CN102857294A - Method and device for suppressing signal fading in laser communication from ground to GEO (geosynchronous) satellite - Google Patents
Method and device for suppressing signal fading in laser communication from ground to GEO (geosynchronous) satellite Download PDFInfo
- Publication number
- CN102857294A CN102857294A CN2011101789707A CN201110178970A CN102857294A CN 102857294 A CN102857294 A CN 102857294A CN 2011101789707 A CN2011101789707 A CN 2011101789707A CN 201110178970 A CN201110178970 A CN 201110178970A CN 102857294 A CN102857294 A CN 102857294A
- Authority
- CN
- China
- Prior art keywords
- laser
- signal
- power
- intensity fluctuation
- beacon beam
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
Images
Landscapes
- Optical Communication System (AREA)
- Radio Relay Systems (AREA)
Abstract
Disclosed are a method and a device for suppressing signal fading in laser communication from ground to a GEO (geosynchronous) satellite. The method includes: measuring intensity fluctuation waveform of downlink beacon light emitted from the GEO satellite by a single-mode fiber on a ground station, and transmitting uplink laser beam along a direction opposite to the downlink beacon light via the same single-mode fiber, and then emitting the uplink laser beam from an end face of the single-mode fiber; modulating to-be-transmitted uplink data waveform according to the reciprocal of the intensity fluctuation waveform of the downlink beacon light measured by the single-mode fiber, driving a laser to emit uplink laser, and transmitting the uplink laser beam to the GEO satellite. Accordingly, atmospheric turbulence and signal fading caused by alignment error of a ground transmitter can be eliminated automatically, and power of laser received by the satellite is stable. In addition, average transmission power of the uplink laser beam can be reduced on the condition of the rated fading probability.
Description
Technical field
The present invention relates to the satellite laser communications technical field, specifically a kind of on ground in the up laser communication of geostationary orbit (GEO) satellite, reduce the signal fadeout that atmospheric turbulance and alignment error cause, thereby reduce a kind of method of average emitted luminous power.
Background technology
Satellite laser communications has the advantages such as message capacity is large, volume is little, antijamming capability is strong, security performance is good, is important development direction of communication technology of satellite.The impact that will inevitably be subject to the earth atmosphere turbosphere to the laser communication of satellite to laser communication and the ground on ground at satellite.Atmospheric turbulance can make the wavefront of laser beam produce distortion, makes laser signal intensity fluctuation (flicker), produces decline, and the time scale of intensity fluctuation is about 10 milliseconds of magnitudes, and this can have a strong impact on the performance of satellite laser communications system.
Impact to the laser communication of satellite is different to atmospheric turbulance to the laser communication on ground and ground on satellite.To the descending laser communication on ground, laser beam at first passes through remote free space transmission for satellite, passes the optical receiver that about 20 kilometers atmospheric turbosphere arrives ground station again.Turbulent flow is only working near in the relatively short segment distance of receiver.For the laser communication system on the satellite-ground of adopting intensity modulated/direct detection, by increasing the terrestrial receiving antenna diameter, utilize wide-aperture aperture smoothing effect or adopt the methods such as array received of multiple aperture can significantly reduce the impact that turbulence intensity is glimmered.
For the up laser communication of ground to satellite, the scintillation that atmospheric turbulance causes is more serious.Up laser beam at first passes approximately 20 kilometers atmospheric turbosphere, and then through the free space transmission of hundreds of kilometer at least.Because receiver aperture size limited (being generally less than 25 centimetres) on the satellite is difficult to adopt large aperture or array received antenna, so after on the laser arrival satellite, scintillation is very large, can produce the deep fading.For the up laser transmission of ground to satellite, the multiple beam lift-off technology is at present the most frequently used a kind of turbulence intensity flicker inhibition technology, has preferably Project Realization.As adopting
NIndividual mutual incoherent beamlet emission, then total scintillation will be reduced to 1/ of single beam intensity flicker
NBut this method requires each beamlet all to have independently catches, follows the tracks of and aim at (ATP) subsystem, and has independently optical antenna.Therefore what the total cost of multiple beam emission system will be for the single beam emission system
NDoubly.And cause the laser communication terminal volume to increase, be not easy to mobile.
The signal strength signal intensity that suppresses wireless channel rises and falls and also has a kind of method that is in daily use, and is exactly the automated power control technology.After the carrier signal that transmitter sends is transmitted through wireless channel, measured the intensity fluctuation that receives signal by receiver, then by reverse link this intensity fluctuation is sent to transmitting terminal, the transmitting power that controls transmitter according to this intensity fluctuation again, thereby the signal strength signal intensity fluctuating quantity that receiver is received weakens, and keeps received power stable.
This transmitting terminal automatic power control method is widely applied in wireless mobile communications, in space optical communication, also can adopt similar method (Liu Zili, Tu Cuixia, the control method of free-space optical communication system and transmitted power thereof, Chinese patent, application number: 200410052212.0), but this method is only applicable to transmitter, receiver at a distance of nearer, and under the lower application conditions of signal strength signal intensity fluctuating frequency.For communicating by letter between ground and the satellite, because distance is far, the passback time-delay of fading signal waveform is very large, and the duration of the signal fadeout that turbulent flow causes only has 10 Milliseconds, this moment, the decline of channel was uncorrelated already, therefore can't adopt the automated power control technology of this form to suppress the fast signal decline that turbulent flow causes.For ease of the laser beam of ground station emission accurately to satelloid, satellite needs the earthward a branch of descending beacon beam of station emission, the imageing sensor of ground station can be restrainted descending beacon beam according to this, obtain the azimuth information of target satellite, then drive quick deflecting mirror and make up laser beam accurately point to satellite, thereby eliminate the impact of various alignment errors.
