Binary Modulation Rangefinder Using Periodic Sequences
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Solution Overview
Problem
Existing distance measurement technologies face inaccuracies due to noise and limited bandwidth, leading to reduced scanning rates and accuracy, especially when multiple measurements are required for surface profiling, and are limited by the number of frequency components in modulated light beams.
Innovation Solution
A method and device for distance evaluation using a periodic binary sequence and harmonic modulation signal to generate a modulated light signal, which is transmitted, reflected, and processed to determine distance based on phase evaluation, amplitude comparison, and phase shifts, allowing for accurate three-dimensional scanning with improved noise resistance and scanning rate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If phase shift measurement is prolonged or repeated multiple times to minimize noise effects, then measurement accuracy is improved, but the time required to obtain accurate distance measurements increases
Solution Approach 1:
The patent uses periodic binary sequences and harmonic modulation signals to create time-periodic measurement patterns. By employing multiple frequency components in periodic modulation, the system can extract distance information through correlation analysis without requiring prolonged single-frequency measurements, thus reducing measurement time while maintaining accuracy through the periodic nature of the signal structure.
Solution Approach 2:
The measurement process is segmented into multiple frequency components rather than using a single continuous measurement. The binary sequence is divided into periodic segments with different frequencies, allowing parallel extraction of distance information from multiple frequency components simultaneously, which reduces the total measurement time required to achieve the same accuracy level.
2Measurement precision
If band-pass filters are employed to minimize noise effects, then measurement accuracy is improved, but the rate at which distance measurements can be accurately obtained is reduced
Solution Approach 1:
The use of periodic binary sequences with multiple frequency components allows the system to achieve noise filtering through signal processing in the frequency domain without requiring narrow band-pass filters. The periodic structure enables correlation-based measurement that inherently rejects noise while maintaining broad bandwidth, thus preserving high measurement rates.
Solution Approach 2:
The patent changes the measurement approach from time-domain filtering with band-pass filters to frequency-domain analysis using multiple frequency components. This parameter change allows the system to achieve noise rejection through the spectral distribution of the binary sequence rather than through filtering, maintaining wide bandwidth and high measurement rates while improving accuracy.
3Measurement precision
If the number of frequency components in modulated light beam is increased to improve measurement accuracy, then measurement precision is improved, but safety regulations and technical properties of light emitting devices limit the overall energy use
Solution Approach 1:
The patent employs periodic binary sequences that naturally distribute energy across multiple frequency components. The periodic structure ensures that the total energy remains within safety limits while the multi-frequency nature provides enhanced measurement accuracy through correlation analysis, efficiently utilizing the available energy budget across the frequency spectrum.
Solution Approach 2:
The system changes from using high power at single frequency to lower power distributed across multiple frequencies. By modulating the light beam with binary sequences containing multiple frequency components, the patent achieves improved measurement precision through spectral diversity while keeping the total energy consumption within safety and device limitations.
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 accuracy and speed of distance measurements by minimizing noise effects and bandwidth limitations, enabling more efficient three-dimensional scanning with improved reflectivity and brightness analysis.
Implementation Method 1
The nature of available photoreceivers also inserts uncertainty into the system. The signal delay of a photoreceiver is dependent upon the intensity of light received
Implementation Method 2
The prior art measurement of phase shift used in an application such as described in the Green patent relies on mixing the measured signal with a reference frequency signal, and determining the frequency difference. The phase difference is measured as a time difference between zero-crossing transitions of the measured periodic signal.
Data Source
AI summary
A method for evaluating distance from a first point to a second point. The method includes the steps of generating a periodic binary sequence, generating a harmonic modulation signal, generating a modulated light signal at a range finding device, wherein the modulated light signal is generated based upon the periodic binary sequence and the harmonic modulation signal, transmitting the modulated light signal from the first point toward an object at the second point, receiving a reflected light signal from the object, and determining a distance between the first point and the second point based upon a phase evaluation of periodic binary sequence and harmonic modulation signal of both the transmitted light signal and the received light signal.