Space and Time Coherence of Acoustic Field in Shallow-Water

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