Fundamental Research Of Through-metal Ultrasonic Communication System

A through-metal ultrasonic communication system is designed,it uses the characterstic that ultrasonic wave has a strong penetrating power in the metal to overcome the influence of the electrostatic shielding effect caused by closed metal containers in traditional wireless communication,it achieves the point-to-point communication through metal containers.Based on the transmission characteristics of ultrasonic waves in metal dielectric and the basic problems of channel,a dissertation analysis of the communication system is given,it separates the ultrasonic channel into primary response channel and echo channel and models them separately.System identification and Steiglitz-McBride iteration method are used to estimate the model parameters,and the model orders is solved based on the mean square error between the channel response and the model response.Then according to the modulation technology of communication system,a point of the combination of OFDM technology and through-metal ultrasonic communication system is proposed,it analyzes the feasibility and related technologies,and explains the improvement on the performance of this communication system.At the same time,from the perspective of improving the system transmission rate,this paper introduces the MIMO technology,focuses on the influence of intersymbol interference in the ultrasonic channel on MIMO,and proposes two solutions.Finally,based on the performance of the system,in order to ensure the reliability of system transmission,the boundary of ISI is established according to the echo attenuation envelope and the relationship between echo and transmitted signal,it gives the constraint of the optimal transmission rate under specified BER.In order to eliminate the interference of echo in ultrasonic channel,the concept of combining through-metal ultrasonic communication and equalization technology is proposed,and it gives two equalization schemes according to the path models ultrasonic channel.The results show that although the simplified equalizer has a lower complexity,the echo is only reduced by 9dB,the inproved equalizer can completely eliminate the effect of the echo signal by the the cancelation pulse at the cost of high complexity.