Underwater sounding method and apparatus

Abstract

Methods and apparatuses process signals. The method according to one aspect of the present invention receives a first signal; obtains a second signal and a third signal from the first signal, wherein a gain of the second signal is smaller than a gain of the third signal; detects saturation in the third signal; and generates a composite signal from the second signal and the third signal, the step of generating a composite signal including selecting a part of the second signal for the composite signal, when the detecting step detects saturation in the third signal, and selecting a part of the third signal for the composite signal, when the detecting step does not detect saturation in the third signal.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

Further aspects and advantages of the present invention will become apparent upon reading the following detailed description in conjunction with the accompanying drawings, in which:

FIG. 1 is a general block diagram of a system including an underwater sounding apparatus according to an embodiment of the present invention;

FIG. 2 is a block diagram illustrating in more detail aspects of an underwater sounding apparatus according to an embodiment of the present invention;

FIG. 3A is a block diagram illustrating conventional technology for processing of signals from underwater targets;

FIG. 3B is a diagram illustrating operations for the conventional technology for processing of signals from underwater targets illustrated in FIG. 3A;

FIG. 4 is a block diagram illustrating an underwater sounding apparatus according to an embodiment of the present invention illustrated in FIG. 2;

FIG. 5A is a flow diagram illustrating operations performed by an underwater sounding apparatus according to an embodiment of the present invention illustrated in FIG. 4;

FIG. 5B illustrates exemplary aspects of operations performed by an underwater sounding apparatus according to the operations illustrated in the flow diagram of FIG. 5A;

FIG. 6 is a block diagram illustrating an underwater sounding apparatus according to a different embodiment of the present invention;

FIG. 7A is a flow diagram illustrating operations performed by an underwater sounding apparatus according to an embodiment of the present invention illustrated in FIG. 6; and

FIG. 7B illustrates exemplary aspects of operations performed by an underwater sounding apparatus according to the operations illustrated in the flow diagram of FIG. 7A.

Claims

1. A method, said method comprising: receiving a first signal;obtaining a second signal and a third signal from said first signal, wherein a gain of said second signal is smaller than a gain of said third signal;detecting saturation in said third signal; andgenerating a composite signal from said second signal and said third signal, said step of generating a composite signal including selecting a part of said second signal for said composite signal, when said detecting step detects saturation in said third signal, andselecting a part of said third signal for said composite signal, when said detecting step does not detect saturation in said third signal.

2. The method as recited in claim 1, wherein said obtaining step includes: performing a low gain amplification of said first signal to obtain said second signal, andperforming a high gain amplification of said first signal to obtain said third signal.

3. The method as recited in claim 1, wherein said detecting step includes: demodulating said third signal to obtain a demodulated signal, anddetecting saturation in said demodulated signal.

4. The method as recited in claim 1, further comprising: performing a gain compensation for at least one of said part of said second signal and said part of said third signal in said composite signal, to obtain a gain compensated signal.

5. The method as recited in claim 4, further comprising: performing a bandpass filtering of said composite signal, before said step of performing a gain compensation.

6. The method as recited in claim 4, further comprising: performing time variable gain control for said gain compensated signal.

7. The method as recited in claim 1, wherein said first signal is an acoustic signal received or reflected from an underwater object.

8. The method as recited in claim 1, wherein said obtaining step includes: performing a low gain amplification of said first signal to obtain a low gain amplified signal,performing an analog to digital conversion of said low gain amplified signal to obtain said second signal,performing a high gain amplification of said first signal to obtain a high gain amplified signal, andperforming an analog to digital conversion of said high gain amplified signal to obtain said third signal.

9. A method, said method comprising: receiving a first signal;obtaining a second signal and a third signal from said first signal, wherein a gain of said second signal is smaller than a gain of said third signal; andgenerating a composite signal, said generating step including performing a gain compensation for said third signal, to obtain a gain compensated third signal,selecting a part of said second signal for said composite signal, when a saturation of said third signal is detected, andselecting a part of said gain compensated third signal for said composite signal, when no saturation is detected in said third signal.

10. The method as recited in claim 9, wherein said obtaining step includes: performing a low gain amplification of said first signal to obtain said second signal, andperforming a high gain amplification of said first signal to obtain said third signal.

