LiDAR Receiver Multi-Phase Detection for Distance-Speed Ambiguity
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Solution Overview
Problem
Coherent LiDAR receivers lack the ability to distinguish between positive and negative frequency components of echo signals, leading to incomplete phase information and uncertainty in determining the frequency component of detected objects.
Innovation Solution
A receiving apparatus and method for LiDAR that utilizes frequency mixing and multi-phase detection with sweep optical signals of varying slopes to separate and identify positive and negative frequencies, employing a frequency mixing detection unit with analog-to-digital converters and photoelectric detectors to process multiple echo signals, reducing the number of converters and detectors needed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of information
If a 180-degree frequency mixer and balanced detector are used, then the receiver can detect the I signal of the echo signal, but complete phase information cannot be obtained and positive/negative frequency components cannot be distinguished
Solution Approach 1:
The patent segments the detection process into multiple time periods, with each period using sweep optical signals with different sweep slopes. This segmentation allows the system to obtain both positive and negative frequency components by comparing results from different time periods, thereby recovering complete phase information without requiring a complex quadrature detector structure.
Solution Approach 2:
The patent employs periodic action by conducting detections in multiple time periods with alternating sweep slopes (positive and negative). This periodic switching of sweep directions enables the system to capture both frequency components of the echo signal, allowing distinction between positive and negative frequencies through temporal modulation rather than spatial complexity.
2Measurement precision
If multiple sweep optical signals with different slopes are used for multi-phase detection, then positive and negative frequency components can be distinguished, but the number of converters and detectors increases
Solution Approach 1:
The patent makes a single frequency mixer and balanced detector universal by reusing them across multiple time periods with different sweep configurations. The same hardware components perform multiple functions: detecting I signals with positive sweep slope in one period, then detecting I signals with negative sweep slope in another period. This multi-functionality allows frequency component distinction without increasing the number of physical converters and detectors.
Solution Approach 2:
The patent discards the conventional approach of using fixed quadrature detectors and instead recovers complete phase information by combining results from sequential detections with alternating sweep slopes. The system temporarily uses only I-signal detection in each period but recovers the full Q-component information through mathematical processing of the alternating sweep results, effectively discarding hardware complexity in favor of temporal processing.
3Reliability
If conventional single-phase detection is used, then the receiver structure is simple, but virtual targets cannot be eliminated and positioning accuracy is reduced
Solution Approach 1:
The patent implements feedback by using the detection results from one time period to validate and correct results from another time period. By comparing the I signal measurements taken with positive sweep slope against those taken with negative sweep slope, the system can identify and eliminate virtual targets through consistency checks, thereby improving positioning reliability without requiring fundamentally more complex detection hardware.
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 accurate determination of object positioning by distinguishing frequency components, eliminating virtual targets, and reducing the size and cost of the receiving apparatus through multiplexing and phase adjustment techniques.
Implementation Method 1
perform signal processing on the N sweep optical signals and the N echo signals to obtain M channels of detection signals, where the signal processing includes frequency mixing and photoelectric detection
Implementation Method 2
perform signal processing on the N sweep optical signals and the N echo signals to obtain M channels of detection signals, where the signal processing includes frequency mixing and photoelectric detection
Data Source
AI summary
A receiving apparatus and a detection method for light detection and ranging (LiDAR) and a LiDAR relate to the field of optical communication technologies and are used to reduce a quantity of used components in a case of distance-speed ambiguity, so as to reduce costs and a size. Sweep optical signals with different slopes are introduced, and multi-phase detection is used during detection. A positive frequency and a negative frequency can be identified through multi-phase detection, so that a virtual target can be eliminated, to resolve a distance-speed ambiguity problem. In addition, signals having different phases are multiplexed, to reduce a quantity of used analog-to-digital converters, to further reduce a size of the receiving apparatus, and reduce costs.