CN103024307A - Space borne laser communication ATP system spot detecting camera and detecting method - Google Patents

Abstract

The invention discloses a space borne laser communication ATP (Acquisition Tracking Pointing) system spot detecting camera and a detecting method. The spot detecting camera and detecting method are used for detecting beaconing light direction of laser communication link so that the system gets an angular deviation of communication link beam direction to get position information of a communication terminal, thus establishing and maintaining the communication link. The spot detecting camera optical system is composed of a receiving telescope, a reflector, a bandpass optical filter and a taking lens and the spot detecting camera electronics system is composed of a 5-volt direct current power supply, a voltage conversion chip, an FPGA (field programmable gate array) chip, a CMOS (complementary metal oxide semiconductor) detector, a clock chip, a communication chip and the like. Beaconing light of the communication system is obtained through the optical system and an image is formed on the surface of the detector, then a spot centroid is obtained after the electronics system processes image data and is transmitted to a tracking system. High precision detection performance of the camera ensures that the ATP system can learn correctly of the communication terminal position and establish and maintain the stable communication link to guarantee the smooth achievement of space scale laser communication.

Description

A kind of satellite borne laser communication ATP system's laser spot detection camera and detection method

Technical field:

The present invention relates to detection camera and detection method in a kind of optical tracking, the sighting system, be specifically related to laser spot detection camera and the detection method of a kind of satellite borne laser communication ATP system.

Background technology:

Between star ground or star in the laser communication, because communication distance is far away, light beam is narrow and have external interference (such as atmospheric effect, Satellite Vibration etc.), must adopt and catch (Acquisition), tracking (Tracking) and aiming (Pointing) system set up and keep optical communication link.This system is called for short the ATP system.In the ATP system, a side of communication link sends a branch of wider beacon beam and scans, and the opposing party searches for this beacon beam.Beacon beam enters this detector field of view and is arrived by correct detection, and this process is called catches; After the ATP system catches beacon beam, the optical axis deviation that both sides provide according to detector, the control follower, the optical axis that makes its optical axis follow incident light changes, and is called tracking; On the basis of following the tracks of, both sides' the optical axis correctly points to the other side's optical axis, is called aiming.After the reliable aiming of both sides' optical axis, transmitting terminal synchronizable optical launch time makes both sides synchronous settling time, and this moment, optical communication link was set up, and can open the narrower signal laser of light beam and communicate.Wherein the laser spot detection camera is used for the beacon beam direction of exploring laser light communication link, makes system obtain the angular deviation of communication link beam-pointing, obtains the positional information of communication terminal with this, and then sets up and keep communication link.

The communication laser angle of divergence very little (about tens μ rad) that common laser space communication system adopts, this has proposed very high following to the ATP system and has taken aim at required precision (generally being less than 20 μ rad).Therefore, laser spot detection camera that be used for to set up and keep communication link must have very high detection accuracy (generally need to less than 1 μ rad).At the ETS-VI of the SILEX of European Space Agency that realized plan, Japan plan and OICETS in the works, their ATP system all reached be better than ± 2 μ rad with taking aim at precision, the thick tracking system of these plans has all used CCD to survey camera, the smart tracking system of SILEX plan has been used the CCD camera, and it then is four-quadrant snowslide pipe detector that the essence of ETS-VI plan and OICETS plan is followed the tracks of camera.But because the constructional defective of these detectors is so that also there are many deficiencies in existing camera system: four-quadrant snowslide pipe detector only has four detection pixels, the detection front is little, the pixel consistency is not good, this causes that detection viewing field of camera take it as basic engineering is little, detection probability and precision are all lower, and can not change flexibly the tracking center; Ccd detector needs multiple voltage to come the transfer signal electric charge, and power consumption is higher, because integrated degree is low, needing the various configurations circuit to cooperate could use, and has increased the complexity of camera again, but also the conditions of streaking when existing frame transfer.

