Generation of underwater acoustic orbital angular momentum and data transmission

Underwater acoustic communication based on the acoustic orbital angular momentum multiplexing is studied.The principle of acoustic Orbital Angular Momentum (OAM) emitted by the phased arrays is derived based on the point source theory.The order of interference terms and the interference terms to the main terms are analyzed.based on the finite element method,a prototype based on the Cymbal transducer was designed.The diameter of the array prototype is Φ180 mm,the number of array elements is 10 and the working frequency is 25 kHz.By adjusting the phase of the array element,it generates 6 OAM charges from-3 to 3,verifies the theory of OAM with different topological charges based on the phase control.By using the on-off state of each order to encode data,an underwater data transmission experiment is carried out.The experimental results show that the acoustic OAM with different topological charges has good orthogonal properties,and the underwater data transmission can be realized by using the multiplexing technology based on the acoustic OAM.