Research And Design Of Acoustic Near Field Communica-tion System Based On Smart Phone

With the rapid development of mobile Internet, smart devices have become a necessity of people’s daily life. The demand of short-range communication between smart devices makes near field communication technology to find its suitable stage. In a variety of near field communication technology, acoustic near field communication technology has the advantages of low cost, easy to use and so on, which can be widely used in mobile payment, equipment matching, small data transmission. Currently, research on near-field acoustic communications technology is relatively few, and there is no uniform standard, so it is needed for further research, which contributes the development of near field communication between smart devices.In this paper, acoustic near field communication technology is studied, and the following works are done:1. Due to the transmission of acoustic near field communication system in the source and the destination is a digital signal, so acoustic near field communication system belongs to the digital communication system. Firstly, the framework and process of digital communication system is introduced, and the key technologies of the system are studied, including channel coding, digital modulation and demodulation.2. Based on the digital communication system, the paper designs the framework and the communication process of the acoustic near field communication system based on the smart phone.3. Refer to the underwater acoustic communication system, the choice of the modulation in the system is Differential Phase Shift Keying(DPSK) and Orthogonal Frequency Division Multiplexing(OFDM), one is the first to be used and the other is the most widely used in the underwater acoustic communication. In order to get the effective demodulation of both signals, the simulations has been done by MATLAB software, and finally, the suitable modulation and demodulation of both signals for smart phone are obtain.4. The author has accomplished software development of the near field acoustic communication system in Android system, which the whole communication process of the signal from the sending end to the receiving end is realized. The sending end process including baseband signal generation, convolutional coding, modulation of DPSK and OFDM signal, control the speaker sends an acoustic signal. The receiving end process including controlling microphone to receive sound wave data, DPSK and OFDM signal demodulation, Viterbi algorithm for decoding convolutional codes. The whole system is written in JAVA programming language, and the system is designed with the idea of object-oriented programming.5. Finally, the performance test of the software, the accurate and effective test results indicate that the system can complete short-range communication between the smart phones, which has a high application value.