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.