Asymmetric Optical Spectrum for Signed Doppler Shift Detection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing LIDAR systems face challenges in determining the signed Doppler frequency shift of optical signals, as the magnitude of the Doppler shift is easily determined but the sign remains ambiguous.
Innovation Solution
The method involves generating a reference signal and a transmission signal with specific optical spectra, directing the transmission signal to a target, receiving a reflection signal, estimating its optical spectrum, and determining the signed Doppler frequency shift based on the estimated and reference spectra.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional LIDAR systems determine Doppler shift magnitude, then the frequency shift value can be obtained, but the sign of the Doppler shift remains ambiguous
Solution Approach 1:
The patent introduces asymmetric frequency components into the optical spectrum, where at least one of the transmission or reference spectra contains frequency components that are asymmetric about the midpoint. This asymmetry creates different correlation responses for positive and negative Doppler shifts, enabling the system to distinguish the sign of the Doppler shift while maintaining measurement precision.
2Measurement precision
If multiple measurement and signal processing methods are used to determine the sign of Doppler shift, then the sign information can be obtained, but the system complexity increases
Solution Approach 1:
The patent applies preliminary action by pre-configuring the optical spectrum with asymmetric frequency components before the measurement process. This preparation eliminates the need for complex real-time signal processing to determine the Doppler shift sign, as the asymmetry is already embedded in the transmitted or reference signal, simplifying the overall measurement system.
3Ease of manufacture
If symmetric frequency components are used in the optical spectrum, then the system is simpler to implement, but the sign of the Doppler shift cannot be determined
Solution Approach 1:
The patent deliberately introduces asymmetry into the frequency spectrum by configuring at least one of the transmission or reference spectra to have asymmetric frequency components about the midpoint. This asymmetric configuration is relatively simple to implement while effectively enabling the determination of the Doppler shift sign, thus resolving the contradiction between ease of implementation and information completeness.
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 allows for the unambiguous determination of both the magnitude and sign of the Doppler frequency shift in a single measurement, overcoming the ambiguity present in traditional LIDAR systems.
Implementation Method 1
determining a signed Doppler frequency shift of an optical signal
Implementation Method 2
mixing the reflection signal with the reference signal, thereby generating a mixed signal
Implementation Method 3
based on the mixed signal, estimating the reflection optical spectrum
Data Source
AI summary
A method and an apparatus for determining a signed Doppler frequency shift of an optical signal. The method comprises generating a reference signal having a reference optical spectrum and a transmission signal having a transmission optical spectrum; directing the transmission signal to at least one target; receiving a reflection signal from the at least one target, the reflection signal having a reflection optical spectrum; estimating the reflection optical spectrum; and based on the estimated reflection optical spectrum and the reference optical spectrum, determining a signed Doppler frequency shift of the reflection optical spectrum, wherein at least one of the transmission optical spectrum and the reference optical spectrum comprises a first component having a first frequency and a first amplitude, and a second component having a second frequency, different from the first frequency, and a second amplitude, different from the first amplitude, and wherein the at least one of the transmission optical spectrum and the reference optical spectrum is asymmetric about the midpoint of the reference optical spectrum.