Distance Sensor Multi-Threshold Scanning Signal Edge Stretching
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Solution Overview
Problem
Conventional distance-measuring sensors face challenges in accurately determining signal reception time due to noise interference and limited time resolution, especially in environments with strong noise or contamination, which affects the accuracy and robustness of distance measurement.
Innovation Solution
The implementation of a multi-threshold scanning method that stretches signal edges in the analog reception path, allowing for lower edge steepness and improved time resolution without requiring high-precision A/D converters, using a digital module such as an FPGA for evaluation, and employing a stretching filter to convert time information into amplitude information for multi-bit sampling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional pulse methods with single pulse evaluation are used, then device complexity is low, but measurement precision deteriorates due to noise interference and limited time resolution
Solution Approach 1:
The patent applies segmentation by dividing the signal evaluation into multiple discrete threshold levels (first threshold, second threshold, third threshold) instead of using a single comparator. This segmentation of the amplitude range allows for more precise temporal resolution of the received signal edge while maintaining relatively simple hardware implementation through multiple comparators working in parallel.
Solution Approach 2:
The patent transitions from single-bit temporal sampling to multi-dimensional evaluation by introducing amplitude discrimination through multiple threshold levels. Instead of only measuring when a single threshold is crossed, the system evaluates which combination of thresholds are exceeded, adding an amplitude dimension to the temporal measurement and significantly improving time resolution without requiring ultra-fast sampling.
2Measurement precision
If multi-threshold scanning with edge stretching is implemented, then measurement precision improves, but device complexity increases due to additional analog components
Solution Approach 1:
The patent applies preliminary action by pre-stretching the incoming signal edge through an analog stretching filter before the signal reaches the multi-threshold comparator stage. This preliminary edge stretching prepares the signal in advance, ensuring that the subsequent digital evaluation can achieve high time resolution without requiring complex ultra-fast sampling hardware. The stretching occurs proactively before the critical measurement point.
3Measurement precision
If high-precision A/D converters are used for fast sampling, then time resolution improves, but loss of energy increases and device complexity increases
Solution Approach 1:
The patent replaces the mechanical/electronic system of high-speed A/D conversion with an optical-like analogy system using multiple voltage thresholds and comparators. Instead of converting the analog signal to digital at extremely high sampling rates requiring powerful A/D converters, the system uses multiple threshold voltages that the analog signal naturally crosses, with each crossing detected by simple comparators. This substitution dramatically reduces power consumption while achieving equivalent or superior time resolution.
4Measurement precision
If signal stretching filter is applied, then time resolution improves by converting time information to amplitude information, but device complexity increases
Solution Approach 1:
The patent applies parameter changes by systematically varying the threshold voltage levels (first, second, and third thresholds at different amplitude levels) to create multiple detection points on the stretched signal edge. By changing the threshold parameters and their spacing, the system optimizes the temporal resolution without requiring complex adaptive filtering. The stretching filter uses fixed RC time constants, and precision is achieved through parameter selection rather than complex adaptive algorithms.
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 enhances the time resolution and accuracy of distance determination, improving the signal-to-noise ratio and measurement precision without the need for expensive or advanced sampling equipment, while meeting safety standards for reliable operation.
Implementation Method 1
stretching edges in the received signal in the analog part of the reception path before multi-threshold sampling and thus flattening them out, thus ensuring a lower edge steepness
Implementation Method 2
light signals are emitted and the time it takes for the light signals remitted or reflected by objects to be received is measured
Implementation Method 3
the time it takes for the light signals remitted or reflected by objects to be received
Implementation Method 4
the time of reception and from this, with the help of the known time of transmission, the searched light propagation time
Data Source
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AI summary
A distance-measuring sensor (10) for detecting and determining the distance of objects (18) in a monitoring area is described, comprising a transmitter (12) for emitting signals, a receiver (20) for generating a received signal from the signals emitted by an object (18) in the monitoring area, a multi-threshold scanning unit (34) for digitizing the received signal into several digital states, and a control and evaluation unit (38) configured to determine a reception time from the digitized received signal and, from this, a measured value for the signal propagation time from the sensor (10) to the object (18). A strain filter (32) is arranged upstream of the multi-threshold scanning unit (34), which flattens the edges of the received signal.