Phase-Encoded LiDAR Doppler Correction for Accurate Range and Velocity
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Solution Overview
Problem
Phase-encoded LIDAR systems face challenges in providing suitable target velocity resolution for autonomous vehicle applications, particularly due to limitations in Doppler signal processing and range accuracy.
Innovation Solution
The implementation of a LIDAR system with a synchronous processing arrangement where the transmitted and reference optical signals are generated from the same carrier, allowing for correlation of Doppler frequency shift and range signals, and an asynchronous processing arrangement where Doppler frequency shift and time delay are measured over different coherent processing intervals, enhancing velocity resolution and signal-to-noise ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If phase-encoded LIDAR systems use conventional Doppler signal processing, then the system structure is simple, but the target velocity resolution is insufficient for autonomous vehicle applications
Solution Approach 1:
The patent divides the signal processing into separate synchronous and asynchronous processing arrangements. The synchronous processing handles range determination while the asynchronous processing specifically targets velocity measurement, allowing each to be optimized independently for their respective functions.
Solution Approach 2:
The patent introduces a time dimension by using different coherent processing intervals for Doppler frequency shift measurement versus range determination. This temporal separation allows velocity resolution to be enhanced without compromising range accuracy, effectively adding a dimensional aspect to the signal processing approach.
2Productivity
If synchronous processing arrangement is used to correlate Doppler frequency shift and range signals, then velocity and range can be measured simultaneously, but signal phase inconsistencies cause range determination errors
Solution Approach 1:
The patent segments the processing into two distinct arrangements: synchronous processing for simultaneous measurement capability and asynchronous processing for accurate range determination. This separation allows the system to leverage the advantages of both approaches while mitigating their respective disadvantages.
Solution Approach 2:
The patent uses the asynchronous processing arrangement as an intermediary step that corrects range determination errors caused by phase inconsistencies. By processing signals through both synchronous and asynchronous paths, the system can identify and correct errors in the range measurements.
3Measurement precision
If asynchronous processing arrangement is used to measure Doppler frequency shift and time delay over different intervals, then velocity resolution is enhanced, but the processing time increases
Solution Approach 1:
The patent employs periodic transmission of optical signals with different phase encodings over multiple coherent processing intervals. This periodic action allows the system to accumulate data for enhanced velocity resolution while maintaining a structured processing rhythm that optimizes time utilization.
Solution Approach 2:
The patent ensures continuous signal transmission and processing across both synchronous and asynchronous arrangements. By maintaining continuous useful action in signal collection and processing, the system maximizes the information extracted from each transmission interval, reducing overall processing time despite the enhanced velocity resolution requirements.
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 improves target velocity resolution and signal-to-noise ratio by compensating for multiple Doppler signals and eliminating range signal errors due to inconsistent phases, enabling more accurate range determination and velocity measurement.
Implementation Method 1
direct ranging based on round trip travel time of an optical pulse to an object
Implementation Method 2
determine a Doppler frequency shift of the second optical signal
Implementation Method 3
receiving an electrical signal generated by mixing a first optical signal and a second optical signal
Data Source
AI summary
A system and method for enhanced velocity resolution and signal to noise ratio in optical phase-encoded range detection includes receiving an electrical signal generated by mixing a first optical signal and a second optical signal, wherein the first optical signal is generated by modulating an optical signal, wherein and the second optical signal is received in response to transmitting the first optical signal toward an object, and determining a Doppler frequency shift of the second optical signal, and generating a corrected electrical signal by adjusting the electrical signal based on the Doppler frequency shift, and determining a range to the object based on a cross correlation of the corrected electrical signal with a radio frequency (RF) signal that is associated with the first optical signal.