Dynamic Distance Meter Using Frequency Wobble and Fourier Analysis
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Solution Overview
Problem
Existing methods for determining absolute distances, particularly using the Fizeau principle, face challenges in achieving high measurement dynamics and accuracy when dealing with dynamic targets due to factors like atmospheric turbulence and reflector conditions, limiting their application in surveying and tracking moving targets.
Innovation Solution
The method involves modulating the transmission radiation with a basic modulation frequency and applying a wobble to the modulation frequency, followed by Fourier transformation of the measurement signal to directly determine the offset from a reference point, enabling continuous and accurate distance measurement even for moving targets.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional Fizeau method with iterative approximation is used to determine absolute distance, then measurement accuracy can be achieved for static targets, but measurement dynamics are insufficient for tracking moving targets
Solution Approach 1:
The patent applies preliminary action by performing a frequency sweep to identify minima positions before actual distance measurement. The minima positions are stored and used as reference points for subsequent measurements, eliminating the need for iterative approximation during dynamic tracking. This pre-established reference framework enables rapid distance updates without sacrificing accuracy.
Solution Approach 2:
The patent implements dynamics by transitioning from static iterative approximation to a dynamic measurement system that continuously tracks minima positions. The system automatically updates reference points as targets move, maintaining measurement accuracy while adapting to changing conditions. The measurement process becomes dynamic rather than requiring repeated static optimization.
2Measurement precision
If measurement duration is extended to improve accuracy by filtering multiple values, then atmospheric turbulence can be compensated, but measurement dynamics decrease and cannot track moving targets
Solution Approach 1:
The patent performs atmospheric compensation and signal filtering in advance during the frequency sweep phase, before actual distance measurement begins. By establishing a robust reference framework that already accounts for atmospheric conditions, the system eliminates the need for extended measurement durations during dynamic tracking, achieving both accuracy and speed.
3Measurement precision
If iterative approximation is used to determine minimum point frequency, then accurate distance measurement is achieved for static targets, but the process is too slow for dynamic targets
Solution Approach 1:
The patent determines minimum point frequencies in advance during an initial frequency sweep and stores them as reference points. Subsequent distance measurements for dynamic targets directly use these pre-determined frequencies without iterative approximation, achieving both accuracy and high measurement speed.
Solution Approach 2:
The patent transforms the static iterative process into a dynamic system where minimum point frequencies are automatically updated and tracked as targets move. The system maintains frequency accuracy while adapting to dynamic conditions, eliminating the speed-accuracy trade-off present in static iterative methods.
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 quick and precise determination of absolute distances to moving targets with radial movement speeds up to ±6 m/sec, overcoming previous limitations by providing high measurement dynamics and accuracy independent of parabola shape and atmospheric fluctuations.
Implementation Method 1
an electro-optical crystal is used as a modulator. The measuring beam is no longer periodically interrupted, but modulated by the modulator. During modulation, for example, the polarization and/or the intensity and/or the frequency of the transmitted radiation are modulated
Implementation Method 2
The emitted beam is superimposed on the beam reflected by the target and received by the measuring device. When the distance changes, the intensity of the superimposed beams changes according to the interference between the two beams
Implementation Method 3
Fourier transformation of the measurement signal to directly determine the offset from a reference point
Data Source
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AI summary
The invention relates to a measuring method and a distance meter for determining an absolute distance to a target moving at a speed radial to the distance meter, wherein a modulated transmitted radiation is emitted to the target and a measurement signal is acquired, such that the measurement signal carries information regarding the absolute distance to the target through at least one reference point of a frequency-dependent signal waveform of the measurement signal, based on a modulation phase of the received radiation with respect to a set basic modulation, wherein for a set basic modulation frequency the offset of this frequency value to a reference point, in particular a minimum point, of the signal waveform of the measurement signal is derived, namely the frequency offset and the offset direction to the reference point.