Characteristic Evaluation of the Mobile Acoustic Communication for Spherical Underwater Robots (SUR III)

The wireless communication as a key technology for the underwater robot will implement the underwater observing, cooperation or collaboration. This paper focuses on the Underwater Acoustic Communication (UWAC) for the third-generation spherical underwater robot (SUR III) which has the advantages like good flexibility, convenience and wide spread. An UWAC system is established for the SUR III. Considering that UWAC needs to overcome the multi-path effects, time-varying effects, narrow available bandwidth and doppler effects, a Micron data modem is chosen as the communication module. This modem uses the CHIRP signal which can change the frequency with time to achieve the acoustic communication. The hardware of the UWAC system is established by using the eZdsp board. This system as a subsystem serves the overall control of the SUR III. With the relative movement of the underwater robot in actual work in mind, the mobile acoustic communication is proposed. The influence of the Doppler shift and propagation loss underwater for the SUR III are analyzed. The experiments for the mobile modem underwater and multi-path effect are carried out to verify its communication performance. And there is no Bit Error Rate (BER) in a specific range.