Multi-Frequency Lidar Signal Processing for Overlapping Target Returns
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Solution Overview
Problem
Conventional lidar devices struggle to differentiate between scattered light from near and far observation targets when their moving speeds are the same, leading to overlapping frequencies and inability to detect the presence of both targets accurately.
Innovation Solution
A signal processing device that generates multiple light pulses with different optical frequencies, calculates Doppler frequencies, and corrects optical frequencies to distinguish between scattered light from multiple observation targets, enabling accurate speed calculation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple light pulses with different optical frequencies are generated to distinguish scattered light from multiple observation targets, then the ability to differentiate between near and far targets is improved, but the device complexity increases
Solution Approach 1:
The patent changes the optical frequency parameter of light pulses to differentiate between scattered light from multiple observation targets. By generating light pulses with different optical frequencies and detecting the frequency characteristics of returned scattered light, the system can distinguish between targets at different distances even when their moving speeds are identical, thus resolving the target differentiation problem without requiring complex spatial or temporal separation methods
2Productivity
If the radiation cycle of light pulse is shortened to increase measurement frequency, then productivity is improved, but the ability to receive scattered light from far targets deteriorates
Solution Approach 1:
The patent uses optical frequency as a distinguishing parameter to enable reliable detection of far targets even with short radiation cycles. By assigning different optical frequencies to different light pulses and detecting these frequency signatures in the scattered light, the system can process returns quickly without losing the ability to identify distant targets, thus maintaining both high productivity and reliable far target detection
3Measurement precision
If optical frequency correction is performed to identify scattered light from different radiation orders, then measurement precision is improved, but the signal processing time increases
Solution Approach 1:
The patent replaces complex temporal analysis methods with optical frequency-based identification. Instead of analyzing the time-of-flight or temporal characteristics of scattered light to determine radiation order, the system uses optical frequency correction to directly identify which radiation order produced each scattered light signal. This substitution of frequency-domain processing for time-domain processing reduces signal processing time while maintaining high identification accuracy
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
Enables the calculation of moving speeds of both near and far observation targets even when their scattered light overlaps, ensuring precise detection and identification of multiple targets.
Implementation Method 1
an optical multiplexing unit that detects multiplexed light of each scattered light and the laser beam
Implementation Method 2
a signal processing unit that calculates a Doppler frequency due to movement of each observation target from an optical frequency of each multiplexed light detected by the optical multiplexing unit
Data Source
AI summary
A signal processing device calculates, as a moving speed of each of a plurality of observation targets, a relative speed of each of the targets with respect to a lidar device. A plurality of light pulses having different frequencies from each other are generated, each of the light pulses radiated and then scattered by each of the targets is received, and multiplexed light of each of the scattered light and the laser beam is detected. The signal processing device includes: a Doppler frequency calculating unit to calculate a Doppler frequency in a frequency of each of the scattered light and due to movement of each of the targets from the frequencies of the plurality of generated light pulses and a detection signal of each of the multiplexed light; and a speed calculating unit to calculate a relative speed of each of the targets from each of the Doppler frequency.