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This work presents the generation, dynamic phase modulation and phase detection of interfering composite optical vortices. This technique demonstrates a new method for encoding information onto an optical beam for potential use in underwater communication as well as sensing applications including object detection and channel characterization.
The underwater object imaging is an important task for the surveillance and monitoring of underwater environment in a non-intrusive manner. The acoustic methods have been proved to be very powerful for the detection and localization of underwater objects. This paper proposes a new method for object imaging based on an acoustic system that uses multiple elements. The image is obtained using two main...
In underwater acoustic networks (UWANs) with bidirectional communication links, channel state information (CSI) plays an important role since having a good channel knowledge allows system performance enhancements. Two communicating nodes can use the information obtained by their respective channel estimation in order to adjust the transmission parameters to the channel characteristics. However forward...
Predicting the performance of underwater acoustic (UWA) communication is a big task because the physical properties of the water. Since sea trial is expensive, prior simulation is a common method to enhance the mission success. However, a simulator cannot predict the real UWA modem performance and behavior. Recently, there is an interest of using an UWA channel emulator for gaining insight of the...
Underwater acoustic sensor networks are characterized by limited transmit power and bandwidth, and a harsh communication environment. Different techniques for reliable communication in underwater networks have been studied in the literature at different layers of the network protocol stack. Among these, the use of fountain codes as a way for improving the quality of the communication over a highly...
This paper presents a technique for extending the bandwidth of chirped active sonar signals. Bandwidth synthesis (BWS) results in improved range resolution, increased signal-to-noise ratio (SNR) and reduced fading due to delay-spread multipath. The approach demonstrated uses a low-order autoregressive (AR) process to model de-chirped segments of the received signal, which are then extrapolated using...
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