Residual Fourier-padding interpolation for instrumentation and measurement
AssigneeTeradyne, Inc.
InventorFang Xu
Life of this patent
Estimating the term…
Abstract
A technique for interpolating a series of samples includes constructing a mathematical model of the series that describes its large signal behavior. The model is subtracted from the original series to yield a residue. A discrete Fourier transform (DFT) is taken of the residue, and the DFT is zero-padded. An inverse DFT of the padded result yields an interpolated residue, which is then added back to the mathematical model to construct an interpolated version of the series of samples. Using this technique, accurate interpolation can generally be attained even when the series of samples is not coherently sampled.
Claims20
A method of transforming an electronic analog signal into an interpolated, digital signal, comprising:
- (A) discretely sampling the electronic analog signal to produce a series of analog samples;
- (B) converting the series of analog samples into a series of digital samples representative of the series of analog samples;
- (C) constructing a mathematical model that approximately describes the series of digital samples;
- (D) subtracting the mathematical model from the series of digital samples, to yield a residue signal;
- (E) computing a DFT (Discrete Fourier Transform) of the residue signal;
- (F) zero-padding the DFT to yield a padded residue signal;
- (G) computing an inverse DFT of the padded residue signal to produce an interpolated residue signal;
- and
- (H) adding the interpolated residue signal to the mathematical model to produce the interpolated, digital signal.
A method of testing a UUT (Unit Under Test) in an ATE system, comprising:
- (A) connecting the UUT to an interface of an automatic test system;
- (B) electronically stimulating the UUT to produce an output signal;
- (C) sampling the output signal;
- (D) interpolating the sampled output signal;
- (E) comparing at least one signal characteristic of the interpolated sampled output signal with a predetermined test limit;
- and
- (F) indicating a passing or failing test result based upon the comparing step,
- wherein the step of interpolating the sampled output signal includes—
- constructing a mathematical model that approximately describes the sampled output signal
- subtracting the mathematical model from the sampled output signal, to yield a residue signal;
- computing a DFT (Discrete Fourier Transform) of the residue signal;
- zero-padding the DFT of the residue signal to yield a padded residue signal;
- computing an inverse DFT of the padded residue signal to produce an interpolated residue signal;
- and
- adding the interpolated residue signal to the mathematical model to produce the interpolated sampled output signal.
A method of calibrating an instrument in an automatic test system, comprising:
- (A) exercising the instrument at each of a plurality of different frequencies;
- (B) measuring a response of the instrument at each of the plurality of frequencies to produce a sampled data set;
- (C) interpolating the sampled data set;
- and
- (D) adjusting the gain and/or phase of the instrument responsive to the interpolated data set,
- wherein the step of interpolating the sampled data set includes—
- constructing a mathematical model that approximately describes the sampled data set,
- subtracting the mathematical model from the sampled data set, to yield a residue;
- computing a DFT (Discrete Fourier Transform) of the residue;
- zero-padding the DFT of the residue to yield a padded residue;
- computing an inverse DFT of the padded residue to produce an interpolated residue;
- and
- adding the interpolated residue to the mathematical model to produce an interpolated version of the sampled data set.
An apparatus for representing an electronic analog signal in digital form, comprising:
- means for sampling the electronic analog signal to produce a sampled signal;
- means for constructing a mathematical model that approximately describes the sampled signal;
- means for subtracting a mathematical model from the sampled signal, to yield a residue signal;
- means for computing a DFT (Discrete Fourier Transform) of the residue signal;
- means for zero-padding the DFT of the residue signal to yield a padded residue signal;
- means for computing an inverse DFT of the padded residue signal to produce an interpolated residue signal;
- and
- means for adding the interpolated residue signal to the mathematical model to produce an interpolated version of the sampled signal.
An apparatus for interpolating a data set, comprising:
- a modeling unit for storing a mathematical model that approximately describes the data set;
- a first summer having a first input for receiving the data set, a second input coupled to the modeling unit, and an output for providing a residue indicative of a difference between the sampled signal and the mathematical model;
- a DFT unit, coupled to the first summer, for computing a DFT (Discrete Fourier Transform) of the residue;
- a zero-padding unit, coupled to the DFT unit, for padding the DFT of the residue to yield a padded residue;
- an IDFT unit, coupled to the zero-padding unit, for computing an inverse DFT of the padded residue to produce an interpolated residue;
- and
- a second summer having a first input coupled to the IDFT unit, a second input coupled to the modeling unit, and an output for providing a sum of the interpolated residue and the mathematical model.
Dependencies are inferred from the claim text.