11. The method as recited in claim 9, further comprising: performing a bandpass filtering of said composite signal to obtain a bandpass filtered signal.

12. The method as recited in claim 11, further comprising: performing time variable gain control for said bandpass filtered signal.

13. The method as recited in claim 9, wherein said first signal is an acoustic signal received or reflected from an underwater object.

14. The method as recited in claim 9, wherein said obtaining step includes: performing a low gain amplification of said first signal to obtain a low gain amplified signal,performing an analog to digital conversion of said low gain amplified signal to obtain said second signal,performing a high gain amplification of said first signal to obtain a high gain amplified signal, andperforming an analog to digital conversion of said high gain amplified signal to obtain said third signal.

15. An apparatus, said apparatus comprising: a signal input unit for providing a first signal;a signal processing unit for obtaining a second signal and a third signal from said first signal, wherein a gain of said second signal is smaller than a gain of said third signal; anda signal selection unit for generating a composite signal from said second signal and said third signal, said signal selection unit generating a composite signal by detecting saturation in said third signal,selecting a part of said second signal for said composite signal, when saturation is detected in said third signal, andselecting a part of said third signal for said composite signal, when no saturation is detected in said third signal.

16. The apparatus according to claim 15, wherein said signal processing unit obtains said second signal and said third signal by performing a low gain amplification of said first signal to obtain said second signal, andperforming a high gain amplification of said first signal to obtain said third signal.

17. The apparatus according to claim 15, wherein said signal selection unit detects saturation in said third signal by demodulating said third signal to obtain a demodulated signal, anddetecting saturation in said demodulated signal.

18. The apparatus according to claim 15, further comprising: a gain compensation unit for performing a gain compensation for at least one of said part of said second signal and said part of said third signal in said composite signal, to obtain a gain compensated signal.

19. The apparatus according to claim 18, further comprising: a bandpass filtering unit for performing a bandpass filtering of said composite signal, before said gain compensation unit performs a gain compensation for at least one of said part of said second signal and said part of said third signal in said composite signal.

20. The apparatus according to claim 18, further comprising: a time variable gain control unit for performing time variable gain control for said gain compensated signal.

21. The apparatus according to claim 15, wherein said first signal is an acoustic signal received or reflected from an underwater object.

22. The apparatus according to claim 15, wherein said signal processing unit obtains said second signal and said third signal by performing a low gain amplification of said first signal to obtain a low gain amplified signal,performing an analog to digital conversion of said low gain amplified signal to obtain said second signal,performing a high gain amplification of said first signal to obtain a high gain amplified signal, andperforming an analog to digital conversion of said high gain amplified signal to obtain said third signal.

23. An apparatus, said apparatus comprising: a signal input unit for providing a first signal;a signal processing unit for obtaining a second signal and a third signal from said first signal, wherein a gain of said second signal is smaller than a gain of said third signal; anda signal selection unit for generating a composite signal, said signal selection unit generating a composite signal by performing a gain compensation for said third signal, to obtain a gain compensated third signal,selecting a part of said second signal for said composite signal, when a saturation of said third signal is detected, andselecting a part of said gain compensated third signal for said composite signal, when no saturation is detected in said third signal.

24. The apparatus according to claim 23, wherein said signal processing unit obtains said second signal and said third signal by performing a low gain amplification of said first signal to obtain said second signal, andperforming a high gain amplification of said first signal to obtain said third signal.

25. The apparatus according to claim 23, further comprising: a bandpass filtering unit for performing a bandpass filtering of said composite signal to obtain a bandpass filtered signal.

26. The apparatus according to claim 25, further comprising: a time variable gain control unit for performing time variable gain control for said bandpass filtered signal.

27. The apparatus according to claim 23, wherein said first signal is an acoustic signal received or reflected from an underwater object.

28. The apparatus according to claim 23, wherein said signal processing unit obtains said second signal and said third signal by performing a low gain amplification of said first signal to obtain a low gain amplified signal,performing an analog to digital conversion of said low gain amplified signal to obtain said second signal,performing a high gain amplification of said first signal to obtain a high gain amplified signal, andperforming an analog to digital conversion of said high gain amplified signal to obtain said third signal.