| Developing the underwater acoustic communication is significant not only in the military affairs but also in the commercial fields. The point-to-point communication is the basement of the underwater acoustic networks which should be real-time, high speed and robust. However, the UWA channel is more complex compared to the wireless channel and the inter-symbol interference (ISI) caused by multipath channel is an important obstacle for realizing the UWA communication. Therefore, this thesis will discuss the topic about Pattern Time Delay Shift Coding (PDS) system and Time Reversal Mirror (TRM) technology.Pattern Time Delay Shift Coding system belongs to the Pulse Position Modulation (PPM) that the digital information are encoded in the time delay shift values of the Pattern. The duty cycle is smaller than 1 which could economize the system energy. By using different Patterns for code division, the communication system has a high ability to mitigate the inter-symbol interference (ISI) caused by multipath channel. PDS system could increase the data rate by using different frequency for channel division. The system should select more Patterns in order to adapt to the bigger multipath spread time, but it is restricted. So we should adopt a more effective method for anti the ISI.Time Reversal Mirror can match the acoustic channel automatically and lead to an adaptive spatial focusing and a temporal compression. The application of the TRM to the UWA communication could eliminate or mitigate the inter-symbol interference (ISI) caused by acoustic channel's multipath and delay spread.The single sensor Passive Time Reversal Mirror (PTRM) is studied in this thesis whose efficiency is higher than Active TRM and the applicability is better than the processing of array. This thesis proposes to apply the single sensor PTRM to the PDS system, which is called PTRM-PDS underwater acoustic communication system.The results of computer simulations and lake trials show that the Passive... |
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