LIDAR Channel Encoding for Interference Rejection
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Solution Overview
Problem
Increasing use of LIDAR systems in dense environments leads to interference from pulse reflections originating from other LIDAR systems, which existing technologies struggle to effectively reject.
Innovation Solution
Implementing channel encoding through modulation of laser light pulses using various schemes such as frequency shift keying, on/off keying, and time offsets, allowing LIDAR systems to identify and reject reflections from different channels, thereby isolating and processing only their own reflections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If LIDAR systems operate in dense environments with multiple systems present, then the quantity of LIDAR systems increases, but interference from other systems increases causing measurement errors
Solution Approach 1:
The patent segments the LIDAR operational space by assigning unique channel codes to different LIDAR systems. Each system operates on a distinct channel identified by a unique code sequence, effectively dividing the dense environment into separate logical segments that prevent mutual interference despite physical proximity.
Solution Approach 2:
The patent changes the temporal and spectral parameters of LIDAR pulses by modulating them with unique channel codes. This parameter modification allows receiving systems to distinguish between pulses from different LIDAR systems through code correlation, transforming the harmful interference into distinguishable signals.
2Productivity
If LIDAR systems transmit pulses simultaneously in dense environments, then the productivity increases, but the measurement precision deteriorates due to interference
Solution Approach 1:
The patent applies preliminary action by pre-modulating transmitted LIDAR pulses with unique channel codes before transmission. This preliminary encoding enables the receiving system to later identify and isolate pulses from its own system amidst simultaneous transmissions from other systems, maintaining measurement precision despite high transmission rates.
Solution Approach 2:
The patent implements feedback through code correlation, where the receiving system compares received pulses against its known channel code. This feedback mechanism confirms the origin of each detected pulse, allowing the system to accept only genuine reflections and reject interference, thereby preserving measurement accuracy at high productivity levels.
3Device complexity
If LIDAR systems use conventional pulse transmission without channel encoding, then the device complexity remains low, but the reliability deteriorates in dense LIDAR environments
Solution Approach 1:
The patent employs periodic action through the use of pseudo-random code sequences for channel encoding. These periodic code patterns are transmitted along with the LIDAR pulses, enabling the receiver to identify and filter signals through correlation detection, thereby achieving reliable interference rejection with minimal additional hardware complexity.
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
Effectively rejects interference from other LIDAR systems, ensuring accurate time-of-flight measurements and reducing errors in dense LIDAR environments by utilizing unique channel signatures for each system.
Implementation Method 1
determine range values based on time-of-flight measurements
Implementation Method 2
frequency shift keying
Implementation Method 3
on/off keying
Implementation Method 4
a pulse detection circuit detects the modulated pulses
Data Source
AI summary
A light detection and ranging system modulates laser light pulses with a channel signature to encode transmitted pulses with channel information. The modulated laser light pulses may be scanned into a field of view. Received reflections not modulated with the same channel signature are rejected. Multiple light pulses of different wavelengths may be similarly or differently modulated.