CN106291578B - The method that laser Doppler shift based on two-way one-way communication tests the speed - Google Patents
The method that laser Doppler shift based on two-way one-way communication tests the speed Download PDFInfo
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- CN106291578B CN106291578B CN201610680767.2A CN201610680767A CN106291578B CN 106291578 B CN106291578 B CN 106291578B CN 201610680767 A CN201610680767 A CN 201610680767A CN 106291578 B CN106291578 B CN 106291578B
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- G—PHYSICS
- G01—MEASURING; TESTING
- 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
- G01S17/00—Systems using the reflection or reradiation of electromagnetic waves other than radio waves, e.g. lidar systems
- G01S17/02—Systems using the reflection of electromagnetic waves other than radio waves
- G01S17/50—Systems of measurement based on relative movement of target
- G01S17/58—Velocity or trajectory determination systems; Sense-of-movement determination systems
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
- H04B10/11—Arrangements specific to free-space transmission, i.e. transmission through air or vacuum
- H04B10/112—Line-of-sight transmission over an extended range
- H04B10/1123—Bidirectional transmission
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- Computer Networks & Wireless Communication (AREA)
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Abstract
The present invention relates to a kind of methods of the Doppler range rate measurement based on two-way one-way communication.By the way of two-way one-way communication, the laser of two places sends signal simultaneously for two places, and at the same time detection receives, the frequency addition for the signal that two places receive is averaged, Doppler frequency shift is can be obtained, then by the relationship of Doppler frequency shift and speed, it can be in the hope of the relative velocity of two places.The present invention under identical transmission power, can transmit longer distance using the communication means of two-way one way relative to traditional Doppler range rate measurement.
Description
Technical field
The present invention relates to free space laser communications and laser velocimeter field, more specifically, being that one kind being based on two-way list
The method of the Laser Doppler speed of Cheng Tongxin.
Technical background
It 1964, poplar (YEN) and accounts for bright this (cumnis) and determines water layer stream first with the Doppler frequency shift of laser
Distribution, to unlock prelude for the development of laser Doppler vibration.Laser Doppler vibration (LDV) is to pass through light
The frequency displacement of electric explorer detecting object surface scattering light or reflected light and reference light, obtains the velocity information of object.With it is traditional
Contact measurement compares, and LDV is a kind of untouchable measurement, it is a kind of noiseless flow field survey technology, has high
Measurement accuracy.It is, in principle, that LDV is not lagged accordingly, the fast pulsation of object can be got caught up in.It can be covered from several millis per second
Rice is to the very wide velocity interval of supersonic speed, and measurement is not influenced by parameters such as object pressure, temperature, density, viscosity, it may be used also
To realize the judgement of one-dimensional, two-dimentional, three-dimensional tachometric survey and the direction of motion, have dynamic response is fast, spatial resolution is high,
Outstanding advantages of measurement range is big and real-time.
The prior art [Zhang Yanyan, Gong Ke etc., laser Doppler vibration be in progress [J] laser with it is infrared, 2011,40
(11):1157-06.] described in laser Doppler vibration be all local reference light by the echo-signal of laser and laser
Signal does difference frequency, and, when laser long-distance transmits, the echo-signal of laser will be very weak for this, and detector is difficult to detect echo letter
Number, so needing high-power laser and highly sensitive photodetector, this adds increased the difficulty of realization.
Invention content
The present invention for existing laser Doppler velocity measurement method (by photodetector detect laser echo-signal and
The difference frequency signal of the local reference optical signal of laser obtains the motion velocity information of object) long range that is difficult to realize laser passes
Defeated deficiency is sent, and detect respective difference frequency signal simultaneously in two places, is passed through by the way of two-way one-way communication simultaneously
The relational expression of Doppler frequency shift and speed obtains the movement velocity of object.The present invention is being swashed by the way of two-way one-way communication
When light long distance transmission, do not increasing under the performance requirement of laser and detector, remaining to the Doppler frequency shift by laser
Measure the movement velocity of object.
