Method and system for signal processing using a sparse approximation of the S-transform

• US 20070027657A1
• Filed: 05/31/2006
• Published: 02/01/2007
• Est. Priority Date: 05/31/2005
• Status: Active Grant

• Current Assignee: Calgary Scientific Inc.
• Original Assignee: Calgary Scientific Inc.
• Inventors: Mitchell, Ross, Pinnegar, Charles
• Granted Patent: US 7,401,006 B2
• Time in Patent Office: Days
• US Class Current: 702/189
• CPC Class Codes: G06F 17/14 Fourier, Walsh or analogous domain transformations , e.g. Laplace, Hilbert, Karhunen-Loeve, transforms for correlation function computation G06F17/156; spectrum analysers G01R23/16

Abstract

The present invention relates to a method and system for processing time series signal data or image signal data indicative of a characteristic of an object. Received signal data are transformed into second signal data within a Stockwell domain based upon a sparse approximation of a S-transform of the signal data. The second signal data are then processed within the Stockwell domain to extract features therefrom. The processing includes determination of local spectra at predetermined locations; determination of voices at predetermined frequencies; and filtering of the signal data using a filter function in dependence upon frequency and time or space. The signal processing method and system according to the invention enables signal processing based on the S-transform using a desktop computer or workstation.

Claims

1. A method for processing signal data indicative of a characteristic of an object comprising:

receiving the signal data;

transforming the signal data into second signal data within a Stockwell domain based upon a sparse approximation of an S-transform of the signal data; and

,

processing the second signal data within the Stockwell domain to extract features therefrom.

2. A method for processing signal data indicative of a characteristic of an object as defined in claim 1 wherein transforming the signal data into second signal data within a Stockwell domain comprises:

transforming the signal data into Fourier domain;

decimating the Fourier transformed signal data across one of time and space; and

,

convolving the decimated Fourier transformed signal data with a frequency-dependent window at specific values of frequency based on Fourier-domain convolution.

3. A method for processing signal data indicative of a characteristic of an object as defined in claim 2 wherein decimating the Fourier transformed signal data across one of time and space comprises constant-Q band-pass filtering the Fourier transformed signal data.

4. A method for processing signal data indicative of a characteristic of an object as defined in claim 2 wherein the Fourier transformed signal data related to lowest frequencies are retained.

5. A method for processing signal data indicative of a characteristic of an object as defined in claim 4 wherein harmonics are omitted when a modulus of the frequency is greater than a predetermined value.

6. A method for processing signal data indicative of a characteristic of an object as defined in claim 5 wherein the retained harmonics are spaced based on a standard deviation of a Fourier-domain form of a Gaussian window function of the S-transform.

7. A method for processing signal data indicative of a characteristic of an object as defined in claim 1 comprising:

selecting at least a point in one of time and space;

determining at least a portion of the second signal data for determining a local spectrum at the at least a point;

interpolating the at least a portion of the second signal data in one of time and space producing at least a set of first interpolated data; and

,

interpolating the at least a set of first interpolated data in frequency producing data indicative of the at least a local spectrum.

8. A method for processing signal data indicative of a characteristic of an object as defined in claim 7 comprising:

adjusting phase of the at least a set of first interpolated data; and

,

adjusting phase of the data indicative of the at least a local spectrum.

9. A method for processing signal data indicative of a characteristic of an object as defined in claim 1 comprising:

selecting at least a frequency of the second signal data; and

,

interpolating the second signal data related to the at least a frequency in one of time and space producing data indicative of at least a voice related to the at least a frequency.

10. A method for processing signal data indicative of a characteristic of an object as defined in claim 1 comprising:

determining at least a filter, the at least a filter being a function in dependence upon frequency and one of time and space;

multiplying the second signal data with the at least a filter producing third signal data; and

,

transforming the third signal data into Fourier domain producing filtered Fourier domain data.

11. A method for processing signal data indicative of a characteristic of an object as defined in claim 10 comprising:

inverse Fourier transforming the filtered Fourier domain data into filtered signal data in one of time and space domain.

12. A storage medium having stored therein executable commands for execution on a processor, the processor when executing the commands performing:

receiving the signal data;

transforming the signal data into second signal data within a Stockwell domain based upon a sparse approximation of a S-transform of the signal data; and

,

processing the second signal data within the Stockwell domain to extract features therefrom.

13. A storage medium as defined in claim 12 having stored therein executable commands for execution on a processor, the processor when executing the commands performing:

determining at least a portion of the second signal data for determining a local spectrum at at least a point in one of time and space;

interpolating the at least a portion of the second signal data in one of time and space producing at least a set of first interpolated data;

adjusting phase of the at least a set of first interpolated data;

interpolating the at least a set of first interpolated data in frequency producing the at least a local spectrum; and

,

adjusting phase of the at least a local spectrum.

14. A storage medium as defined in claim 12 having stored therein executable commands for execution on a processor, the processor when executing the commands performing:

selecting at least a frequency of the second signal data; and

,

interpolating the second signal data related to the at least a frequency in one of time and space producing at least a voice related to the at least a frequency.

15. A storage medium as defined in claim 12 having stored therein executable commands for execution on a processor, the processor when executing the commands performing:

determining at least a filter, the at least a filter being a function in dependence upon frequency and one of time and space;

multiplying the second signal data with the at least a filter producing third signal data;

transforming the third signal data into Fourier domain producing filtered Fourier domain data; and

,

inverse Fourier transforming the filtered Fourier domain data into one of time and space domain.

16. A system for processing signal data indicative of a characteristic of an object comprising:

an input port for receiving the signal data, the signal data being one of time series signal data and image signal data;

a processor in communication with the first port for;

transforming the signal data into second signal data within a Stockwell domain based upon a sparse approximation of a S-transform of the signal data; and

,

processing the second signal data within the Stockwell domain to extract features therefrom; and

,

an output port in communication with the processor for providing at least a portion of the processed second signal data.

17. A system for processing signal data indicative of a characteristic of an object as defined in claim 16 wherein the processor comprises electronic circuitry designed for performing at least a portion of transforming the signal data into second signal data and processing the second signal data.

18. A system for processing signal data indicative of a characteristic of an object as defined in claim 16 comprising a control port in communication with the processor for receiving control commands for controlling of transforming the signal data into second signal data and processing the second signal data.

19. A system for processing signal data indicative of a characteristic of an object as defined in claim 18 comprising a graphical display in communication with the processor for displaying the at least a portion of the processed second signal data in a graphical fashion.

20. A system for processing signal data indicative of a characteristic of an object as defined in claim 19 wherein the graphical display comprises a graphical user interface.