星地激光鏈路高精度跟瞄偏差角度獲取方法研究
發(fā)布時(shí)間：2018-07-17 21:29
【摘要】：在星地激光通信系統(tǒng)中，激光束寬非常窄且接收視場(chǎng)小，為了快速建立和穩(wěn)定保持長(zhǎng)距離星地激光通信鏈路，激光通信終端必須具有高精度光束瞄準(zhǔn)能力和高精度穩(wěn)定跟蹤能力。獲得高精度跟瞄偏差角是長(zhǎng)距離星地激光通信系統(tǒng)能夠快速建立和穩(wěn)定保持星地激光通信鏈路的重要保證。研究高精度跟瞄偏差角獲取方法是十分緊迫和必要的。 大氣信道是星地激光通信信道的組成部分，作為信息載體的激光光束穿過(guò)大氣層時(shí)會(huì)受到大氣湍流的影響。在星地激光通信系統(tǒng)中，大氣的湍流效應(yīng)將影響信標(biāo)激光光束在跟瞄系統(tǒng)接收終端形成的光斑光強(qiáng)分布，產(chǎn)生光斑畸變，降低瞄準(zhǔn)捕獲跟蹤精度，使系統(tǒng)探測(cè)精度下降，瞄準(zhǔn)偏差增大，接收功率降低，誤碼率增加，嚴(yán)重時(shí)甚至使星地激光鏈路的建立和保持變得困難。尋找能夠有效校正或降低大氣湍流影響的激光光斑中心獲取方法，對(duì)星地激光鏈路的建立和穩(wěn)定保持具有重要意義。 本文研究的問(wèn)題是，如何利用接收激光終端CMOS獲得的入射激光信標(biāo)光束的光斑光強(qiáng)分布，抑制大氣湍流對(duì)跟瞄偏差角探測(cè)精度造成的影響，尋找獲得高精度跟瞄偏差角的方法。這是星地激光通信鏈路快速建立和穩(wěn)定保持的關(guān)鍵問(wèn)題之一。 首先對(duì)國(guó)內(nèi)外星地衛(wèi)星激光通信技術(shù)的研究進(jìn)展進(jìn)行了概述，，介紹了跟瞄偏差角度基礎(chǔ)理論和探測(cè)機(jī)理，對(duì)跟瞄偏差角度的獲取方法進(jìn)行了分析。在此基礎(chǔ)上進(jìn)一步開展了本文的研究工作。 提出了利用接收激光終端CMOS獲得的光強(qiáng)分布灰度數(shù)字圖像，再生縱橫單向凸圖像的方法。在濾除畸變二值含噪光斑圖像噪聲過(guò)程中，利用亮點(diǎn)像素到全圖幾何中心的歐氏距離作為判斷該像素是否為單點(diǎn)噪聲的判別準(zhǔn)則。沿水平方向和垂直方向?qū)⒐獍咧貥?gòu)為單連通凸圖像。以此再生縱橫單向凸圖像的幾何中心接近入射激光光束在接收激光終端CMOS上的理想光斑中心，獲得了更高精度的跟瞄偏差角。給出了再生縱橫單向凸圖像形心方法計(jì)算公式的幾何意義。研究了濾除畸變二值含噪光斑圖像單點(diǎn)噪聲的濾波閾值獲取。結(jié)合不斷變化的大氣湍流對(duì)光斑的影響，將每一幀受到大氣擾動(dòng)的畸變光斑與單點(diǎn)噪聲的濾波閾值聯(lián)系起來(lái)，提出了二值圖像單點(diǎn)噪聲濾波閾值長(zhǎng)記憶動(dòng)態(tài)優(yōu)化方法，綜合濾波閾值的歷史記憶逐幀優(yōu)化當(dāng)前濾波閾值。 提出高精度跟瞄偏差角獲取的迭代頻譜相位分布再生方法。根據(jù)衍射光學(xué)理論迭代生成頻譜相位分布，只利用遠(yuǎn)距離接收激光終端CMOS獲得的光強(qiáng)分布，構(gòu)成入射激光光束在CMOS處的光場(chǎng)分布，經(jīng)過(guò)近似卷積處理得到相位校正后光斑的光強(qiáng)分布，并結(jié)合再生縱橫單向凸圖像形心方法，穩(wěn)定獲得高精度跟瞄偏差角。給出了迭代頻譜相位校正后，跟瞄偏差角度的計(jì)算公式。對(duì)迭代頻譜相位分布再生方法確定迭代初值選取進(jìn)行了研究。將相位迭代初值的選取與光斑峰值相聯(lián)系，使相位迭代初值隨著大氣湍流不斷變化。研究了采用迭代初值選取策略后迭代頻譜相位分布再生方法收斂速度變化，并與傳統(tǒng)方法相對(duì)比。分析了對(duì)迭代頻譜相位分布再生方法產(chǎn)生的誤差，確定校正系數(shù)。 根據(jù)大氣信道下光傳播理論，模擬激光光束經(jīng)長(zhǎng)距離傳輸后的光畸變場(chǎng)，建立數(shù)值仿真模型。利用兩個(gè)光學(xué)終端在距離為11.2km的城市鏈路上進(jìn)行了星地激光鏈路跟瞄偏差角度探測(cè)地面模擬實(shí)驗(yàn)。通過(guò)仿真及實(shí)驗(yàn)對(duì)不同大氣閃爍指數(shù)下的靜態(tài)光斑圖像和沿一定軌跡移動(dòng)的動(dòng)態(tài)光斑圖像進(jìn)行研究。 本文提出了再生縱橫單向凸圖像形心方法和迭代頻譜相位分布再生方法，利用星地激光通信系統(tǒng)接收激光終端CMOS獲得的入射激光光束光斑的光強(qiáng)分布，抑制大氣湍流對(duì)星地激光通信激光光束的影響，計(jì)算獲得高精度跟瞄偏差角，有利于提高星地激光通信捕獲瞄準(zhǔn)跟蹤系統(tǒng)的性能，快速建立并穩(wěn)定保持星地激光通信鏈路。這些研究工作對(duì)于星地激光通信系統(tǒng)的優(yōu)化設(shè)計(jì)和提高系統(tǒng)的通信性能具有重要理論指導(dǎo)意義和實(shí)際應(yīng)用價(jià)值。