The technology of the present invention solution, including following steps：
Step 1：By Liang Ge rangings communication station, i.e. the signal of the two places A, B emits to other side simultaneously, the local on the ground wherein A
Signal frequency is fA, the local signal frequency on the ground B is fB；
Step 2：Through t0After time, the signal from the ground B, frequency f are received to AAR, by the local signal on the ground A and
The signal received on the ground A does difference frequency, and the frequency for obtaining signal after difference frequency is fAR-fA；Receive the letter from the ground A to B simultaneously
Number, frequency fAR, the signal of the local signal on the ground B and the ground B received is done into difference frequency, the frequency for obtaining signal after difference frequency is
fBR-fB；
Step 3：Receive to A the frequency f of signalAR=fB+fdB, fdBIt is the Doppler frequency shift that generates of the ground B,
Receive to B the frequency f of signalBR=fA+fdA, fdAIt is the Doppler frequency shift that generates of the ground A；
The Doppler frequency shift average value that the two places A, B generate is calculated, formula is as follows：
In formula,Wherein, c is the light velocity；
The relative velocity for calculating the two places A, B is v, and formula is as follows：
In formula,
By the way of two-way one-way communication, even if under up to ten thousand kilometers of distance, it can also be measured by Doppler frequency shift
The relative velocity of two places.
The v of gained is the opposite momentary rate of the two places A, B, it is possible to the movement speed of translation stage is judged by v
Uniformity.
The present invention has following features：
1, by the way of being sent simultaneously using two places while detecting difference frequency signal, the long distance transmission of laser may be implemented.
2, when two places are by Doppler frequency shift finding speed, what is obtained is the instantaneous velocity of object, it is possible to judge speed
Spend the uniformity of translation stage movement speed.
The technique effect of the present invention：
1, the present invention is sent, while detecting reception, even if up to ten thousand simultaneously by the way of two-way one-way communication in two places
Under the distance of kilometer, the relative velocity of two places can also be measured by Doppler frequency shift.
2, compared with existing Laser Doppler Technique For Measuring Velocity, the present invention, in long distance transmission, do not increase to laser,
Under the performance requirement of the devices such as detector, the movement velocity that object is measured by the Doppler frequency shift of laser is remained to.
Description of the drawings
Fig. 1 is the principle of the present invention block diagram
Fig. 2 is the structure chart of one embodiment of the present of invention.
Specific implementation mode
Invention is further described in detail with example below in conjunction with the accompanying drawings, but the protection of the present invention should not be limited with this
Range.
Fig. 1 is the principle of the present invention block diagram, and specific implementation includes following steps：
Step 1：The signal of the two places A, B is emitted to other side simultaneously, the signal frequency on the ground wherein A is fA, the signal on the ground B
Frequency is fA。
Step 2：Through t0After time, the signal from the ground B, frequency f are received to AAR, by the local signal on the ground A and
The signal received on the ground A does difference frequency, and the frequency that can obtain signal after difference frequency is fAR-fA；Receive the letter from the ground A to B simultaneously
Number, frequency fAR, the signal of the local signal on the ground B and the ground B received is done into difference frequency, can be to the frequency of signal after difference frequency
fBR-fB。
Step 3：Receive to A the frequency f of signalAR=fB+fdB, fdBIt is the Doppler frequency shift that generates of the ground B, receives letter to B
Number frequency be fBR=fA+fdA, fdAIt is the Doppler frequency shift that generates of the ground A.So the difference frequency signal addition of the two places A, B is averaged
It is worth to
By the relational expression of Doppler frequency shift and speedWherein, c is the light velocity.So
Wherein,It can be obtained the relative velocity v of two places.
