Short Range Wide Beam-width High Speed PPP-based Underwater Acoustic Network System

摘要

A prototype underwater acoustic network system with 600 kilo bits per second (kbps) and Point-to-Point Protocol (PPP) implementation was developed last year using a Binary Phase Shift Keying (BPSK) modulation for a new effective seafloor geodeuc observing robot network system. As mesa order high frequency is used for career, the beam width becomes too narrow for transducers to face each other for practical uses. In order to improve the directivity of the transducers, an arc surfaced piezo-composite transducer has been designed. Moreover, in order to mimaturize the system, DSPs are planned to be developed for signal processing in the prototype, in replacement of PCs. Hereunder the present situation and future plan of this study is introduced. The new prototype acoustic network system consists of two nodes--the server node and the client node. Each node comprises a data processing DSP, transmitter and receiver board, projector, and hydrophone. The projector and hydrophone are newly designed piezo-composite transducers with 30° directivity angle. In order to eliminate degradatton of the acoustic signal and intersymbol interference (ISI) by multipath, an adaptive filter is used. Now the DSP circuits are being developed to minaturize the system for practical uses.