Detector Sensor Histogram Processing for Pile-Up and Cross-Talk Correction
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Solution Overview
Problem
Current time-of-flight ranging systems face challenges with pile-up and cross-talk issues, leading to inaccurate distance measurements and increased power consumption due to high sampling rates required for precise timing.
Innovation Solution
Implementing a processing device that corrects for pile-up and cross-talk by using adaptive width filters to process histogram data, enabling accurate range extraction through median point calculation and noise estimation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If high sampling rates are used for precise timing in time-of-flight ranging systems, then measurement precision is improved, but power consumption increases
Solution Approach 1:
The patent changes the parameter of sampling rate from high to low, and introduces histogram-based processing to compensate for the reduced sampling frequency. By accumulating photon detection events into histogram bins and using statistical methods (median calculation, mode detection) to determine flight time, the system achieves accurate distance measurement without requiring high sampling rates, thus reducing power consumption.
2Measurement precision
If high sampling rates are used for precise timing, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent replaces the mechanical/electronic approach of high-speed sampling and processing with a statistical histogram-based method. Instead of using complex high-speed timing circuits and processors, the system uses simple event accumulation in histogram bins followed by statistical analysis (finding median or mode values), significantly reducing device complexity while maintaining measurement precision.
3Device complexity
If conventional histogram processing is used without pile-up correction, then device complexity is reduced, but measurement precision deteriorates due to pile-up and cross-talk effects
Solution Approach 1:
The patent applies preliminary correction for pile-up and cross-talk effects by using reference histograms obtained under known conditions (e.g., with reflectors at known distances). These reference histograms are used to calculate correction factors that are applied before the final distance measurement, allowing the system to maintain high precision without requiring complex real-time correction mechanisms.
Solution Approach 2:
The patent creates reference histograms that copy the characteristics of actual measurements under controlled conditions. These reference histograms serve as templates for comparing and correcting actual measurements, allowing the system to account for pile-up and cross-talk effects without directly measuring or modeling these complex phenomena in real-time.
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
Improves range measurement accuracy by reducing the need for high sampling rates and power consumption while effectively addressing pile-up and cross-talk effects.
Implementation Method 1
A photon may generate a carrier in the SPAD through the photo electric effect
Implementation Method 2
The photo generated carrier may trigger an avalanche current in one or more of the SPADs in an SPAD array
Implementation Method 3
This method comprises sending a light signal towards the object and measuring the time taken by the signal to travel to the object and back
Implementation Method 4
The calculation of the time taken by the signal for this travel may be obtained by measuring the phase shift between the signal coming out of the light source and the signal reflected from the object
Data Source
AI summary
A method includes receiving a histogram output from a detector sensor, and calculating a median point of a pulse waveform within the histogram. The pulse waveform has an even probability distribution over at least one quantization step of the histogram around the median point. A corresponding apparatus can include a detector sensor and a co-processor coupled to the detector sensor.