And day by day ripe along with cmos detector utilizes cmos detector to realize that the laser spot detection camera of spaceborne ATP system also becomes realistic plan, also can avoid above-mentioned shortcomings.The high power consumption of the integrated degree of cmos detector is little, is easy to realize extensive face battle array, its flexibly windowing function also can further improve frame frequency, and be easy to revise hot spot and follow the tracks of the center.These advantages are slightly followed the tracks of the demand of surveying the large visual field of camera so that cmos detector is content with very little in the long distance laser communication ATP system, also are easy to realize the smart high frame frequency of following the tracks of the detection camera.Do not use in laser space communication ATP system but so far also have based on the laser spot detection camera of cmos detector.

Summary of the invention:

The object of the invention is to between star or star ground laser communication ATP system, a kind of high-precision laser spot detection camera and correct effectively detection method are provided, make laser communication system when being transmitted into the space track, can realize the detecting and tracking to communication target, set up and keep stable communication link.The present invention is equally applicable to ground surface end laser communication ATP system.

Method of the present invention is to utilize bigbore cassette telescope to receive extraneous light beam, after mating plate is processed after filtration only remaining beacon beam enter the detector front, this guarantees that camera detects to such an extent that be beacon beam, has got rid of extraneous light disturbance.Cmos detector with Radiation hardness and inner integrated analog-to-digital conversion (ADC) is finished opto-electronic conversion and analog-to-digital conversion under programmable gate array chip (FPGA) control at the scene, and then view data is exported to FPGA.The centroid algorithm of fpga chip employing high accuracy, low delay is finished the extraction to beacon beam facula mass center position, and finishes information interaction by three communication ports and the external world.

Wherein FPGA obtains the running parameter of camera by the RS-422 receive path, finishes the configuration efforts such as the size of windowing to detector, the time of integration, threshold value setting, bad point rejecting; Send the barycenter information calculate by the RS-422 sendaisle to tracking system, the positional information of communication terminal is provided for whole ATP system; Send in real time the image information that collects by the LVDS communication port simultaneously, can be used for Real-Time Monitoring, analyze the operating state of camera, when communicating by letter between star ground, the high frame frequency view data that is obtained by this passage also can be used for the research to atmosphere.

It is cmos detector that the present invention adopts detector, and its pixel is independent addressing.It is to carry out direct addressin by row address and column address, and then the electric charge with this place, address pixel accumulation amplifies through amplifier, is converted into digital quantity through ADC again and is read.Utilize this characteristics that are addressed directly to pixel, so that the present invention can change the size of windowing that image is read according to demand flexibly, when opening wicket, not only avoided a large amount of image data transmission but also improved frame frequency.The mode that this pixel independently reads has also been avoided shifting the halation phenomenon that causes because of electric charge in the ccd detector.The detector that camera adopts has capability of resistance to radiation, and this is so that the present invention can adapt to the high radiation environment of space.

Can realize the satellite borne laser communication ATP system laser spot detection camera of the inventive method as shown in Figure 1, comprise: receiving telescope 1, speculum 2, bandpass filter 3, imaging lens 4, cmos detector 5, fpga chip 6, RS-422 communications reception chip 7, RS-422 communication sends chip 8, and LVDS communication sends chip 9, FPGA configuring chip 10,5V power supply 11,5V turns 3.3V voltage transitions chip 12, and 5V turns 2.5V voltage transitions chip 13, and 5V turns 1.8V voltage transitions chip 14,5V turns 1.5V voltage transitions chip 15, clock chip 16.Wherein 4 four parts of receiving telescope 1, speculum 2, bandpass filter 3 and imaging lens form optical system 17, and fpga chip 6, RS-422 communications reception chip 7, RS-422 communication send chip 8, LVDS communication and send chip 9, FPGA configuring chip 10,5V DC power supply 11,5V and turn 3.3V voltage transitions chip 12,5V and turn that 2.2V voltage transitions chip 13,5V turn 1.8V voltage transitions chip 14,5V turns 1.5V voltage transitions chip 15 and 160 two parts of clock chip form electronic system 18.

