Research And Implementation Of OFDM Underwater Image Transmission System Based On ARM And DSP

Orthogonal Frequency Division Multiplexing is a special technology of multicarrier transmission, in which the channel is splitted into several orthogonal channels at different frequencies. The data stream is modulated over a number of sub-carriers and transmitted parallel. The benefits of OFDM are high spectral efficiency, low crosstalk between subcarriers and robustness against frequency selective fading. It has an advantage over the underwater acoustic channel, which is time-varying, frequency-dependent with a serious multi-path interference.With the development of computer and multimedia communication technology, embedded system is further applied in various fields. Advanced RISC Machine (ARM) is the industry's leading provider of 32-bit embedded RISC microprocessors. Because of their high performance and power saving feature, ARM CPUs are widely used in a number of embedded designs, such as industrial control, wireless communication and consumer electronics. As the increase of the system complexity, embedded operating system has become an indispensable part of the embedded system. Apart from the fact that it's freely distributed, embedded Linux is increasingly being used owing to its functionality, adaptability and robustness.Digital Signal Processor(DSP) is a microprocessor designed specifically for digital signal processing work. It has a powerful capability in real-time computing, but limited addressing range and weaker IO function. A dual-processor system combing ARM with DSP can make full use of their advantages.The paper researches an underwater acoustic image transmission system based on OFDM technology, and implements it with ARM+DSP hardware platform. The main research contents include: basic principle of OFDM system, bottom hardware driver of ARM and DSP, Linux OS transplant, design of human-computer interface with MiniGUI and related program for its wider application. Besides, OFDM modulation and demodulation are implemented by using TMS320VC5502. This paper has reference value for the further realization of underwater image transmission system.