Pulse Accumulation Approach Based on Signal Phase Estimation for Doppler Wind Lidar

Area of Science:

• Atmospheric Science
• Optical Remote Sensing
• Signal Processing

Background:

• Coherent Doppler Wind Lidar (CDWL) is crucial for wind velocity measurement.
• Atmospheric turbulence degrades CDWL echo signal quality, reducing the signal-to-noise ratio (SNR).
• Existing pulse accumulation methods struggle to effectively mitigate noise and enhance SNR.

Purpose of the Study:

• To propose and evaluate a novel pulse accumulation method for improving CDWL SNR.
• To enhance the correlation between lidar signals for greater SNR gains.
• To validate the method's effectiveness in both simulated and real-world atmospheric and motor turntable measurements.

Main Methods:

• A pulse accumulation method based on cross-correlation function for signal phase estimation was developed.
• Simulations were conducted to assess the method's performance and robustness against noise.
• A CDWL system was implemented for indoor motor turntable and outdoor atmospheric wind field measurements.

Main Results:

• The proposed method achieved significant SNR gains of 28.18 dB (500 accumulations) and 32.03 dB (1500 accumulations).
• Motor turntable speed error was reduced by an average of 9.18% compared to incoherent accumulation.
• In atmospheric measurements, the linear fit slope between measured and commercial lidar wind speeds improved from 1.146 to 1.093.

Conclusions:

• The cross-correlation-based pulse accumulation method effectively enhances CDWL SNR and measurement accuracy.
• This technique offers substantial improvements over incoherent accumulation for wind speed measurements.
• The method demonstrates robustness and applicability in diverse environments, from controlled setups to atmospheric fields.