Theoretical And Application Research On Mobile Phone Acoustic Communication

Acoustic communication uses sound to transfer data in short distance,which shows a lot of advantages such as well security performance,low cost etc.With the development of communication technology and the popularity of smart phone,acoustic communication has been widely applied in areas of voice recognition system,mobile acoustic pay,smart community certification,oil exploration and become one of the most heated topics.In this dissertation,development and research condition of acoustic communication has been presented,along with the application field and some related technologies including fast Fourier transformation(FFT),window function,PSWF,CRC and RS code.After investigating the frequency characteristics of non-stationary noise,a fundamental frequency extraction algorithm has been proposed.An access control system using mobile acoustic communication based on the algorithm has been realized.The main work and contribution are presented as follows:(1)Interference could be easily introduced during transportation of acoustic data.To solve this,the frequency characteristics of non-stationary noise were firstly analyzed to investigate its statistical regularity.And according to the analysis,the acoustic data exaction algorithm has been proposed based on the characteristics.Mobile transmitting terminal need to encode the acoustic data by producing a specific PSWF for every single code word;several FFT need to be done after the acoustic receiving terminal receiving the PSWF.Then exact the most and second most powerful frequency point for successive 3 times and determine the base frequency of PSWF using statistics,weighting methods.The theoretical and experimental results prove the powerful anti-jamming capacity and high accuracy.(2)An access control system has been developed based on the mobile acoustic communication.The features,composition,main function modules and communicating procedure of the system have also been introduced in the dissertation.The structure of APDU and core layer,acoustic synchronization scheme,data serialization and the communication interface between the acoustic receiving terminal and the controller of the system have also been determined to realize the system.(3)The access control system has been designed based on Android system by using C,Java language.The system consists of three parts:mobile transmitting terminal,acoustic receiving terminal,the communication interface of the controller of the system.Data encode,PSWF producing are the main task of mobile transmitting terminal;the acoustic receiving terminal has functions like sonic sampling,synchronization,Sonic Extraction Algorithm,MLPX;the communication interface uses the library functions in Java android.hardware.usb to realize the communication between the receiving terminal and the controller.At last,the function,accuracy,and identification time of the system have been tested.The results show that the system could function well,the accuracy is up to 98%and the average responding time is 0.8s.The system reaches the origin goal.