SODAR System Doppler Error Correction via Wind Profile Adjustment
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Solution Overview
Problem
SODAR systems face systematic Doppler errors in wind speed and direction measurements due to the use of wideband acoustic chirps, leading to resolution and height errors in wind speed profiles.
Innovation Solution
A method is introduced to correct systematic Doppler errors by processing wind shear profiles through subtraction of a measured wind speed and addition of another measured wind speed, with the option of applying a correction factor using a look-up table or algorithm, specifically designed for SODAR systems to improve accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If wideband acoustic chirps are used in SODAR systems to achieve pulse compression, then gain and resolution are improved, but systematic Doppler errors are introduced in wind speed and direction measurements
Solution Approach 1:
The patent introduces an intermediary correction process that uses independently measured ground-level wind speeds (from anemometers) as a reference to identify and correct systematic Doppler errors in the SODAR measurements. This intermediary reference measurement allows the system to detect and compensate for the systematic errors introduced by wideband chirp signals, thereby maintaining both the high resolution/gain benefits and the measurement reliability.
2Manufacturing precision
If wideband acoustic chirps are used in SODAR systems, then gain and resolution are improved, but height errors in wind speed profiles occur
Solution Approach 1:
The patent implements a feedback mechanism where ground-level wind speed measurements from independent anemometers are used to detect systematic Doppler errors in the SODAR system. This feedback information is then applied to correct the height and wind speed profile measurements, allowing the system to maintain high resolution while compensating for the height errors introduced by wideband chirp signals.
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 method significantly enhances the accuracy of wind speed and direction measurements by correcting systematic errors, reducing variability and improving resolution in wind speed profiles, particularly at lower altitudes.
Implementation Method 1
SODAR systems use pulse compression of acoustic signals (preferably acoustic chirps) to obtain vertical wind speed and direction as well as large and small scale turbulence
Implementation Method 2
the component tones in a transmitted chirp are mixed, differenced, correlated or otherwise compared with the component tones in an echo chirp resulting from the reflection, refraction and/or scattering of the transmitted chirp
Data Source
AI summary
This invention relates to a method of improving performance of a SODAR system adapted to locate discontinuities in the atmosphere by transmitting pulse compression signals such as a plurality of acoustic chirps, the method comprising: transmitting one or more acoustic chirps; receiving one or more acoustic echoes of the transmitted chirps; processing the acoustic echoes to provide an indication of the discontinuities in the atmosphere, thereby providing a wind shear profile; processing the wind shear profile to correct systematic Doppler errors associated with the acoustic echoes by: subtracting a first measured wind speed from the wind shear profile; and adding a second measured wind speed to the wind shear profile.