US5524124A
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Multiple-filter equalizer for structured digitally modulated signals
Assignee: Exelis Inc
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Filing: 1993-11-17
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Granted: 1996-06-04
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Expires: 2013-11-17
Abstract
Abstract An equalization and demodulation method for a structured digitally modulated signal provides a multiple filter equalizer, which comprises multiple, parallel, automatically adjustable processors. The multiple filter equalizer is applicable to a structured digitally modulated signal, such as a signal from time division multiplexing (TDM) of multiple data sources. The multiple filter equalizer exploits the repetitive structure of TDM signal data by employing multiple parallel processors each constructed according to the specific requirements at the position in the frame of a symbol to be demodulated. Each processor comprises one or more adaptive digital transversal filters, one or more nonlinear threshold operators, and a symbol decision operator. The transversal filters equalize the data, remove interfering signals, reduce intersymbol interference, and mitigate multipath and other propagation effects. After the samples corresponding to one frame of information symbols are equalized in parallel, the equalized samples are demodulated in parallel to generate demodulated information symbols for that frame. The method is applicable to adaptive equalization both with and without a known training sequence.
Inventors
- 👤 Carolyn T. Koenig
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 19:58
CPC Classifications
H; H04; H04L; H04L25/00; H04L25/02; H04L25/03; H04L25/03006; H04L25/03012; H04L25/03019; H04L25/03038
Claims Analysis
Total Claims: 32
Claim 1
Independent Claim
102 words
A structure for equalizing and demodulating a structured signal, said structured signal having a predetermined number of symbols transmitted in a frame, said structure comprising a separate processor for each symbol position in said frame, each processor comprising: a transversal digital filter computing a weighted sum of a predetermined number of samples of said structured signal and providing said weighted sum as an equalized sample; and a decision device, coupled to receive said equalized sample, for determining from said equalized sample, independently of symbol decisions at other symbol positions in said frame, a symbol transmitted at said symbol position in said frame.
Claim 2
Dependent Claim
102 words
A structure for equalizing and demodulating a structured signal, said structured signal having a predetermined number of symbols transmitted in a frame, said structure comprising a separate processor for each symbol position in said frame, each processor comprising: a transversal digital filter computing a weighted sum of a predetermined number of samples of said structured signal and providing said weighted sum as an equalized sample; and a decision device, coupled to receive said equalized sample, for determining from said equalized sample, independently of symbol decisions at other symbol positions in said frame, a symbol transmitted at said symbol position in said frame.
Claim 3
Dependent Claim
36 words
A structure as in claim 1, wherein each processor further comprises means, coupled to receive one or more of said samples, said symbol and said weighted sum, for updating the weights of said transversal digital filter.
Claim 4
Dependent Claim
30 words
A structure as in claim 1, wherein each processor further comprises means, coupled to receive said symbol and said weighted sum, for correcting a phase error in said weighted sum.
Claim 5
Dependent Claim
96 words
A structure as in claim 1, wherein, within each processor, each transversal filter is one of a plurality of transversal filters in a first level structure of said processor, said processor further comprising: a plurality of non-linear operators, each non-linear operator operating on an output value of a corresponding one of said plurality of transversal filters to provide a first level equalized output value; and a transversal digital filter in a second level structure receiving said first level equalized output values for computing a weighted sum of said equalized output values to obtain said equalized sample.
Claim 6
Dependent Claim
17 words
A structure as in claim 2, wherein said weights are updated in accordance with an adaptive algorithm.
Claim 7
Dependent Claim
17 words
A structure as in claim 4, wherein said weights are updated in accordance with a backpropagation algorithm.
Claim 8
Dependent Claim
18 words
A structure as in claim 4, wherein said non-linear operators each comprise means for providing a differentiable function.
Claim 9
Independent Claim
97 words
A method for equalizing and demodulating a structured signal, said structured signal having a predetermined number of symbols transmitted in a frame, said method comprises, for each symbol position in said frame, the steps of: computing in a separate transversal digital filter a weighted sum of a predetermined number of samples of said structured signal and providing said weighted sum as an equalized sample; and determining in a decision device, coupled to receive said equalized sample, independently of symbol decisions at other symbol positions in said frame, a symbol transmitted at said symbol position in said frame.
Claim 10
Independent Claim
97 words
A method for equalizing and demodulating a structured signal, said structured signal having a predetermined number of symbols transmitted in a frame, said method comprises, for each symbol position in said frame, the steps of: computing in a separate transversal digital filter a weighted sum of a predetermined number of samples of said structured signal and providing said weighted sum as an equalized sample; and determining in a decision device, coupled to receive said equalized sample, independently of symbol decisions at other symbol positions in said frame, a symbol transmitted at said symbol position in said frame.
Claim 11
Dependent Claim
19 words
A method as in claim 8, further comprising the step of updating the weights of said transversal digital filter.
Claim 12
Dependent Claim
25 words
A method in claim 8, further comprising the step of correcting a phase error in said weighted sum using said symbol and said weighted sum.
Claim 13
Dependent Claim
93 words
A method as in claim 8, wherein said step of computing in a separate transversal digital filter provides a plurality of transversal filters in a first level structure, said method further comprising the steps of: providing a plurality of non-linear operators, each non-linear operator operating on an output value of a corresponding one of said plurality of transversal filters to provide a first level equalized output value; and computing in a transversal digital filter in a second level a weighted sum of said first level equalized output values to obtain said equalized sample.
