Time-of-Flight Distance Meter Blind Range Elimination
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Solution Overview
Problem
Modern pulse time-of-flight distance meters face challenges in clearly assigning transmitted and received pulses due to the 'multiple time around' problem, leading to blind ranges at MTA zone boundaries, especially in high-speed or long-range measurements, where reflections from targets near these boundaries cannot be received.
Innovation Solution
The method involves selecting a first pulse repetition rate and shifting to a second rate when the time interval between transmission and reception approaches a predetermined threshold, effectively offsetting blind ranges by adjusting pulse intervals, allowing for continuous pulse assignment and reducing blind spots.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a high pulse repetition rate is used to increase measurement speed and spatial resolution, then productivity and measurement precision are improved, but blind ranges appear at MTA zone boundaries where reflections cannot be received
Solution Approach 1:
The patent applies dynamics by making the pulse repetition rate adjustable and variable during operation. The system dynamically switches between a first pulse repetition rate (higher) for normal measurements and a second pulse repetition rate (lower) when approaching MTA zone boundaries, thereby adapting the measurement parameters to avoid blind ranges while maintaining high productivity when possible.
Solution Approach 2:
The patent changes the pulse repetition rate parameter from a fixed value to a variable parameter that can be adjusted based on the measured distance and detected MTA zone proximity. This parameter change allows the system to optimize between measurement speed and reception reliability by selecting appropriate pulse repetition rates for different measurement conditions.
2Ease of operation
If a fixed pulse repetition rate is used to simplify device operation, then ease of operation is improved, but blind ranges cannot be avoided in varying measurement scenarios
Solution Approach 1:
The patent implements self-service by enabling the distance measurement device to automatically detect when it is approaching an MTA zone boundary and autonomously switch between different pulse repetition rates without requiring manual intervention. The system monitors the time interval between transmitted and received pulses and automatically adjusts parameters to avoid blind ranges, maintaining ease of operation while improving adaptability.
Solution Approach 2:
The patent uses feedback by continuously monitoring the time interval between transmitted pulses and received reflections, and using this information to automatically adjust the pulse repetition rate. The system detects when reflections are approaching the transmission time point and responds by changing the pulse repetition rate, creating a closed-loop control system that adapts to varying measurement scenarios.
3Measurement precision
If pulse position modulation is used to determine correct MTA zones, then measurement precision is improved, but device complexity increases due to additional processing requirements
Solution Approach 1:
The patent applies partial action by implementing a simplified version of pulse position modulation that only processes the necessary information to detect MTA zone boundaries. Instead of full pulse position modulation processing, the system monitors the time interval between transmitted and received pulses and only triggers pulse repetition rate changes when approaching MTA zones, reducing processing complexity while maintaining measurement 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 reduces or eliminates blind ranges, enabling more accurate and high-resolution distance measurements by ensuring that reception times do not coincide with transmission times, thereby preventing reception gaps and improving measurement accuracy across larger areas and moving targets.
Implementation Method 1
method for measuring the distance of targets in the surroundings by way of a time-of-flight measurement of pulses reflected at said targets
Implementation Method 2
pulses reflected at said targets
Data Source
AI summary
The present invention relates to a method for measuring the distance of targets in the surroundings by way of a time-of-flight measurement of pulses, in particular laser pulses, reflected at said targets, said pulses each being successively emitted at a transmission time in accordance with a predeterminable pulse repetition rate and said pulses, after the reflection thereof, each being received at a reception time, said method comprising the following steps:selecting a first pulse repetition rate from a set of at least two different pulse repetition rates and predetermining the selected pulse repetition rate for the emission,ascertaining a transmission time lying closest in time to the reception time of a reflected pulse and a time interval between these, and,if the ascertained time interval drops below a predetermined first threshold, selecting a second pulse repetition rate from the set and predetermining the second pulse repetition rate for the emission.