CN111211838B - Target extraction and tracking camera and method of inter-satellite laser communication PAT system - Google Patents
Target extraction and tracking camera and method of inter-satellite laser communication PAT system Download PDFInfo
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Abstract
The invention discloses a target extraction and tracking camera and a method of an inter-satellite laser communication PAT system. The invention integrates the functions of detector driving and data processing, target detection and extraction and galvanometer control tracking in two aspects of software and hardware, can reduce miss distance delay, improve the closed-loop control bandwidth of the system and further improve the tracking precision of the PAT system. The basic working principle of the camera is as follows: the short wave infrared detector receives the slave precise beacon light, under the excitation of analog voltage and the digital time sequence of the FPGA chip, the detection and the output of the precise beacon light are completed, the output signal is processed by the amplifying circuit and the analog-to-digital conversion circuit, and a digital image signal is formed and enters the FPGA chip. The digital image data is subjected to a series of processing such as preprocessing, high-precision light spot extraction and galvanometer control in the FPGA chip, a digital quantity is output to the digital-to-analog converter to generate a control voltage, and finally the fine tracking galvanometer is controlled to complete fine beacon light tracking with high precision and low time delay.
Description
Technical Field
The invention relates to the field of space laser communication, in particular to a target extraction and tracking camera and a target extraction and tracking method of an inter-satellite laser communication PAT system.
Background
Due to the high speed, low power consumption and long distance, the communication light of the inter-satellite laser communication system is often emitted at a diffraction limit close to the diffraction limit (10-30 μ rad). Due to the influence of factors such as relative motion between satellites, vibration of a satellite platform, attitude of the satellite and the like, the establishment and maintenance of a high-speed communication link between the satellites are difficult to be completed by directly utilizing communication light with a very narrow angle. In order to realize high-speed laser communication between satellites with link distances of tens of thousands of kilometers, an initial Pointing (Pointing), beam scanning and capturing (Acquisition) and beam Tracking (Tracking) system, namely a PAT system, must be adopted to ensure the rapid establishment and stable maintenance of the communication link between the satellites.
The initial pointing of the PAT system refers to a process of achieving initial alignment of optical axes of both sides of a communication link by using position and attitude information of a satellite. Due to pointing errors, this process can only ensure that the optical axes point into an indeterminate zone that may occur with each other. The light beam scanning and capturing means that a transmitting end of a communication link sends out wide-angle coarse beacon light (coaxial with communication light) to scan an uncertain region where a receiving end is located, and the receiving end transmits own coarse beacon light while detecting the beacon light, so that both communication parties detect the coarse beacon light. The scanning and capturing process preliminarily realizes that the optical axes of the two parties are aligned in a controllable range. The beam tracking is a process of performing active photoelectric tracking on detected beacon light in real time on the basis of completing capture, so that the influence of relative motion, platform vibration and the like on the alignment precision of the optical axes of the two parties is overcome, and the alignment error of the optical axis is controlled within a small range (less than 5 mu rad).
In order to realize the high dynamic range of communication and the high-precision maintenance of a link, a rough and fine composite axis tracking scheme is generally adopted in the conventional inter-satellite laser communication PAT system. The reason is that the control bandwidth and the precision of the actuator are limited, the alignment precision of the optical axis is reduced while the system capture probability is improved by the wide-angle coarse beacon light, a stable and reliable communication link cannot be established only by tracking the coarse beacon light, a smaller-angle and more energy-concentrated fine beacon light (obtained by splitting communication light) needs to be tracked on the basis, and the high-precision alignment of the optical axis is realized through high-bandwidth and high-precision control. Under the condition that the optical axis alignment error ensures that the energy continuously coupled into the communication system meets the requirement, the communication link is successfully established, and at the moment, communication light with extremely narrow angle can be efficiently coupled into the communication system, so that high-speed laser communication is started.
