Hardware Design And Implementation Of A Software-Defined Underwater Acoustic Modem Applied On OMAP Platform

As the only way of long-distance underwater wireless communications,underwa-ter acoustic(UWA)communications is the main means to realize the underwater infor-mation perception and interaction.However,UWA channel features long time delay and large Doppler spread.These varying characteristics have brought to high-speed and high-reliability UWA communications with great challenges.Therefore,the research on high-speed UWA communication system has key important scientific significance and practical value.The core idea of the software-defined radio(SDR)technology is to use standard-ized hardware as a common platform,and to achieve as many communication functions as possible with the scalable software.We use the SDR technology to guide the UWA com-munication system top-level design,which can simplify the underlying hardware modules.In the meantime,this reserves the development interface for the function upgrade of the communication algorithm software in the future.This thesis combines the SDR technology and the embedded development technology.A set of software-defined UWA modem hardware platform is partially implemented.The main work of this thesis is to study the various process steps of the transmitter and the receiver of the UWA communication system.The communication parameters and simulation are given to testify the theoretical performance of the communication system.In addition,UWA communication system needs to complete a large number of signal pro-cessing operations and data transmission control.So we choose OMAPL138 as an embed-ded development platform.OMAPL138 is a low-power processor with a C6748 DSP core and an ARM9 core,which has powerful capability of data processing and system control.Hence,it is suitable for UWA communication system.Based on the OMAPL138 embedded platform,we develop the UWA modem software platform and analyze the working mode of the system.Finally,it is verified that the system has basic communication capability and good working reliability through a series of experiments.The trials contain the independent test-ing of the ADC module and the transducer.The complete system sine waveform transceiver testing is also carried out in an anechoic tank.