Frequency division, energy comparison signal processing system

• US 5,261,007 A
• Filed: 06/10/1991
• Issued: 11/09/1993
• Est. Priority Date: 11/09/1990
• Status: Expired due to Fees

• Current Assignee: Visidyne, Inc.
• Original Assignee: Visidyne, Inc.
• Inventors: Hirsch, Peter
• Primary Examiner(s): Boudreau, Leo H.
• Application Number:
  US07/712,973
• Time in Patent Office: 883 Days
• Field of Search: 382/1, 382/17, 382/29, 73/648, 364/484, 381/45, 381/49, 381/50, 367/32, 367/43, 367/49
• US Class Current: 704/237
• CPC Class Codes: G01S 3/80 using ultrasonic, sonic or infrasonic waves
• CPC Class Codes: G06F 17/15 Correlation function computation including computation of convolution operations arithmetic circuits for sum of products per se, e.g. multiply-accumulators G06F7/5443; digital filters, e.g. FIR, IIR, adaptive filters H03H17/00

Abstract

A frequency division, energy comparison signal processing system for detecting the presence of, and separating the contributions from, sources that compose a wide-band sound signal, in which the system divides at least part of the wide-band sound signal into a number of discrete narrow frequency band components, generates the energy envelope of each of those components, normalizes the envelopes, multiplies each normalized envelope with each of the other normalized envelopes to obtain a plurality of envelope correlation coefficients for each frequency band, and then identifies from the correlation coefficients a sound source seed frequency band component and then, using the seed, identifies the remaining frequency components of a sound source.

Claims

1. A frequency division, energy comparison signal processing system for detecting the presence of, and separating the contributions from, sources that compose a wide-band sound signal, comprising:

means for dividing at least part of a wide-band sound signal into a plurality of discrete narrow frequency band components;

means for generating the energy envelope of each of the narrow band components;

means for normalizing each said envelope;

means for multiplying each normalized envelope with each of the other normalized envelopes to obtain a plurality of envelope correlation coefficients for each frequency band component; and

means for identifying a sound source seed frequency band for determining sound signal frequency components associated with a sound source.

2. The system of claim 1 in which said means for identifying includes means for comparing the envelope correlation coefficients to a correlation coefficient threshold value to identify coefficients above the threshold value.

3. The system of claim 2 in which said mean for identifying further includes means for counting the number of identified correlation coefficients in each frequency band.

4. The system of claim 3 in which said means for identifying further includes means for resolving the frequency band having the largest number of identified correlation coefficients.

5. The system of claim 3 further including means for resolving the signal power in each frequency band.

6. The system of claim 5 which said means for identifying further includes means for multiplying the identified correlation coefficient count in each frequency band by the frequency band power to obtain a frequency band weighted power value.

7. The system of claim 6 in which said means for identifying further includes means for resolving the frequency band having the largest weighted power value.

8. The system of claim 1 in which said means for identifying includes means for summing the correlation coefficients in each frequency band.

9. The system of claim 8 in which said means for identifying further includes means for resolving the frequency band having the largest correlation coefficient sum.

10. The system of claim 8 further including means for resolving the signal power in each frequency band.

11. The system of claim 10 in which said means for identifying further includes means for multiplying the correlation coefficient sum in each frequency band by the band power to obtain a frequency band summed weighted power value.

12. The system of claim 11 in which said means for identifying further includes means for resolving the frequency band having the largest summed weighted power value.

13. The system of claim 1 in which said means for identifying includes means for determining the largest correlation coefficient.

14. The system of claim 13 in which said means for identifying includes means for resolving the two frequency bands corresponding to the largest correlation coefficient.

15. The system of claim 1 further including means for resolving the signal power in each frequency band.

16. The system of claim 15 in which said means for identifying includes means for multiplying each correlation coefficient by the signal power in both frequency bands corresponding to the correlation coefficient to obtain frequency band covariance values.

17. The system of claim 16 in which said means for identifying further includes means for determining the largest covariance value.

18. The system of claim 17 in which said means for identifying further includes means for resolving the two frequency bands corresponding to the largest covariance value.

19. The system of claim 14 in which said means for identifying further includes means for identifying the bands with envelopes that correlate above a threshold with the two resolved frequency bands.

20. The system of claim 19 in which said means for identifying further includes means for resolving the largest contiguous group of identified frequency bands.

21. The system of claim 20 in which said means for identifying further includes means for summing the energy envelopes of the resolved frequency bands to create a seed energy envelope.

22. The system of claim 21 further including means for correlating each energy envelope with the seed energy envelope to obtain a plurality of seed/envelope correlation coefficients.

23. The system of claim 22 further including means for analyzing the seed/envelope correlation coefficients to obtain a pattern of seed/envelope correlation coefficients indicative of the presence of one or more sound sources.

24. The system of claim 1 further including means for resolving a cluster of envelopes with high correlation within said seed frequency band.

25. The system of claim 24 in which said means for resolving includes means for comparing the envelope correlation coefficients in said seed frequency band to a correlation coefficient threshold value to identify coefficients above the threshold value.

26. The system of claim 25 in which the identified cluster includes frequency bands corresponding to the coefficients above the threshold value.