Fig. 2 is the structure chart of one embodiment of the present of invention.As seen from the figure, in index path of the invention the ground A structure packet
Include the first tunable laser 1, the 1st point of 2 fiber optic splitters 2, the first optical fiber circulator 3, the first optical fiber collimator 4, speed
Control translation stage 5, the first 2*2 optical fiber directional couplers 6, the first photoelectricity balanced detector 7, the first digital oscilloscope 8.The ground B
Structure includes the second tunable laser 9, the 2nd 1 points of 2 fiber optic splitters 10, the second optical fiber circulator 11, second fiber optic collimators
Device 12, the 2nd 2*2 optical fiber directional couplers 13, the second photoelectricity balanced detector 14, the second digital oscilloscope 15.
Tunable laser 1 export light field be
Wherein, A1Represent optical field amplitude, ωAFrequency of light wave is represented,Represent the phase noise of light field.Laser output light
Signal is divided into the strong equal two ways of optical signals of two-beam by the one 1 point of 2 fiber optic splitter 2, wherein the local oscillator as the ground A all the way
Signal is expressed as
Another way enters the port 1 of the first optical fiber circulator 3, the transmitting signal as optical fiber circulator.So the ground A
Emitting signal is
The output light field of tunable laser 9 is
Wherein, A2Represent optical field amplitude, ωBFrequency of light wave is represented,Represent the phase noise of light field.Laser output light
Field is divided into the strong equal two ways of optical signals of two-beam by the 2nd 1 point of 2 fiber optic splitter 10, wherein the local oscillator as the ground B all the way
Signal is expressed as
Another way enters the port 1 of the second optical fiber circulator 11, the transmitting signal as circulator.So the hair on the ground B
Signal is penetrated to be expressed as
The transmitting signal on the ground A by the first optical fiber collimator 4 by Gauss light collimation be directional light, free-space propagation away from
After for S (t), after the second optical fiber collimator 12, it is transferred to the port 2 of the first optical fiber circulator, and in the first fiber optic loop
The port 3 of shape device is received, so, the light field of the reception optical signal on the ground B is expressed as
Wherein, v is the movement speed of speed control translation stage 5, and translation stage to B translates, and it is "+", S (t) to take the symbol of v
=S0- vt, S0When being that speed control translation stage 5 is static, the distance of the two places A, B.
As can be seen that receiving the frequency of signal from above formula
So the reception light field of B is represented by
The reception optical signal E on the ground BrB(t) and local oscillator optical signal ELOB(t) input as the 2nd 2*2 fiber couplers 13
The coupling ratio of signal, 2*2 fiber couplers is 1:1, then the light field of the output signal of the 2nd 2*2 fiber couplers 13 be expressed as
The optical signal received is switched to voltage signal by the first balance photodetector 7, is expressed as
C.c represents the complex conjugate of preceding paragraph,It is the amplitude of signal, wherein R is photodetection
The responsiveness of device, D are the photosensitive area of the first balanced detector, and r is detector resistance.
The voltage signal of first photoelectricity balanced detector detector 7 output is shown to 8 on the first digital oscilloscope, and to it
It is Fast Fourier Transform (FFT) FFT, the corresponding frequency of peak value is f1
f1=fA+fdA-fB+δf1
Wherein δ f1It is laser phase noiseThe frequency error brought.
The angular frequency measured ideallyA+ωdA-ωB,It is constant, does not influence as a result, considering random phase
Position itemThe frequency error δ f brought1
V‘1(t) auto-correlation function is
Definition
BecauseBe mean value be 0, variance be 2 π Δs υB| τ | random Gaussian variable, wherein Δ υBIt is tunable sharp
The line width of light device 9；Be mean value be 0, variance be 2 π Δs υA| τ | random Gaussian variable, wherein Δ υAIt is adjustable
The line width of humorous laser 1；Su soIt is also gaussian variable.
