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Distributed sensing with free space optics

A distributed sensing system utilizes multiple geographically separated sensors to observe the world. The sensor systems can process data and then transmit it, receive data and then process it, or some combination of the two. For this chapter, we will examine a distributed radio frequency (RF) sensor system set on mobile platforms. The main challenges of any distributed system are localization, synchronization, and processing capabilities. This paper presents a novel solution that utilized a free space optical (FSO) link for communication between nodes. The FSO link will aid in localization and synchronization while also providing a high-speed communications path between sensor units to allow maximum flexibility in processing optimization. An example of FSO communication link between unmanned air vehicles (UAVs) is given to show the viability of establishing multi-Gbit/s optical communication links in presence of atmospheric turbulence. Optical communication offers the advantages of sensor information exchanges at high data rates as well as secure communications needed for a number of tactical applications. Before we discuss about the distributed system, a brief introduction into signals, systems, and signal processing is provided.