Optical-Electronic Distance Measuring Device Burst Modulation
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Solution Overview
Problem
Existing optoelectronic distance measuring devices face limitations in signal/noise ratio and accuracy due to the long active burst time required for synchronization, which reduces the effectiveness of burst modulation in improving measurement precision.
Innovation Solution
The implementation of a receiving circuit that utilizes burst modulation for emitting intensity-modulated optical radiation, with a sample-and-hold member to sample the signal during active burst times and hold it during dead times, avoiding unnecessary filtering and oscillation processes, and using a transimpedance amplifier for continuous amplification and low-pass filtering during active burst times.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If burst modulation with long active burst time is used for synchronization, then the device can achieve stable signal detection, but the signal/noise ratio deteriorates and measurement accuracy decreases
Solution Approach 1:
The patent applies periodic burst modulation to the laser radiation, where the radiation is emitted in periodic bursts rather than continuously. This periodic action allows the system to achieve stable synchronization while limiting the total active transmission time, thereby improving the signal/noise ratio and measurement accuracy compared to continuous emission or long-duration bursts.
2Measurement precision
If continuous amplification and low-pass filtering are applied during active burst times, then the signal integrity is maintained, but the device complexity increases
Solution Approach 1:
The patent implements continuous amplification via a transimpedance amplifier throughout the active burst time, ensuring that the photodetector signal is continuously strengthened without interruption. This continuous useful action maintains signal integrity and enables accurate phase measurement, while the amplifier's inherent low-pass filtering特性 provides noise reduction without requiring additional complex filtering stages.
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 enhances the signal/noise ratio and improves measurement accuracy by reducing noise suppression and maintaining signal integrity, allowing for more effective phase measurement-based distance determination.
Implementation Method 1
a receiver (5) for converting at least a part of the measuring radiation (23) reflected by a measured object (33) into an electrical input measuring signal (ES)
Implementation Method 2
a transimpedance amplifier (7), connected between the receiver and the sample-and-hold member (10), for converting the input measuring signal (ES) into an output voltage signal
Implementation Method 3
a sample-and-hold member (10) for converting the output voltage signal of the transimpedance amplifier (7) into a measuring signal (MS), wherein the output signal of the sample-and-hold member (10) assumes values dependent on the input measuring signal (ES), during a sampling time linked to an active burst time (tBurst-on), and is kept constant, during a holding time linked to a dead time (tBurst-off)
Data Source
AI summary
The invention relates to an optical-electronic distance measuring method according to the phase measurement principle by emitting of optical measuring radiation, which is modulated according to the burst modulation principle, having a burst period duration made of an active burst time and a dead time, receiving at least a part of the measuring radiation (23), which is reflected on the measured object, wherein transforming into an input measuring signal (ES) is performed, and determining a distance to the measured object by analyzing a measuring signal (MS, gMS) generated from the input measuring signal (ES).