The early-stage Study of applicant is found, for the ground of adopting the duplexer system and the transmission of the two-way laser between the satellite, as make spatial amplitude and the PHASE DISTRIBUTION of the up laser beam of terrestrial optical antenna place emission, spatial amplitude and the PHASE DISTRIBUTION of descending beacon beam is consistent with without turbulent flow the time, when then having turbulent flow, descending beacon beam receives optical antenna focus place on ground intensity fluctuation will be consistent, strong correlation with the intensity fluctuation of up laser beam on the optical axis of satellite plane.Utilize this characteristic, by descending beacon beam, ground station not only can obtain the azimuth information of target satellite, also can obtain the light intensity fluctuation waveform of up laser beam on satellite, and need to not measure the intensity fluctuation waveform of up laser beam and pass back to ground station at satellite, thereby can continue to adopt the automated power control technology automatically to control the transmitting power of up laser beam, reach and reduce up laser signal decline, improve the purpose of laser communication system performance.
For ground to the GEO(geostationary orbit) the up laser communication of satellite, in order to overcome the signal fadeout of the up laser beam that atmospheric turbulance and ground transmitter alignment error cause.Utilizing descending beacon beam receives optical antenna back focus place on ground intensity fluctuation and the intensity fluctuation rule of up laser beam at GEO satellite place is these consistent characteristics, adopt a monomode fiber to measure in real time the intensity fluctuation waveform of descending beacon beam, then utilize this intensity fluctuation waveform that the transmitting power of up laser beam is carried out adaptive control, the signal power that the GEO satellite reception is arrived is steady, thereby suppress the signal fadeout of up laser beam, because the angle that the light intensity of up laser beam on satellite is relevant with the intensity fluctuation of descending beacon beam at terrestrial optical antenna back focus place is very little, therefore this turbulence intensity flicker restraint method can only be applied to ground station's (but high-speed motion) in the up laser communication of GEO satellite.
Summary of the invention
Technical problem to be solved by this invention: because the light intensity of up laser beam on the satellite angle relevant with the intensity fluctuation of descending beacon beam at terrestrial optical antenna back focus place is very little, the turbulence intensity flicker restraint method can only be applied to ground station and arrive the GEO(geostationary orbit for prior art) in the up laser communication of satellite.
The technical scheme that the present invention solves the problems of the technologies described above is: the inhibition method that proposes the signal fadeout in the GEO satellite laser communications of a kind of ground.The method comprises, the descending beacon laser that sends from the GEO satellite is received by optical antenna (1-1) by behind the atmospheric turbulance, behind quick deflecting mirror (1-2) and spectroscope (1-3), descending beacon beam is coupled in the monomode fiber (1-6) of back focal plane by lens (1-5), through with photodetector (1-8) beacon beam being converted to the signal of telecommunication behind the wavelength division multiplexer (1-7), after signal processing module (1-9) amplifies this signal of telecommunication and filtering processes, can obtain the intensity fluctuation waveform of descending beacon beam.Because descending beacon beam intensity fluctuation is identical with up laser beam intensity fluctuating rule, so this intensity fluctuation waveform can reflect along the intensity fluctuation of the up laser beam of same turbulent flow path transmission.This intensity fluctuation waveform is sent into the judgement of signal processing center (1-10) settling signal power, by sending control module (1-11) power is automatically controlled and is finished again the modulation of data to be transferred, wherein the method for the automatic control of power can compare by the required power of the power after the opto-electronic conversion of input signal and emission, by the Feedback of Power circuit power is compensated, make it reach required performance number; The modulated process of data to be transferred then is to utilize the waveform reciprocal of descending beacon beam intensity fluctuation to remove to modulate upstream data waveform to be passed.
The drive current that utilizes at last power demand to obtain mating, drive laser (1-12) is sent laser, and this laser power just has the power fluctuation of descending beacon beam intensity fluctuation waveform form reciprocal.The laser that laser (1-12) sends is coupled in the monomode fiber (1-6) by wavelength division multiplexer (1-7), along transmitting with the antipodal direction of descending beacon beam signal.Through being launched by optical antenna (1-1) behind lens (1-5), spectroscope (1-3), the quick deflecting mirror (1-3), form the up laser beam of collimation, arrive at last the GEO satellite.
Because the existence of alignment error and atmospheric turbulance inclination of wave front, for guaranteeing correct being coupled in the monomode fiber (1-6) of descending beacon beam, guarantee that up laser beam accurately points to the GEO satellite, also need an automatic tracking system to eliminate the inclination of wave front of alignment error and atmospheric turbulance.
Automatic tracking system is told a part of beacon light beam by spectroscope (1-3), by the afterwards imaging on imageing sensor (1-14) of diaphragm (1-15), lens (1-13).Can be obtained the incident orientation of descending beacon beam by the upper light spot image of imageing sensor (1-14), make quick deflecting mirror (1-2) deflection by drive control module (1-16), eliminate the inclination of wave front of alignment error and atmospheric turbulance.
Because descending beacon beam and up laser beam are by same monomode fiber, its transmission path is identical, it is opposite direction, therefore tracing process can be finished simultaneously descending beacon beam and aim at the GEO satellite to coupling and the up laser beam of monomode fiber (1-6) automatically, diaphragm (1-15) is used for limiting the beacon light beam diameter, makes the inclination of wave front that is caused by turbulent flow of being measured by imageing sensor (1-14) can substantially reflect the turbulent wave top rake of up laser beam.
In the present invention, adopt the intensity fluctuation waveform of the descending beacon beam of monomode fiber (1-6) acquisition, and the while is as the output channel of up laser beam.The spatial amplitude that is realized the up laser beam that terrestrial optical antenna (1-1) is located to launch by this root monomode fiber (1-6) distributes, the spatial amplitude of the descending beacon beam coupling that distributes with without turbulent flow the time.The spatial amplitude that is transferred to optical antenna (1-1) from the up laser beam of back focal plane monomode fiber (1-6) output is distributed as Gaussian Profile, and its Wave-front phase is a plane.
And the Wave-front phase that descending beacon beam is located at terrestrial optical antenna (1-1) during without turbulent flow also is a plane, but its spatial amplitude is distributed as even distribution.This uniform plane wave continues to be transferred to back focal plane monomode fiber (1-6) and is coupled in the optical fiber.Theoretical according to optical coupling, this root monomode fiber plays the space filtering effect to the amplitude of descending beacon beam, and equivalence is on optical antenna (1-1) plane, and the actual distribution of amplitudes that works will be identical with the gaussian-shape distribution of amplitudes of up laser beam after the filtering.Like this, exist under the condition of turbulent flow, the intensity fluctuation of the descending beacon beam that monomode fiber (1-6) receives can reflect the intensity fluctuation of the up laser beam that receives on the satellite fully.
