Echo measurement arrangement
First Claim
1. Apparatus for ranging and converging on at least one of a plurality of echoes occurring at respective locations along a communications line comprisingmeans for storing in a memory samples of a signal that is being transmitted to said communications line and samples of a signal that is being simultaneously received from said communications line,at least one filtering means having respective coefficients for filtering overlapping sequences of said stored samples of said transmitted signal into a plurality of filtered signals, said one filtering means including means for changing the values of said respective coefficients as a function of each of said filtered signals and respective signals representative of respective ones of said stored received signal samples and for freezing the values of said coefficients when they reach respective final values as an indication that said one filtering means has converged on said at least one echo, andmeans for determining the propagation delay associated with said at least one echo as a function of the effective number of said transmitted signal samples that are filtered up to the point at which said coefficients reach their respective final values.
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Accused Products
Abstract
A digital signal processor is provided with the facility to range and converge on each of a plurality of echoes occurring at respective locations along a communications line. Specifically, the digital signal processor is arranged to adaptively process samples of a signal that has been transmitted to the communications line correlated with samples of a signal that have been received from the communications line. In the processing of the samples, the digital signal processor separates and measures the magnitude of each echo that it converges on, beginning with a so-called near-end echo. In addition, the digital signal processor calculates the propagation delay of each echo that it converges on using the number of sampling intervals that have been processed in order to position the processor on the dispersion of that echo.
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Citations
10 Claims
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1. Apparatus for ranging and converging on at least one of a plurality of echoes occurring at respective locations along a communications line comprising
means for storing in a memory samples of a signal that is being transmitted to said communications line and samples of a signal that is being simultaneously received from said communications line, at least one filtering means having respective coefficients for filtering overlapping sequences of said stored samples of said transmitted signal into a plurality of filtered signals, said one filtering means including means for changing the values of said respective coefficients as a function of each of said filtered signals and respective signals representative of respective ones of said stored received signal samples and for freezing the values of said coefficients when they reach respective final values as an indication that said one filtering means has converged on said at least one echo, and means for determining the propagation delay associated with said at least one echo as a function of the effective number of said transmitted signal samples that are filtered up to the point at which said coefficients reach their respective final values.
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4. A filter circuit for ranging and converging on each of a plurality of echoes occurring at respective locations along a communications line comprising
means for storing in a memory samples of a signal that is being transmitted to said communications line and samples of a signal that is being simultaneously received from said communications line, and a plurality of filtering means each having a respective group of filter coefficients, each of said filtering means being arranged to generate a filtered signal by sequentially and iteratively filtering respective overlapping sequences of said transmitted signal samples supplied to its input, a first one of said filtering means receiving at another input a respective sequence of said received signal samples and other ones of said filtering means each receiving at its other input an error signal outputted by a respective preceding one of said filtering means, said first one of said filtering means generating its error signal as a function of the value of its respective filtered signal and a respective one of said received signal samples and each of said other ones of said filtering means generating its error signal as a function of the value of its respective filtered signal and the value of the error signal that it receives at its other input, each of said filtering means converging on a respective one of said echoes by changing the values of its respective coefficients as a function of the current value of the error signal that it generates and freezing said values when the value of said error signal that it generates reaches a minimum.
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10. A method for ranging and converging on at least one of a plurality of echoes occurring at respective locations along a communications line, said method comprising the steps of
storing in a memory samples of a signal that is being transmitted to said communications line and samples of a signal that is being simultaneously received from said communications line, filtering overlapping sequences of said stored samples of said transmitted signal into a plurality of filtered signals using at least one filtering means having a plurality of respective coefficients, changing the values of said respective coefficients as a function of each of said filtered signals and respective signals representative of respective ones of said stored received signal samples, freezing the values of said coefficients when they reach respective final values as an indication that said one filtering mean has converged on said at least one echo, and determining the propagation delay associated with said at least one echo as a function of the effective number of said transmitted signal samples that have been filtered up to the point at which said coefficients reach their respective final values.
Specification