FMCW Lidar Pixel Waveforms for Faster Return Signal Resolution
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
FMCW lidar systems face reduced frame rates due to the need for additional time between transmit signals to separate and associate return signals, which compromises their reaction time and viability for automotive applications.
Innovation Solution
The system transmits signals with different waveforms for consecutive pixels, allowing return signals to be resolved by comparing them to template signals in the frequency domain, thereby reducing the time between transmit signals and enabling faster frame rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If additional time is included between transmit signals for different pixels to temporally separate return signals, then return signals can be correctly associated with their corresponding pixels, but scan time increases and frame rate decreases
Solution Approach 1:
The patent changes the waveform parameter (amplitude modulation pattern) of transmit signals for different pixels. Each pixel's transmit signal has a unique amplitude modulation waveform, allowing the receiver to identify which pixel a return signal belongs to by matching it against template waveforms, thereby eliminating the need for temporal separation between pixel transmissions
Solution Approach 2:
The patent employs periodic amplitude modulation waveforms with distinct patterns for different pixels. By using periodic actions with different characteristics (e.g., different duty cycles, frequencies, or modulation depths), the system can distinguish between return signals from different pixels without requiring time gaps between transmissions
2Reliability
If additional time is included between transmit signals to reduce signal overlap, then return signals can be resolved, but reaction time decreases
Solution Approach 1:
The patent modifies the amplitude modulation parameters of transmit signals to create uniquely identifiable waveforms for each pixel. This allows the system to confidently resolve and associate return signals with their source pixels immediately upon receipt, without waiting for temporal separation, thus maintaining high reliability while minimizing time loss
3Productivity
If transmit signals for consecutive pixels are transmitted without temporal separation, then frame rate increases, but return signals from different pixels cannot be distinguished
Solution Approach 1:
The patent encodes pixel identification information into the amplitude modulation parameters of each transmit signal. By varying waveform characteristics (such as modulation depth, frequency, or pattern) based on pixel position, the system transmits multiple pixel signals simultaneously without temporal separation while preserving the ability to distinguish and identify each pixel's return signal
Solution Approach 2:
The patent creates template copies of amplitude modulation waveforms for each pixel before transmission. These template waveforms serve as reference patterns that the receiver uses to match and identify return signals, effectively copying the unique waveform signature of each pixel into the return signal for later recognition and association
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 allows FMCW lidar systems to operate at faster frame rates and react more quickly, enhancing their suitability for automotive applications by confidently resolving multiple return signals within a detection window.
Implementation Method 1
Frequency-modulated continuous-wave (FMCW) lidar is a promising technology for next-generation autonomous-driving sensors because it allows for strong signal-to-noise ratio (SNR), immunity to ambient light, and concurrent measurement of range and range-rate information for nearby objects.
Implementation Method 2
FMCW lidar systems measure range and range-rate information by comparing a reflected return signal to its corresponding emitted laser signal.
Data Source
AI summary
This document describes techniques and systems to resolve return signals among pixels in lidar systems. The described lidar system transmits signals with different waveforms for consecutive pixels to associate return signals with their corresponding pixels. During a detection window, the lidar system receives a return signal and compares it in the frequency domain to at least two template signals. The template signals include the waveform of an initial pixel and a subsequent pixel of two consecutive pixels, respectively. The lidar system then determines, based on the comparison to the template signals, the pixel to which the return signal corresponds and determines a characteristic of an object that reflected the return signal. In this way, the lidar system can confidently resolve detections to reduce the time between pixels. This improvement allows the described lidar system to operate at faster scanning speeds and realize a faster reaction time for automotive applications.