Described receiving telescope 1 is transmission-type or autocollimator system, and enlargement ratio is 8 times; Described speculum 2 is greater than 97% level crossing at 671nm visible light wave range reflectivity; 3 pairs of 671nm wave bands of described bandpass filter light belt is logical; Described imaging lens 4 is parabolic convex lens; Described cmos detector 5 is the cmos detectors with radioresistance, large face battle array and integrated inner ADC; Described fpga chip 6 has the Block RAM memory space greater than 3Mbits; Described RS-422 communications reception chip 7 is DS26LV31W chips of being produced by NSC company; It is DS26LV32AW chips of being produced by NSC company that described RS-422 communication sends chip 8; It is SNJ55LVDS31W chips of being produced by TI company that described LVDS communication sends chip 9; Described FPGA configuring chip 10 is the PROM chips for configuration fpga chip program; Described is that the Voltage-output precision is better than 2% DC power supply for electronic system 18 provides the 5V power supply 11 of 5V voltage; Described is that voltage accuracy is better than 1%, the linear voltage regulator of maximum output current 3A for electronic system 18 provides the 5V of 3.3V voltage to turn 3.3V voltage transitions chip 12; Described is that voltage accuracy is better than 1%, the linear voltage regulator of maximum output current 3A for electronic system 18 provides the 5V of 2.5V voltage to turn 2.5V voltage transitions chip 13; Described is that voltage accuracy is better than 1%, the linear voltage regulator of maximum output current 3A for electronic system 18 provides the 5V of 1.8V voltage to turn 1.8V voltage transitions chip 14; Described is that voltage accuracy is better than 1%, the linear voltage regulator of maximum output current 3A for electronic system 18 provides the 5V of 1.5V voltage to turn 1.5V voltage transitions chip 15; Described when providing 25 ℃ of clock chip 16 temperature of 48MHz system works clock for FPAG chip 6 clock jitter less than 8ps.

Camera receives the beacon beam light beam by the receiving telescope 1 of its optical system 17, through passing through bandpass filter 3 after speculum 2 reflections; Light beam will be attenuated through the light except the 671nm wavelength in the light beam behind the bandpass filter 3, and the beacon beam transmission is passed through; Enter cmos detector 5 fronts by imaging lens 4 again, further finish opto-electronic conversion and view data is exported to fpga chip 6.

The running parameter of camera obtains and sends to fpga chip by RS-422 communications reception chip 7; Fpga chip 6 is controlled cmos detector 5 and is finished opto-electronic conversion under these running parameters, and will obtain view data by cmos detector 5 and export to fpga chip 6; After fpga chip obtains image information, the employing centroid algorithm is finished the calculating to the facula mass center position, and while cache image information, send chip 8 by RS-422 communication again and outwards send the barycenter information that calculates, send chip 9 by LVDS communication simultaneously and send real-time view data.

Realize the concrete steps of laser spot detection method:

1. after camera is started working, at first by FPGA configuring chip 10 program is write fpga chip 6.Turn 3.3V voltage transitions chip 12,5V by 5V DC power supply 11,5V and turn every voltage that 2.5V voltage transitions chip 13,5V turn to be needed when 1.8V voltage transitions chip 14,5V turn 1.5V voltage transitions chip 15 and provide work for whole camera electronic system 18.Clock chip 16 provides work clock for fpga chip 6;

2. when carrying out laser space communication, receive the beacon beam light beam by receiving telescope 1, through passing through bandpass filter 3 behind the speculum 2, bandpass filter 3 is finished the optical filtering to light beam;

3. after light beam passes through imaging lens 4, imaging on cmos detector 5 fronts;

4. camera obtains running parameter by RS-422 communications reception chip 7, parameter comprises detector window size, the original position of windowing, the time of integration and threshold size etc., and fpga chip 6 is finished opto-electronic conversion and obtained view data by parameter control cmos detector 5;

5.FPGA chip 6 is at first done threshold process with the raw image data that collects and is obtained weight in the centroid calculation process, and caching image data is in the internal RAM of fpga chip.When judging original image value v (x, y) greater than setting threshold T, weighted value W (x, y)=v (x, y)-T; If original image value v (x, y) is during less than setting threshold T, weighted value W (x, y)=0.After obtaining weighted value, obtain centroid position according to the centroid calculation formula, computational accuracy is 1/32, centroid position (C _x, C _y) computing formula is as follows, wherein x, y are the detector cell coordinate, S is the acquisition range of test surface epigraph:

