COHERENCE EFFWXX ON THE DETECTION FEQFORhl.4NCE OF QUADRATIC ARRAY F'ROCESOW, WITH APPLICATIONS TO LARGE-ARRAY MATCHED-FIELD BEAMFOILMING
Dennis R. Morgan, Thomas M. Smi · 1989
Tk effect of coherence on the detection performance of quadratic array ym is examined using an expmential-pawex-law model for the signal wavefront correlation. Detection performance is quantified by the mall-signal deflection criterion, which is fim reviewed in the geneid setting of quadratic detecton, and then applied to matched-field and optimal quadratic beamformem. It is shown that the detection performance of matched-field beamforming is substantially degraded for large arrays and typical coherence lengths. The aptmal quadratic 7 reducea this cohermz lm, however, at a cnst of greatly increased praxsmr complexity. Several suk@irnal beamformers with reduced computational load are also developed and their detection performance is compared to that of the matched-field and optimal beamfonnem. One suboptimal pmr, the subarray beamformer, has proved outstanding for this application in three respec@: it can realize within 1 dB of optimal performance; is robust over a class of correlation functions; and, entails a computational burden no greater than full-array matched-field beamforming.