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S pace- T ime A daptive M atched-field P rocessing (STAMP)

S pace- T ime A daptive M atched-field P rocessing (STAMP). Yung P. Lee (ASAP 2001, March 14, 2001) Science Applications International Corporation 1710 SAIC Drive McLean, VA 22102 Yung@osg.saic.com. Sonar Signal Processing Background.

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S pace- T ime A daptive M atched-field P rocessing (STAMP)

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  1. Space-Time Adaptive Matched-field Processing (STAMP) Yung P. Lee (ASAP 2001, March 14, 2001) Science Applications International Corporation 1710 SAIC Drive McLean, VA 22102 Yung@osg.saic.com

  2. Sonar Signal Processing Background Fourier Transform Spectral (Frequency) Content Spatial Beamforming Direction (Angle) of Arrival (DOA)

  3. Matched Field Processing Matched Field Processing 3D (Range,depth, bearing) Localization Matched Field Tomography Modal Information Environmental Info.

  4. Synthetic Aperture Matched Field Processing source at 76 m towed at 2.5 m/s from 9.18 km

  5. Space Time Matched Field Processing Localization & Doppler (velocity) Discrimination Matched Field Processing Space Time Matched Field Processing Phone-Doppler Space Beam-Doppler Space

  6. BACKGROUND/OBJECTIVE • Space-Time Adaptive Processing (STAP) coherently combines signals from the elements of an array and the multiple snapshots of signals, to achieve large spatial/temporal signal gain, to suppress interference, and to provide target detection in azimuth and velocity. • Matched-field processing (MFP) coherently combines complex multi-path arrivals, to recover signal multi-path spreading loss and to provide range/depth localization. • STAMP combines STAP and MFP to improve detection and localization performance for the mobile multi-line-towed-array sonar systems.

  7. STAP Detect the dot Null the Jammer and the slanted clutter STAMP Detect/combine/class/localize the dots Null the Jammer and the clutter 0 90 180 FWD Target Jammer (own-ship) Jammer Clutter (Bottom Bounce) Clutter (Bottom Reverberation) Azimuth (deg) Target Passive Forward-sector processing AFT -Dfmax0 Dfmax -Dfmax0 Dfmax Doppler (Hz) Doppler (Hz)

  8. Multi-path Doppler/Angle Spread C1 ,Df1 Cm ,Dfm Dfm=f0*v/cm Higher Mode (Path,Angle), Larger cm Larger cm, Higher Angle (off horizontal), Smaller Doppler

  9. OUTLINE • STAMP Processing • Simulation scenario for forward-sector processing • Simulation Results

  10. Space-Time Adaptive Matched-field Processing (STAMP) Doppler Processing Xr(f) Conventional Beamforming Br(f) Propagation Code to generate Replica xr(t) Br(f0) Beam-space replica (Selected Beams and Dopplers) AEL Environ. Search R,Z,q ,v *Plane-wave ~ STAP WB/NB Adaptive MFP Phone 1 Line 1 x11(t) Doppler Processing X1(f) Conventional Beamforming B1(f) Output Ambiguity Surface R,Z,q ,v B(f) Beam-Space Vector (selected Beams and Dopplers) Phone n Line 1 xn1(t) Forming Covariance Matrix R = < B(f) B+(f)>f & Decomposition Phone 1 Line k x1k(t) Doppler Processing Xk(f) Conventional Beamforming Bk(f) Phone n Line k xnk(t) Bk(f) = [bk(f,q1)…… bk(f,ql)] B(f) = [B1(f)…. B1(f+mDf),…….., Bk(f)…. Bk(f+mDf)]

  11. Adaptive Processing Adaptive Weight Vector Adaptive Output **A is the steering vector **R is the measured covariance matrix High resolution Sidelobe suppression Subject to mismatch – Robust Methods (widen the peak)

  12. Wideband-Narrowband (WB/NB) Feedback-Loop White-Noise-Constrained (FLWNC) Adaptive Processing Br(f0) Beam-space replica (Selected Beams and Dopplers) yes e = s no Covariance Matrix R = < B(f) B+(f)>f & Decomposition Adaptive weight W no yes e = s WB/NB Processing S(f)=W+B(f) * B(f) is “narrowband” (single f) R and W are “broadband” (averaged over band of f)

  13. Simulation Geometry (F=200 Hz) target(NB)=120 dB, own-ship(BB)=120 dB, bottom bounce(BB)=115 dB WNL=70 dB, 0.1 l random phase error Single-Line No environmental mismatch 4-Line-Sequential 4-Line-Vertical 3 kts 10 km own-ship noise towed array 188 m 3 kts bottom bounce

  14. Own-Ship Noise Bottom Bounce Target Responses at 10o Azimuth __ Own-ship __ Bottom Bounce __ Target Single-Line BTRs of Each Signal Component Forward Endfire at 0o

  15. Own-Ship Noise Bottom Bounce Target Responses at 10o Azimuth __ Own-ship __ Bottom Bounce __ Target Selected beams (0o-30o) & Dopplers (6 bins for 6-kt search) Single-Line Doppler/Azimuth Responses integration time =256-sec, Target Range=10 km, Forward Endfire at 0o

  16. Conventional Plane-Wave (10o) Adaptive Plane-Wave (10o) Adaptive MFP (target track) Peak Level over Dopplers __ Adaptive PW __ Adaptive MFP Single-Line Beam/Cell Spectrograms

  17. Adaptive Plane-Wave (10o) Single Vertical Adaptive MFP 4_Line_Vertical Adaptive MFP Peak Level over Dopplers __ PW __ Single Line MFP __ 4_Line_Vert MFP Adaptive Beam/Cell Spectrograms

  18. Single Line, Conventional MFP Single Line, Adaptive MFP 4_Line_Sequential, Adaptive MFP 4_Line_Vertical, Adaptive MFP Array Size Dependence of MFP Range Tracking search at target depth and target speed

  19. Depth=10 m Depth=60 m Depth=90 m Depth=180 m Depth Discrimination of Adaptive MFP Range Tracking 4_Line_Vertical Array search at target speed

  20. Speed= 3 m/s Speed= 1 m/s Speed= -1 m/s Speed= -3 m/s Speed Discrimination of Adaptive MFP Range Tracking 4_Line_Vertical Array search at target depth

  21. SUMMARY • STAMP processing that combines STAP and MFP has been developed. • Simulations show that STAMP coherently combines signal multi-path spread in azimuth and Doppler and greatly enhances target detection as well as providing target range and depth classification and localization.

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