In addition, monomode fiber (1-6) can guarantee that also the transmission path of the descending beacon beam that receives and ground-launched up laser beam is in full accord, but opposite direction is realized more high-precision beam alignment.And in this case, the intensity fluctuation of the up laser beam that receives on the satellite that is caused by the residual alignment error of automatic tracking system, the intensity fluctuation of the descending beacon beam that receives with monomode fiber, its Changing Pattern also is identical.So this method can suppress atmospheric turbulance simultaneously without distinction and residual alignment error causes the earth signal decline.
The invention has the beneficial effects as follows:
(1) can obtain in real time the intensity fluctuation waveform that laser signal that transmitter sends arrives receiver end at transmitter terminal, avoided at receiver end measured intensity fluctuating waveform, and the intensity fluctuation waveform is sent back to the passback process of transmitter from receiver, so that on remote ground in the laser communication between the GEO satellite, still can carry out adaptive control to the transmitting power of transmitter and suppress turbulent flow and cause the fast signal decline.
(2) only adopt a up laser beam just can suppress greatly the atmospheric turbulence intensity flicker, reduced the dafing depth of up laser signal.
(3) the present invention also can suppress the signal fadeout of the up laser beam that the ground transmitter alignment error causes.
(4) technical scheme is simple, and with respect to the single beam emission, cost increases little, but can significantly reduce the turbulence intensity flicker.Compare with the multiple beam lift-off technology, can greatly reduce cost.
Description of drawings
Fig. 1 is structural representation of the present invention.
Fig. 2 adopts the intensity fluctuation waveform of forward signal prediction to obtain and process structural representation.
Fig. 3 is the useful as a result figure according to the embodiment of the invention of Multiple-Phase-Screen numerical simulation.
Embodiment
The correlation of utilizing the intensity fluctuation of descending beacon beam and up laser beam intensity to rise and fall suppresses a embodiment that up laser beam intensity rises and falls as shown in Figure 1.From the GEO(geostationary orbit) the descending beacon laser that sends of satellite by behind the atmospheric turbulance by terrestrial optical antenna (1-1) (diameter
Approximately 5～20 centimetres) receive, optical antenna (1-1) is a confocal optical system, still is collimated light beam behind the descending beacon beam process optical antenna (1-1), but beam diameter
Compressed.And then through behind quick deflecting mirror (1-2), spectroscope (1-3) and the lens (1-5), be coupled in the monomode fiber (1-6) at lens (1-5) back focal plane, through with photodetector (1-8) beacon beam being converted to the signal of telecommunication behind the wavelength division multiplexer (1-7), after signal processing module (1-9) amplifies this signal of telecommunication and filtering processes, can obtain descending beacon beam intensity fluctuation waveform.This intensity fluctuation waveform is sent into the judgement of signal processing center (1-10) settling signal power, by sending control module (1-11) power is automatically controlled and is finished again the modulation of data to be transferred, wherein the method for the automatic control of power can compare by the required power of the power after the opto-electronic conversion of input signal and emission, by the Feedback of Power circuit power is compensated, make it reach required performance number.The modulated process of data to be transferred then is to utilize the waveform reciprocal of descending beacon beam intensity fluctuation to remove to modulate upstream data waveform to be passed.
The drive current that utilizes at last power demand to obtain mating, drive laser (1-12) is sent laser, and this laser power just has the power fluctuation of descending beacon beam intensity fluctuation waveform form reciprocal.The laser that laser (1-12) sends is coupled in the monomode fiber (1-6) by wavelength division multiplexer (1-7), is transferred to the right focus place output of lens (1-5) along the direction opposite with descending beacon beam signal.Pass through again spectroscope (1-3), arrive optical antenna (1-1) surface behind the deflecting mirror (1-2) fast, form the up laser beam of collimation.The distribution of amplitudes of up laser beam is Gaussian Profile herein, and Wave-front phase is approximately a plane.
For the alignment error of elimination ground transmitter and the inclination of wave front of atmospheric turbulance, descending beacon beam is efficiently entered in the monomode fiber (1-6), and make up laser beam accurately point to the GEO satellite, also need an automatic tracking system.(1-3) tells a part of beacon beam by spectroscope, by the afterwards imaging on imageing sensor (1-14) of diaphragm (1-15), lens (1-13).Can be obtained the incident orientation of descending beacon beam by the upper light spot image of imageing sensor (1-14), make quick deflecting mirror (1-3) deflection by drive control module (1-16), eliminate alignment error and atmospheric turbulance inclination of wave front.This automatic tracing process can be finished simultaneously descending beacon beam and aim at the GEO satellite to coupling and the up laser beam of monomode fiber (1-6).
May have the relative position drift between monomode fiber (1-6) and the imageing sensor (1-14), the reference position of automatic tracking system is changed, its result makes the optical axis deviation GEO satellite position of up laser beam.Common solution is to increase an electronic shutter (1-17) and prism of corner cube (1-4), makes the also actual exit direction of detectable up laser beam of imageing sensor (1-14), thus the tracking benchmark of calibration automatic tracking system.
The short wavelength (0.85
) spot size of monomode fiber
General approximately about 2～3 microns, more can enter in the monomode fiber (1-6) by efficient coupling for making the beacon beam after the compression, need satisfy following condition:
, in the formula
Be the focal length of lens,
Be optical maser wavelength, lens (1-5) diameter is
,
Spot size for monomode fiber.Under the usual conditions
, under this condition, beacon beam is 81.45% to the maximum coupling efficiency of monomode fiber, such as the loss of considering that again other factors causes, 50% coupling efficiency can be accomplished.When reaching lens (1-5) from the Gaussian beam of monomode fiber end face outgoing, the beam waist radius of Gaussian beam is
Diaphragm (1-15) is used for being limited in the descending beacon light beam diameter of the upper imaging of imageing sensor (1-14), the inclination of wave front that is caused by turbulent flow that makes that imageing sensor (1-14) measures can reflect the turbulent wave top rake of up laser beam substantially, then the inclination of wave front and the alignment error that cause of the deflection elimination turbulent flow by quick deflecting mirror (1-2).The aperture radius of general diaphragm (1-15)
Locate up Gaussian beam beam waist radius with lens (1-13)
Quite, namely
Adopt different wavelength such as descending beacon beam from up laser beam, then need optical antenna (1-1) and lens (1-5) achromatism, when guaranteeing monomode fiber (1-6) end after descending beacon beam can be focused at lens (1-5), guarantee that the up laser beam that sends from the monomode fiber end face collimates after optical antenna (1-1) outgoing.Optical antenna (1-1) can adopt the transmission-type antenna, also can adopt mirror antenna, and there is not the aberration problem in mirror antenna.
