Phase-Encoded Doppler Lidar Sidelobe Suppression for Accurate Ranging
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Solution Overview
Problem
Conventional LIDAR systems implementing phase-encoded Doppler LIDAR suffer from spurious sidelobes that degrade detection capability, particularly in optical range measurements for vehicle operations.
Innovation Solution
The system employs methods and hardware configurations for sidelobe suppression in phase-encoded Doppler LIDAR, including Doppler compensation and cross-spectrum analysis to correct cross-correlation calculations, using optical mixers and digital signal processing to enhance range and velocity detection accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If phase-encoded Doppler LIDAR is used for optical range measurements, then range resolution and detection capability are improved, but spurious sidelobes are generated that degrade detection accuracy
Solution Approach 1:
The patent applies autocorrelation processing to the received phase-encoded signal to convert the harmful sidelobe interference into beneficial range information. By computing the autocorrelation function, the system identifies peak locations that correspond to actual target ranges while suppressing sidelobe artifacts, thereby transforming the harmful interference pattern into useful measurement data for accurate range detection
Solution Approach 2:
The patent introduces an intermediate processing step using cross-spectrum analysis and Doppler compensation as a mediator between the received signal and the final range measurement. This intermediate processing layer filters out spurious sidelobes while preserving genuine target signals, enabling accurate range measurement despite the presence of harmful sidelobe interference
2Adaptability or versatility
If Doppler shift is present in returned signals, then velocity information can be extracted, but cross-correlation calculations become inaccurate due to frequency shifts
Solution Approach 1:
The patent implements feedback through iterative Doppler compensation, where the system continuously estimates the Doppler shift from the received signal and adjusts the cross-correlation calculation accordingly. By feeding back the Doppler information and using it to correct subsequent processing steps, the system maintains accurate range measurements even in the presence of varying velocity conditions
Solution Approach 2:
The patent changes the processing parameters dynamically based on the detected Doppler shift. By adjusting the frequency compensation parameters and modifying the cross-correlation calculation based on the measured velocity, the system adapts to different Doppler conditions while maintaining measurement accuracy across varying operational scenarios
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
Improves the capability of LIDAR systems to perform accurate optical range measurements by reducing sidelobes and enhancing detection sensitivity, particularly for vehicle operations.
Implementation Method 1
phase-encoded detection based on a sequence of single frequency phase changes that are distinguishable from natural signals
Implementation Method 2
determine a Doppler shift from the returned signals using a Fast-Fourier Transformation
Implementation Method 3
using optical mixers and digital signal processing to enhance range and velocity detection accuracy
Data Source
Figure 1A
Figure 1B~1C
Figure 1D~1E
AI summary
A system and method for sidelobe suppression in phase-encoded Doppler LIDAR to support the operation of a vehicle includes determining a sequence code that is indicative of a sequence of phases for an optical signal; modulating an optical signal based on the sequence code to produce a phase-encoded optical signal; transmitting the phase-encoded optical signal to an environment; receiving, from the environment, a returned optical signal in response to transmitting the phase-encoded optical signal; generating, based on the returned optical signal, an electrical signal; and determine a Doppler frequency shift in the returned optical signal.