$\left\{\begin{array}{c}{C}_x=\frac{\underset{(x,y)\∈S}{\mathrm{\Σ}}x\·W(x,y)}{\underset{(x,y)\∈S}{\mathrm{\Σ}}W(x,y)}\\ C_y=\frac{\underset{(x,y)\∈S}{\mathrm{\Σ}}y\·W(x,y)}{\underset{(x,y)\∈S}{\mathrm{\Σ}}W(x,y)}\end{array}\right.$

6.FPGA chip is with the centroid position (C that calculates _x, C _y) outwards transmit by RS-422 communication transmission chip 8, send chip 9 output image datas by LVDS communication simultaneously, to be used for the work of monitoring camera.

The present invention has following beneficial effect:

By the cmos detector that uses pixel independently to address, so that the laser spot detection camera can change the size of windowing flexibly according to the detection demand, wicket is windowed can reach the above detection frame frequency of 2KHz when surveying, large window can satisfy again the large visual field demand of thick tracking system in the ATP system when windowing; Owing to adopted the stronger device of radiation resistance, therefore so that the present invention has the ability of working in space environment; According to Optical System Design of the present invention and centroid calculation precision, so that camera has the detection accuracy that is better than 0.2 μ rad, satisfied the detection demand of ATP system on the other hand.More than these advantages so that the present invention is highly suitable for the laser communication of space scale.

Description of drawings:

Fig. 1 is the satellite borne laser communication ATP laser spot detection camera structure figure of system that uses the inventive method;

Among the figure: 1. receiving telescope; 2. speculum; 3. bandpass filter;

4. imaging lens; 5.CMOS detector; 6.FPGA chip;

7.RS-422 communications reception chip; 8.RS-422 communication sends chip;

9.LVDS communication sends chip; 10.FPGA configuring chip;

11.5V DC power supply; 12.5V turn 3.3V voltage transitions chip;

13.5V turn 2.2V voltage transitions chip; 14.5V turn 1.8V voltage transitions chip;

15.5V turn 1.5V voltage transitions chip; 16. clock chip;

17. optical system; 18. electronic system.

Embodiment:

The whole satellite borne laser communication ATP system's laser spot detection phase machine mechanism that can be used for surveying beacon beam and parts composition are as shown in Figure 1.In this instance system, the combined focal length of optical system is 2500mm, and the detector pixel dimension is 15 μ m * 15 μ m, and the centroid calculation precision is 1/32 pixel, so the camera detection accuracy is better than 0.2 μ rad.Further set forth the star loaded camera System Implementation mode that the present invention can realize the high accuracy laser spot detection of using in conjunction with Fig. 1:

1. after camera is started working, the PROM chip XCF16PVO48C that is at first produced by FPGA configuring chip 10(XILINX company) program is write the XQ2VP40 field programmable gate array that fpga chip 6(XILINX company produces).Provide 5V voltage by 5V DC power supply 11,5V turns the MSK5232-1.8HTS that 3.3V voltage transitions chip 12(MSK company produces) 3.3V voltage is provided, 5V turns the MSK5232-2.5HTS that 2.5V voltage transitions chip 13(MSK company produces) 2.5V voltage is provided, 5V turns the MSK5232-1.8HTS that 1.8V voltage transitions chip 14(MSK company produces) provide 1.8V voltage, 5V to turn the MSK5232-1.5HTS that 1.5V voltage transitions chip 15(MSK company produces) 1.5V voltage is provided.The QT78LD9M-48MHZ that clock chip 16(Q-TECH company produces) provides 48MHz system works clock for fpga chip 6.

