal data until said converting means and said determining means have finished processing said signal data; and means for applying weighting values to said edges in said second set of said signal data, said weighting values tending to reduce said spectral splatter and tending to limit said edge to a narrow bandwidth.
Claim 14
Dependent Claim
13 words
Apparatus as claimed in claim 10 wherein said signal comprises an electromagnetic wave.
Claim 15
Dependent Claim
19 words
Apparatus as claimed in claim 10 wherein said means for receiving signal data comprises an analog to digital converter.
Claim 16
Dependent Claim
29 words
Apparatus as claimed in claim 10 wherein said weighting values reduce said spectral splatter when said data with said weighting values applied to each of said edges is processed.
Claim 17
Dependent Claim
30 words
Apparatus as claimed in claim 10 further comprising means for processing said weighted signal data, and wherein said means for processing said weighted signal data comprises a Fast Fourier Transform.
Claim 18
Independent Claim
190 words
A method for reducing spectral splatter in a signal receiver comprising the steps of: receiving signal data in digital form; processing said data along two paths; along the first of said two paths, converting said digital data to real-value data; determining when a series of said real-value data comprise an edge including calculation b j 's from said real-value data labeled a j ; and determining when one of said b j 's is greater than its two nearest neighbors b j -l and b j +1, and is greater than a threshold value t j such that a j comprises an edge, wherein b j is the weighted offset value at data point j for which an edge test is performed, a j is the magnitude of the data at point j , and j is a point in the data at which an edge appears; along the second of said paths, delay buffering said digital data; determining weighting values for applying to said detected edges; and, in the second of said paths, applying said weighting values to said detected edges while said digital data traverses said second path.
Claim 19
Independent Claim
190 words
A method for reducing spectral splatter in a signal receiver comprising the steps of: receiving signal data in digital form; processing said data along two paths; along the first of said two paths, converting said digital data to real-value data; determining when a series of said real-value data comprise an edge including calculation b j 's from said real-value data labeled a j ; and determining when one of said b j 's is greater than its two nearest neighbors b j -l and b j +1, and is greater than a threshold value t j such that a j comprises an edge, wherein b j is the weighted offset value at data point j for which an edge test is performed, a j is the magnitude of the data at point j , and j is a point in the data at which an edge appears; along the second of said paths, delay buffering said digital data; determining weighting values for applying to said detected edges; and, in the second of said paths, applying said weighting values to said detected edges while said digital data traverses said second path.
Claim 20
Dependent Claim
63 words
The method of claim 15 wherein calculating b j includes: calculating a first sum of 2m+1 said a j 's around a j+n ; calculating a second sum of 2m+1 said a j 's around a j-n ; and subtracting said second sum from said first sum, wherein m is defined as the summation bound for calculated weighted offset values b j .
Claim 21
Dependent Claim
96 words
The method of claim 15 further comprising forming a threshold value t j by: calculating a first sum of 2m+1 said a j's around a j+n ; calculating a second sum of 2m+1 said a j 's around a j-n ; and letting t j equal a number S times the minimum of said first sum and of said second sum, wherein m is defined as the summation bound for calculated weighted offset values b j , n is defined as an offset value, and S is defined as the relative sensitivity for thresholding said edge.
Claim 22
Independent Claim
151 words
An apparatus for reducing spectral splatter in a signal receiver comprising: means for receiving signal data in digital form; means for converting said data into real-valued data; means for determining when a series of said real-valued data comprise an edge, including: means for calculating b j 's from said real-valued data labeled a j ; means for determining when one of said b j 's is greater than its two nearest neighbors b j -1 and b j +1, and is greater than a threshold value t j such that a j comprises an edge, wherein b j is the weighted offset value at data point j for which an edge test is performed, a j is magnitude of the data at point j , and j is a point in the data at which an edge appears; and means for applying weighting values to said edges of said signal data.
Claim 23
Independent Claim
151 words
An apparatus for reducing spectral splatter in a signal receiver comprising: means for receiving signal data in digital form; means for converting said data into real-valued data; means for determining when a series of said real-valued data comprise an edge, including: means for calculating b j 's from said real-valued data labeled a j ; means for determining when one of said b j 's is greater than its two nearest neighbors b j -1 and b j +1, and is greater than a threshold value t j such that a j comprises an edge, wherein b j is the weighted offset value at data point j for which an edge test is performed, a j is magnitude of the data at point j , and j is a point in the data at which an edge appears; and means for applying weighting values to said edges of said signal data.
Claim 24
Dependent Claim
72 words
The apparatus of claim 18 further comprising means for calculating b j including means for calculating a first sum of 2m+1 said a j 's around a j+n ; means for calculating a second sum of 2m+1 said a j 's around a j-n ; and means for subtracting said second sum from said first sum, wherein m is defined as the summation bound for calculated weighted offset values b j .
Claim 25
Dependent Claim
99 words
The apparatus of claim 19 further comprising means for forming a threshold value t j by: calculating a first sum of 2m+1 said a j 's around a j+n ; calculating a second sum of 2m+1 said a j 's around a j-n ; and letting t j equal a number S times the minimum of said first sum and of said second sum, wherein m is defined as the summation bound for calculated weighted offset values b j , n is defined as an offset value, and S is defined as the relative sensitivity for thresholding said edge.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
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| 3.5 Years (Year 4) | 1993-09-17 | 1994-03-19 | 1994-09-18 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-09-17 | 1998-03-19 | 1998-09-18 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-09-17 | 2002-03-19 | 2002-09-18 | $7700.00 | Window Closed / Lapsed |