Optoelectronic Scanner Frequency Spread Spectrum Interference Immunity
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Solution Overview
Problem
Existing optoelectronic scanners face challenges in achieving a high signal-to-noise ratio and resistance to extraneous light, particularly due to the high proportion of low frequencies in conventional pulse train methods which cannot be filtered without losing useful signal components.
Innovation Solution
The optoelectronic scanner employs a frequency spread spectrum method with an output signal based on a binary sequence of zeros and ones, where the number of zeros is increased by a factor greater than one, using an m-sequence and optimal filtering to generate a pulse sequence with a higher proportion of zeros, shifting the frequency distribution towards higher frequencies for improved interference immunity and signal quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional pulse train methods are used, then the scanning function is achieved, but the signal-to-noise ratio is low and extraneous light resistance is poor due to high proportion of low frequencies
Solution Approach 1:
The patent changes the temporal distribution parameter of the pulse train by increasing the number of zeros by a factor N>1, which shifts the frequency spectrum from low-frequency dominant to high-frequency dominant. This parameter change enables the use of high-pass filtering to reject extraneous light while preserving the useful signal.
Solution Approach 2:
The patent uses periodic pulse trains with modified duty cycles where zeros are repeated N times more than in conventional systems. This periodic structure with increased zero repetition creates a frequency spectrum shifted toward higher frequencies, enabling better filtering of low-frequency extraneous light.
2Reliability
If the number of zeros in the pulse sequence is increased by a factor N>1, then the frequency distribution shifts to higher frequencies improving interference immunity, but the pulse train duration increases
Solution Approach 1:
The patent accepts the time extension as a necessary trade-off for achieving high-frequency dominant spectrum. By changing the zero repetition parameter N, the system shifts the frequency distribution to achieve better interference immunity, with the understanding that longer pulse trains are required.
3Object-affected harmful factors
If high-pass filtering is applied to remove low frequencies, then extraneous light resistance is improved, but useful signal components are lost in conventional pulse trains
Solution Approach 1:
The patent changes the frequency spectrum characteristics by increasing zero repetition N times, which shifts the signal energy to higher frequencies. This parameter change enables high-pass filtering to separate useful signal from extraneous light without losing signal components, as the useful signal now resides in the high-frequency passband.
Solution Approach 2:
The patent converts the previously harmful low-frequency dominance into a benefit by deliberately shifting the spectrum to high frequencies. The high-frequency dominant structure allows high-pass filtering to work in favor of signal preservation while rejecting low-frequency extraneous light.
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-to-noise ratio and reduces sensitivity to interference, allowing for more effective monitoring with improved reliability and reduced thermal load on the light emitter.
Implementation Method 1
the light signals emitted by the light transmitter into the monitoring area are each generated on the basis of an output signal modulated - in particular according to a frequency spread spectrum method
Implementation Method 2
the light emitter being on when a one is transmitted and off when a zero is transmitted
Implementation Method 3
a light deflection unit for - in particular periodically - deflecting the light signals emitted by the light transmitter into the monitored area
Implementation Method 4
a light receiver for receiving light emitted by a monitored area located object is thrown back
Implementation Method 5
the number of consecutive zeros of the m-sequence being increased by a factor N which is greater than one, shifting the frequency distribution towards higher frequencies
Data Source
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AI summary
An optoelectronic scanner for monitoring a surveillance area is described, comprising a light transmitter for emitting light signals, a light deflection unit for deflecting the light signals emitted by the light transmitter into the surveillance area, a light receiver for receiving light reflected from an object located in the surveillance area, and a control unit for generating and/or influencing the light signals. The light signals emitted by the light transmitter into the surveillance area are each generated based on an output signal modulated, in particular by a frequency band spread spectrum method and/or an optimal filter method, and the output signal is represented as a binary signal consisting of zeros and ones, which has more zeros than ones.