LiDAR Ranging Using Modulated Signal Codes
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Solution Overview
Problem
Existing LiDAR systems face errors in ranging operations due to incorrect identification of return signals, often caused by noise and interference from other vehicles' signals, leading to inaccurate distance and reflectivity measurements.
Innovation Solution
A Light Detection and Ranging (LiDAR) module that employs a code storage system to differentiate between return signals by using unique combinations of timing and amplitude information for transmitted signals, allowing the controller to identify correct return signals through matched filters and reduce interference by dynamically switching codes based on vehicle proximity and communication.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional LiDAR systems transmit simple unmodulated light signals, then the system complexity is low, but the accuracy of ranging operations deteriorates due to incorrect identification of return signals from noise and interference
Solution Approach 1:
The patent applies parameter changes by modulating the transmitted light signals with unique codes that vary in timing and amplitude parameters. Each LiDAR system uses a distinct code pattern, allowing the receiver to identify return signals through correlation detection. This transforms simple unmodulated signals into coded modulated signals, improving measurement precision while managing system complexity through structured code design
Solution Approach 2:
The system implements feedback through correlation detection where the received signals are correlated with the transmitted code patterns. The correlation peak identifies the correct return signal, providing feedback verification that distinguishes true returns from noise and interference. This feedback mechanism significantly improves ranging accuracy in multi-vehicle environments
2Reliability
If LiDAR systems use identical transmission codes, then the ease of operation is high, but the reliability deteriorates due to interference from other vehicles' signals
Solution Approach 1:
The patent applies segmentation by dividing the code space into unique segments assigned to different LiDAR systems. Each vehicle receives or selects a distinct code from the codebook, creating segmented transmission patterns that prevent interference. The codebook itself is segmented into multiple valid code options, allowing systematic assignment while maintaining ease of operation through standardized code structures
Solution Approach 2:
The patent introduces an intermediary codebook as a mediator between multiple LiDAR systems. The codebook contains predefined code patterns that act as intermediaries to coordinate transmissions. By referencing this shared codebook, systems can select non-conflicting codes, reducing direct interference while managing complexity through the intermediary code structure
3Measurement precision
If the system transmits high-power signals to improve detection range, then the measurement precision improves, but the loss of energy increases
Solution Approach 1:
The patent applies periodic action by transmitting signals in coded pulses rather than continuous high-power signals. The periodic pulse transmission with code modulation allows energy-efficient operation while maintaining detection range through correlation integration. The system transmits at lower average power but achieves equivalent detection performance by integrating signal energy across the coded pulse sequence
Solution Approach 2:
The system uses code copying where the transmitted code pattern is replicated across multiple signal pulses. This copying approach allows the receiver to integrate multiple lower-power transmissions to achieve the same detection range as a single high-power transmission, reducing overall energy loss while maintaining measurement precision
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
The solution enhances the accuracy of ranging operations by correctly identifying return signals and reducing interference, thereby improving the robustness and performance of LiDAR systems in environments with multiple vehicles.
Implementation Method 1
each code specifying timing information and amplitude information of the one or more signals... control the transmitter circuit to transmit the first group of one or more signals having the one or more signal levels at the one or more transmission times
Implementation Method 2
The signal can reach and reflect off the object to become a return signal, and the return signal can be detected by a receiver of the observer
Implementation Method 3
measuring time-of-flight of signals propagating between the observer and the object... The difference between the first time and the second time can represent a total time-of-flight of the signal
Data Source
AI summary
Methods and apparatus for performing a ranging operation are provided. In one example, an apparatus comprises a transmitter circuit, a receiver circuit, a controller, and a code storage. The controller can obtain a first code from the code storage, determine, from the first code, first timing information and first amplitude information of a corresponding first group of one or more signals, and control the transmitter circuit to transmit the first group of one or more signals based on the first timing information and the first amplitude information. The controller can configure a matched filter based on the first timing information and the first amplitude information, identify return signals of the first group of one or more signals based on processing received signals using the configured matched filter, and perform a ranging operation based on the identified return signals and the first group of one or more signals.