Bidirectional Laser Communication System for Telemetry Data
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Solution Overview
Problem
Free-space laser communication systems face issues with atmospheric turbulence causing beam wander and signal fading due to destructive interference, and incompatibility between Gigabit Ethernet and Synchronous Optical Network protocols, leading to errors in high-speed telemetry data transmission.
Innovation Solution
A dual atmospheric effect mitigation approach using an optical communications receiver array to address beam wander and a framer/forward error correction/interleaver device to correct signal fading, along with a smart media converter to convert between GBE and SONET protocols, enabling error-free bidirectional communication over long distances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If free-space laser communication is used for high-speed telemetry data transmission, then data transmission speed is improved, but atmospheric turbulence causes beam wander and signal fading leading to transmission errors
Solution Approach 1:
The optical receiver is divided into multiple elements (at least two) that are spatially separated. Each receiver element receives a portion of the optical signal independently. By segmenting the receiver, the system can process multiple signal paths simultaneously, mitigating the impact of atmospheric turbulence on any single element and improving overall signal reliability while maintaining high transmission speeds
Solution Approach 2:
A beam combiner is introduced as an intermediary component that combines the optical signals from multiple receiver elements. The beam combiner integrates the segmented signal paths into a unified output, allowing the system to benefit from diversity reception while maintaining the high-speed data transmission capability of the free-space optical link
2Productivity
If Gigabit Ethernet protocol is used for high-speed telemetry data, then data rate is improved, but incompatibility with existing SONET protocol laser communication equipment occurs
Solution Approach 1:
A protocol converter is introduced as an intermediary device that translates between Gigabit Ethernet and SONET protocols. The converter receives high-speed GBE data, converts it to SONET format compatible with existing laser communication equipment, and transmits it over the free-space optical link. This intermediary enables compatibility with existing SONET infrastructure while maintaining support for high-rate Gigabit Ethernet telemetry data
3Length of stationary object
If optical signals are transmitted through free space for long-distance communication, then communication distance is improved, but destructive interference from reflected signals causes fading and bit errors
Solution Approach 1:
The optical receiver is segmented into multiple spatially separated elements that independently receive optical signals over long distances. By distributing the reception across multiple elements, the system captures diverse signal paths that experience different fading conditions, allowing combination of signals to recover from destructive interference and maintain signal integrity
Solution Approach 2:
The beam combiner acts as an intermediary that processes signals from multiple receiver elements. It combines the signals in a manner that mitigates the effects of fading caused by destructive interference, enabling reliable long-distance communication by recovering signal strength and quality from the combined diverse paths
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
The system effectively mitigates atmospheric effects and protocol incompatibilities, providing a seamless, high-speed, error-free bidirectional laser communication link for telemetry data transmission over a kilometer, utilizing commercially available components.
Implementation Method 1
an optical communications receiver array that is optically coupled to the array of lenses and configured to convert light impinging on the array of lenses into differential electrical signals
Implementation Method 2
Optical signals in free space experience a fading effect which is caused by destructive interference of reflected signals from other objects in the free space to the receiver
Data Source
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Figure 3~4
AI summary
A free-space laser communication system for bidirectional transmission of telemetry data in Gigabit Ethernet (GBE) protocol using a dual atmospheric effect mitigation approach. This free-space bidirectional GBE laser communication system utilizes an Optical Combining Receiver Array and a Framer/Forward Error Correction/Interleaver (FFI) device to mitigate the combined effects of atmospheric turbulence and channel fading. Since the FFI device is designed for Synchronous Optical Network (SONET) protocol, an intelligent (or smart) media converter is used to convert GBE telemetry data to SONET frames, which enables the FFI device to perform an error correction algorithm and provide a seamless error-free GBE laser communication link for distance over a kilometer. This bidirectional laser communication system can be implemented with low-cost commercially available components.