# US 11,112,502 B2 · Laser radar system

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- Number: US 11,112,502 B2
- Document ID: US11112502B2
- Status: Granted
- Kind: B2
- Application number: 16/078,256
- Filed: 2016-04-05
- Published: 2019-02-28
- Granted: 2021-09-07
- Earliest claimed: 2016-04-05
- Assignees: Mitsubishi Electric Corporation
- Applicants: Mitsubishi Electric Corporation
- Inventors: Nobuki Kotake; Shumpei Kameyama
- Web page: https://patentgrep.com/patent/US11112502B2

## CPC

- G01S 17/42: Simultaneous measurement of distance and other co-ordinates (indirect measurement G01S17/46)
- G01S 17/58: Velocity or trajectory determination systems; Sense-of-movement determination systems
- G01S 7/4818: {using optical fibres}
- G01S 7/4861: Circuits for detection, sampling, integration or read-out
- G01S 7/4865: Time delay measurement, e.g. time-of-flight measurement, time of arrival measurement or determining the exact position of a peak (peak detection in noise, signal conditioning G01S7/487)
- G01S 7/487: Extracting wanted echo signals {, e.g. pulse detection}
- G01S 17/26: wherein the transmitted pulses use a frequency-modulated or phase-modulated carrier wave, e.g. for pulse compression of received signals
- G01S 17/95: for meteorological use
- G01S 7/02: of systems according to group G01S13/00
- G01S 17/34: using transmission of continuous, frequency-modulated waves while heterodyning the received signal, or a signal derived therefrom, with a locally-generated signal related to the contemporaneously transmitted signal
- Y02A 90/10: Information and communication technologies [ICT] supporting adaptation to climate change, e.g. for weather forecasting or climate simulation
- G01S: RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- Y02A: TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE

## Abstract

In conventional laser radar systems, the wind velocity measurement accuracy cannot be improved without changing their time gate widths, which is a problem. A laser radar system according to the present invention includes: an optical oscillator to perform laser light oscillation; an optical modulator to modulate the laser light by oscillation of the optical oscillator; an optical antenna to emit the laser light modulated by the optical modulator into the atmosphere and to receive scattered light from an irradiated target as reception light; an optical receiver to perform heterodyne detection on the reception light received by the optical antenna; and a signal processor to calculate a spectrum of a reception signal obtained by the optical receiver's performing heterodyne detection, to decompose the spectrum using signal-to-noise ratios, and to calculate a velocity of an irradiated target from a decomposed spectrum.

## Claims

### Claim 1

A laser radar system, comprising:
an optical oscillator to perform laser light oscillation;
an optical modulator to modulate the laser light by oscillation of the optical oscillator;
an optical antenna to emit the laser light modulated by the optical modulator into the atmosphere and to receive scattered light from an irradiated target as reception light;
an optical receiver to perform heterodyne detection on the reception light received by the optical antenna; and
a signal processor to calculate a spectrum of a reception signal obtained by the optical receiver's performing heterodyne detection, to decompose the spectrum using signal-to-noise ratios, and to calculate a velocity of the irradiated target from a decomposed spectrum, wherein
the signal processor comprises:
a range bin divider to divide the reception signal at intervals of a preset width of time gates;
a Fourier transform processor to perform Fourier transform on a reception signal divided by the range bin divider and to calculate a spectrum of the reception signal for each of the time gates;
an integrator to integrate spectrums calculated by the Fourier transform processor for each of the time gates;
a Signal-to-Noise Ratio (SNR) calculator configured to obtain a signal-to-noise ratio for a target distance from the spectrum integrated by the integrator;
a number-of-decomposition setter to set the number of segments for the spectrum integrated by the integrator to be decomposed;
a spectrum decomposer to decompose the spectrum integrated by the integrator by using the number of segments set by the number-of-decomposition setter and the signal-to-noise ratios calculated by the SNR calculator; and
a wind velocity calculator to calculate a wind velocity of the irradiated target from a spectrum decomposed by the spectrum decomposer.

### Claim 2 (depends on 1)

The laser radar system according to claim 1, wherein the number-of-decomposition setter determines the number of segments for the spectrum to be decomposed by using a threshold for the signal-to-noise ratio.

### Claim 3 (depends on 2)

The laser radar system according to claim 2, wherein the integrator changes the number of integration times of spectrums according to the number of segments.

### Claim 4 (depends on 2)

The laser radar system according to claim 2, wherein the range bin divider changes, according to the number of segments, the width of the time gates which is used when the spectrum is calculated.

### Claim 5 (depends on 2)

The laser radar system according to claim 2, wherein the optical modulator changes, according to the number of segments, a pulse width which is used when the laser light is modulated.