2. when carrying out laser space communication, by receiving telescope 1(transmission-type or autocollimator system, enlargement ratio is 8 times) receiving beam, through speculum 2(at 671nm wavelength reflectivity greater than 97%) after logical to 671nm wavelength light belt by bandpass filter 3(), bandpass filter 3 is finished and is filtered the veiling glare outside the intrafascicular 671nm wavelength of attenuate light to the light beam band is logical;

3. light beam is the 312.5mm non-spherical lens through imaging lens 4(focal length) after, the STAR1000 detector of producing in cmos detector 5(ON Semiconductor company, has the capability of resistance to radiation greater than 250Krad, survey front 1024 * 1024, pixel dimension 15 μ m * 15 μ m) imaging on the front;

4. camera is by the DS26LV31W of RS-422 communications reception chip 7(NSC company production) acquisition camera running parameter, parameter comprises detector window size, the original position of windowing, the time of integration and threshold size etc., fpga chip (6) is according to the opto-electronic conversion of parameter control cmos detector 5, and the acquisition view data;

5.FPGA chip 6 is at first done threshold process with the raw image data that collects and is obtained weight in the centroid calculation process, and caching image data is in the internal RAM of fpga chip.When judging original image value v (x, y) greater than setting threshold T, weighted value W (x, y)=v (x, y)-T; If original image value v (x, y) is during less than setting threshold T, weighted value W (x, y)=0.After obtaining weighted value, obtain centroid position according to the centroid calculation formula, computational accuracy is 1/32, centroid position (C _x, C _y) computing formula is as follows, wherein x, y are the detector cell coordinate, S is the acquisition range of test surface epigraph:

$\left\{\begin{array}{c}{C}_x=\frac{\underset{(x,y)\∈S}{\mathrm{\Σ}}x\·W(x,y)}{\underset{(x,y)\∈S}{\mathrm{\Σ}}W(x,y)}\\ C_y=\frac{\underset{(x,y)\∈S}{\mathrm{\Σ}}y\·W(x,y)}{\underset{(x,y)\∈S}{\mathrm{\Σ}}W(x,y)}\end{array}\right.$

6. the DS26LV32AW that produces by RS-422 communication transmission chip 8(NSC company) outwards transmit hot spot centroid position (C _x, C _y), send the SNJ55LVDS31W that chip 9(TI company produces by LVDS communication simultaneously) output image data, to be used for the work of monitoring camera.

Claims (2)

1. satellite borne laser communication ATP system laser spot detection camera, it comprises: by receiving telescope (1), speculum (2), the optical system (17) that (4) four parts of bandpass filter (3) and imaging lens form, cmos detector (5) and by fpga chip (6), RS-422 communications reception chip (7), RS-422 communication sends chip (8), LVDS communication sends chip (9), FPGA configuring chip (10), 5V DC power supply (11), 5V turns 3.3V voltage transitions chip (12), 5V turns 2.2V voltage transitions chip (13), 5V turns 1.8V voltage transitions chip (14), 5V turns the electronic system (18) of 1.5V voltage transitions chip (15) and clock chip (16) composition, it is characterized in that:

Described receiving telescope (1) is transmission-type or autocollimator system, and enlargement ratio is 8 times; Described speculum (2) is greater than 97% level crossing at 671nm visible light wave range reflectivity; Described bandpass filter (3) is logical to 671nm wave band light belt; Described imaging lens (4) is that combined focal length is the set of lenses of 312.5mm; Described cmos detector (5) is the cmos detector with radioresistance, large face battle array and integrated inner ADC; Described fpga chip (6) has the BlockRAM memory space greater than 3Mbits; Described RS-422 communications reception chip (7) is the DS26LV31W chip of being produced by NSC company; It is the DS26LV32AW chip of being produced by NSC company that described RS-422 communication sends chip (8); It is the SNJ55LVDS31W chip of being produced by TI company that described LVDS communication sends chip (9); Described FPGA configuring chip (10) is the PROM chip for configuration fpga chip program; Described is that the Voltage-output precision is better than 2% DC power supply for electronic system (18) provides the 5V power supply (11) of 5V voltage; Described is that voltage accuracy is better than 1%, the linear voltage regulator of maximum output current 3A for electronic system (18) provides the 5V of 3.3V voltage to turn 3.3V voltage transitions chip (12); Described is that voltage accuracy is better than 1%, the linear voltage regulator of maximum output current 3A for electronic system (18) provides the 5V of 2.5V voltage to turn 2.5V voltage transitions chip (13); Described is that voltage accuracy is better than 1%, the linear voltage regulator of maximum output current 3A for electronic system (18) provides the 5V of 1.8V voltage to turn 1.8V voltage transitions chip (14); Described is that voltage accuracy is better than 1%, the linear voltage regulator of maximum output current 3A for electronic system (18) provides the 5V of 1.5V voltage to turn 1.5V voltage transitions chip (15); Described for FPAG chip (6) when providing clock chip (16) temperature of 48MHz system works clock to be 25 ℃ clock jitter less than 8ps;

