Experimental study in correlation variation of acoustic propagation channel in Philippine sea

The variation of correlation in acousic propagation channel is mainly caused by the time-space variation of the acoustic channel's multipath structure. In general, there is little innuence from the sea bottom in deep sca, so the multipath structure of the acoustic channels is simple. Thus in deep sca it is not morc difficult to realize the correction match for the acoustic channel. In this experiment, a towed powerful low-frequency transducer is used to transmit linear frequency modulated pulse,and at the receiving terminal the copy-correlation and the pulse to pulse correlation are used to obtain the time-space variation of acoustic channel correlation. Because the broadband, long duration pulse and corresponding signal processing method are made use, the noise influence to the correlation is reduced as greatly as possible.Therefor our experimental results prove that the time-space correlation of acoustic channel is mainly determined by the time-space variation of channel's multipath structure, and coherent part of such a multipath channel makes up about 40 per cent of its total. Meanwhile the experimental results deseribed in this paper would be helpful to study thc correction match of the dcep sea acoustic channel.