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The Accuracy Research of Doppler Wind Lidar Based on Edge Technique

Author: ZhangHeYong
Tutor: RenDeMing
School: Harbin Institute of Technology
Course: Physical Electronics
Keywords: Edge Technology Wind measurement accuracy Fabry-Perot etalon Seed implantation Frequency Stability
CLC: TN959.4
Type: Master's thesis
Year: 2009
Downloads: 76
Quote: 4
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Abstract

Edge-based Doppler wind radar technology in today's world will become more important. Wind field measurement accuracy is every important technical parameters of radar systems. This topic focuses on the edge of technology to improve the accuracy gun system, the first is based on laboratory measurements with the target speed, the ultimate goal is atmospheric wind field. In this paper, both theoretical and experimental aspects of the existing experimental conditions with the goal of improving the speed measurement accuracy. Experimental results show that the system can be applied to speed atmospheric wind field measurements. Theory mainly includes two aspects: the frequency discriminator device FP etalon defect correction; novel prism design. On the FP etalon transmittance classical parallel plate model is based on multiple-beam interference theory, does not consider the actual processing of the defects attributed to the defect by a Gaussian distribution, and thus the transmittance is corrected from the theoretical expression, in good agreement with the experimental. Based on a double edge angle tuning technology, the angle slight adjustment is difficult, therefore, our group has developed can precisely adjust the angle between the two beams emitted light of the new prism, in theory, can improve the accuracy of the angle adjustment from 1 to 2 orders of magnitude. Experiment includes six aspects: pulse counting method with the goal of measuring speed; prism performance test; seed implantation single longitudinal mode laser frequency stabilization Spitlight 1200 stability test; single-edge technology to measure with the target speed; dual-edge technology with the goal of measuring speed ; atmospheric echo signal detection and EMD noise reduction. Using He-Ne laser and the use of accurate measurement of the pulse counting principle with the target rotation speed, whether clockwise or counterclockwise rotation, speed measurement standard deviation of no more than 0.08m / s. Use 1064nm pulsed laser prism performance test, indicating that the laser incident angle 17 ° near the output beam angle adjustment accuracy can be increased by 50 times. For seed source divergence angle 1.9mrad, 1.5mrad, 1.3mrad 3 cases were measured on the FP etalon transmission characteristics, the final choice divergence angle 1.5mrad seed source frequency stability measurement, the measurement results show that the seed source of short-term stability degree at 5MHz, equivalent to 1.77 × 10-8, with 2% of the test point frequency fluctuation over 5MHz. Single edge velocity measurements in the frequency correction before using speed accuracy 2.1m / s, corrected velocity accuracy of 1.9m / s. The working area of ??the largest gun sensitivity 0.34% / (m / s), the sensitivity is not less than 0.3% / (m / s), the speed dynamic range ± 50m / s. Double edge maximum deviation measuring forward speed 2.1m / s, the maximum negative deviation 2.6m / s, the maximum sensitivity of double edge detection 0.46% / (m / s), than single edge detection sensitivity is increased by 1.4 times, which is weak signal detection is more favorable for the sensitivity of not less than 0.42% / (m / s), the speed dynamic range ± 70m / s. Detection of atmospheric backscatter echo signal, without amplifier, radar signal detection distance of 1.3km. By numerical simulation of the radar equation, indicating that after 200m, good agreement of theory and practice. And the echo signal through decomposition of EMD 10 IMF components and a margin, the reconstructed signal is removed by high-frequency component of the noise reduction processing of radar signals.

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