Camera receives the beacon beam light beam by the receiving telescope (1) of its optical system (17), and is rear by bandpass filter (3) through speculum (2) reflection; Light beam will be attenuated through the light except the 671nm wavelength in the rear light beam of bandpass filter (3); Enter cmos detector (5) front by imaging lens (4) again, further finish opto-electronic conversion and view data is exported to fpga chip (6);

The running parameter of camera obtains and sends to fpga chip (6) by RS-422 communications reception chip (7); Fpga chip (6) is controlled cmos detector (5) and is finished opto-electronic conversion under these running parameters, and will obtain view data by cmos detector (5) and export to fpga chip (6); After fpga chip obtains image information, the employing centroid algorithm is finished the calculating to the facula mass center position, and while cache image information, send chip (8) by RS-422 communication again and outwards send the barycenter information that calculates, send chip (9) by LVDS communication simultaneously and send real-time view data.

2. laser spot detection method based on the described satellite borne laser of claim 1 communication ATP system laser spot detection camera is characterized in that may further comprise the steps:

1). after camera is started working, at first by FPGA configuring chip (10) program is write fpga chip (6), turn 3.3V voltage transitions chip (12), 5V by 5V DC power supply (11), 5V and turn that 2.5V voltage transitions chip (13), 5V turn 1.8V voltage transitions chip (14), 5V turns every voltage that 1.5V voltage transitions chip (15) needs when work is provided for whole camera electronic system (18), clock chip (16) provides the 48MHz work clock for fpga chip (6);

2). when carrying out laser space communication, receive the beacon beam light beam by receiving telescope (1), through passing through bandpass filter (3) behind the speculum (2), bandpass filter (3) is finished the optical filtering to light beam;

3). behind the light beam process imaging lens (4), imaging on cmos detector (5) front;

4). camera obtains running parameter by RS-422 communications reception chip (7), parameter comprises detector window size, the original position of windowing, the time of integration and threshold size etc., and fpga chip (6) is finished opto-electronic conversion and obtained view data by parameter control cmos detector (5);

5) .FPGA chip (6) is at first done threshold process with the raw image data that collects and is obtained weight in the centroid calculation process, caching image data is in the internal RAM of fpga chip simultaneously, judge original image value v (x, during y) greater than setting threshold T, weighted value W (x, y)=v (x, y)-T; If original image value v (x, y) is during less than setting threshold T, weighted value W (x, y)=0, obtain weighted value after, obtain centroid position according to the centroid calculation formula, computational accuracy is 1/32, centroid position (C _x, C _y) computing formula is as follows, wherein x, y are the detector cell coordinate, S is the acquisition range of test surface epigraph:

$\left\{\begin{array}{c}{C}_x=\frac{\underset{(x,y)\∈S}{\mathrm{\Σ}}x\·W(x,y)}{\underset{(x,y)\∈S}{\mathrm{\Σ}}W(x,y)}\\ C_y=\frac{\underset{(x,y)\∈S}{\mathrm{\Σ}}y\·W(x,y)}{\underset{(x,y)\∈S}{\mathrm{\Σ}}W(x,y)}\end{array}\right.$

6) the .FPGA chip is with the centroid position (C that calculates _x, C _y) send outwards transmission of chip (8) by RS-422 communication, send chip (9) output image data by LVDS communication simultaneously, to be used for the work of monitoring camera.

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