Design Of Acoustic Data Transmission System Based On DSP And Application Of OFDM Technology

Since the limited frequency and bandwidth of acoustic carrier, acoustic data transmission systems which MFSK and QPSK modulation techonolgies applied in cannot meet the requirement for the transmission of high-speed data. The thesis researches on the OFDM technology applied in acoustic transmission, thus improving data transmission rate.The thesis commences with an introduction of the theory for OFDM modulation and demodulation, a discussion of factors associated with system performance, and the OFDM frame structure as well as parameters when a 7.5 KHz sound wave is chosen as the carrier. Based on analysis of OFDM theory and application of modern signal processing technology, it is proposed a scheme for acoustic data transmission system with DSP as its processing core and FPGA as its controlling core.The thesis introduces the Software development process based on Visual DSP++, provides the program structure for DSP, and detailedly deduces AGC adjust algorithm, Dcli detection & symbol synchronization algorithms, and channel estimation algorithm, which are implemented in ADSP-BF532. FPGA logical construction is implemented on the platform of Quartus II according to circuit function. Also included in the thesis are a detailed introduction of the principles of logic for SPORT interface logic, SPI interface logic, DUC logic and DDC logic, and a brief introduction of implementation methods for AD7945, AD7801 and AD7492 control logic.The thesis concludes with FPGA logic test and data transmission test. The test results reveal that the design realizes acoustic data transmission.