The target extraction and tracking camera works in a fine beacon light tracking stage and is used for detecting fine beacon light obtained by light splitting of communication light, and the fine tracking galvanometer is controlled to reduce the alignment error of an optical axis to a very small range through target extraction and tracking processing, so that the communication error rate is not influenced by energy fluctuation caused by optical axis jitter in the communication process. Based on the requirement, the overall tracking precision of the PAT system of the inter-satellite laser communication terminal is usually within 2 μ rad to 5 μ rad, which requires the tracking precision of the target extraction and tracking camera to be usually within 1 μ rad.
At present, cameras for realizing precise beacon detection only perform target detection, then transmit optical axis deviation information (miss distance) to an independent galvanometer control unit through a cable, and then perform algorithm conversion by the galvanometer control unit to output control quantity to a precise tracking galvanometer. The transmission and processing delay in the process seriously restricts the improvement of the closed-loop control bandwidth of the system, so that the tracking precision of the PAT system cannot be further improved. In recent years, deep space communication technologies represented by spark detection have been rapidly developed, which have extremely strict requirements on optical axis alignment errors of laser communication systems (no more than 1 μ rad), and for PAT systems, it is necessary to improve control bandwidth, reduce miss-target delay, and perform software and hardware integration design on imaging, detection, extraction, and galvanometer control, but until now, such cameras have not been applied to PAT systems.
On the other hand, the existing laser communication system mostly adopts a module decentralized design, so that the volume, power consumption and weight of the system are difficult to meet the carrying requirements of the microsatellite platform on one arrow and more stars, the emission cost is not reduced, and the development requirements of the constellation layout in the current laser communication field are not met. Therefore, in view of performance indexes and application development, high-performance, high-integration, lightweight and miniaturized design of the functional unit is urgently developed.
Disclosure of Invention
The method aims at solving the problem that the tracking precision cannot be further improved due to the fact that the closed-loop control bandwidth of a system cannot be improved due to the miss distance delay caused by the separation of target extraction and a galvanometer control unit mentioned in the background; the invention provides a target extraction and tracking camera of an inter-satellite laser communication PAT system, which is used for integrally designing a target extraction and galvanometer control function module in software and hardware, and provides a target extraction and tracking method of the inter-satellite laser communication PAT system, so that the tracking performance of the system is improved, and the light and small design of the PAT system is effectively guaranteed.
The basic implementation principle of the invention is as follows:
the short wave infrared detector receives the fine beacon light obtained by light splitting of the communication light, detection and output of the fine beacon light are completed under the excitation of analog voltage and the digital time sequence of the FPGA chip, and the output signal is processed by the amplifying circuit and the analog-to-digital conversion circuit to form a digital image signal which enters the FPGA chip. The digital image data is subjected to a series of processing such as preprocessing, high-precision light spot extraction and galvanometer control in the FPGA chip, a digital quantity is output to the digital-to-analog converter to generate a control voltage, and finally the fine tracking galvanometer is controlled to complete fine beacon light tracking with high precision and low time delay.
