Adding an on Off Keying (OOK) Communications Signal to a Free Space Optical Beacon Pointing Focal Plane Array System

In addition to the primary high rate communications signal, optical communications systems can include lower power beacon signals to aid in the pointing alignment between the transmitter and receiver. The beacon can be a simple always-on signal at a separate wavelength that the receiver can use for spatial tracking. The beacon signal may also be modulated at a low frequency for the purpose of discrimination between potentially multiple optical transmitting terminals. Applying data modulation to the beacon signal to form a low rate communications signal is also possible. The practical application of applying data modulation to a beacon signal along with associated system trades are discussed.