LiDAR ADC Dynamic Range Switching for Low-SNR Distance Sensing
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Solution Overview
Problem
LiDAR devices face challenges in accurately measuring distances for objects at remote distances or with low reflectance due to low signal-to-noise ratio (SNR) signals, leading to deteriorated performance in detecting valid signals and generating accurate depth images.
Innovation Solution
A LiDAR device with a processor that adjusts the dynamic range of an analog-to-digital converter (ADC) to sample pulsed laser reflected light signals, reducing the dynamic range to ¼ of the reference range for low SNR signals, allowing for valid signal detection and subsequent restoration to the reference range after sampling is complete, thereby improving signal sampling accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the ADC uses a reference dynamic range to sample pulsed laser reflected light signals, then the device can maintain a standard operating range, but the measurement precision deteriorates for low SNR signals from remote or low-reflectance objects
Solution Approach 1:
The patent implements dynamic range adjustment of the ADC based on signal strength detection. The processor detects whether the pulsed laser reflected light signal is a low SNR signal and accordingly adjusts the ADC dynamic range between a first dynamic range (for low SNR signals) and a second dynamic range (for other signals). This dynamic adaptation resolves the contradiction by allowing the system to optimize measurement precision for specific signal conditions while maintaining versatility across different operating scenarios.
Solution Approach 2:
The patent changes the operational parameters of the ADC by adjusting its dynamic range based on the detected signal characteristics. When a low SNR signal is detected, the system switches to a first dynamic range configured for high precision sampling of weak signals. This parameter change enables the system to achieve high measurement precision for remote or low-reflectance objects while maintaining the ability to handle various signal conditions through parameter adaptation.
2Measurement precision
If the ADC dynamic range is reduced to ¼ of the reference range for low SNR signals, then the measurement precision improves for valid signal detection, but the device complexity increases due to dynamic range adjustment mechanisms
Solution Approach 1:
The patent employs a feedback mechanism where the processor continuously monitors the signal strength of pulsed laser reflected light and provides feedback to adjust the ADC dynamic range accordingly. When the processor detects a low SNR signal, it triggers the ADC to switch to the first dynamic range (¼ of reference range) for high-precision sampling. This feedback-based control achieves high measurement precision for valid signal detection while managing device complexity through intelligent software control rather than complex hardware modifications.
Solution Approach 2:
The patent performs preliminary detection of signal strength before the ADC sampling process. The processor evaluates whether the incoming pulsed laser reflected light signal is a low SNR signal and pre-configures the ADC dynamic range accordingly before the actual measurement takes place. This preliminary action ensures that the ADC is optimally configured for the expected signal conditions, achieving high measurement precision while keeping the control system relatively simple through pre-planned parameter adjustment.
3Measurement precision
If the ADC dynamic range is adjusted dynamically for each low SNR signal, then the measurement precision improves for remote objects, but the processing time increases due to signal analysis and range adjustment
Solution Approach 1:
The patent performs preliminary signal strength analysis and ADC dynamic range configuration before the actual distance measurement sampling process. The processor quickly evaluates whether the pulsed laser reflected light signal is a low SNR signal and pre-configures the ADC dynamic range in advance. This preliminary action minimizes processing time during the critical measurement phase while still achieving high distance measurement accuracy for remote objects by ensuring the ADC is optimally configured before sampling begins.
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 enhances the LiDAR device's ability to accurately measure distances for objects at various distances, improving operational performance and accuracy in generating depth images, which is crucial for applications like autonomous vehicles.
Implementation Method 1
a laser light irradiator configured to irradiate a pulsed laser light towards an object
Implementation Method 2
measuring a time of flight (ToF) from when the pulsed laser light is irradiated to when the pulsed laser reflected light signal is received
Implementation Method 3
a laser light receiver configured to detect a pulsed laser reflected light signal based on receiving the pulsed laser light reflected from the object
Data Source
AI summary
A light detection and ranging (LiDAR) device includes a laser light irradiator configured to irradiate a pulsed laser light towards an object, a laser light receiver configured to detect a pulsed laser reflected light signal based on receiving the pulsed laser light reflected from the object, a signal analyzer configured to determine whether the pulsed laser reflected light signal is a low signal to noise ratio (SNR) signal based on comparing a level of the pulsed laser reflected light signal with a reference signal level, and a processor configured to, in response to a determination that the pulsed laser reflected light signal is the low SNR signal, adjust a dynamic range of an analog-to-digital converter (ADC) to sample the pulsed laser reflected light signal.