The specific technical scheme of the invention is as follows:
the invention provides a target extraction and tracking camera of an inter-satellite laser communication PAT system, which is characterized in that: the device comprises a front end detection part, a rear end processing part, a cable and a voltage stabilizing part;
the front-end detection part comprises a short wave infrared detector, an operational amplifier and an analog-digital converter driver;
the short wave infrared detector receives the fine beacon light, performs photoelectric conversion on the fine beacon light, and outputs a voltage signal to the analog-to-digital converter driver; the analog-to-digital converter driver converts the voltage signal into a differential analog signal; the operational amplifier provides reference for the differential input of the analog-to-digital converter driver;
the back-end processing part comprises a reference voltage source, an analog-to-digital converter, a crystal oscillator, an FPGA chip, a read-back refreshing chip, a Flash memory, an SDRAM chip, an LVDS interface chip and a digital-to-analog converter;
the analog-to-digital converter receives a differential analog signal sent by the analog-to-digital converter driver through a cable, and after sampling and analog-to-digital conversion are carried out on the differential analog signal, the analog-to-digital converter transmits a digital signal to the FPGA chip; the reference voltage source provides a common-mode reference level for the analog-to-digital converter;
the FPGA chip is used for carrying out time sequence control and image preprocessing on the short wave infrared detector, detecting and extracting the position of a light spot of the fine beacon and calculating a galvanometer control signal;
the crystal oscillator is used as a time sequence synchronization source to provide a system working clock for the FPGA chip;
the read-back refreshing chip is used for dynamically refreshing the FPGA chip or reloading a program, and is also used as an interface control chip to realize the loading of the power-on program and the reconstruction of on-orbit software of the FPGA chip;
the Flash memory is used for storing a power-on loading program of the FPGA chip and a detector correction parameter;
the SDRAM chip is used for caching data in the data processing process of the FPGA chip;
the LVDS interface chip is used for receiving related control instruction data, sending camera state data, sending image data and receiving software reconstruction data for in-orbit software reconstruction;
the digital-to-analog converter is used for converting the galvanometer control digital signal calculated by the FPGA chip into a motion control analog signal and transmitting the motion control analog signal to an external fine tracking galvanometer;
the voltage stabilizing part provides stable voltage for the FPGA chip, the read-back refreshing chip, the LVDS interface chip, the short wave infrared detector, the analog-to-digital converter driver and the analog-to-digital converter respectively.
Further, the voltage stabilizing part comprises a switching regulator and a low dropout regulator;
the switching regulator provides 1.2V and 3.3V voltage for the FPGA chip, and the 3.3V voltage simultaneously supplies power for the read-back refreshing chip and the LVDS interface chip;
the low-dropout linear voltage stabilizer provides 2.5V voltage for the FPGA chip, provides 3.6V and 1.8V voltage for the short-wave infrared detector, provides 2.5V voltage for the analog-to-digital converter and provides 4.3V voltage for the analog-to-digital converter driver.
Further, the program modules running in the FPFA chip comprise an image preprocessing program module, a target detection and extraction program module and a galvanometer control program module;
the image preprocessing program module is used for preprocessing the digital image signals;
the target detection and extraction program module extracts the centroid of the precise beacon light from the preprocessed digital image signal;
and the galvanometer control program module processes the optical centroid of the precise beacon to generate galvanometer control signals.
Furthermore, the front-end detection part and the rear-end data processing part both adopt anti-radiation protection and thermal control design.
Based on the description of the software and hardware architecture of the target extraction and tracking camera, a method for extracting and tracking a target by using the camera is introduced, and the method specifically comprises the following implementation steps:
step 1: the short wave infrared detector receives the fine beacon light obtained by light splitting of the communication light, converts the fine beacon light into a voltage signal, converts the voltage signal into a differential analog signal through an analog-to-digital converter driver, and outputs the differential analog signal to the analog-to-digital converter through a cable;
step 2: the analog-to-digital converter converts the differential analog signal into digital image data and inputs the digital image data into the FPGA chip;
and step 3: an image preprocessing process;
the FPGA chip firstly caches digital image data into an SDRAM chip, and then performs blind pixel correction, non-uniformity correction and noise reduction filtering processing on the digital image data after reading detector correction parameters from a Flash memory for use in a target detection and extraction process;
and 4, step 4: a target detection and extraction process;
step 4.1: the FPGA chip firstly caches two lines of preprocessed digital image data, and then performs sub-pixel four-subdivision processing point by point and line by line;
step 4.2: the FPGA chip adopts a centroid algorithm with a threshold value to perform target detection and position extraction on the subdivided digital image data to obtain the centroid (x) of the precise beacon light0,y0)；
And 5: calculating a galvanometer control signal and outputting the signal to an external fine tracking galvanometer;
FPGA chip pair precision beacon light centroid (x)0,y0) And processing to generate a galvanometer control signal, sending the galvanometer control signal to a digital-to-analog converter through an interface, generating a corresponding motion control analog signal by the digital-to-analog converter, and transmitting the corresponding motion control analog signal to the precise tracking galvanometer to complete the closed-loop tracking of the precise beacon light spot.
