US 4,901,244 A · Apparatus for, and method of, analyzing signals

Abstract

The spectral components of both an original signal and a shifted version of the signal, for example a signal which is subjected to a time delay relative to the original signal, are obtained by means of Fourier Transform. This gives sets of first and second spectral components corresponding respectively to the original signal and the shifted signal. The phases of at least one pair of corresponding first and second spectral components are obtained, and subtracted to give a phase difference. The first aspect of the method measures the frequency of corresponding constituent of the original signal from the said phase difference based on a prior knowledge of the amount of shift. Further, having measured the frequency, one can measure the initial phase and amplitude of corresponding constituent of the signal. A second aspect of the method and an apparatus measure the amount of shift between two received signals from the said phase difference by means of a prior knowledge of the frequency of corresponding constituent of the signal. A third aspect of the method and an apparatus detect the existence of dominant constituent of the signal. This approach compares the difference in phases between adjacent spectral components of a signal with a constant value, (1-1/N).pi.. The measured signals can vary temporally or spatially.

Claims33

Dependent claims

A method of measuring the frequency of the respective constituents of an analysed signal, the method comprising the steps of:

(i) obtaining signal samples corresponding to the discrete spectral components of the analysed signal on a first basis set to create a plurality of first spectral components respective of the said analysed signal;
(ii) separately applying a shift to the said analysed signal to create a shifted signal;
(iii) obtaining signal samples corresponding to the discrete spectral components of the said shifted on a second basis set to create a plurality of second spectral components representative of the said shifted signal;
(iv) obtaining at least one pair of signal samples corresponding to the phases of the first and second spectral components;
(v) subtracting said signal samples corresponding to the phases of the first and second spectral components, to derive a signal sample corresponding to the phase difference;
and
(vi) obtaining the frequency of the corresponding constituent of the analysed signal from the said phase difference derived in step (v) and the amount of shift applied to step (ii).

4 more elements

A method of measuring the frequency of the respective dominant constituents of an analysed signal, the method comprising the steps of:

(i) obtaining signal samples corresponding to the discrete spectral components of the analysed signal on a first basis set to create a plurality of first spectral components representative of the said analysed signal;
(ii) separately applying a shift to the said analysed signal to create a shifted signal;
(iii) obtaining signal samples corresponding to the discrete sspectral components of the said shifted signal on a second basis set to create a plurality of second spectral components representative of the said shifted signal;
(iv) selecting the dominant spectral components, corresponding to the dominant constituents of the analysed signal from the first spectral components or the second spectral components, the subsequent steps being effected on the dominant spectral components;
obtaining at least one pair of signal samples corresponding to the phases of the first and second spectral components;
(v) subtracting said signals samples corresponding to the phases of the first and second spectral components, to derive a signal sample corresponding to the phase difference;
and
(vi) obtaining the frequence of the corresponding constituent of the analysed signal from the said phase difference derived in setp (v) and the amount of shift applies to setp (ii).

5 more elements

A method of measuring the amount of time-shift between the corresponding consitutents of the two signals, the method comprising the steps of:

(i) obtaining signal samples corresponding to the discrete spectral components of a signal on a first basis set to create a plurality of first spectral components representative of the said first;
(ii) obtaining signal samples corresponding to the discrete spectral components of the shifted signal on a second basis set to create a plurality of second spectral components representative of the said shifted signal;
(iii) detecting the dominant spectral components, corresponding to the dominant constituents of the signal, from the first spectral components or the second spectral components, the subsequent steps being effected on the dominant spectral components;
obtaining at least one pair of signal samples corresponding to the phases of the first and second spectral components;
(iv) subtracting said signal samples corresponding to the phases of the first and second spectral components, to derive a signal sample corresponding to the phase difference;
and
(v) obtaining the amount of time-shift between the corresponding signal constituent in the two signals from the said phase difference derived from step (iv) and the frequency of the signal constituent.

4 more elements

An apparatus, for use in measuring the amount of shift between the corresponding signal constituents of two signals, the apparatus comprising:

(i) first transform means for applying a Fourier Transform to a signal, to create a plurality of first spectral components representative of the said signal, and having an output for the first spectral components;
(ii) second transform means connected to the input of the shifted signal, for applying a Fourier Transform to the said shifted signal to create a plurality of second spectral components representative of the said shifted signal, and having an output for the second spectral components;
(iii) phase obtaining means connected to the outputs of the first and second transform means for obtaining the phases of the corresponding first and second spectral components and having an output for the said phases;
(iv) phase difference obtaining means, connected to the output of the phase obtaining means, and having an output for the phase difference;
and
(v) shift obtaining means, connected to the output of the phase difference obtaining means, for obtaining the amount of shift between the corresponding signal constituents in the two signals, from the said phase difference of step (iv) and the frequency of the signal constituent.

3 more elements

An apparatus, for use in selecting or detecting the presence of dominant spectral constituents in a signal, the apparatus comprising:

(i) a subtractor having an input for a phase of one spectral component, and an input for the phase of the adjacent spectral component of the same signal;
and
(ii) a comparison means connected to an output of the subtractor for comparing the output of the subtractor with the quantity (1-1/N).pi., the comparison means sending a signal indicative of a dominant spectral component if the difference between the output of the subcontractor and the value, (1-1/N).pi., is less than predetermined tolerances.

Dependencies are inferred from the claim text.

Apparatus for, and method of, analyzing signals

Life of this patent

Apparatus for, and method of, analyzing signals

Life of this patent

Abstract

Claims33