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Frequency-modulated multifunction lidar for anemometry, range finding, and velocimetry-1. Theory and signal
Applied Optics
|December 15, 2017
Summary
This study introduces new signal processing for frequency-modulated continuous-wave lidar (FMCW lidar) to improve range finding and air speed measurements. The methods enhance lidar performance in atmospheric turbulence and reduce unwanted echoes for applications like laser anemometry.
Area of Science:
- Optical Engineering
- Remote Sensing
- Signal Processing
Background:
- Frequency-modulated continuous-wave lidar (FMCW lidar) is crucial for various remote sensing applications.
- Existing FMCW lidar systems face challenges with range limitations, ambiguities, and atmospheric interference.
- Accurate air speed measurement, particularly in complex environments like helicopter proximity, requires robust signal processing.
Purpose of the Study:
- To develop and evaluate novel waveforms and signal processing techniques for FMCW lidar.
- To enhance range finding capabilities, extending lidar range and mitigating ambiguities.
- To improve laser anemometry performance for accurate air speed measurements in challenging conditions, such as atmospheric turbulence and avoiding parasitic echoes.
Main Methods:
- Development of original waveforms tailored for FMCW lidar applications.
- Implementation of optimized signal processing algorithms for range finding and velocimetry.
- Analysis of atmospheric turbulence effects on lidar efficiency for different target types (infinite and finite).
- Consideration of wind-induced bistatic effects in lidar performance analysis.
- Application of signal processing for laser anemometry to measure air speed near helicopter rotors while rejecting unwanted echoes.
Main Results:
- Proposed signal processing extends FMCW lidar range and reduces ambiguities in range finding.
- Analysis quantifies the impact of moderate atmospheric turbulence and wind-induced bistatism on lidar efficiency.
- Demonstrated capability for laser anemometry to measure air speed at short distances, avoiding rotor-induced turbulence and parasitic echoes from clouds or hard targets.
Conclusions:
- The developed waveforms and signal processing significantly advance FMCW lidar capabilities for range finding and velocimetry.
- The findings provide a better understanding of lidar performance under atmospheric disturbances.
- The optimized techniques enable more reliable air speed measurements in complex scenarios, crucial for applications like aviation safety and environmental monitoring.
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