Multi-Wavelength LiDAR Beat-Frequency Filtering Without FFT

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Solution Overview

Problem

FMCW LiDAR systems require significant computing resources due to the need for high bandwidth and large data processing to achieve high distance resolution, particularly in converting time-domain data to frequency-domain data.

Innovation Solution

The LiDAR system employs an optical coupler, photodiode, and band pass filter array to analyze beating frequencies in an analog state before digital conversion, using a parallel array of band pass filters to extract frequencies, reducing the need for extensive digital processing.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a wide chirp bandwidth is used to achieve high distance resolution, then measurement precision is improved, but computing resources and data processing requirements increase significantly

Engineering Contradiction:

Improvedistance resolutionVSAvoidcomputing resources

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent replaces the digital signal processing system (ADC + FFT processor) with an analog frequency analysis system using a filter bank. The filter bank directly extracts frequency components from the beat signal in the analog domain, eliminating the need for high-speed ADC conversion and complex digital FFT processing while maintaining the ability to resolve distance based on frequency analysis

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent divides the frequency spectrum into multiple discrete bands using a filter bank with multiple band-pass filters. Each filter corresponds to a specific frequency range, allowing parallel extraction of frequency components. This segmentation enables the system to handle wide chirp bandwidths by distributing the frequency analysis across multiple simple analog filters rather than requiring a single complex digital processing system

Inventive Principle:

Principle #1Segmentation

2Measurement precision

If high sampling rate is used to accurately acquire frequency information, then measurement precision is improved, but productivity decreases due to large data volumes

Engineering Contradiction:

Improvefrequency acquisition accuracyVSAvoiddata processing speed

Core Design Contradiction:

Measurement precisionVSProductivity

Solution Approach 1:

The patent replaces the digital sampling and processing chain with an analog filter bank system. The filters directly pass specific frequency components to their corresponding detectors, enabling simultaneous extraction of multiple frequency components without the need for high-speed sequential sampling. This parallel analog processing dramatically reduces data volume while maintaining frequency acquisition accuracy

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Measurement precision

If digital signal processing is used to convert time domain to frequency domain, then measurement precision is improved, but device complexity increases due to processing requirements

Engineering Contradiction:

Improvefrequency domain analysis accuracyVSAvoidprocessing complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent substitutes the digital FFT processing system with an analog filter bank. Each band-pass filter in the filter bank corresponds to a specific frequency bin, and the center frequency of each filter is predetermined based on the expected beat frequencies. This analog frequency decomposition achieves the same frequency domain analysis goal as FFT but with simpler hardware components and reduced processing complexity

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 reduces computing resources required for frequency analysis, improving processing speed and efficiency by directly detecting beating frequencies in the analog domain, thereby minimizing the need for binarization and Fast Fourier Transform processes.

Implementation Method 1

an optical coupler configured to generate an optical signal by mixing a transmission signal with a reception signal

Methodology Applied

Scientific EffectOptical mixing: Heterodyne

Implementation Method 2

a photodiode configured to convert the optical signal into an analog beating signal

Methodology Applied

Scientific EffectPhotoelectric conversion: Photoelectric Effect

Implementation Method 3

a band pass filter array configured to filter the analog beating signal to extract a beating frequency

Methodology Applied

Scientific EffectFrequency filtering: Filter (electronic)

Data Source

PatentUS20250321327A1Lidar system using multiple wavelengths and operating method thereof

Publication Date: 2025.10.16 SAMSUNG ELECTRONICS CO LTD

AI summary

Provided is a light detection and ranging (LiDAR) system including an optical coupler that generates an optical signal by mixing a transmission signal with a reception signal, in which the transmission signal is reflected back from a target, a photodiode that converts the optical signal into an analog beating signal, and a band pass filter array that filters the analog beating signal to extract a beating frequency.