수중 센서 네트워크 시스템을 위한 통신용 모뎀 설계 및 구현

Abstract

Underwater sensor nodes will find applications in oceanographic data collection, pollution monitoring, offshore exploration, disaster prevention, assisted navigation and tactical surveillance applications. Moreover, unmanned or autonomous underwater vehicles (UUVs, AUVs), equipped with sensors, will enable the exploration of natural undersea resources and gathering of scientific data in collaborative monitoring missions. Underwater acoustic networking is the enabling technology for these applications. Underwater networks consist of a variable number of sensors and vehicles that are deployed to perform collaborative monitoring tasks over a given area. Underwater acoustic communication have received much attention as their applications, have begun to shift from military toward commercial. The growing interest in underwater acoustic communications come as a response to the rapidly growing needs for wireless underwater communications, brought in part by the broadening of applications, such as military and commercial ones. Commercial applications which have received much attention lately are pollution monitoring in environmental systems, remote control in off-shore oil industry, and collection of scientific data recorded at benthic station without the need for retrieving the instruments. Many developing applications include of commercial and military are now calling for real-time communication with submarines and autonomous underwater vehicles, not only in point-to-point links, but also in network configurations.

In this thesis, several fundamental key aspects of underwater acoustic communications are investigated. Different architectures for global sand local communication modem for underwater sensor networks are discussed, and the characteristics of the underwater communication modem is detailed. The main challenges for the development of efficient networking solutions posed by the underwater environment are detailed and a cross-layer approach to the integration of all communication functionalities is suggested. The performance of a digital baseband signal processing and data transmission rate depends on the modulation technique. Communication modem for Underwater sensor network is implemented using by DBPSK modem technique. In order to implement underwater sensor network modem, SNR detection block is suggested. SNR detection block has the reference SNR value that selects between base mode and additive user mode. In this thesis, suggested system is based on software interface and all Hardware(PLL, modem, filter, equalizer etc) is implemented by software, exclusive of DSP, A/D, D/A converter, SDRAM and Flash memory.