Multiple-filter equalizer for structured digitally modulated signals
First Claim
1. 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.
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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.
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Citations
28 Claims
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1. 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:
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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. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. 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:
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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. - View Dependent Claims (9, 10, 11, 12, 13, 14)
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15. 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:
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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. - View Dependent Claims (16, 17, 18, 19, 20, 21)
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22. 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:
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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. - View Dependent Claims (23, 24, 25, 26, 27, 28)
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Specification