Further, the sub-pixel four-subdivision algorithm in the step 4.1 has the following calculation formula:
wherein, img _ in (i, j), img _ in (i, j +1), img _ in (i +1, j +1) respectively represent four pixel values in the original digital image data, img _ out (z _ out)i,zj) The resulting subdivided pixel values are calculated based on the four pixel values.
If the resolution of the original image is MxN, the value range of i is 0 to M, the value range of j is 0 to N, and ziIs in the range of 1 to 4 xM, zjThe value range of (1) to (4) xN; i, j, u, v, zi，zjThe conversion relationship between them is as follows:
wherein mod and rem are the modulo and remainder operations, respectively.
Further, the centroid algorithm with the threshold in the step 4.2 specifically calculates the formula as follows:
wherein x is0,y0Represents the centroid of the fine beacon light;
t is a threshold value and has a value range of img _ out (z)i,zj) 1/3 to 1/2 of medium maximum;
if img _ out (z)i,zj)<T, then img _ out (z)i,zj)-T＝0。
The invention has the following beneficial effects:
1. the invention integrates the functions of detector driving and data processing, target detection and extraction and galvanometer control tracking in two aspects of software and hardware, can reduce miss distance delay, improve the closed-loop control bandwidth of the system and further improve the tracking precision of the PAT system.
2. The invention follows the design principle of high reliability, physically separates the rear end data processing part from the front end detection part, ensures the mechanical stability of the front end detection part coupled with the light path, and greatly reduces the optical axis deviation degree caused by vibration impact to the system in the transportation and launching processes.
3. Based on the design scheme of physical separation, the front-end detection part has small volume and low power consumption, and is subjected to targeted anti-irradiation protection and thermal control design, so that the high reliability can be ensured, and the system resources are not burdened; the back-end data processing part has strong temperature adaptability and radiation resistance, and consumes little system resources, so the invention has high temperature adaptability and radiation resistance.
4. Through the hardware integration design, the invention can effectively reduce the indexes of system volume, power consumption and weight, and provides powerful guarantee for the light weight and miniaturization of the whole system.
Drawings
Fig. 1 is a schematic structural view of the present invention.
Fig. 2 is a schematic diagram of the control algorithm employed in the present invention.
The reference numbers are as follows:
the device comprises a 1-short wave infrared detector, a 2-analog-to-digital converter driver, a 3-operational amplifier, a 4-front end detection part, a 5-cable, a 6-reference voltage source, a 7-FPGA chip, an 8-crystal oscillator, a 9-read-back refreshing chip, a 10-Flash memory, an 11-rear end data processing part, a 12-low-voltage-difference linear voltage stabilizer, a 13-analog-to-digital converter, a 15-switching voltage stabilizer, a 16-digital-to-analog converter, a 17-LVDS interface chip and an 18-SDRAM chip.
Detailed Description
To make the objects, advantages and features of the present invention clearer, the following describes in detail a target extracting and tracking camera and method of an inter-satellite laser communication PAT system according to the present invention with reference to the accompanying drawings and specific embodiments. The advantages and features of the present invention will become more apparent from the following description. It should be noted that: the drawings are in simplified form and are not to precise scale, the intention being solely for the convenience and clarity of illustrating embodiments of the invention; second, the structures shown in the drawings are often part of actual structures.
As shown in fig. 1, the camera includes a front end detection section (a section in the figure), a rear end processing section (B section in the figure), a cable 5, and a voltage stabilization section; the front-end detection part and the rear-end data processing part are physically separated and connected through a cable 5, and the front-end detection part and the rear-end data processing part are both designed to be radiation-resistant protection and thermal control.
