| Shallow water acoustic channel is one of the most complex wireless communication channels. The inherent characteristics, such as space-time-frequency varying, narrow-band, high-noise, strong multipath interference, long transmission delay, large fluctuation, etc., making effectiveness and reliability performance of shallow water acoustic communication face enormous challenges. On the other hand, owing to the special economic and military-strategic position of shallow water, which involved the national interest and development, shallow water acoustic communication technique become a hot research area in recent years. Frequency-hopping communication as a major method of Spread-spectrum communication has many advantages, for example, anti-jamming ability, in particular the ability to narrow-band interference, anti-noise, anti-multipath, confidential and easy to implement Code Division Multiple Access (CDMA) technique. Consequently, shallow water acoustic frequency-hopping communication deserved extensive attention.With NI CompactRIO embedded module, an anti-multi-path frequency-hopping acoustic communication system was constructed, benefiting from its high-speed digital signal processing capability and the advantages of easy programming. A number of field test were carried out in Xiamen Harbor, and good results were achieved.The main work of this dissertation is as follows:1. Former researches in the field of underwater acoustic communication were introduced objectively. shallow water acoustic channel features and the impact on the underwater acoustic communication were analyzed;2. The transmission characteristics of the shallow water acoustic channel are studied in simulation. Transfer function and multi-path delay spread in the Taiwan Strait acoustic channel were simulated by BELLHOP ray model and fast field program respectively. The comb filter characteristics of shallow water channel and the impact on sound transmission performance were researched;3. Performance of error correcting coding-Turbo Code in shallow water acoustic channel was studied by simulation for reduce bit error rate;4. For the most critical issues of shallow water acoustic frequency-hopping communication - synchronization, Short-time Fourier Transform was used to fulfill a new software-based digital signal processing method time-frequency coding synchronization programme;5. Hilbert transform with related algorithms and wavelet transform were used to amplitude equilibrium and removing peak noise for the signal large fluctuations and peak pulse interference which will obstruct shallow water acoustic communication. Satisfactory signal conditioning was accomplished;6. An anti-multipath frequency-hopping communication system in shallow water acoustic channel was designed and implemented based on NI CompactRIO embedded module. A number of field experiments had done in the laboratory pond and Xiamen Harbor. Experimental results show that the bit error rate on the order of 10-2～10-3, by using Turbo Code, the bit error rate reduce to on the order of 10-4 on the channel of distance of 6 km, average water depth of 15m, at data rate of 500 bit/s. The system has strong anti-interference capability, achieved a stable communication.The originalities of this dissertation are as follows:1. Proposed a new software-based digital signal processing programme to fulfill a time-frequency coding synchronization;2. Hilbert transform and wavelet transform were used to carry out amplitude equilibrium and removing peak noise ;3. Based on NI CompactRIO embedded module, an anti-multipath frequency-hopping shallow water acoustic communication system was designed and performed in field test in Xiamen Harbor...
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