Laser Radar Frequency Modulation for Distance Speed Separation
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Solution Overview
Problem
Laser radar devices face challenges in separating frequency information resulting from distance to a target and speed of the target due to complex waveforms caused by light scattering from aerosols in wind measurement applications.
Innovation Solution
The laser radar device employs discrete frequency modulation with intervals, allowing TOF information to appear in units of frequency difference F, and Doppler frequency to be distinguished as finer changes, using a mechanism that separates frequency information by a simple method.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If continuous frequency modulation is used to obtain both distance and speed information, then measurement capability is improved, but waveform complexity increases making frequency information separation difficult
Solution Approach 1:
The patent segments the frequency modulation into discrete frequency values at regular intervals rather than continuous modulation. This segmentation allows distance information (TOF) to appear in units of frequency difference F, while Doppler frequency appears as finer changes within each unit, enabling straightforward separation of the two types of frequency information through simple signal processing.
2Measurement precision
If FMCW technique is used to convert TOF to frequency information, then distance measurement is improved, but frequency information from distance and speed becomes mixed and difficult to separate
Solution Approach 1:
The patent applies local quality by making the frequency modulation have discrete values at regular intervals rather than continuous variation. This creates a local structure where TOF information manifests at specific frequency intervals (units of F) while Doppler information appears as smaller variations within each interval, allowing easy differentiation and separation of the two information types through frequency analysis.
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 configuration enables effective separation of frequency information related to distance and speed, improving signal processing and accuracy in wind measurement.
Implementation Method 1
a light source 10 that emits laser light
Implementation Method 2
a frequency modulator 20 that performs frequency modulation on the laser light... or a phase modulator 20B that performs phase modulation on the laser light
Implementation Method 3
a phase modulator 20B that performs phase modulation on the laser light
Implementation Method 4
light scattered by the aerosol at the plurality of places is received
Implementation Method 5
a first balanced detector 81 that receives received light and first local oscillator light and converts each of the received light and the first local oscillator light into a first electrical signal
Implementation Method 6
a Doppler frequency corresponding to a speed of the target appears as a finer change than the frequency difference F
Data Source
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AI summary
In a laser radar device according to the present disclosed technique, a frequency of laser light to be emitted adopts discrete values based on intervals of a frequency difference F are adopted. Therefore, TOF corresponding to a distance to a target appears in units of the frequency difference F for each time T, and a Doppler frequency corresponding to a speed of the target appears as a finer change than the frequency difference F. As described above, the present disclosed technique provides a laser radar device including a mechanism for separating frequency information resulting from the distance to the target from frequency information resulting from a speed of the target by a simple method.