From monomode fiber (1-6), obtain the intensity fluctuation waveform of descending beacon beam, and go to control the transmitting power of up laser beam with this intensity fluctuation waveform, need certain signal processing time, at this section in the period, because the impact of wind speed, atmospheric turbulance can change, and makes the intensity fluctuation of up laser beam not exclusively the same with the intensity fluctuation possibility of descending beacon beam, and mechanical oscillation also can make the position of monomode fiber change in addition.The scintillation of general atmosphere turbulent flow and the frequency of mechanical oscillation be to reduce the error that time delay causes below 100Hz, signal processing time must be enough short, need less than 1 millisecond, preferably can reach below 0.1 millisecond.
To the intensity fluctuation waveform obtain and in the processing time, atmospheric turbulance and monomode fiber position may change.A kind of better signal processing mode is the correlation of utilizing intensity fluctuation, according to former intensity fluctuation value prediction time-delay
After the intensity fluctuation value.
As shown in Figure 2, the intensity fluctuation waveform of the descending beacon beam of measuring from monomode fiber (1-6) becomes digital signal through A/D converter (2-1), then by the digital signal of forward signal prediction module (2-2) according to a front n sampling instant
,
...,
, can adopt the prediction algorithm prediction time delays such as self adaptation least mean-square error forward signal prediction algorithm
After value
Be converted to analog signal by D/A converter (2-3) again, this analog signal is sent into the judgement that signal processing center (1-10) is finished its signal power, by sending control module (1-11) power is automatically controlled and is finished again the modulation of data to be transferred, then the drive current that utilizes power demand to obtain mating, last drive laser (1-12) is sent laser.
Suppose the signal sampling time interval
With signal processing time
Equate (
), forward signal is predicted namely according to signal
Former constantly sampled value
, obtain
Estimated value,
Expression is used for the number of the given data of prediction.Can adopt following self adaptation least mean-square error forward signal prediction algorithm:
(1) by the sampled signal in the former moment
,
,
Sample data number when auto-correlation is calculated in expression,
The integer ordinal number of expression sampled data,
Require enough greatly to obtain more accurately signal autocorrelation value, the calculating signal
Autocorrelation value
,
,
Represent that two are adopted the signal time difference.
(2) basis
Write out signal
With
Autocorrelation matrix
,
,
,
The integer ordinal number of expression sampled data,
With
Represent respectively
Individual and
The signal sampling value in the individual moment.Then ask
Inverse matrix
And
All be
Matrix.
(3) basis
Write out signal
With
Autocorrelation matrix
,
For
Matrix.
(4) calculate the signal estimation coefficient
(5) at last according to formula:
,
, obtain signal
Estimated value.
In the implementation case, the intensity fluctuation source of the descending beacon beam that measures from monomode fiber (1-6) mainly contains following several respects: the intensity noise of laser on (1) GEO satellite, (2) descending laser beam causes intensity fluctuation to the alignment error of ground station, (3) intensity fluctuation that causes of atmospheric turbulance, (4) lens (1-5) back focal plane beacon hot spot can not be aimed at fully with monomode fiber and cause intensity fluctuation, the measure error that (5) photodetection circuit noise causes.
And the intensity fluctuation of the up laser beam that receives on GEO satellite source comprises: the intensity noise of planar laser (1), (2) atmospheric turbulence intensity rises and falls, (3) intensity fluctuation that causes of ground transmitter alignment error, the intensity fluctuation of (4) descending beacon beam intensity fluctuation form reciprocal.Such as time delay and descending beacon beam and the inconsistent impact of up laser beam wavelength of not considering that signal is processed, the intensity fluctuation of light signal on the GEO satellite that is then caused to the alignment error of GEO satellite by atmospheric turbulance and up laser beam, it is on all four can not aiming at the intensity fluctuation rule that causes light signal in the monomode fiber with atmospheric turbulance and lens (1-5) back focal plane beacon hot spot fully with monomode fiber, after adopting the solution of the present invention, the impact of these two kinds of factors can be offset.
The light signal that receives on the therefore last GEO satellite will comprise the intensity fluctuation that following several factor causes:
(1) intensity noise of laser on the GEO satellite, the intensity noise of planar laser (2), (3) descending laser beam causes intensity fluctuation to the alignment error of ground station, the measure error that (4) photodetection circuit noise causes.
The intensity noise of general laser is smaller, substantially can ignore, and descending laser beam to power averaging reduction amount and the intensity fluctuation variance that the alignment error of ground station causes is
In the formula
Be the uniaxial alignment error to standard deviation
With descending beacon light beam width
(
The power points overall with) ratio,
Largest light intensity on the optical axis when aiming at error for nothing,
The light intensity of the terrestrial optical antenna reception when alignment error is arranged.Requirement on the common engineering
, corresponding intensity fluctuation variance
, power averaging reduction amount
(average intensity be on the optical axis largest light intensity value 86%).Increase descending beacon light beam width
Can reduce the intensity fluctuation variance and make average intensity
Increase.The inverse of the intensity fluctuation waveform that causes to the alignment error of ground station with descending laser beam (namely
) remove to modulate upstream data to be passed after, can not cause signal fadeout on the GEO satellite, signal is strengthened, but the up laser beam average power that correspondingly needs to launch can increase by 1.16 times (approximately 0.6dB), Power penalty is also little.
