A NEW INNOVATIVE MULTIMODULATION ACOUSTIC COMMUNICATION-SYSTEM

In most applications, underwater acoustic transmissions have to be ada pted to the environmental conditions (vertical, horizontal or slant li nk, multipaths, noise...). The Multimodulation Acoustic Transmission S ystem is a new concept which acts as a modern whose modulation schemes and baud rates are remotely controlled by the operator. Three types o f modulation are implemented in the same system: Phase Shift Keying (P SK) for vertical transmission, Chirp and Frequency Hopping modulations for horizontal communication. The user can select in real time the tw o main parameters (modulation and baud rate), test the reliability of the transmission and finally decide to use the modulation scheme and t he baud rate which will insure the best quality. The underwater unit i s then remotely programmed by the acoustic link. The system is describ ed in detail with emphasis on the types of modulation; results obtaine d during campaigns at sea are presented.