The main reasons for this design are: (1) the short wave infrared detector is sensitive to temperature and radiation, if the short wave infrared detector and the rear end data processing part are designed integrally, in order to meet the temperature range of the detector, a large amount of heat consumption of the rear end data processing part needs to be considered during thermal control design, and undoubtedly, a large amount of thermal control resources are consumed, and the temperature control effect is general; (2) because the internal space is limited, the radiation-resistant protection design of the detector is difficult to perform in a targeted manner, and if the whole machine shell is designed, excessive weight resources are consumed; (3) if the front-end detection part and the rear-end data processing part are integrally designed, the envelope and the weight of the light path coupling part are increased, so that the mechanical stability is influenced, and the probability that the optical axis of the system is influenced by vibration impact is increased.
Specifically, the method comprises the following steps:
the front-end detection part comprises a short wave infrared detector 1, an operational amplifier 3 and an analog-digital converter driver 2;
the short wave infrared detector 1 receives the fine beacon light, performs photoelectric conversion on the fine beacon light, and outputs a voltage signal to the analog-to-digital converter driver 2; the analog-to-digital converter driver 2 converts the voltage signal into a differential analog signal; the operational amplifier 3 provides a reference for the differential input of the analog-to-digital converter driver;
the back-end processing part comprises a reference voltage source 6, an analog-to-digital converter 13, a crystal oscillator 8, an FPGA chip 7, a read-back refreshing chip 9, a Flash memory 10, an SDRAM chip 18, an LVDS interface chip 17 and a digital-to-analog converter 16;
the analog-to-digital converter 13 receives the differential analog signal sent by the analog-to-digital converter driver 2 through the cable 5, and the analog-to-digital converter 13 samples and converts the differential analog signal into an analog-to-digital signal and then transmits the digital signal to the FPGA chip 7; the reference voltage source 6 provides a common mode reference level for the analog-to-digital converter 13;
the program modules running in the FPGA chip 7 comprise an image preprocessing program module, a target detection and extraction program module and a galvanometer control program module; the image preprocessing program module is used for preprocessing the digital image signals; the target detection and extraction program module extracts the centroid of the precise beacon light from the preprocessed digital image signal; and the galvanometer control program module processes the optical centroid of the precise beacon to generate galvanometer control signals.
The crystal oscillator 8 is used as a time sequence synchronization source to provide a system working clock for the FPGA chip 7;
the read-back refreshing chip 9 is used for dynamically refreshing the FPGA chip 7 or reloading a program, and is also used as an interface control chip to realize the loading of the power-on program and the reconstruction of on-orbit software of the FPGA chip 7;
the Flash memory 10 is used for storing a power-on loading program of the FPGA chip 7 and correction parameters of the short wave infrared detector 1; the SDRAM chip 18 is used for caching data in the data processing process of the FPGA chip 7;
the LVDS interface chip 17 is used for receiving related control instruction data, sending camera state data and sending images
Data, receiving software reconfiguration data for in-orbit software reconfiguration;
the digital-to-analog converter 16 is used for calculating a galvanometer control signal for the FPGA chip 7, converting the signal into a motion control analog signal in a digital-to-analog mode and transmitting the motion control analog signal to an external fine tracking galvanometer;
the voltage stabilizing part comprises a switching regulator 15 and a low dropout linear regulator 12; the switching regulator 15 provides 1.2V and 3.3V voltages for the FPGA chip 7, and the 3.3V voltage simultaneously supplies power for the read-back refreshing chip 9 and the LVDS interface chip 17;
the low dropout linear regulator 12 provides 2.5V voltage for the FPGA chip 7, 3.6V and 1.8V voltage for the short wave infrared detector 1, 2.5V voltage for the analog-to-digital converter 13, and 4.3V voltage for the analog-to-digital converter driver 2.