Intensity fluctuation waveform how to measure accurately descending beacon beam in the monomode fiber is to need a carefully problem of processing, the photodetection circuit noise can make the intensity fluctuation waveform measurement inaccurate, can be reflected at last on the light intensity of GEO satellite reception, need to adopt the descending beacon beam intensity fluctuation of low noise detection circuit measuring waveform, the fluctuating frequency of atmospheric turbulance and alignment error generally below 100Hz, therefore need pay special attention to suppress the interference of various low-frequency noises.Intensity fluctuation waveform signal to noise ratio needs greater than more than 20dB～30dB.
Be specifically described from following 2, the one, descending beacon beam has strong correlation at intensity fluctuation waveform and the intensity fluctuation waveform of up laser beam at the satellite place of terrestrial optical antenna back focus.The 2nd, monomode fiber can carry out space filtering to the amplitude of the approximate equally distributed descending beacon beam of mean amplitude of tide on the optical antenna, makes the gaussian-shape distribution of amplitudes of the actual descending beacon beam distribution of amplitudes that works and up laser beam identical.
For first problem, adopt the method for Multiple-Phase-Screen, turbulent flow is divided into many sublayers
(
Be the integer ordinal number, expression the
Layer), the distance between each layer is respectively
, in each turbulent flow sublayer, turbulent flow is respectively the additional phase perturbation of light wave generation of transmission
, the Fresel diffraction principle is adopted in propagation between layers.Whole process is similar to the Multiple-Phase-Screen numerical simulation of laser transmission.
For up laser beam, the initial light wave COMPLEX AMPLITUDE of establishing transmitting optics aerial position place is
, the complex amplitude when then laser upwards is transferred to each sublayer
,
...,
For:
(2)
…
In the formula
Be laser free space wave number,
Be optical maser wavelength,
Represent the two-dimensional coordinate on each sublayer,
Expression imaginary part unit.
The top layer atmosphere is from the distance of satellite
Very large, after light wave reaches the turbulent flow top layer, can be according to the complex amplitude of Fraunhofer diffraction Calculation of Satellite place light wave
(4)
Do not write out the coefficient irrelevant with the complex amplitude spatial distribution in formula (1)～(4)
With formula (1)～(3) substitution formula (4),
(suppose identical with up laser beam wavelength for descending beacon beam, differ very little in the practical application, can ignore its difference), pass through first remote free-space propagation, beam diameter is very large when arriving the atmospheric turbulance top, can think uniform plane wave, supposes that amplitude is 1, then propagate into from top to bottom terrestrial optical antenna place, the complex amplitude when being transferred to each sublayer
Be respectively
…
On ground, the spot diameter of descending beacon beam is very large, generally reach more than 10 meters, and the optical antenna diameter that is used for beam-capturing, aligning and tracking is smaller, be generally less than 0.2～0.3 meter, in the beacon beam receiver aperture, can think during without turbulent flow that the space COMPLEX AMPLITUDE of beacon beam is uniform like this.This equally distributed complex amplitude is applied a space complex amplitude filter function
, then at the complex amplitude that receives optical antenna back focus place light wave be
As before, do not write out the coefficient irrelevant with the complex amplitude spatial distribution in formula (6)～(9) yet
With formula (6)～(8) substitution formula (9),
By formula (5) and formula (10) as seen, such as the space complex amplitude filter function of descending beacon beam
Initial complex amplitude with up laser beam
Spatial distribution identical, namely
=
, (A is invariant), then light wave complex amplitude on the satellite
With line focus place, terrestrial optical sky multiplexed optical wave amplitude
Changing Pattern with identical.The intensity fluctuation waveform that is the up beacon beam signal that receives on beacon beam intensity fluctuation waveform and the satellite at line focus place, terrestrial optical sky is identical.
The following describes and adopt same monomode fiber to launch up laser beam and receive descending beacon beam, can make
If terrestrial optical antenna radius is
, focal length is
Spot size is
Monomode fiber be placed on the focus place, then the Gaussian beam of unit power is after the monomode fiber outgoing, the COMPLEX AMPLITUDE that arrives the optical antenna place is:
Wherein
Be the up Gaussian beam beam waist radius in terrestrial optical antenna place.
Be coupled into the descending beacon beam complex amplitude of monomode fiber
Can calculate in the monomode fiber end, also can calculate at place, optical antenna plane, two kinds of methods are (Wallner O of equal value, Winzer P J, Leeb W R. Alignment tolerances for plane wave to single-mode fiber coupling and their mitigation by use of pigtailed collimators. Appl.Opt, 2002,41 (4): 637-643).As calculating at the antenna plane place, be equivalent to the descending beacon beam complex amplitude at terrestrial optical antenna place
With the complex amplitude that arrives optical antenna from the Gaussian beam of monomode fiber outgoing
Carry out related operation, namely
(12)
Compare with formula (9), have
, namely utilize the space filtering effect of monomode fiber, can make the actual descending beacon beam COMPLEX AMPLITUDE that works and initial up laser beam COMPLEX AMPLITUDE identical.Even in the situation that monomode fiber location error and optical antenna edge produce truncation effect to Gaussian beam, they also are identical.Such as monomode fiber location error (random fluctuation), then site error will produce an inclination of wave front amount in formula (11), this inclination of wave front makes up laser beam produce alignment error, makes up laser beam optical axis deviation satellite position, and satellite received signal produces intensity fluctuation.On the other hand, the site error of monomode fiber also can make the descending beacon beam that is coupled in the monomode fiber produce intensity fluctuation.Both fluctuating rules are identical.Therefore adopt same monomode fiber also can suppress the up laser beam intensity fluctuating that the ground transmitter alignment error causes.
Have the stronger zone of a turbulent flow at distance ground 10km At The Height, flicker has larger contribution to up laser beam intensity, and should the zone wind speed larger, can reach 30 meter per seconds.
Then descending beacon beam turns back to this regional time by ground-launched up laser beam from this zone process 10km turbulent flow propagated to ground, needs at least 0.07 millisecond, and larger such as zenith angle, this time can be longer.Therefore time obtaining and producing up laser beam according to its waveform modulated laser reciprocal of descending beacon beam intensity fluctuation waveform, can be with reference to this time design, desirable 0.1～1 millisecond, shorter signal processing time has little significance.
