Abstract:
As shown at the 131st meeting [R. Dwyer, ``Wideband higher-order spatial processing of active sonar echoes,'' J. Acoust. Soc. Am. 99, 2497(A) (1996)] when linear sonar arrays are operated well beyond their design frequency, spatial resolution is reduced at low frequencies and grating lobes appear at higher frequencies. Because the higher-order spectrum provides more flexibility in choosing the frequency response at the output of a beamformer the deliterious effects of wide bandwidths can be reduced. New higher-order processing results will be presented for broadband active sonar waveform transmissions using general array configurations and with returns that can be expected in shallow-water environments.