Mobile FSO Platforms
FSO communication is not always stationary. Think of an on-the-ground ground-to-space communication station, such as the ones at Goddard. What if optical communication was needed somewhere nearby, but not exactly at, the Goddard Center? It wouldn’t be practical to move the entire station to a new location. Instead, a mobile FSO platform can be used to meet communication needs.
Mobile platforms are used in FSO to help facilitate communication for end users that are changing locations, currently moving, or are generally too mobile to consider using an on-the-ground station. For example, a mobile FSO platform would be used in war time where the battlefield may change several miles in a single day. It wouldn’t be practical to travel several miles back to the original stationary site to communicate strategy or receive orders. A mobile FSO platform lets the end user choose where the signal should be sent from. This gives the end user flexibility that a stationary platform cannot provide, especially when used in ground-to-air communication links. Mobile FSO platforms are also helpful for hikers and mountaineers who would need to re-travel previous terrain to make a communication link.
Common mobile FSO platforms include antennas mounted on trucks and tanks, ancillary transmitters and receivers which can be stored and deployed anywhere and usually fit in movable crates, and removable miniature transmitters and receivers small enough to fit in a backpack. Newer mobile FSO platforms are being mounted on drones and other unmanned aerial vehicles (UAVs).  Mobile UAV FSO platforms enable an end user to move the point of transmission or reception away from their current location, increasing positional security and possibly allowing the UAV to find an area of stronger signal strength. UAVs can also act as miniature relays, receiving a main signal from an outside transmitter and relaying it to the end user through a smaller transmitter housed on the device’s body.