Figure 1. WAM conception of target acquisition and engagement

BEAMFORMING PRINCIPLES

Bartlett and Capon maximum-likelihood beamformers

Estimation and conditioning of the correlation matrix

Formation of spatial correlation matrix

Spatial correlation matrix conditioning

Figure 5. Histograms of cross-power amplitude and phase estimates at 20 Hz for a synthetic sine wave series

FIELD DATA ACQUISITION AND EXPERIMENTAL CONDITIONS

Table 2. Physical properties of borehole soil samples

Figure 7. Generating shear waves for the site characterization measurements

Table 3. Analysis of seismic refraction travel time

Environmental characterization

Array description and recording procedures

Characterization of the Grayling array

DISCUSSION OF SOURCE CHARACTERISTICS

Impulsive acoustic source

Figure 18. Microphone spectrum for .45 caliber pistol shot

Impulsive seismic source

Figure 23. Time-domain microphone subarray response to M60 tank moving at 4.5 m s-1

Figure 25. Spectra of microphone subarray response to an M60 tank moving at 4.5 m s-1

PROCESSING RESULTS FOR FIELD RECORDS

Figure 27. ML wavenumber spectrum at 78 Hz for vertical geophone subarray

Figure 28. Estimated ML wave-number spectrum at 23 Hz for vertical geophone subarray

Moving sources

Figure 32. Average array spectra for vertical geophone subarray to M60 tank moving at 4.5 m s-1

Figure 33. Example of an ML wavenumber estimate from a vertical geophone array at 11 Hz for an M60 tank moving at 4.5 m s-1

Affect of spectral estimation parameters on beam response

Figure 36. ML wavenumber estimate at 11 Hz for waveforms shown in Fig. 35: Blackman taper 20 blocks

Figure 37. ML wavenumber estimate at 11 Hz for waveforms shown in Fig. 35: boxcar taper, 20 blocks

Figure 39. ML wavenumber estimate at 11Hz for waveforms shown in Fig. 35: boxcar taper, three blocks

Figure 41. ML wavenumber estimate at 11 Hz for waveforms shown in Fig. 35: boxcar taper, one block

CONCLUSIONS - CR96_080036

LITERATURE CITED-continue - CR96_080037

Report Documentation Page - CR96_080038

CR96_08