FPGA Optoelectric Controller for Satellite Laser Ranging
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Solution Overview
Problem
The existing satellite laser ranging systems using commercial computers face challenges with high-speed signal processing, leading to noise production and maintenance issues due to variations in computer performance and interface card configurations, affecting the accuracy of laser light arrival time measurement.
Innovation Solution
An optoelectric controller is developed without relying on a computer, utilizing a single semiconductor device with Lagrange interpolation and error correction through a conversion table to accurately predict and measure the arrival time of laser light, controlling the gate of a Compensated Single Photon Avalanche Diode (C-SPAD) for precise satellite data reception.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a commercial computer with high-performance CPU is used for real-time data processing in satellite laser ranging system, then processing speed and convenience are improved, but system complexity increases and maintenance becomes difficult due to variations in computer performance and interface card configurations
Solution Approach 1:
The patent extracts the essential function of real-time data processing from the commercial computer system and implements it in a dedicated FPGA device. The optoelectric control apparatus is separated from the computer, with only necessary data (laser firing time, arrival time, distance) being transferred between systems. This extraction eliminates the complexity of computer-based processing while maintaining real-time capabilities through hardware implementation in FPGA.
Solution Approach 2:
The patent replaces the software-based processing system (computer with OS and development software) with a hardware-based FPGA system. The FPGA implements Lagrange interpolation and arrival time calculation directly in hardware, substituting the mechanical/software system with an electronic/hardware system that is more stable and maintains consistent performance across different deployments.
2Ease of operation
If commercial computer power supply devices are used in satellite laser ranging system, then system convenience is improved, but noise is generated that interferes with high-speed signal processing
Solution Approach 1:
The patent extracts the optoelectric control function from the commercial computer system and places it in a separate FPGA-based apparatus. This physical separation removes the noise-generating power supply devices of the computer from proximity to the sensitive signal processing path, eliminating electromagnetic interference while maintaining operational convenience through the dedicated hardware system.
3Speed
If interface cards are used for signal and data transmission between computer and satellite laser ranging system, then real-time data transfer is enabled, but maintenance becomes complex due to variations in transfer rates and configurations
Solution Approach 1:
The patent extracts the essential real-time data transfer requirements and implements them through a minimal interface between the FPGA-based optoelectric control apparatus and the computer. Only three critical parameters (laser firing time, arrival time, and distance) are transferred, eliminating the need for complex interface cards with varying configurations. The FPGA handles all processing locally, requiring only simple data output to the computer for recording and analysis.
Solution Approach 2:
The patent changes the interface parameters from complex, variable configurations to a fixed, minimal set of three parameters. By standardizing the data transfer to only these essential values and handling all computation in the FPGA, the system achieves real-time performance with a simple, maintainable interface that does not vary with different computer configurations.
Data Source
AI summary
An optoelectric control apparatus for a satellite laser ranging system comprises a communication controller for externally receiving optoelectric control data. Memory is connected to the communication controller and stores a round trip distance to a satellite. A laser generation control unit is connected to the communication controller and outputs a laser fire signal. A signal measurement unit receives a laser start time. A real-time conversion unit is connected to the signal measurement unit and the communication controller, and converts a predicted laser arrival time into real time. A Lagrange interpolation processor is connected to the real-time conversion unit and the memory, and calculates a time at which laser light fired by a laser transmission unit returns back to a laser reception unit (laser arrival time). The clock unit is connected to a time measurement unit, the real-time conversion unit, a register unit, and a delay unit, and outputs time information.