Free space optical communication (FSOC) technology has been developed rapidly and practically applied in many scenarios such as satellite-related ones, in unmanned aerial vehicles, for underwater use, etc. In certain applications, it is very important to obtain the high-precision position and distance information. The laser ranging technology is one of the main ways to realize it.
View Article and Find Full Text PDFFast steering mirrors (FSMs) offer a potential alternative for large-range deflection of light beams. However, for a large-stroke FSM, its pointing precision is unacceptably deteriorated due to the actuator non-uniformity, mechanical axis coupling, and the coupling of line-of-sight (LOS) kinematics. This Letter proposes a comprehensive beam-pointing algorithm by decoupling the LOS kinematic model and establishing a two-dimensional correction mapping to compensate for the non-uniformity and mechanical coupling.
View Article and Find Full Text PDFWe propose and experimentally demonstrate a large-range and seamless rate-adaptive free-space optical (FSO) scheme based on rate compatible modulation (RCM). It utilizes a mapping method through weighted summation, enabling an even increase of bit energy. This allows the system to seamlessly adjust the throughput.
View Article and Find Full Text PDFHow to measure the pointing angle precisely without the beacon light is crucial for beaconless laser communication. The conventional intensity method directly measures the intensity of a part of the communication signal beam, which has low sensitivity. We propose the characteristic signal method by superimposing a low-frequency sinusoidal signal on the communication signal to promote the measuring sensitivity.
View Article and Find Full Text PDFThe function and performance of acquisition, pointing, and tracking (APT) for the space laser communication terminals must be characterized on the ground before the launching. However, short working distance causes the terminals to not be viewed as a point, leading to the challenge for the whole-process equivalent test. A novel equivalent test method is proposed, to the best of our knowledge, by using a narrow laser beam and the imaging relationship between two terminals.
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