Communication Distance Correlates Positively with Emitter Current in Underwater Electric Current Communication

Underwater communication is challenging for small underwater robots that have stringent power and size constraints. In our previous work, we have demonstrated that electric current communication is an alternative method for small underwater robot communication. This paper studies how the emitter current affects the communication distance of electric current communication between two fish models. First, the working principle of electric current communication is explained by a simplified electric dipole model. Then, the explicit function between the emitter current and the critical communication distance is mathematically derived. After that, systematic design of the electric current communication system is proposed for small underwater robots. Finally, the communication distance experiments are conducted between two fish models with 15 different emitter currents. The results well validate the derived model that the critical distance r(c) correlates positively with the emitter current I-0 in the form of r(c) = K3 root I-0 where K is a constant related to the system and environmental parameters.