Single-vector Transducer Channel Equalization Technology Of Time-varying Underwater Acoustic Communication

Underwater acoustic(UWA)communication has been the focus of research in recent years.Due to the bad channel conditions,such as the high noise of the Marine environment,the complicated multi-channel structure and the high propagation loss.In order to obtain higher received SNR,usually with large size receiving array receiving signals.However,this is not applicable in underwater vehicle,so it is very necessary to study the small size receiver with stable performance.This paper according to the characteristics of UWA channel established the physical models of time-varying UWA channel,the vector channel and time-varying vector channel.After the study of the relative characteristics of the sound pressure and the velocity of the vector field we knew that the sound pressure and horizontal vibrating velocity in the vector signal field were coherent,but the sound pressure and vertical velocity were not coherent.In the time-varying vector noise field,the sound pressure noise was not coherent with the velocity noise.This provides a physical basis for the study of adaptive channel equalization base on vector sensor.In this paper,the adaptive multi-channel Decision Feedback Equalization(AMDFE)was studied to suppression channel multipath interference and channel multipath fading.It improve the output gain of equalizer effectively,but that was at the cost of the bigger size of the receiver.Vector hydrophone can synchronize output the sound pressure and speed information of the vector field at the common point.The adaptive channel equalization system based on single vector hydrophone was studied,which was based on the sound pressure and horizontal vibrating velocity in the vector signal field were coherent,but the sound pressure and vertical velocity were not coherent,and the sound pressure noise was not coherent with the velocity noise in the time-varying vector noise field.By comparing the equalization performance of the single vector equalization system with the scalar equalization system,the vector equalization system has a better balanced effect than the scalar equalization system.The equalization performance of AMDFE was the best in the analysis of the equalization performance of different equilibria in a single vector equalization system.In order to further improve the balance of single vector equalization system performance,using an empty-focus features of the Time-Reversal to effectively suppress channel of multiplicity and using adaptive decision feedback equalizer(ADFE)to eliminate residual inter-symbol interference,it reduces the bit error rate(BER)of thebalance effectively.In view of the DFE will lead to the phenomenon of error transfer when it judgment mistakes,two-way DFE was studied for further lower the BER,which using the UWA channel about the time characteristics of asymmetric.The performance of single vector adaptive equalization in different environment parameters and different communication parameters was analyzed.The performance of single vector adaptive equalization algorithm in time-varying channel was studied and analyzed.Finally,the simulation and field experiments were carried out for the above theoretical analysis,the adaptive equalization algorithm for single vector adaptive equalization algorithm,two-way DFE algorithm,the adaptive equalization algorithm with Time-Reversal mirror technique and the equalization performance of the fractional interval equalizer were verified.