After adopting method of the present invention, ground can reduce greatly to the scintillation value of the up laser beam of GEO satellite.Figure 3 shows that according to the useful as a result figure (only having considered the impact of atmospheric turbulance) after the invention process of Multiple-Phase-Screen numerical simulation.Simulated conditions: adopt Hufnagel-Valley 5/7 atmospheric turbulance Refractive Index Model, Bufton wind model (Chen Jingyuan, atmospheric turbulance intermittent and on the impact of light wave propagation, China Engineering Physics Research Institute's doctorate paper, 2005.1), zenith angle
, up laser beam is Gaussian beam, the waist diameter is 7.5 centimetres, 0.85 micron of wavelength, 0.83 micron of descending beacon wavelength.Do not adopt (up laser beam Initial Trans is constant) when of the present invention, near the scintillation index of up laser beam optical axis was about 0.21 after the turbulent wave top rake was followed the tracks of.When application the present invention and signal processing time were 0.1 millisecond, near the scintillation index of up laser beam optical axis was about 0.0045 after the turbulent wave top rake was followed the tracks of, and the scintillation index reduces more than 40 times.When application the present invention and signal processing time were 1 millisecond, near the scintillation index of up laser beam optical axis was about 0.036 after tilting to follow the tracks of, and scintillation reduces nearly six times.
Because the angular range that up laser beam is relevant with descending beacon beam intensity fluctuation is very little, only has several microradians.Preferably the angular deviation between up laser beam and the descending beacon beam is controlled at below 1 microradian in actual applications, at this moment just has obvious beneficial effect.Larger such as the angular deviation between up laser beam and the descending beacon beam, the intensity fluctuation of the light signal that then receives on the satellite can increase on the contrary.
The present invention can only be in the face of in the up laser communication of GEO satellite with being used in addition, because if the relative ground station of satellite motion, then up laser beam needs lead, and this lead angle can reach tens microradians generally speaking, considerably beyond the related angle of up laser beam and descending beacon beam intensity fluctuation.But it is static that ground station might not require, and can be high-speed motion.Such as ground station's high-speed motion, then require shorter signal processing time, requirement and ground station's movement velocity of signal processing time is inversely proportional to.
Claims (10)
1. the restraining device of ground signal fadeout in the GEO satellite laser communications, it is characterized in that: the terrestrial optical antenna is coupled into monomode fiber with the descending beacon beam that the GEO satellite that receives sends, the intensity fluctuation waveform of up laser beam light signal on the GEO satellite that acquisition atmospheric turbulance and ground transmitter alignment error cause, measure the intensity fluctuation waveform of beacon beam in the monomode fiber, the signal processing center is carried out power to this intensity fluctuation waveform and is judged, send control module and power is automatically controlled and finished the modulation of data to be transferred, drive laser is sent up laser, this up laser is coupled in the monomode fiber by wavelength division multiplexer, be transferred to the end face output of monomode fiber along the direction opposite with descending beacon beam signal, pass through again lens, spectroscope, behind the deflecting mirror, form the up laser beam of collimation from the optical antenna outgoing fast.
2. restraining device according to claim 1, it is characterized in that: be the alignment error of elimination ground transmitter and the inclination of wave front of atmospheric turbulance, tell a part of beacon beam by spectroscope, by imaging on imageing sensor behind diaphragm, the lens, obtained the incident orientation of descending beacon beam by the light spot image that forms on the imageing sensor, make quick deflecting mirror deflection by drive control module, eliminate alignment error and atmospheric turbulance inclination of wave front.
3. restraining device according to claim 1 is characterized in that: the described power that carries out is judged and is specially, the intensity fluctuation waveform of descending beacon beam, through behind the A/D converter by the digital signal of forward signal prediction module according to a front n sampling instant
,
...,
, prediction time delay
After value
, be converted to analog signal by D/A converter, send into the judgement that the signal processing center is finished its signal power.
4. restraining device according to claim 1 is characterized in that: enter in the monomode fiber for making the beacon beam efficient coupling, need satisfy following condition:
, in the formula
Be the monomode fiber spot size
Be the focal length of lens,
Be optical maser wavelength,
Be lens diameter.
5. restraining device according to claim 1, it is characterized in that: described power is being specially of control automatically: the required power of the power after the conversion of input signal photoelectricity and emission compares, the Feedback of Power circuit compensates power, makes it reach required performance number; The modulation of data to be transferred is specially: utilize the waveform reciprocal of descending beacon beam intensity fluctuation to remove to modulate upstream data waveform to be passed.
6. the inhibition method of ground signal fadeout in the GEO satellite laser communications, it is characterized in that: the terrestrial optical antenna is coupled into monomode fiber with the descending beacon beam that the GEO satellite that receives sends, the intensity fluctuation waveform of up laser beam light signal on the GEO satellite that acquisition atmospheric turbulance and ground transmitter alignment error cause, measure the intensity fluctuation waveform of beacon beam in the monomode fiber, the signal processing center is carried out power to this intensity fluctuation waveform and is judged, send control module and power is automatically controlled and finished the modulation of data to be transferred, drive laser is sent up laser, this up laser is coupled in the monomode fiber by wavelength division multiplexer, be transferred to the end face output of monomode fiber along the direction opposite with descending beacon beam signal, pass through again lens, spectroscope, behind the deflecting mirror, form the up laser beam of collimation from the optical antenna outgoing fast.
7. inhibition method according to claim 6, it is characterized in that: be the alignment error of elimination ground transmitter and the inclination of wave front of atmospheric turbulance, tell a part of beacon beam by spectroscope, by imaging on imageing sensor behind diaphragm, the lens, obtained the incident orientation of descending beacon beam by the light spot image that forms on the imageing sensor, make quick deflecting mirror deflection by drive control module, eliminate alignment error and atmospheric turbulance inclination of wave front.
8. inhibition method according to claim 6 is characterized in that: the described power that carries out is judged and is specially, the intensity fluctuation waveform of descending beacon beam, through behind the A/D converter by the digital signal of forward signal prediction module according to a front n sampling instant
,
...,
, prediction time delay
After value
, be converted to analog signal by D/A converter, send into the judgement that the signal processing center is finished its signal power.
