Investigation of the propagation stability of a doubly spread underwater acoustic channel

Investigation of acoustic propagation in an underwater channel is presented. Propagation between fixed transmitting and receiving sites is studied using a 420-Hz CW tone and a binary pulse sequence with 19 ms of time-delay resolution. The channel is shown to be underspread (BL < 1) so that unambiguous instantaneous measurements of the channel's approximate impulse response are obtained. The experiment is designed, in cooperation with the channel, to allow simultaneous and independent frequency spread, time spread, and broad-band noise power measurements. Some results and a preliminary model of the channel are presented.