New experimental measurements of signal coherence in shallow water are presented. For signals with Iow frernquencies of about 500 Hz in iso-velocity shallow water with a silt-sand bottom and a water depth of about 45 tn,rnthe vertical coherence has no distinct depth dependence at ranges of 18.5, 55.5 and 92.5 kin, but it has obvious rnrange dependence. The horizontal coherence lengths are all greater than 40 wavelengths, and the time coherence rnlengths are all greater than 510s at these ranges. These experimental results show that a low-frequency acoustic rnfield has strong spatial coherence and temporal stability in iso-velocity shallow water.
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