9. inhibition method according to claim 6 is characterized in that: enter in the monomode fiber for making the beacon beam efficient coupling, need satisfy following condition:
, in the formula
Be the focal length of lens,
Be optical maser wavelength,
Be lens diameter.
10. inhibition method according to claim 1, it is characterized in that: the described power automatically method of control is specially: the required power of the power after the conversion of input signal photoelectricity and emission compares, the Feedback of Power circuit compensates power, makes it reach required performance number; The modulation of data to be transferred is specially: utilize the waveform reciprocal of descending beacon beam intensity fluctuation to remove to modulate upstream data waveform to be passed.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201110178970.7A CN102857294B (en) | 2011-06-29 | 2011-06-29 | Method and device for suppressing signal fading in laser communication from ground to GEO (geosynchronous) satellite |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201110178970.7A CN102857294B (en) | 2011-06-29 | 2011-06-29 | Method and device for suppressing signal fading in laser communication from ground to GEO (geosynchronous) satellite |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN102857294A true CN102857294A (en) | 2013-01-02 |
| CN102857294B CN102857294B (en) | 2014-12-31 |
Family
ID=47403513
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201110178970.7A Active CN102857294B (en) | 2011-06-29 | 2011-06-29 | Method and device for suppressing signal fading in laser communication from ground to GEO (geosynchronous) satellite |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN102857294B (en) |
Cited By (17)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107813962A (en) * | 2017-12-08 | 2018-03-20 | 中国科学院长春光学精密机械与物理研究所 | Flash load system, load the satellite and active visual method of flicker load system |
| CN108333692A (en) * | 2018-02-08 | 2018-07-27 | 中国科学院光电技术研究所 | Space light-to-optical fiber coupling system |
| CN108540235A (en) * | 2018-02-08 | 2018-09-14 | 南京大学 | Spatial chaos laser communication system ground based terminal error in pointing calibration system and method |
| CN108631865A (en) * | 2018-03-14 | 2018-10-09 | 北京盛安同力科技开发有限公司 | A kind of laser space communication terminal |
| CN108833010A (en) * | 2018-06-20 | 2018-11-16 | 上海卫星工程研究所 | Satellite-ground laser communication beam drift self-adapting compensation method and system |
| CN108964761A (en) * | 2018-07-02 | 2018-12-07 | 北京卫星信息工程研究所 | Highly reliable space optical communication signal modulation terminal and method based on software radio |
| CN109067452A (en) * | 2018-08-14 | 2018-12-21 | 西安理工大学 | A kind of unmanned plane relaying laser communication system |
| CN109474339A (en) * | 2018-10-30 | 2019-03-15 | 宁波光舟通信技术有限公司 | Signal adjusting method and device between star |
| CN109632262A (en) * | 2018-12-29 | 2019-04-16 | 深圳航星光网空间技术有限公司 | A kind of calibration system of block prism |
| CN109781141A (en) * | 2018-12-29 | 2019-05-21 | 深圳航星光网空间技术有限公司 | The scaling method and device of cube edge microscope group |
| CN109921856A (en) * | 2019-01-25 | 2019-06-21 | 长沙天仪空间科技研究院有限公司 | A kind of low-speed communication method and system of the optical flare based on low orbit satellite |
| CN110289904A (en) * | 2019-05-24 | 2019-09-27 | 中国人民解放军陆军工程大学 | Turbulent flow restraining method and device for precompensating transmitting optical power in reverse modulation optical communication |
| CN112636815A (en) * | 2021-03-10 | 2021-04-09 | 南京英田光学工程股份有限公司 | Small satellite platform laser communication terminal based on MEMS beam control |
| CN113472433A (en) * | 2021-06-25 | 2021-10-01 | 山东航天电子技术研究所 | Beacon optical center coordinate calculation error evaluation method suitable for laser communication |
| CN113612534A (en) * | 2021-07-01 | 2021-11-05 | 中国科学院西安光学精密机械研究所 | Optical system of miniaturized space laser communication terminal and use method |
| CN114422034A (en) * | 2022-03-29 | 2022-04-29 | 南京英田光学工程股份有限公司 | Ultra-small expandable bidirectional laser communication device |
| CN115468533A (en) * | 2022-11-10 | 2022-12-13 | 南京英田光学工程股份有限公司 | Rapid orientation device and orientation method for laser communication ground station |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1633043A (en) * | 2004-11-08 | 2005-06-29 | 深圳市世纪人无线通讯设备有限公司 | Free space optical communication system and transmission power control method thereof |
| CN201044011Y (en) * | 2007-04-25 | 2008-04-02 | 江阴龙跃信息科技有限公司 | Laser beacon for self-adaption optical system |
-
2011
- 2011-06-29 CN CN201110178970.7A patent/CN102857294B/en active Active
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1633043A (en) * | 2004-11-08 | 2005-06-29 | 深圳市世纪人无线通讯设备有限公司 | Free space optical communication system and transmission power control method thereof |
| CN201044011Y (en) * | 2007-04-25 | 2008-04-02 | 江阴龙跃信息科技有限公司 | Laser beacon for self-adaption optical system |
Non-Patent Citations (3)
| Title |
|---|
| JEFFREY H.SHAPIRO,: ""Optimal Power Transfer Through Atmospheric Turbulence Using State Knowledge"", 《IEEE TRANSACTIONS ON COMMUNICATION TECHNOLOGY》 * |
| 向劲松,: ""采用光纤耦合及光放大接收的星地光通信系统及关键技术"", 《中国博士学位论文全文数据库 信息科技辑》 * |
| 向劲松，么周石，胡渝，: ""大气湍流中空间光至单模光纤耦合的跟踪算法"", 《强激光与粒子束》 * |
Cited By (23)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107813962A (en) * | 2017-12-08 | 2018-03-20 | 中国科学院长春光学精密机械与物理研究所 | Flash load system, load the satellite and active visual method of flicker load system |
| CN108333692B (en) * | 2018-02-08 | 2019-12-24 | 中国科学院光电技术研究所 | Space light-to-optical fiber coupling system |
| CN108333692A (en) * | 2018-02-08 | 2018-07-27 | 中国科学院光电技术研究所 | Space light-to-optical fiber coupling system |
| CN108540235A (en) * | 2018-02-08 | 2018-09-14 | 南京大学 | Spatial chaos laser communication system ground based terminal error in pointing calibration system and method |
