Research And Design Of Sound Wave Based Wireless Communication System

The continuous enrichment of application scenarios of wireless communication technology has led to the rapid development of wireless communication technology.WIFI,NFC and other wireless communication technologies rely on the corresponding hardware and bring about the increase of equipment costs.Therefore,this article has designed a set of wireless communication systems with sound waves as the carrier,which can be applied to the scene of near field communication.The hardware that this system realizes depends on the speaker and microphone that are included in the smart phone.Therefore,there is no need to add additional hardware modules.Compared with other wireless technologies,it has advantages in terms of cost,application convenience,and is easy to popularize.The main work of this paper is as follows:(1)The necessary preparations for the design of the acoustic wave communication system are made through the attenuation,multipath,and other characteristics of the sound wave propagation in the air medium and the research of modern digital communication systems.The masking effect of human ears on different frequency sound waves was studied,as well as the test of the frequency response characteristics of mainstream smart phone audio devices.The acoustic wave near the 20 kHz frequency range supported by audio equipment was selected as the carrier,and the carrier amplitude was limited.The user is unaware of the communication process.(2)In order to facilitate the upgrade and maintenance of the system in the later period,a hierarchical design framework was adopted to design the overall model framework of the acoustic wave communication system.For sound waves and equipment characteristics,negative frequency modulation and other methods are commonly used,and QPSK is used as the modulation method for the sound wave communication system.The noise in the air channel causes a certain degree of interference to the communication system.Therefore,a convolutional code is introduced to correct the communication data.To ensure the security of communication data,AES-128 algorithm is used to encrypt data.(3)The communication speed of the acoustic wave communication system is far inferior to the wireless communication system using electromagnetic waves.Therefore,a set of communication protocols without connection is designed for the characteristics of the sonic wave communication.The connectionless communication protocol eliminates the time for feedback confirmation in the connection-oriented protocol,and does not require the same time-consuming pairing process as Bluetooth and other technologies,making the sound wave communication system more user-friendly and streamlined protocols.Provide more flexibility for third-party application development.At the same time,the communication protocol has two forms of transmission,point-to-point and broadcast,which are beneficial to the adaptation of the acoustic communication system to different application scenarios.(4)On the Android platform,a complete sound wave communication test system was developed and tested.When the sound wave communication system uses only built-in equipment,the effective communication distance can reach 2.5 meters.After the external speaker and microphone,the most The far-distance communication distance reaches 5 meters,and the performance is better than the system designed by Evan Lynch.The sonic wireless communication system designed in this paper will not produce human audible sounds in the communication process,and does not need to cover up the noise with music and other methods like Alipay's sound wave payment scheme.The connectionless communication protocol designed for acoustic characteristics enables normal communication between multiple devices.Sonic communication technology provides a solution for wireless communication applications,relying on popular smartphones and has strong competitiveness.