Laser Scanner Pulse Detection With High-Resolution Correlation Templates
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Solution Overview
Problem
Laser scanner apparatuses face challenges in high measurement speeds, noise immunity, and accurate pulse discrimination due to the need for improved pulse detection and correlation templates without increasing digitizer sampling rates.
Innovation Solution
A calibration system generates a high-resolution correlation template by incrementally offsetting digitizer sampling phases to produce a reference sample set, allowing laser scanner apparatuses to detect objects with higher fidelity using the same digitizer sampling rate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the base sampling rate of the digitizer is increased to improve time resolution for detecting reflection pulses, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent segments the sampling process into multiple passes, where the digitizer samples the photodetector signal at different time offsets relative to the laser pulse transmission. Each pass captures a portion of the signal waveform, and these segmented samples are then reassembled to form a complete high-resolution representation of the reflection pulse, achieving fine time resolution without requiring the digitizer to operate at a proportionally high sampling rate in any single pass.
Solution Approach 2:
The system performs preliminary sampling at multiple predetermined time offsets before final pulse detection and correlation. By pre-sampling the signal at various phases of the expected pulse waveform and storing these samples, the system prepares the data in advance, allowing subsequent correlation operations to achieve high time resolution without requiring the digitizer to continuously operate at maximum sampling rates.
2Reliability
If multiple sampling phases are implemented to improve correlation template resolution, then pulse discrimination is improved, but processing time increases
Solution Approach 1:
The patent implements periodic sampling at multiple fixed phases, where the digitizer repeatedly samples the photodetector signal at predetermined time offsets corresponding to different phases of the expected reflection pulse waveform. This periodic multi-phase sampling approach efficiently captures the essential temporal characteristics of the pulse across multiple cycles, enabling robust pulse discrimination through correlation while maintaining predictable and manageable processing timing.
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 system enhances object detection accuracy and reliability by producing a correlation template with higher time resolution than the digitizer sampling rate, improving pulse detection without requiring increased digitizer speed.
Implementation Method 1
a photodetector that outputs a photodetector signal that varies responsive to backscattered light impinging on the photodetector
Implementation Method 2
emits a laser pulse into a surrounding physical environment and detects one or more 'return' or 'reflection' pulses, as backscattered from one or more objects
Implementation Method 3
Determining the temporal offset—the timewise location—of such signal pulses in relation to the transmission time of the outgoing laser pulse allows the scanner to estimate object distance, according to Time-of-Flight (ToF) calculations
Data Source
AI summary
One or more types of laser scanner apparatuses perform object detection by emitting laser pulses and detecting corresponding reflected pulses by correlating a digitized detection signal against a correlation template representing a characteristic signal pulse. Regions of the digitized detection signal exhibiting high correlation with the template correspond to reflection pulses caused by backscattering of the emitted laser pulses. A calibration system and corresponding calibration method improve detection operations by such laser scanner apparatuses by producing a high-resolution correlation template. Among the several advantages associated with the system and method is the ability to produce correlation templates of high resolution, without requiring any increase in the base sampling rate of the digitizers used by the calibration system and the laser scanner apparatuses for digitizing their respective detection signals.