UWA Communication Module Based On OMAP And Orthogonal Frequency Division Multiplexing

With the development of marine exploitation and the information industry, the demand for using marine channel to transfer information has greatly increased. However, narrow bandwidth of the channel and strong multi-path disturbance make how to realize high speed transmission in underwater acoustic channel to be one of the hot schemes of underwater communications technology.Aim at the shortage of realization scheme for traditional underwater acoustic communication system, an underwater communication module based on the orthogonal frequency division multiplexing (OFDM) technology is researched and designed under the platform of open multimedia application platform (OMAP) in this paper.In this thesis, the advantages and disadvantages of OFDM technology is firstly introduced, and fast FFT algorithm in OFDM is induced based on the study of the basic principles of OFDM technology. How to actualize the Guard Interval in the OFDM systems and the significance of using cyclic prefix as a guard interval are proposed. Analyze and Construct system model ground on OFDM. Apply LS criterion to estimate the pilot position of channel. The autocorrelation of LFM signal is used to conduct time synchronization. Four realization schemes of OFDM and their advantages and disadvantages are mainly discussed in this paper. Then parameters of OFDM systems are chosen according to the transmission properties of underwater acoustic channel, based on which the influence on coed current and received signal are simulated by computer in the case of presence and absence disturbance technology.The OMAP3530 processor's unique ARM Cortex-A8 core, the structure of TMS320C64x+ DSP core with two cores and dual-core communication mechanism are demonstrated in this paper. On the basis of above analysis, the multilayer software architecture with the core of Linux operating system and its construction process are investigated. Finally, software structure of the communication system is designed, whose communication code are also optimized.Communication module is tested by underwater acoustic communication experiment, the results of which show that adopt underwater communication with OFDM technology is feasible.