Distance measuring device, water level measurement system, and distance measurement method

Patent metadata

Field	Value
Publication number	US-2018259633-A1
Application number	US-201815913979-A
Country	US
Kind code	A1
Filing date	Mar 7, 2018
Priority date	Mar 13, 2017
Publication date	Sep 13, 2018
Grant date	—

Abstract

A distance measuring device includes one or more processors configured to: detect a wave formed by synthesizing a frequency-swept electromagnetic wave transmitted to an object with a wave reflected on the object; measure, based on the synthesized wave, a distance to the object; calculate a displacement-caused inclination, caused by the displacement of the object, of a power spectrum of the synthesized wave; and measure the distance based on a signal in which the displacement-caused inclination has been removed from the power spectrum.

First claim

What is claimed is:

1 . A distance measuring device comprising:
one or more processors configured to: detect a wave formed by synthesizing a frequency-swept electromagnetic wave transmitted to an object with a wave reflected on the object; measure, based on the synthesized wave, a distance to the object; calculate a displacement-caused inclination, caused by the displacement of the object, of a power spectrum of the synthesized wave; and measure the distance based on a signal in which the displacement-caused inclination has been removed from the power spectrum.

2 . The distance measuring device according to claim 1 ,
wherein the one or more processors is configured to calculate a regression line, corresponding to the displacement-caused inclination, of the power spectrum of the synthesized wave.

3 . The distance measuring device according to claim 1 , further comprising:
an orthogonal wave detector configured to separate the synthesized wave into real-part data and imaginary-part data, wherein the one or more processors is configured to calculate a real-part inclination corresponding to the real-part data and an imaginary-part inclination corresponding to the imaginary-part data.

4 . The distance measuring device according to claim 1 ,
wherein the one or more processors are configured to calculate, based on Equation A provided below, a displacement component V, corresponding to the displacement-caused inclination, of the power spectrum in a real-part region of the synthesized wave and calculate, based on Equation B provided below, a displacement component V, corresponding to the displacement-caused inclination, of the power spectrum in an imaginary-part region of the synthesized wave, while

V
=

2


A
2



sin


(

4



π




fd
0

c

-
φ

)

·

4



π




f
0


B

c


t

,
and

Equation



A

V
=

2


A
2



cos


(

4



π




fd
0

c

-
φ

)

·

4



π




f
0


B

c


t

,

Equation



B

where A is an amplitude level of the transmitted wave, f is the frequency of the transmitted wave, d 0 is a central value of the distance, c is the speed of light, ϕ is the amount of a change in the phase due to the reflection, f 0 is a central frequency of the transmitted wave, B is a velocity coefficient that gives the displacement Δd of the object to be measured, and t is time.

5 . The dis

Assignees

• Fujitsu Ltd

Inventors

• Kikuchi Yoshio
• Tsuboi Osamu

Classifications

• G01S13/34 Primary

  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 · CPC title

• G01F23/284 Primary

  Electromagnetic waves · CPC title

• G01F23/804

  containing circuits handling parameters other than liquid level · CPC title

• G01S13/343

  using sawtooth modulation · CPC title

• G01S13/88

  Radar or analogous systems specially adapted for specific applications (electromagnetic prospecting or detecting of objects, e.g. near-field detection, G01V3/00) · CPC title