[Abstract]:In the satellite ground laser communication system, the width of the laser beam is very narrow and the receiving field is small. In order to quickly establish and maintain a long distance satellite and ground laser communication link, the laser communication terminal must have high precision beam aiming ability and high precision stability tracking ability. It is very urgent and necessary for us to establish and maintain the satellite laser communication link quickly.
Atmospheric channel is part of the satellite ground laser communication channel. The laser beam, as the information carrier, will be affected by atmospheric turbulence when it passes through the atmosphere. In the satellite ground laser communication system, the turbulence effect of the atmosphere will affect the intensity distribution of the light spot formed by the beacon laser beam in the receiving terminal of the tracking system, produce the spot distortion and reduce the aim. The quasi capture tracking accuracy reduces the accuracy of the system detection, increases the aim deviation, reduces the receiving power, and increases the bit error rate, and even makes the establishment and maintenance of the satellite and ground laser links difficult. Holding is of great significance.
The problem is how to use the light intensity distribution of the incident laser beacon beam obtained by the receiving laser terminal CMOS, to suppress the influence of the atmospheric turbulence on the detection accuracy of the tracking deviation angle, and to find a method to obtain the high precision tracking deviation angle. This is the key problem for the rapid establishment and stability of the satellite ground laser communication link. 1.
First, the research progress of satellite and earth satellite laser communication technology at home and abroad is summarized. The basic theory and detection mechanism of tracking deviation angle are introduced, and the method of obtaining the angle of tracking deviation is analyzed. On this basis, the research work of this paper is further carried out.
