Orthogonally Encoded Optical Beacons for FSO Tracking
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Solution Overview
Problem
Free space optical (FSO) communication systems face challenges in maintaining accurate beam pointing and tracking between terminals, especially when terminals are subject to movement due to environmental factors like strong winds or vehicle motion, leading to unpredictable communication links.
Innovation Solution
The use of encoded and spatially structured optical beams, where a transmitter emits multiple orthogonally encoded beacons with a known pattern of spatial overlap, allowing a receiver terminal to determine its position and orientation relative to the transmitter using an optical sensor and computing system, enabling precise alignment and tracking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If FSO terminals use high directionality for beam transmission, then communications capacity and privacy are improved, but beam pointing accuracy and link reliability deteriorate when terminals move
Solution Approach 1:
The system segments the beacon signal into multiple orthogonally encoded components that can be separately detected and processed. Each beacon carries unique encoding information that allows the receiver to distinguish and track individual beam positions, enabling accurate pointing measurement even when the overall beam pattern shifts due to terminal movement
Solution Approach 2:
The system changes the encoding parameters of the beacons using orthogonal codes, allowing the receiver to differentiate between multiple beacons and determine precise positional and orientational relationships. This parameter encoding enables the system to maintain reliable tracking despite environmental movements by providing distinct measurable parameters for each beam
2Adaptability or versatility
If FSO terminals are mounted on moving platforms (towers in wind, flying vehicles), then adaptability to different environments is improved, but beam alignment accuracy deteriorates
Solution Approach 1:
The system implements feedback by having the receiver terminal measure the relative position and orientation based on detected beacon patterns, then communicate this information back to the transmitter. This feedback loop enables continuous adjustment and maintenance of accurate beam alignment despite movements of the platform, as the system constantly monitors and corrects for positional changes
Solution Approach 2:
The transmitter terminal preliminarily establishes a known pattern of spatially overlapping beacons with orthogonal encodings before communication begins. This pre-configured beacon pattern provides a reference framework that the receiver can use to immediately determine relative positioning and orientation, enabling rapid adaptation to the moving platform's position without requiring real-time recalibration
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enhances the reliability and stability of FSO communication links by enabling accurate positioning and orientation of receiver terminals relative to transmitter terminals, even in dynamic environments, thereby improving data transfer rates and maintaining alignment during movement.
Implementation Method 1
The optical sensor senses the overlapping optical beacons and produces an (e.g., electrical) output signal indicative of an optical power of each of the overlapping optical beacons
Data Source
AI summary
A free space optical (FSO) transmitter emits multiple, orthogonally encoded, beacons having a known pattern of spatial overlap. A receiver includes a sensor and a computing system. The sensor senses the overlapping optical beacons and produces an output signal indicative of an optical power of the overlapping optical beacons. The computing system separates the output signal into components from the different beacons according to the orthogonal encoding of the beacons. Based on strengths of the components and on the known pattern of spatial overlap, the computing system may determine at least one of: (1) a position of the receiver relative to the transmitter, (2) a position of the receiver in the beacon pattern, or (3) an orientation of the receiver relative to the transmitter.