| CN108631865A (en) * | 2018-03-14 | 2018-10-09 | 北京盛安同力科技开发有限公司 | A kind of laser space communication terminal |
| CN108833010A (en) * | 2018-06-20 | 2018-11-16 | 上海卫星工程研究所 | Satellite-ground laser communication beam drift self-adapting compensation method and system |
| CN108964761A (en) * | 2018-07-02 | 2018-12-07 | 北京卫星信息工程研究所 | Highly reliable space optical communication signal modulation terminal and method based on software radio |
| CN109067452A (en) * | 2018-08-14 | 2018-12-21 | 西安理工大学 | A kind of unmanned plane relaying laser communication system |
| CN109474339A (en) * | 2018-10-30 | 2019-03-15 | 宁波光舟通信技术有限公司 | Signal adjusting method and device between star |
| CN109632262A (en) * | 2018-12-29 | 2019-04-16 | 深圳航星光网空间技术有限公司 | A kind of calibration system of block prism |
| CN109781141A (en) * | 2018-12-29 | 2019-05-21 | 深圳航星光网空间技术有限公司 | The scaling method and device of cube edge microscope group |
| CN109921856A (en) * | 2019-01-25 | 2019-06-21 | 长沙天仪空间科技研究院有限公司 | A kind of low-speed communication method and system of the optical flare based on low orbit satellite |
| CN110289904A (en) * | 2019-05-24 | 2019-09-27 | 中国人民解放军陆军工程大学 | Turbulent flow restraining method and device for precompensating transmitting optical power in reverse modulation optical communication |
| CN110289904B (en) * | 2019-05-24 | 2022-05-27 | 中国人民解放军陆军工程大学 | Turbulent flow restraining method and device for precompensating transmitting optical power in reverse modulation optical communication |
| CN112636815A (en) * | 2021-03-10 | 2021-04-09 | 南京英田光学工程股份有限公司 | Small satellite platform laser communication terminal based on MEMS beam control |
| CN112636815B (en) * | 2021-03-10 | 2021-06-04 | 南京英田光学工程股份有限公司 | Small satellite platform laser communication terminal based on MEMS beam control |
| CN113472433A (en) * | 2021-06-25 | 2021-10-01 | 山东航天电子技术研究所 | Beacon optical center coordinate calculation error evaluation method suitable for laser communication |
| CN113472433B (en) * | 2021-06-25 | 2024-05-31 | 山东航天电子技术研究所 | Beacon light center coordinate calculation error evaluation method suitable for laser communication |
| CN113612534A (en) * | 2021-07-01 | 2021-11-05 | 中国科学院西安光学精密机械研究所 | Optical system of miniaturized space laser communication terminal and use method |
| CN113612534B (en) * | 2021-07-01 | 2022-05-20 | 中国科学院西安光学精密机械研究所 | Optical system of miniaturized space laser communication terminal and using method |
| CN114422034A (en) * | 2022-03-29 | 2022-04-29 | 南京英田光学工程股份有限公司 | Ultra-small expandable bidirectional laser communication device |
| CN115468533A (en) * | 2022-11-10 | 2022-12-13 | 南京英田光学工程股份有限公司 | Rapid orientation device and orientation method for laser communication ground station |
| CN115468533B (en) * | 2022-11-10 | 2023-02-28 | 南京英田光学工程股份有限公司 | Rapid orientation device and orientation method for laser communication ground station |
Also Published As
| Publication number | Publication date |
|---|---|
| CN102857294B (en) | 2014-12-31 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN102857294B (en) | Method and device for suppressing signal fading in laser communication from ground to GEO (geosynchronous) satellite | |
| US10819429B2 (en) | Free-space optical communication apparatus and method | |
| Mai et al. | Beam size optimization and adaptation for high-altitude airborne free-space optical communication systems | |
| CN106911381A (en) | Laser link communication measurement hybrid system | |
| CN102096071B (en) | Relay light-amplified laser ranging method and device for cooperative target | |
| Dat et al. | A universal platform for ubiquitous wireless communications using radio over FSO system | |
| CN108631865B (en) | Space laser communication terminal | |
| CN110999129A (en) | System and method for high speed communications | |
| CN109728855B (en) | Bidirectional same-frequency-band self-adaptive optical laser communication optical terminal | |
| CA2957523C (en) | Apparatus and method for reducing signal fading due to atmospheric turbulence | |
| CN104393930A (en) | Device for improving spatial coherent light communication quality based on adaptive optics technology | |
| CN104954070A (en) | Self-adaptive optical fiber array type laser transceiving system for spatial coherent optical communication | |
| CN110739994B (en) | Free space optical communication link establishing method | |
| US20040179848A1 (en) | Scintillation free laser communication system | |
| CN108732742A (en) | Satellite-ground same-frequency-band optical communication self-adaptive optical correction system and method based on sodium guide star | |
| US20210036777A1 (en) | Optical communication network for pico satellites | |
| Mai et al. | Mitigation of effects of angle-of-arrival fluctuation and pointing error on airborne free-space optical systems | |
| CN100454790C (en) | All optical satellite communication network route terminal | |
| Mai et al. | Beaconless angle-of-arrival tracking with improved receiver sensitivity and tracking precision for free-space optical communications | |
| CN209358549U (en) | Bidirectional same-frequency-band adaptive optical laser communication optical terminal | |
| García-Talavera et al. | Optical Ground Station: Requirements and Design, Bidirectional Link Model and Performance | |
| US20240162990A1 (en) | Optical communication transmitter and receiver with misalignment measurement and correction | |
| Wilfert et al. | Fully photonic wireless link for transmission of synchronization signals | |
| Barrios et al. | Adaptive optics for free space optical communications | |
| O'Toole et al. | Fiber bundle-based beam tracking demonstrated across 30 km terrestrial FSO communications link |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C06 | Publication | ||
| PB01 | Publication | ||
| C10 | Entry into substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant |