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Angular Spectrum Analysis of Ocean Noise Using Discrete Noise Source suppression

PRUAC 2007, Vancouver. Angular Spectrum Analysis of Ocean Noise Using Discrete Noise Source suppression. Yuanliang Ma, Bo Lei, Kunde Yang ( N W Polytech. Univ., Xi’an, China ). 1.0 introduction. Angular spectrum of ocean noise has strong connection to spatial coherence of the noise

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Angular Spectrum Analysis of Ocean Noise Using Discrete Noise Source suppression

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  1. PRUAC 2007, Vancouver Angular Spectrum Analysis of Ocean Noise Using Discrete Noise Source suppression Yuanliang Ma, Bo Lei, Kunde Yang ( N W Polytech. Univ., Xi’an, China )

  2. 1.0 introduction • Angular spectrum of ocean noise has strong connection to spatial coherence of the noise • The angular spectrum of ambient noise may be seriously disturbed by discrete interfering sources appeared in the observation region • To have a good estimate of the angular spectrum the effect of the interference should be suppressed as much as possible

  3. Discrete source introduces multipath structure

  4. How is it possible to restore the angular spectrum without the effect of discrete interference ? • Authors group is developing a method i.e. MFNS—Matched Field Noise Suppression for discrete interference suppression • It may be applicable in this case • A test from experimental data is required

  5. 2 MFNS principle--brief Using complex linear weighting for beam forming, beam output can be expressed as The power output of the beam will be Constrained minimization of J yields optimalsolution of W:

  6. This can be solved to give a general solution as follows: • To calculate V, the source-receiver • geometry and the characteristic • parameters of the noise transmission • channel should be known as a priori • This can be approximately satisfied in a number of practical applications

  7. Main references: • Ma Yuanliang, Yan Shefeng, Yang Kunde, “Matched field noise suppression: Principle with application to towed hydrophone line array,” Chinese Science Bulletin, 48, 1207-1211.2003 • 2. Yang Kunde, Ma Yuanliang, “The robust approach of matched field noise suppression,” Acta Armamen tarii, 26, 746-750.2004 • 3. Ma Yuanliang, Yan Shefeng, Yang Kunde, Zhou Shixin, ,Principles and Technical Issues on the Matched Field Noise Suppression, Wespac IX,2006,Seoul,Korea

  8. Main references: 4. Yan Shefeng, Ma Yuanliang, “Matched field noise suppression: A generalized spatial filtering approach,” Chinese Science Bulletin, 49, 2220-2223.2004 5. Bo Lei, Kunde Yang, Yuanliang Ma, “Matched field noise suppression based on Matrix Filter,” Oceans2007, Vancouver.

  9. Robustness issues of MFNS: • multiple-constraints for tow-ship noise • suppression • postbeamformer interference cancellation

  10. MFNS with matrix filtering

  11. 3. Experimental test • Mediterranean benchmark shallow water experimental data is used to test the feasibility of MFNS for noise measurement • Data available from Donald F. Gingras, “North Elba Sea Trial Summary,” spib.rice.edu/spib/saclant.html, 1994.

  12. Set up for angular spectrum analysis N=48,d=2m,f=250Hz

  13. 4 Result INR:30dB

  14. It seems that • MFNS is successful for the angular • spectrum restoration • It can be extended to cover many • cases in which discrete interferences • make problems • Related concept has been formulated • and called Generalized Spatial Filtering

  15. Thank you !

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