Research On Ultrasonic Communication Technology For Wall Medium

With the rapid development of science and technology,wireless communication technology has been widely used in the fields of intelligent manufacturing,Internet of Vehicles,telemedicine,and smart cities.However,in some specific working scenarios,for example,the electrostatic shielding generated by closed metal containers limits the transmission of electromagnetic waves,and wireless electromagnetic wave communication cannot be used normally in the case of strong electromagnetic interference.This paper proposes to use ultrasonic wave instead of electromagnetic wave as the carrier of information transmission.Taking advantage of the advantages of good directionality and strong penetration,it can overcome the influence of electrostatic shielding and strong electromagnetic interference on electromagnetic wave wireless communication,and at the same time does not occupy spectrum resources.In this dissertation,a low-rate half-duplex communication system based on ultrasonic is designed.The system uses the method of the host to ask the slave to respond to the data transmission between the master and the slave.The slave is connected to the data acquisition terminal and other equipment,and transmits the data collected by the terminal equipment to the host.This system is built on the basic and general hardware circuits platform.Through programming,each part of the communication function is defined by software in the MCU.The quality change adaptively adjusts the transmission rate and modulation mode combination mode.The design of this system is mainly divided into two parts: hardware circuits design and software program design:(1)Hardware circuits design.This part mainly includes signals receiving circuits,signals transmitting circuits,half-duplex switching circuits and system power supply circuits.The signals receiving circuits mainly includes a band-pass filter circuits and a level shift circuits,which filters and amplifies the received signals,and transfers the signals level as a whole to the voltage acquisition range of the ADC;the signals transmission circuits mainly includes a bandpass filter circuits and a power amplifier circuits.,filter out the DC and high-order harmonic components in the DAC output signals,amplify the power of the signals,and drive the ultrasonic transducer to perform electro-acoustic signals conversion;half-duplex transceiver switching is used to switch the circuits function state of system signals transceiver.(2)Software programming.This part mainly includes the overall workflow of the system,system data reception and processing,system data transmission processing and modulation rate mode customization.The system data transceiver processing part realizes communication functions such as error control coding and decoding of transmission data,DSSS spread spectrum despreading,DPSK and π/4-QDPSK modulation and demodulation,and modulation waveform definition and synthesis through DDS;modulation rate mode customization Partly by using the HARQ error control principle to realize the adaptation of the modulation mode and the transmission rate,and by evaluating the channel quality,the modulation mode and transmission rate can be adaptively adjusted to achieve a balance between the reliability and effectiveness of ultrasonic communication,and improve the system.availability,so that the system can transmit information in the best communication scheme.In this dissertation,the circuits schematic design and PCB drawing of the ultrasonic communication system are carried out;the software program of each part of the communication module is written;the production of the communication system prototype is completed;the joint debugging of software and hardware is carried out.As well as the functional test of each circuits and the bit error rate performance test of the information transmitted by the communication system.