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

2. Fourier Transform Spectral (Frequency) Content Sonar Signal Processing Background 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.

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

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

8. 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.

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

10. C m,  f m  f m =f 0 *v/c m Higher Mode (Path,Angle), Larger c m Larger c m, Higher Angle (off horizontal), Smaller Doppler C 1,  f 1 Multi-path Doppler/Angle Spread

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

12. B r (f 0 ) Beam-space replica (Selected Beams and Dopplers) Phone 1 Line 1 x 11 (t) Phone n Line 1 x n1 (t) Doppler Processing X 1 (f) Conventional Beamforming B 1 (f) B(f) Beam-Space Vector (selected Beams and Dopplers) WB/NB Adaptive MFP Doppler Processing X r (f) Conventional Beamforming B r (f) Phone 1 Line k x 1k (t) Phone n Line k x nk (t) Doppler Processing X k (f) Conventional Beamforming B k (f) Propagation Code to generate Replica x r (t) Output Ambiguity Surface R,Z  v Space-Time Adaptive Matched-field Processing (STAMP) Search R,Z  v Forming Covariance Matrix R = f & Decomposition B(f) = [B 1 (f)…. B 1 (f+m  f),…….., B k (f)…. B k (f+m  f)] B k (f) = [b k (f,  1 )…… b k (f,  l )] AEL Environ. *Plane-wave ~ STAP

13. 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)

14. Wideband-Narrowband (WB/NB) Feedback-Loop White-Noise-Constrained (FLWNC) Adaptive Processing B r (f 0 ) Beam-space replica (Selected Beams and Dopplers) Covariance Matrix R = f & Decomposition Adaptive weight W yes  = s yes  = s no WB/NB Processing S(f)=W + B(f) * B(f) is “narrowband” (single f) R and W are “broadband” (averaged over band of f)

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

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

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

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

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

20. Single Line, Conventional MFP 4_Line_Sequential, Adaptive MFP4_Line_Vertical, Adaptive MFP Single Line, Adaptive MFP Array Size Dependence of MFP Range Tracking search at target depth and target speed

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

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

23. 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.