Distance Measurement Sampling for Aliasing-Resistant Precision
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Solution Overview
Problem
Existing distance measurement technologies face challenges with signal sampling and reconstruction, particularly when dealing with variable or distorted signals, leading to aliasing effects that reduce measurement accuracy, and are limited by the Nyquist theorem, which restricts the use of higher-frequency signal components.
Innovation Solution
The method involves sampling a target signal with different sampling rates to shift the relative positions of sampling points, allowing for optimized sampling rates that enable accurate measurements by canceling or accounting for aliasing effects, and using a multichannel design or repeated sampling with varying rates to ensure accurate digitization without the need for pre-filtering.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the Nyquist sampling theorem is strictly complied with by filtering high-frequency components, then aliasing effects are suppressed and signal reconstruction is accurate, but higher-frequency signal components are lost and measurement precision is reduced
Solution Approach 1:
The patent converts the harmful aliasing effects into beneficial information by deliberately allowing aliasing to occur and then using multiple sampling rates to capture different aliasing patterns. These patterns are processed to extract the original high-frequency signal components that would otherwise be lost, thus converting the harmful aliasing into a useful sampling mechanism for preserving high-frequency information.
Solution Approach 2:
The patent changes the sampling rate parameter dynamically by performing sampling at multiple different rates. This allows the system to capture signal components at different frequency representations, enabling reconstruction of high-frequency components that would be filtered out by traditional single-rate Nyquist-compliant sampling.
2Reliability
If high-order filters are used to reduce signal bandwidth before sampling, then the Nyquist condition is fulfilled and distance-relevant signals can be reconstructed, but device complexity increases and measurement accuracy is compromised for varying signals
Solution Approach 1:
The patent replaces the mechanical/analog high-order filter system with a digital signal processing approach. Instead of using complex analog filter circuits to reduce bandwidth before sampling, the system uses multiple digital sampling rates followed by digital signal processing to achieve the same reconstruction accuracy, thereby reducing analog device complexity while maintaining or improving reliability.
Solution Approach 2:
The patent introduces dynamic sampling rate selection where the sampling rate is adjusted based on the specific measurement conditions and signal characteristics. This dynamic approach allows the system to optimize between bandwidth reduction and high-frequency preservation for each measurement scenario, improving reliability for varying signals without requiring fixed complex high-order filtering.
3Loss of information
If sampling rates are increased to capture higher-frequency components, then more signal information is preserved, but the cost of analog-to-digital converters increases and slower converters cannot achieve accurate measurements
Solution Approach 1:
The patent segments the sampling process into multiple stages with different sampling rates. Instead of using a single high-speed ADC to capture all frequency components, the system divides the sampling task into multiple lower-rate sampling operations at different rates, each capturing different aspects of the signal. This segmentation allows the use of slower, lower-cost ADCs while still preserving high-frequency information through the combined data from multiple sampling rates.
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 allows for highly accurate distance measurements in the mm or sub-mm range, even with slow analog-to-digital converters, and enables the use of higher-frequency signal components without restrictions, achieving precise results in nonlinearly distorted conditions.
Implementation Method 1
the distance to the target to be measured is determined on the basis of the time of flight of the pulse
Implementation Method 2
The other approach is based on the sampling of the backscattered pulse. An emitted signal is detected by virtue of the fact that the radiation detected by a detector is sampled
Data Source
AI summary
The invention relates to a distance measuring method comprising at least the step of emitting at least one measurement signal to a target object, in which at least one start signal is produced, and the measurement signal is back scattered from the target object as a target signal. Said target signal and optionally also the start signal is sampled in a first and a second sampling at various sampling rates and determines the distance to the target object from the relative position from the start signal and the target signal.