Multicarrier Based Data Transmission System With Ultrasonic In Solid Media

Utrasonic which can spread in solid media with low attenuation can be used in situation that wire can't be setted and wirless wave can't penetrate for communication.However,the narrow bandwith and multi-path effect in solid media of ultrasonic carrier causes bad communication performance.This thesis desined a hardware and software platform based on multicarrier which is widely used in morden communication and using other communication algorithms to make research on it's abiliy of improving the communication performance of ultrasonic in solid media.First,this thesis analyzed the feature of ultrasonic transducer and the spreading regularity of ultrasonic in solid media and builded a sender-receiver model with multicarrier modulation to analyze its performance and convolution encoding which can enhance the error controlling ability of the system.Then,parameters of the system are determined by simulation of the main algorithms.Moreover,this thesis used two STM32F407 as the central controller to realize a hardware and software system with a sender and a receiver.In hardware,the system mainly contains: D-A converter,transducer driver,signal processing circuit and A-D converter.In software,by mainly using C and C# language the system realizes a embedded controlling program including: multicarrier modulation algorithm,digital FIR filter,convolution encoding/decoding algorithm,testing program in host computer and it's communication interface.Finally,this theis tested the system and analysed the result.The research and the result of experiment showed that phase shift caused by transducer and multipath effect can be reduced by using multicarrier modulation.Symbol interval can be reduced to make communication speed further increased with good communication quality.Moreover,convolution encoding can fix most of occasional symbol error.There is some practical and referentail value in specific sphere where using ultrasonic to penetrate solid media for communication,for the reason that this system has the feature of low costing,high communication rate and high reliability.