Laser Distance Module Sampling-Time Shift for ADC Error Compensation
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Solution Overview
Problem
Existing distance measurement technologies using fast analog-to-digital converters (ADCs) face errors due to timing, gain, and offset differences between ADC conversion stages, leading to inaccuracies in digitized signal representation and measurement distances, especially in interleaved and pipelined ADC architectures.
Innovation Solution
The method involves shifting received signal samples relative to the ADC sampling grid to ensure identical sampling points are recorded by multiple ADC stages, allowing for error cancellation through averaging, and using a combination of initial and secondary sampling points to cover varying error zones, thereby reducing the impact of ADC conversion errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If fast ADCs with multiple conversion stages are used to achieve high sampling rates and high resolution, then measurement speed and resolution are improved, but timing, gain, and offset errors between ADC stages introduce measurement inaccuracies
Solution Approach 1:
The patent applies preliminary action by performing error characterization before actual distance measurements. The system pre-characterizes the timing, gain, and offset errors of each ADC conversion stage by measuring known reference distances, then stores these error parameters for compensation during subsequent measurements. This preliminary error mapping enables the system to correct measurements in real-time without sacrificing the high sampling rate capability of the multi-stage ADC architecture.
Solution Approach 2:
The patent utilizes parameter changes by dynamically adjusting the sampling time based on the measured error characteristics. The system varies the sampling time parameters to optimize the trade-off between utilizing multiple ADC stages for high speed while compensating for their inherent timing and gain differences. By changing sampling parameters adaptively, the system maintains high resolution and speed while minimizing measurement errors.
2Productivity
If multiple ADC conversion stages are used to achieve high sampling rates, then productivity is improved, but device complexity increases due to interleaved or pipelined architectures
Solution Approach 1:
The patent implements feedback by continuously monitoring and characterizing the performance of each ADC conversion stage. The system measures the actual timing, gain, and offset parameters of each stage and uses this feedback information to adjust subsequent sampling and processing operations. This feedback mechanism enables the complex multi-stage ADC system to operate as a coordinated unit, managing the complexity through adaptive control while maintaining high measurement throughput.
3Measurement precision
If sampling times are varied to compensate for ADC errors, then measurement precision is improved, but measurement time increases due to additional sampling operations
Solution Approach 1:
The patent applies preliminary action by pre-characterizing ADC errors during a calibration phase before actual measurements. The timing, gain, and offset parameters of each ADC stage are measured and stored in advance. During subsequent distance measurements, the system uses these pre-determined parameters to quickly compensate errors without requiring extended sampling times, thus maintaining measurement speed while improving precision.
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 significantly improves measurement accuracy and resolution by averaging out conversion errors, ensuring precise distance measurements even under noisy or disturbed conditions.
Implementation Method 1
a laser transmitter for generating transmission signals of a transmission signal series, in particular by means of pulsed laser measurement radiation
Implementation Method 2
digitizing the received signals of the received signal series into digital signals of a digital signal series with an analog-to-digital converter, hereinafter referred to as ADC
Data Source
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Figure 2a~2b
Figure 3~4a
AI summary
The present invention relates to a distance measurement method and an electronic laser distance measurement module, in particular for use in a distance measuring device, specifically designed as a laser tracker, tachymeter, laser scanner, or profiler, for fast signal acquisition with an analog-to-digital converter, wherein conversion errors arising during signal digitization, in particular timing, gain, and offset errors of the ADC, are compensated by varying the sampling times.