Reflectometry test system using a sliding pseudo-noise reference
AssigneeUniversity of Utah Research Foundation
InventorsReid Harrison, Cynthia Furse, Chirag Sharma
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Abstract
A technique for reflectometry testing of a signal path is disclosed. The technique includes injecting a test signal based on a probe pseudo-noise sequence into the signal path and obtaining a response signal. A sliding reference pseudo-noise sequence is correlated against the response signal. Both the probe sequence and the reference sequence are generated at a chip rate. The correlation is obtained for integer chip time delays, and sub-chip resolution of a peak correlation delay is estimated from at least two samples of the correlation.
Claims30
A system for reflectometry testing of a signal path, comprising:
- a system clock configured to output a clock at a chip rate;
- a pseudo-noise generator coupled to the system clock and configured to output a probe sequence of pseudo-random chips at the chip rate, wherein the sequence repeats every L chips;
- a sliding pseudo-noise generator coupled to the system clock and configured to output a reference sequence at the chip rate, wherein the reference sequence repeats every L+1 chips and the reference sequence is equal to the probe sequence over a continuous segment of length L chips;
- a signal path interface coupled to the pseudo-noise generator and configured to inject the probe sequence into the signal path and obtain a resulting response signal from the signal path;
- a correlator coupled to the signal path interface and the sliding pseudo-noise generator and configured to determine a correlation of the response signal and the reference sequence and output samples of the correlation at intervals of L+1 chips;
- and
- an estimator coupled to the correlator and configured to estimate a peak correlation delay time from at least two of the samples of the correlation, wherein the peak correlation delay time includes an integer chip number portion and a fractional chip number portion.
A system for reflectometry testing of a signal path, comprising:
- means for generating a probe sequence at a chip rate, the probe sequence being a pseudo-noise sequence which repeats every L chips;
- means for generating a reference pseudo-noise sequence at the chip rate, the reference pseudo-noise sequence being equal to the probe pseudo-noise sequence over a segment of length L chips and repeating every L+1 chips;
- means for injecting the probe sequence into a signal path;
- means for obtaining a response of the signal path to the probe pseudo-noise sequence;
- means for estimating a correlation of the response of the signal path with the reference sequence to obtain a correlation function at a plurality of samples;
- and
- means for estimating a time delay corresponding to a peak of the correlation function, wherein the time delay has an integer chip number portion and a fractional chip number portion.
A method of reflectometry testing a signal path comprising:
- generating a probe sequence of pseudo-random chips at a chip rate R, the probe sequence repeating every L chips;
- injecting a test signal into the signal path, the test signal based on the probe sequence;
- extracting a response signal from the signal path corresponding to the time domain response of the signal path to the injected test signal;
- generating a reference sequence of pseudo-random chips at the chip rate R, the reference sequence repeating every L+1 chips and being equal to the probe sequence over L sequential chips;
- correlating the response signal with a signal based on the reference sequence to obtain a plurality of correlation values, a correlation value obtained every L+1 chips;
- and
- estimating a time delay from at least two correlation values, the time delay having resolution of a fraction of the chip time 1/R.
Dependencies are inferred from the claim text.