Claim 14
Dependent Claim
17 words
A method as in claim 9, wherein said weights are updated in accordance with an adaptive algorithm.
Claim 15
Dependent Claim
17 words
A method as in claim 11, wherein said weights are updated in accordance with a backpropagation algorithm.
Claim 16
Dependent Claim
14 words
A method as in claim 11, wherein said non-linear operator applies a differentiable function.
Claim 17
Dependent Claim
129 words
A structure for equalizing and demodulating a structured signal, said structured signal having a predetermined number of symbols transmitted in a frame, said structure comprising a first processor and a second processor, each processor being provided for a corresponding one of a first symbol position and a second symbol position in said frame, each of said first and second processors comprising: a transversal digital filter computing a weighted sum of a predetermined number of samples of said structured signal and providing said weighted sum as an equalized sample; and a decision device, coupled to receive said equalized sample, for determining from said equalized sample, independently of symbol decisions at other symbol positions in said frame, a symbol transmitted at said symbol position corresponding to said processor in said frame.
Claim 18
Dependent Claim
129 words
A structure for equalizing and demodulating a structured signal, said structured signal having a predetermined number of symbols transmitted in a frame, said structure comprising a first processor and a second processor, each processor being provided for a corresponding one of a first symbol position and a second symbol position in said frame, each of said first and second processors comprising: a transversal digital filter computing a weighted sum of a predetermined number of samples of said structured signal and providing said weighted sum as an equalized sample; and a decision device, coupled to receive said equalized sample, for determining from said equalized sample, independently of symbol decisions at other symbol positions in said frame, a symbol transmitted at said symbol position corresponding to said processor in said frame.
Claim 19
Dependent Claim
36 words
A structure as in claim 15, wherein each processor further comprises means, coupled to receive one or more of said samples, said symbol and said weighted sum, for updating the weights of said transversal digital filter.
Claim 20
Dependent Claim
30 words
A structure as in claim 15, wherein each processor further comprises means, coupled to receive said symbol and said weighted sum, for correcting a phase error in said weighted sum.
Claim 21
Dependent Claim
97 words
A structure as in claim 15, wherein, within each processor, each transversal digital filter is one of a plurality of transversal filters in a first level structure of said processor, said processor further comprising: a plurality of non-linear operators, each non-linear operator operating on an output value of a corresponding one of said plurality of transversal filters to provide a first level equalized output value; and a transversal digital filter in a second level structure receiving said first level equalized output values for computing a weighted sum of said equalized output values to obtain said equalized sample.
Claim 22
Dependent Claim
17 words
A structure as in claim 16, wherein said weights are updated in accordance with an adaptive algorithm.
Claim 23
Dependent Claim
17 words
A structure as in claim 18, wherein said weights are updated in accordance with a backpropagation algorithm.
Claim 24
Dependent Claim
18 words
A structure as in claim 18, wherein said non-linear operators each comprise means for providing a differentiable function.
Claim 25
Independent Claim
105 words
A method for equalizing and demodulating a structured signal, said structured signal having a predetermined number of symbols transmitted in a frame, said method comprises, for each of a first symbol position and a second symbol position in said frame, the steps of: computing in a separate transversal digital filter a weighted sum of a predetermined number of samples of said structured signal and providing said weighted sum as an equalized sample; and determining in a decision device, coupled to receive said equalized sample, independently of symbol decisions at other symbol positions in said frame, a symbol transmitted at said symbol position in said frame.
Claim 26
Independent Claim
105 words
A method for equalizing and demodulating a structured signal, said structured signal having a predetermined number of symbols transmitted in a frame, said method comprises, for each of a first symbol position and a second symbol position in said frame, the steps of: computing in a separate transversal digital filter a weighted sum of a predetermined number of samples of said structured signal and providing said weighted sum as an equalized sample; and determining in a decision device, coupled to receive said equalized sample, independently of symbol decisions at other symbol positions in said frame, a symbol transmitted at said symbol position in said frame.
Claim 27
Dependent Claim
19 words
A method as in claim 22, further comprising the step of updating the weights of said transversal digital filter.
Claim 28
Dependent Claim
26 words
A method as in claim 22, further comprising the step of correcting a phase error in said weighted sum using said symbol and said weighted sum.
Claim 29
Dependent Claim
93 words
A method as in claim 22, wherein said step of computing in a separate transversal digital filter provides a plurality of transversal filters in a first level structure, said method further comprising the steps of: providing a plurality of non-linear operators, each non-linear operator operating on an output value of a corresponding one of said plurality of transversal filters to provide a first level equalized output value; and computing in a transversal digital filter in a second level a weighted sum of said first level equalized output values to obtain said equalized sample.
Claim 30
Dependent Claim
17 words
A method as in claim 23, wherein said weights are updated in accordance with an adaptive algorithm.
Claim 31
Dependent Claim
17 words
A method as in claim 25, wherein said weights are updated in accordance with a backpropagation algorithm.
Claim 32
Dependent Claim
14 words
A method as in claim 25, wherein said non-linear operator applies a differentiable function.
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| 7.5 Years (Year 8) | 2003-06-04 | 2003-12-04 | 2004-06-04 | $3760.00 | Window Closed / Lapsed |
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