Research On Two-way Underwater Acoustic Communication System Based On Broadband Transduce

Underwater communication system consists of hydroacoustic transducer and electronic signal processing system,the performance of both has a great impact on the whole system,both of which are studied in this paper.The composite material technology is used to add flexible polymers to the piezoelectric ceramic pillars,thereby expanding the bandwidth of the transducer;at the same time,in order to improve the channel utilization and increase the maximum information transmission rate of the channel,a two-way communication system based on 1-3-2 piezoelectric ceramic/epoxy resin composite broadband transducer is designed for two-way hydroacoustic communication.In the study of the electromechanical performance of the transducer,the electromechanical theoretical analysis of the 1-3-2 composite material was carried out and the electromechanical equivalent diagram was established by the equivalent circuit method,and the resonant frequency variation law of the 1-3-2 composite material under different piezoelectric substrate thickness and piezoelectric pillar height was obtained.The effects of piezoelectric substrate thickness,piezoelectric pillar height and piezoelectric pillar width on the resonant frequency and anti-resonant frequency of the sensitive unit are also simulated and analyzed by finite element simulation software.The process implementation scheme of the broadband transducer was designed by combining the theoretical and simulation results,and the prototype of the broadband transducer was fabricated.the transducer prototype was tested for underwater performance,the results show that the resonant frequency of the transducer is about 299 k Hz,the maximum transmit voltage response can reach 172.4 d B,the-3 d B transmit bandwidth is 45 k Hz,the maximum receive sensitivity can reach-182.9d B,the-3 d B receive bandwidth is 50 k Hz,both transmit and receive bandwidths are larger than that of the pure piezoelectric ceramic material underwater acoustic transducer(whose bandwidth less than 20 k Hz),achieving the design goal of broadband transducer.Based on the 2ASK(amplitude shift keying)modulation theory,the circuit of each module of the single circuit hydroacoustic communication system was designed,and the PCB boards of the transmitter and receiver were fabricated,and the underwater test proved that the designed circuit could realize underwater digital communication.A second hydroacoustic communication system was built using the integrated modules,and a two-way hydroacoustic communication system was fabricated based on the frequency division multiplexing principle.The two-way digital communication system is tested underwater,and the results show that when two digital signals modulated by different frequency sinusoidal carriers are transmitted in the same channel,the receiver can receive the mixed signals and separate the two signals,demodulate and restore the two original digital signals respectively,with the bit error rate less than 1%.The designed two-way communication system has excellent performance and achieves the design goal.