FPGA Laser Altimeter Range Detection Precision
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Solution Overview
Problem
Existing laser altimeters for range finding in satellites and spacecraft face challenges in achieving reliable, robust, and accurate range detection due to limited computational power and power constraints, particularly in extracting useful information from back-reflected optical signals.
Innovation Solution
A hardware-based approach using a field programmable gate array (FPGA) as a hardware control unit for processing digital sensor data samples, employing arbitrary Finite Impulse Response (FIR) templates and parametric time of arrival estimation, along with a Kalman predictor for weighting and range window tracking, to correlate pulse features with varying generic pulse shapes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If software-based approaches are used for processing sensor data samples, then device complexity is reduced, but measurement precision and reliability of range detection deteriorate
Solution Approach 1:
The patent replaces software-based processing with a hardware-based Field Programmable Gate Array (FPGA) system. The FPGA implements parallel correlation processing of sensor data samples with reference waveforms, providing deterministic timing and higher precision range detection. This hardware substitution maintains relatively low device complexity while significantly improving measurement precision through parallel processing capabilities and deterministic execution.
2Measurement precision
If hardware-based processing with FPGA is used, then measurement precision and reliability improve, but use of energy and device complexity increase
Solution Approach 1:
The FPGA implementation processes sensor data samples through parallel correlation with reference waveforms, performing more computational work than strictly necessary for basic range detection. This excessive action improves measurement precision and reliability by thoroughly analyzing the back-reflected laser signals, even though it increases energy consumption compared to minimal software processing.
3Measurement precision
If computational power is increased to improve range detection accuracy, then measurement precision improves, but device complexity and power supply constraints are worsened
Solution Approach 1:
The FPGA serves multiple functions: it performs correlation processing of sensor data samples with reference waveforms, determines time delays for range detection, extracts features from back-reflected signals, and can be reconfigured for different processing algorithms. This multi-functionality provides high computational power for improved measurement precision while maintaining relatively low device complexity compared to dedicated high-performance computing systems.
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 solution provides a powerful and flexible method for accurate range detection and feature extraction, reducing the probability of false alarms and achieving high reliability in range finding operations, even under noisy conditions, by leveraging the FPGA's processing capabilities to handle complex calculations efficiently.
Implementation Method 1
a laser source for emitting a high energy laser pulse towards a surface to be investigated or scanned
Implementation Method 2
A sensor is provided for receiving a portion of the back reflected laser pulse
Data Source
Figure 1~2
Figure 3
Figure 4~5
AI summary
Apparatus (10) for range finding. The apparatus (10) comprises a laser source (T1) for emitting a high energy laser pulse (p(t)) towards a surface (22) to be investigated. A sensor (32) is employed for receiving a portion (p'(t)) of the laser pulse (p(t)) after it has been reflected at said surface (22). Means (33) perform an analog-to-digital conversion of the output signals (s'(t)) provided by the sensor (32) to obtain digital sensor data samples (sk). A sample storage (31) for storing a set of said sensor data samples is provided and a hardware control unit (30) for processing the set of said sensor data samples (sk) is employed. This processing is done by scanning the sensor data samples (sk) with generic pulse shapes which are allowed to vary continuously over one or more variation parameters.