Laser Radar Wind Velocity Search Scope Optimization
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Solution Overview
Problem
Conventional laser radar apparatuses face challenges in accurately calculating wind velocities due to the limited search scope for spectrum signals, leading to a high probability of noise being erroneously detected as the peak signal, especially in low Signal-to-Noise Ratio (SNR) areas.
Innovation Solution
A laser radar apparatus and method that includes a wind velocity searching unit which determines a search center for a Doppler frequency using a selected wind velocity model when the signal strength is below a threshold, allowing for a focused search within a defined scope to reduce noise detection errors and enhance accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the search scope for spectrum signal peak is limited to reduce noise detection errors, then measurement precision is improved, but the risk of missing the actual peak increases when the search center is inaccurate
Solution Approach 1:
The patent applies preliminary action by using wind velocity models to predict and determine the search center before performing the peak search. The model-based prediction prepares the search in advance by establishing a likely region where the peak should occur, allowing the subsequent limited search to be both efficient and reliable. This preliminary estimation based on atmospheric wind velocity models ensures that even with a limited search scope, the actual peak is not missed.
2Manufacturing precision
If coherent integration time is shortened to improve distance resolution, then distance resolution is improved, but signal amount decreases and observation distance becomes shorter
Solution Approach 1:
The patent applies segmentation by dividing the signal processing into distinct stages: coherent integration over short periods to maintain distance resolution, followed by separate incoherent integration of spectrum signals to accumulate signal amount. This segmentation allows each integration type to perform its optimal function - coherent integration preserves temporal and spatial resolution, while incoherent integration boosts signal strength through cumulative addition of spectral information.
3Measurement precision
If incoherent integration is performed multiple times to improve SNR, then SNR is improved by √N, but the complexity of signal processing increases
Solution Approach 1:
The patent uses the spectrum signal as an intermediary between the raw received signal and the final wind velocity calculation. By performing Fourier transforms to obtain spectrum signals and then conducting incoherent integration on these spectral representations, the system improves SNR while maintaining manageable processing complexity. The spectrum domain serves as an intermediate space where signal accumulation can occur more efficiently than direct time-domain integration.
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 approach reduces the likelihood of noise being misidentified as the peak signal, enabling more accurate wind velocity calculations and extending the measurable distance while maintaining high accuracy.
Implementation Method 1
receives the laser light which is reflected by an aerosol in the atmosphere and then returns thereto, i.e., the laser light which has received a Doppler frequency shift that depends on the moving velocity of the aerosol in the atmosphere
Implementation Method 2
performs heterodyne detection on the laser light and local light, thereby detecting a Doppler signal corresponding to a wind velocity
Data Source
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AI summary
A wind velocity searching unit 30 is configured so as to, when a spectrum signal calculated by a spectrum calculating unit 22 is one in a range bin having a signal strength less than a first threshold Th1, determine a search center IF of the search scope for a Doppler frequency corresponding to a wind velocity in the range bin by using a wind velocity model selected by a wind velocity model selecting unit 29, and search for the wind velocity in the range bin from the spectrum signal within the search scope whose search center IF is determined thereby. As a result, the probability that the peak of noise is detected erroneously as the peak of the spectrum signal is reduced.