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US 6,816,575 B2Granted
Single ended loop loss measurement by frequency domain reflectometry-based signal processing
AssigneeHarris Corporation
InventorsAlan Blair Lowell, Travis Lee Berrier
Life of this patent
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Abstract
A single ended, frequency domain reflectometry signal processing based scheme measures loop loss of a telecommunications wireline. A distortion-corrected, normalized data array is differentially combined with an associated set of wireline noise spectrum values. The resulting noise margin data is processed by a Shannon Theorem operator, to produce a set of N frequency bins, each containing the number of bits which the link will support for a respective tone. The bit contents of the bins represent a composite bit rate that is available for use for ADSL signalling.
Claims6
A method of deriving a measure of signal transport loss of a wireline telecommunication link comprising the steps of:
- (a) coupling a varying frequency waveform of a prescribed bandwidth to a first location of said wireline telecommunication link;
- (b) at said first location of said wireline telecommunication link, measuring variations in signal level response in association respective frequencies of said varying frequency waveform;
- and
- (c) generating a measure of said signal transport loss over said prescribed bandwidth based upon said variations in signal level response measured in step (b), wherein step (c) comprises:
- c1—normalizing said variations in signal level response in accordance with reference data representative of simulated characteristics of said line;
- c2—modifying said normalized variations in signal level response to correct for constructive and destructive interference associated with reflections from discontinuities along said wireline, and thereby produce a distortion-corrected normalized signal response;
- c3—differentially combining said distortion-corrected normalized signal response with power spectral density values associated with the type of transceiver employed at a remote end of said wireline, to produce a modified differential data set;
- c4—summing said modified differential data set with a signal-to-noise gap constant required for reliable operation and coding gain values associated with the coding gain of said transceiver, to produce a coding gain-modified data set;
- c5—measuring background noise of said wireline telecommunication link;
- c6—differentially combining said coding gain-modified data set with said background noise measured in step c5, to obtain a set of noise margin data values associated with said respective frequencies of said varying frequency waveform;
- and
- c7—processing said set of noise margin data values obtained in step c6 to produce a set of frequency bins having bit contents which effectively represent a composite bit rate available for digital signal transport over said wireline telecommunication link.
9 more elements
For use with a test device for measuring one or more characteristics of a telecommunication wireline, an arrangement for deriving a measure of signal transport loss of said wireline telecommunication link comprising:
- a signal interface for coupling signals to and receiving signals from a single-ended location of said telecommunication wireline;
- and
- a digitally controlled signal generation and response measurement unit, which is coupled with said signal interface and is operative to perform the following steps:
- (a) supplying a varying frequency waveform of a prescribed bandwidth for to said signal interface and application thereby to said single-ended first location of said wireline telecommunication link;
- and
- (b) processing variations in signal level response, as received by said signal interface in association respective frequencies of said varying frequency waveform, to generate therefrom a measure of said signal transport loss over said prescribed bandwidth, wherein (b) comprises:
- b1—normalizing said variations in signal level response in accordance with reference data representative of simulated characteristics of said line;
- b2—modifying said normalized variations in signal level response to correct for constructive and destructive interference associated with reflections from discontinuities along said wireline, and thereby produce a distortion-corrected normalized signal response;
- b3—differentially combining said distortion-corrected normalized signal response with power spectral density values associated with the type of transceiver employed at a remote end of said wireline, to produce a modified differential data set;
- b4—summing said modified differential data set with a signal-to-noise gap constant required for reliable operation and coding gain values associated with the coding gain of said transceiver, to produce a coding gain-modified data set;
- b5—measuring background noise of said wireline telecommunication link;
- b6—differentially combining said coding gain-modified data set with said background noise measured in step b5, to obtain a set of noise margin data values associated with said respective frequencies of said varying frequency waveform;
- and
- b7—processing said set of noise margin data values obtained in step b6 to produce a set of frequency bins having bit contents which effectively represent a composite bit rate available for digital signal transport over said wireline telecommunication link.
11 more elements
Dependencies are inferred from the claim text.