1. Based on the above-mentioned camera structure, the working principle of the camera will now be described in detail: after the camera starts to work, a read-back refreshing chip 9 reads a program from a Flash memory 10 and writes the program into an FPGA chip 7, and the FPGA chip 7 starts to run the program under the power supply of a switching regulator 15 and a low-dropout linear regulator 12 and the common excitation of a system clock of a crystal oscillator 8;
2, the FPGA chip 7 receives the control instruction through the LVDS interface chip 17, analyzes working parameters such as exposure time, windowing size, windowing position, working frame frequency and the like, generates corresponding time sequence and configuration parameters, and sends the corresponding time sequence and configuration parameters to the short-wave infrared detector 1 through the cable 5;
3. the short wave infrared detector 1 receives the fine beacon light obtained by light splitting of the communication light, under the condition that power supply of the low-dropout linear voltage regulator 12 and timing sequence and configuration of the FPGA chip 7 are jointly excited, the fine beacon is detected and output, the analog output signal is firstly converted into a differential signal through the analog-to-digital converter driver 2, is input into the analog-to-digital converter 13 through the cable 5, is converted into a digital image signal and enters the FPGA chip 7;
an image preprocessing program module in the FPGA7 firstly caches the digital image data in the SDRAM chip 18, reads correction parameters from the Flash memory 10, then performs preprocessing work such as blind pixel correction, non-uniformity correction, noise reduction and filtering, and sorts the image data according to a convention protocol for a target detection and extraction module to use;
and 5, a target detection and extraction program module in the FPGA7 firstly caches two lines of the sorted image, and then performs sub-pixel four-subdivision processing point by point and line by line, so that the spatial resolution of the original image is improved at an algorithm end, and the target extraction precision is improved. The calculation formula of the sub-pixel four-subdivision algorithm is as follows:
wherein, img _ in (i, j), img _ in (i, j +1), img _ in (i +1, j +1) respectively represent four pixel values in the original digital image data, img _ out (z _ out)i,zj) The resulting subdivided pixel values are calculated based on the four pixel values.
If the resolution of the original image is MxN, the value range of i is 0 to M, the value range of j is 0 to N, and ziIs in the range of 1 to 4 xM, zjIs in the range of 1 to 4 XN. i, j, u, v, zi，zjThe conversion relationship between them is as follows:
wherein mod and rem are the modulo and remainder operations, respectively.
And 6, carrying out target detection and position extraction on the subdivided image by using a target detection and extraction program module in the FPGA chip 7, wherein the specific algorithm is a centroid algorithm with a threshold value, and compared with the common centroid algorithm, the algorithm can eliminate all uniform background noise and is equivalent to improving the signal-to-noise ratio, so that the detection precision is higher. Precision beacon light centroid (x)0,y0) The calculation formula is as follows:
wherein x is0,y0Represents the centroid of the fine beacon light;
t is a threshold value and has a value range of img _ out (z)i,zj) 1/3 to 1/2 of medium maximum;
if img _ out (z)i,zj)<T, then img _ out (z)i,zj)-T＝0。
And 7, converting the precise beacon light centroid (x0, y0) by a galvanometer control program module in the FPGA chip 7 to obtain the miss distance representing the optical axis deviation information, and then realizing the motion control of the galvanometer by adopting an incremental control algorithm. Because the algorithm needs to obtain the relative displacement of two adjacent frames of targets, the off-target angle conversion needs to be performed on the off-target amount of the current frame and the off-target amount of the previous frame respectively, then the correlation operation is performed, finally the motion control digital quantity is generated, the control quantity is sent to the digital-to-analog converter 16 through the interface, the corresponding motion control analog quantity is generated by the digital-to-analog converter and is transmitted to the fine tracking galvanometer, and the closed-loop tracking of the beacon light spot is completed. The schematic diagram of the incremental control algorithm is shown in fig. 2, wherein the conversion coefficient, the P parameter and the I parameter are determined according to the system parameters in the process of system joint adjustment, the galvanometer stroke belongs to the system design index, and N is the quantization digit of the selected DAC;
8, the FPGA chip 7 calculates the calculated precise beacon light centroid (x) through the LVDS interface chip 170,y0) And the motion control digital quantity and the state parameters of the camera are sent out for system monitoring.
Finally, it should be noted that the above description is only for describing the preferred embodiments of the present invention, and not for limiting the scope of the present invention, and that any changes and modifications made by those skilled in the art according to the above disclosure are all within the scope of the appended claims.
