As an important part of modern communication,the underwater acoustic communication can realize long-distance information transmission and play an important role in the fields of deep-sea exploration and military.However,due to the narrow bandwidth of the transducer and the long wavelength of acoustic waves,the application of the traditional underwater acoustic communication is still limited by the large attenuation,low channel capacity and insufficient spectrum utilization.In this paper,the multi-channel underwater acoustic communication using circular transceiver arrays is established by combining the multiplexing of acoustic-vortex(AV)beams and the orbital angular momentum(OAM)spectrum decomposition.Based on the ASCII code of transmitted data,holographic signals of amplitude and phase modulation are used to drive the transmitter array to generate multi-channel OAM-multiplexed beam.Through circular acoustic sampling and OAM spectrum decomposition,the OAM modes carried in the multiplexed AV are decoded successfully to realize the high-efficient data transmission in parallel.The experimental 6-channel underwater acoustic communication is carried out with the 8-source circular transceiver arrays.The field measurement and OAM decoding of the OAM-multiplexed AVs are accomplished,and the performance of data communication is compared with that of the traditional one-channel serial one.Theoretical and experimental results show that the channel number based on OAM spectrum decomposition is determined by the source number N of the transmitter array,and the decoding accuracy is decided by the phase accuracy of the transmitters and sampling number of the receiver array.For a large system of N transceivers with N≥1,the transmission speed is proved to be about N larger than times that of the traditional acoustic communication system at a same baud rate.The multi-channel technology can greatly improve the channel capacity and the efficiency of spectrum utilization,and provides a practical scheme for its practical application in underwater acoustic communication.
维普
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