BecauseWithIt is the gaussian variable that incoherent two mean values are 0, so
V‘1(t) spectral density function is
Its spectrum width is 4 π (Δ υB+ΔυA), so δ f1=4 π (Δ υB+ΔυA)
Gauss light collimation is directional light by the second optical fiber collimator 12 by the transmitting signal on the ground B, in free-space propagation
After distance is S (t), after the first optical fiber collimator 4, it is transferred to the port 2 of the first optical fiber circulator, and in the first optical fiber
The port 3 of circulator is received, so, the light field of the reception optical signal on the ground A is expressed as
Because receiving the frequency of signal
So the light field of the reception optical signal on the ground A can be expressed as again
The reception optical signal E on the ground ArA(t) and local oscillator optical signal ELOA(t) believe as the input of the first 2*2 fiber couplers 6
Number, the coupling ratio of 2*2 fiber couplers is 1:1, then the light field of the output signal of the first 2*2 fiber couplers 6 be expressed as
The optical signal received is switched to voltage signal by the first balance photodetector, is expressed as
C.c represents the complex conjugate of preceding paragraph,It is the amplitude of signal, wherein R is photodetection
The responsiveness of device, D are the photosensitive area of the first balanced detector, and r is detector resistance.
The voltage signal of photodetector output is shown on digital oscilloscope, and does Fast Fourier Transform (FFT) to it
FFT, the corresponding frequency of peak value are f2
f2=fB+fdB-fA+δf2
Wherein δ f2It is laser phase noiseThe frequency error brought
Ignore V2(t) the center angular frequency item (ω inB+ωdB-ωA) t and constant termOnly consider laser phase
NoiseFormula can be written as
Then v '2(t) auto-correlation function is
Definition
BecauseBe mean value be 0, variance be 2 π Δs υA| τ | random Gaussian variable,It is equal
Value is 0, and variance is 2 π Δs υB| τ | random Gaussian variable, soIt is also gaussian variable.
Similarly,
V‘2(t) spectral density function is
Its spectrum width is 4 π (Δ υB+ΔυA), so δ f2=4 π (Δ υB+ΔυA)
So since the frequency error that laser phase grass comes is δ f
δ f=δ f1+δf2=8 π (Δ υB+ΔυA)
Claims (1)
1. a kind of method that the laser Doppler shift based on two-way one-way communication tests the speed, it is characterised in that：Including following
Step：
Step 1：By Liang Ge rangings communication station, i.e. the signal of the two places A, B emits to other side simultaneously, the local signal frequency on the ground wherein A
Rate is fA, the local signal frequency on the ground B is fB；
Step 2：Through t0After time, the signal from the ground B, frequency f are received to AAR, by the local signal on the ground A and A
The signal received do difference frequency, the frequency for obtaining signal after difference frequency is fAR-fA；The signal from the ground A is received to B simultaneously,
Frequency is fAR, the signal of the local signal on the ground B and the ground B received is done into difference frequency, the frequency for obtaining signal after difference frequency is fBR-
fB；
Step 3：Receive to A the frequency f of signalAR=fB+fdB, fdBIt is the Doppler frequency shift that generates of the ground B,
Receive to B the frequency f of signalBR=fA+fdA, fdAIt is the Doppler frequency shift that generates of the ground A；
The Doppler frequency shift average value that the two places A, B generate is calculated, formula is as follows：
In formula,Wherein, c is the light velocity；
The relative velocity for calculating the two places A, B is v, and formula is as follows：
In formula,
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| CN113552383A (en) * | 2021-07-29 | 2021-10-26 | 深圳市宏电技术股份有限公司 | Bidirectional Doppler velocimeter and bidirectional Doppler velocimetry method |
| CN115712001A (en) * | 2021-08-23 | 2023-02-24 | 华为技术有限公司 | Speed measuring method and electronic equipment |
| CN115913361B (en) * | 2022-11-14 | 2023-11-03 | 中国科学院国家空间科学中心 | Space laser communication and speed measurement method |
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| CN102236097B (en) * | 2010-04-29 | 2013-04-03 | 西安近代化学研究所 | Two-path lateral Doppler speed measuring method for impact exciting calibration |
| CN101887126B (en) * | 2010-06-27 | 2013-04-03 | 清华大学 | Double-frequency laser Doppler velocity measurement method and device |
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