Claims (7)
1. The utility model provides a target of inter-satellite laser communication PAT system draws and tracks camera which characterized in that: the device comprises a front end detection part, a rear end processing part, a cable and a voltage stabilizing part;
the front-end detection part comprises a short wave infrared detector, an operational amplifier and an analog-digital converter driver;
the short wave infrared detector receives the fine beacon light, performs photoelectric conversion on the fine beacon light, and outputs a voltage signal to the analog-to-digital converter driver; the analog-to-digital converter driver converts the voltage signal into a differential analog signal; the operational amplifier provides reference for the differential input of the analog-to-digital converter driver;
the back-end processing part comprises a reference voltage source, an analog-to-digital converter, a crystal oscillator, an FPGA chip, a read-back refreshing chip, a Flash memory, an SDRAM chip, an LVDS interface chip and a digital-to-analog converter;
the analog-to-digital converter receives a differential analog signal sent by the analog-to-digital converter driver through a cable, and after sampling and analog-to-digital conversion are carried out on the differential analog signal, the analog-to-digital converter transmits a digital signal to the FPGA chip; the reference voltage source provides a common-mode reference level for the analog-to-digital converter;
the FPGA chip is used for carrying out time sequence control and image preprocessing on the short wave infrared detector, detecting and extracting the position of a light spot of the fine beacon and calculating a galvanometer control signal;
the crystal oscillator is used as a time sequence synchronization source to provide a system working clock for the FPGA chip;
the read-back refreshing chip is used for dynamically refreshing the FPGA chip or reloading a program, and is also used as an interface control chip to realize the loading of the power-on program and the reconstruction of on-orbit software of the FPGA chip;
the Flash memory is used for storing a power-on loading program of the FPGA chip and a detector correction parameter;
the SDRAM chip is used for caching data in the data processing process of the FPGA chip;
the LVDS interface chip is used for receiving related control instruction data, sending camera state data, sending image data and receiving software reconstruction data for in-orbit software reconstruction;
the digital-to-analog converter is used for converting the galvanometer control digital signal calculated by the FPGA chip into a motion control analog signal and transmitting the motion control analog signal to an external fine tracking galvanometer;
the voltage stabilizing part provides stable voltage for the FPGA chip, the read-back refreshing chip, the LVDS interface chip, the short wave infrared detector, the analog-to-digital converter driver and the analog-to-digital converter respectively.
2. The target extraction and tracking camera of the inter-satellite laser communication PAT system of claim 1, characterized in that: the voltage stabilizing part comprises a switching regulator and a low dropout linear regulator;
the switching regulator provides 1.2V and 3.3V voltage for the FPGA chip, and the 3.3V voltage simultaneously supplies power for the read-back refreshing chip and the LVDS interface chip;
the low-dropout linear voltage stabilizer provides 2.5V voltage for the FPGA chip, provides 3.6V and 1.8V voltage for the short-wave infrared detector, provides 2.5V voltage for the analog-to-digital converter and provides 4.3V voltage for the analog-to-digital converter driver.
3. The target extraction and tracking camera of the inter-satellite laser communication PAT system of claim 1, characterized in that: the program modules running in the FPFA chip comprise an image preprocessing program module, a target detection and extraction program module and a galvanometer control program module;
the image preprocessing program module is used for preprocessing the digital image signals;
the target detection and extraction program module extracts the centroid of the precise beacon light from the preprocessed digital image signal;
and the galvanometer control program module processes the optical centroid of the precise beacon to generate galvanometer control signals.
4. The target extraction and tracking camera of the inter-satellite laser communication PAT system of claim 1, characterized in that: the front-end detection part and the rear-end data processing part both adopt anti-radiation protection and thermal control design.
