Method and apparatus for filtering signals using a gamma delay line based estimation of power spectrum

• US 6,073,152 A
• Filed: 04/03/1998
• Issued: 06/06/2000
• Est. Priority Date: 04/03/1998
• Status: Expired due to Fees

• Current Assignee: Sarnoff Corporation (SRI International, Inc.)
• Original Assignee: Sarnoff Corporation (SRI International, Inc.)
• Inventors: De Vries, Aalbert
• Primary Examiner(s): Malzahn, David H.
• Application Number:
  US09/055,043
• Time in Patent Office: 795 Days
• Field of Search: 708/321, 708/322, 708/319, 708/301, 708/300
• US Class Current: 708/321
• CPC Class Codes: H03H 21/0012 Digital adaptive filters

Abstract

A signal processing system for generating a signal component reduced output signal by estimating the power spectrum of a non-stationary signal component within a non-stationary input signal is disclosed. The estimated power spectrum of the signal component is determined by using a gamma delay line (GDL) filter. The weights of the GDL filter are adaptively updated in accordance with a detection method that is designed to detect the presence of the non-stationary signal component. By subtracting the estimated power spectrum of the signal component from the power spectrum of the entire input signal, a signal component reduced output signal can be generated.

Claims

1. A signal processing method for generating a signal component reduced output signal from a non-stationary input signal having at least one signal component, said method comprising the steps of:

a) determining a power spectrum for the non-stationary input signal; and

b) estimating a power spectrum for the at least one signal component by applying a gamma delay line (GDL) filter to said power spectrum of the non-stationary input signal.

2. The method of claim 1, wherein said GDL filter comprises a plurality of first weights (w), where said plurality of first weights are adaptively updated.

3. The method of claim 2, wherein said GDL filter further comprises a plurality of second weights (μ

), for controlling a resolution of said GDL filter.

4. The method of claim 2, wherein said plurality of first weights are adaptively updated in accordance with a detection method, where said detection method detects a presence of the at least one signal component.

5. The method of claim 4, wherein said detection of said presence of the at least one signal component is in accordance with a power spectrum threshold.

6. The method of claim 1, further comprising the steps of:

c) subtracting said estimated power spectrum of the at least one signal component from said power spectrum of the non-stationary input signal to produce a remaining power spectrum; and

d) generating the component reduced output signal from said remaining power spectrum.

7. The method of claim 6, wherein said GDL filter comprises a plurality of first weights (w), where said plurality of first weights are adaptively updated.

8. The method of claim 1, wherein said non-stationary input signal is organized into at least one frame and said spectrum is determined for said at least one frame.

9. A signal processing apparatus for generating a component reduced output signal from a non-stationary input signal having at least one signal component, said apparatus comprising:

a power spectrum calculator for computing a power spectrum for the non-stationary input signal; and

a gamma delay line (GDL) filter, coupled to said power spectrum calculator, for estimating a power spectrum for the at least one signal component from said power spectrum of the non-stationary input signal.

10. The signal processing apparatus of claim 9, further comprising a detection module, coupled to said GDL filter, and wherein said GDL filter comprises a plurality of first weights (w), where said plurality of first weights are adaptively updated in accordance with said detection module.

11. The signal processing apparatus of claim 10, wherein said GDL filter further comprises a plurality of second weights (μ

), for controlling a resolution of said GDL filter.

12. The signal processing apparatus of claim 10, wherein said detection module detects a presence of the at least one signal component.

13. The signal processing apparatus of claim 12, wherein said detection module detects said presence of the at least one signal component in accordance with a power spectrum threshold.

14. The signal processing apparatus of claim 9, further comprising:

a subtractor, coupled to said GDL filter, for subtracting said estimated power spectrum of the at least one signal component from said power spectrum of the non-stationary input signal to produce a remaining power spectrum; and

a signal generator, coupled to said subtractor, for generating the component reduced output signal from said remaining power spectrum.

15. The signal processing apparatus of claim 14, further comprising a detection module, coupled to said GDL filter, and wherein said GDL filter comprises a plurality of first weights (w), where said plurality of first weights are adaptively updated in accordance with said detection module.

16. A signal processing apparatus for generating a component reduced output signal from a non-stationary input signal having at least one signal component, where said non-stationary input signal is organized into at least one frame, said apparatus comprising:

a means for computing a power spectrum for the at least one frame of the non-stationary input signal; and

a gamma delay line (GDL) filtering means, coupled to said power spectrum computing means, for estimating a power spectrum for the at least one signal component from said power spectrum for the at least one frame of the non-stationary input signal.

17. The signal processing apparatus of claim 16, further comprising a detecting means, coupled to said GDL filtering means, and wherein said GDL filtering means comprises a plurality of first weights (w), where said plurality of first weights are adaptively updated in accordance with said detecting means.

18. The signal processing apparatus of claim 17, wherein said detecting means detects a presence of the at least one signal component.

19. The signal processing apparatus of claim 18, wherein said detecting means detects said presence of the at least one signal component in accordance with a power spectrum threshold.

20. The signal processing apparatus of claim 16, further comprising:

a subtracting means, coupled to said GDL filtering means, for subtracting said estimated power spectrum of the at least one signal component from said power spectrum of the non-stationary input signal to produce a remaining power spectrum; and

a signal generator means, coupled to said subtracting means, for generating the component reduced output signal from said remaining power spectrum.

21. A computer-readable medium having stored thereon a plurality of instructions, the plurality of instructions including instructions which, when executed by a processor, cause the processor to perform the steps comprising of:

a) determining a power spectrum for the non-stationary input signal; and

b) estimating a power spectrum for the at least one signal component by applying a gamma delay line (GDL) filter to said power spectrum of the non-stationary input signal.

22. The computer-readable medium of claim 21, wherein said GDL filter comprises a plurality of first weights (w), where said plurality of first weights are adaptively updated.

23. The computer-readable medium of claim 22, wherein said GDL filter further comprises a plurality of second weights (μ

), for controlling a resolution of said GDL filter.

24. The computer-readable medium of claim 22, wherein said plurality of first weights are adaptively updated in accordance with a detection method, where said detection method detects a presence of the at least one signal component.

25. The computer-readable medium of claim 21, further comprising the steps of:

c) subtracting said estimated power spectrum of the at least one signal component from said power spectrum of the non-stationary input signal to produce a remaining power spectrum; and

d) generating the component reduced output signal from said remaining power spectrum.

26. The computer-readable medium of claim 21, wherein said non-stationary input signal is organized into at least one frame and said spectrum is determined for said at least one frame.