Laser Distance Measuring Module INL Compensation for Accurate ADC Sampling
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Solution Overview
Problem
Existing distance measurement systems using analog-to-digital converters (ADCs) suffer from architecture-specific errors such as differential nonlinearity (DNL) and integral nonlinearity (INL), which vary over time and temperature, leading to distorted digitized signal waveforms and inaccurate distance measurements.
Innovation Solution
A method and system that superimpose a varying bias signal on the received signal series, using a bias signal with a low-frequency oscillation component, to shift individual received signals across different error zones of the INL error curve, allowing for averaging or summing to minimize local INL errors and improve distance measurement accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a fast analog-to-digital converter (ADC) with high sampling rate and high resolution is used, then signal acquisition speed and measurement precision are improved, but architecture-specific errors (DNL and INL) increase, leading to distorted digitized signal waveforms
Solution Approach 1:
The patent applies preliminary action by pre-characterizing the ADC's INL error to create a lookup table containing correction values before actual distance measurements are performed. This pre-computed correction data is then applied during measurement to compensate for the ADC's nonlinearity, resolving the contradiction between using fast ADCs for high precision while maintaining waveform accuracy.
2Productivity
If multiple ADC conversion stages are used to achieve high sampling rate and resolution, then productivity and measurement speed are improved, but device complexity and architecture-specific errors increase
Solution Approach 1:
The patent extracts the INL error characteristic from the complex multi-stage ADC architecture and separates it as a distinct, measurable parameter. By characterizing the error independently and storing correction values in a lookup table, the system simplifies the handling of complexity while maintaining the high productivity benefits of the multi-stage ADC design.
3Manufacturing precision
If internal corrections in the ADC are used to minimize DNL and INL errors, then manufacturing precision is improved, but errors still vary over time and temperature, reducing reliability
Solution Approach 1:
The patent implements feedback by continuously monitoring the ADC's actual performance and using pre-characterized INL error data to apply real-time corrections through a lookup table. This feedback mechanism compensates for drifts in DNL and INL errors caused by temperature changes and aging, maintaining reliable measurement accuracy despite variations in manufacturing precision over time.
Data Source
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AI summary
The present invention relates to a distance measuring method and an electronic laser distance measuring module, in particular for use in a distance measuring device, specifically designed as a laser tracker, tachymeter, laser scanner, or profiler, for rapid signal acquisition with an analog-to-digital converter, with compensation for an integral non-linearity of the analog -Digital converter takes place.