5. A target extraction and tracking method of an inter-satellite laser communication PAT system is characterized by comprising the following implementation steps:
step 1: the short wave infrared detector receives the fine beacon light obtained by light splitting of the communication light, converts the fine beacon light into a voltage signal, converts the voltage signal into a differential analog signal through an analog-to-digital converter driver, and outputs the differential analog signal to the analog-to-digital converter through a cable;
step 2: the analog-to-digital converter converts the differential analog signal into digital image data and inputs the digital image data into the FPGA chip;
and step 3: an image preprocessing process;
the FPGA chip firstly caches digital image data into an SDRAM chip, and then performs blind pixel correction, non-uniformity correction and noise reduction filtering processing on the digital image data after reading detector correction parameters from a Flash memory for use in a target detection and extraction process;
and 4, step 4: a target detection and extraction process;
step 4.1: the FPGA chip firstly caches two lines of preprocessed digital image data, and then performs sub-pixel four-subdivision processing point by point and line by line;
step 4.2: the FPGA chip adopts a centroid algorithm with a threshold value to perform target detection and position extraction on the subdivided digital image data to obtain the centroid (x) of the precise beacon light0,y0)；
And 5: calculating a galvanometer control signal and outputting the signal to an external fine tracking galvanometer;
FPGA chip pair precision beacon light centroid (x)0,y0) And processing to generate a galvanometer control signal, sending the galvanometer control signal to a digital-to-analog converter through an interface, generating a corresponding motion control analog signal by the digital-to-analog converter, and transmitting the corresponding motion control analog signal to the precise tracking galvanometer to complete the closed-loop tracking of the precise beacon light spot.
6. The method for extracting and tracking the target of the PAT system for laser communication between satellites as claimed in claim 5, wherein: the calculation formula of the sub-pixel four-subdivision algorithm in the step 4.1 is as follows:
wherein, img _ in (i, j), img _ in (i, j +1), img _ in (i +1, j +1) respectively represent four pixel values in the original digital image data, img _ out (z _ out)i,zj) For a subdivided image calculated on the basis of the four pixel valuesThe prime value;
if the resolution of the original image is MxN, the value range of i is 0 to M, the value range of j is 0 to N, and ziIs in the range of 1 to 4 xM, zjThe value range of (1) to (4) xN; i, j, u, v, zi，zjThe conversion relationship between them is as follows:
wherein mod and rem are the modulo and remainder operations, respectively.
7. The method for extracting and tracking the target of the PAT system for laser communication between satellites as claimed in claim 5, wherein: the specific calculation formula of the centroid algorithm with the threshold in the step 4.2 is as follows:
wherein x is0,y0Represents the centroid of the fine beacon light;
t is a threshold value and has a value range of img _ out (z)i,zj) 1/3 to 1/2 of medium maximum;
if img _ out (z)i,zj)<T, then img _ out (z)i,zj)-T＝0。
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| CN103024307A (en) * | 2012-11-30 | 2013-04-03 | 中国科学院上海技术物理研究所 | Space borne laser communication ATP system spot detecting camera and detecting method |
| CN106375000A (en) * | 2016-08-30 | 2017-02-01 | 西安空间无线电技术研究所 | Spatial light reception demodulation device |
| CN109274432A (en) * | 2018-08-29 | 2019-01-25 | 西安电子科技大学 | Coherent tracking system and compensation method based on free space optical communication |
Family Cites Families (2)
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| CN109725325A (en) * | 2019-01-10 | 2019-05-07 | 中国科学院微电子研究所 | Laser tracking measurement system and method |
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Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103024307A (en) * | 2012-11-30 | 2013-04-03 | 中国科学院上海技术物理研究所 | Space borne laser communication ATP system spot detecting camera and detecting method |
| CN106375000A (en) * | 2016-08-30 | 2017-02-01 | 西安空间无线电技术研究所 | Spatial light reception demodulation device |
| CN109274432A (en) * | 2018-08-29 | 2019-01-25 | 西安电子科技大学 | Coherent tracking system and compensation method based on free space optical communication |
Non-Patent Citations (1)
| Title |
|---|
| 空间激光通信最新进展与发展趋势;高铎瑞 等;《中国光学》;20181212;第901-913页 * |
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