Free Space Optical Link Acquisition Using Segmented Search Patterns
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Solution Overview
Problem
Communication devices using free space optical links face challenges in establishing accurate alignment, leading to misalignment issues that hinder the formation of communication links, requiring efficient search and acquisition methods to ensure proper orientation and data transmission.
Innovation Solution
The method involves designating one communication device as primary and the other as secondary, with the primary device transmitting a beacon beam while the secondary device rotates in a spiral search pattern to detect the beam, and vice versa, using processors to determine alignment and adjust search patterns to establish a communication link.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional search patterns are used for optical alignment, then the optical link can be established, but the alignment process is time-consuming and inefficient
Solution Approach 1:
The search pattern is segmented into multiple levels: a coarse search pattern that covers a large area to quickly locate the general direction of the beacon, followed by a fine search pattern that concentrates on a smaller area for precise alignment. This hierarchical segmentation allows the system to efficiently progress from rough localization to accurate tracking without exhaustively searching the entire possible space.
Solution Approach 2:
The system performs preliminary actions by first executing the coarse search pattern to establish an approximate alignment before initiating the fine search pattern. This preliminary coarse alignment reduces the search space for the subsequent fine tuning phase, significantly reducing the total time required to establish the optical link.
2Area of stationary object
If the optical systems rotate continuously to search for alignment, then coverage area increases, but the system complexity and difficulty of maintaining stable detection increase
Solution Approach 1:
The search space is segmented into distinct zones handled by different search patterns. The coarse search pattern covers outer regions with larger step sizes, while the fine search pattern operates in inner regions with smaller step sizes. This segmentation allows comprehensive coverage without requiring a single complex search pattern to handle all scenarios.
Solution Approach 2:
The search pattern dynamically adapts its parameters based on the detection stage. The system transitions from a dynamic coarse search with larger rotational steps to a more static fine search with smaller steps as alignment is approached. This dynamic adjustment optimizes the balance between coverage area and detection stability throughout the alignment process.
3Duration of action of moving object
If the primary device remains fixed during search, then the secondary device has more time to detect the beacon, but the primary device may miss detection opportunities when the secondary device is misaligned
Solution Approach 1:
The primary device performs periodic rotational movements according to the coarse search pattern, creating periodic opportunities for beacon detection. This periodic action ensures that even if the secondary device is misaligned during certain phases, the primary device will eventually present the correct orientation during its rotational cycle, maintaining detection reliability while providing extended detection windows.
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 enables efficient detection of beacon beams and establishment of communication links with high accuracy, ensuring reliable data transmission between communication devices, even in remote or dynamic environments.
Implementation Method 1
a first optical system of a first communication device... a beacon beam transmitted from the first communication device
Implementation Method 2
the receiving terminal may use a position sensor to locate the transmitting terminal and to monitor the beacon laser
Data Source
AI summary
Aspects of the disclosure provide for a method of forming a communication link between two communication devices using a primary search pattern and a secondary search pattern. A misalignment between a first optical system of a first communication device and a second optical system of a second communication device is detected. The first optical system is rotated according to the primary search pattern, and the second optical system according to the secondary search pattern. At the second communication device, a set of frames is captured. Then, it is determined whether a beacon beam transmitted from the first communication device is detected in the one or more of the captured frames. When it is determined that the beacon beam is detected, the communication link is formed between the first communication device and the second communication device.