In the process of filtering the noise of the distorted two valued spot image, the Euclidean distance from the bright pixel to the full image geometry center is used as a criterion to judge whether the pixel is a single point noise in the process of filtering the noise of the distorted two valued spot, and it is a criterion to determine whether the pixel is a single point noise. In the vertical direction, the light spot is reconstructed into a single connected convex image. The geometric center of the regenerated longitudinal and horizontal unidirectional convex image is close to the ideal spot center of the incident laser beam on the receiving laser terminal CMOS. The higher precision of the tracking deviation angle is obtained. The geometric meaning of the calculation formula of the regenerated longitudinal and horizontal unidirectional convex image centroid method is given. In addition to the filtering threshold of the single point noise in the distorted two valued spot image, combined with the influence of the changing atmospheric turbulence on the spot, the dynamic optimization method of the threshold length memory of the two value image single point noise filtering is proposed, and the comprehensive filtering threshold is proposed. The historical memory optimizes the current filter threshold by frame by frame.
An iterative spectrum phase distribution regeneration method obtained by high precision tracking deviation angle is proposed. The spectrum phase distribution is generated according to the diffractive optical theory. Only the light intensity distribution obtained by the long distance receiving laser terminal CMOS is used to form the light field distribution of the incident laser beam at CMOS, and the phase corrected spot is obtained after the approximate convolution processing. The distribution of light intensity is combined with the regenerated vertical and horizontal convex image centroid method, and the high precision tracking deviation angle is obtained. The calculation formula of the angle of tracking deviation is given after the phase correction of iterative spectrum. The selection of iterative initial value is determined by the iterative method of phase distribution regeneration of the iterative spectrum. To make the phase iterative initial value change with the atmospheric turbulence, the convergence rate of the iterative spectrum phase distribution regeneration method after the iterative initial value selection strategy is studied and compared with the traditional method. The error generated by the iterative method of the phase distribution regeneration of the iterative spectrum is analyzed, and the correction coefficient is determined.
According to the theory of light propagation under the atmospheric channel, a numerical simulation model is established to simulate the optical distortion field of laser beam after long distance transmission. The ground simulation experiment of the satellite ground laser link heel tracking deviation angle is carried out on a city link with distance of 11.2km. Through simulation and experiment, two optical terminals are used in the different atmospheric scintillation index. The static spot image and the dynamic spot image moving along a certain trajectory are studied.
In this paper, the image centroid method of regenerated longitudinal and horizontal unidirectional convex image and the method of regenerating the phase distribution of the iterative spectrum are proposed. The intensity distribution of the incident laser beam obtained by the satellite ground laser communication system received by the laser terminal CMOS is used to suppress the influence of atmospheric turbulence on the laser beam of the satellite and ground laser communication, and the high precision tracking deviation angle is calculated. In order to improve the performance of the satellite ground laser communication acquisition and tracking system, the satellite ground laser communication link is quickly established and maintained. These research work has important theoretical guiding significance and practical application value for the optimization design of the satellite and ground laser communication system and the improvement of the communication performance of the system.
【學(xué)位授予單位】：哈爾濱工業(yè)大學(xué)
【學(xué)位級(jí)別】：博士
【學(xué)位授予年份】：2014
【分類號(hào)】：TN929.1
本文編號(hào)：2130993
[Abstract]:In the satellite ground laser communication system, the width of the laser beam is very narrow and the receiving field is small. In order to quickly establish and maintain a long distance satellite and ground laser communication link, the laser communication terminal must have high precision beam aiming ability and high precision stability tracking ability. It is very urgent and necessary for us to establish and maintain the satellite laser communication link quickly.
Atmospheric channel is part of the satellite ground laser communication channel. The laser beam, as the information carrier, will be affected by atmospheric turbulence when it passes through the atmosphere. In the satellite ground laser communication system, the turbulence effect of the atmosphere will affect the intensity distribution of the light spot formed by the beacon laser beam in the receiving terminal of the tracking system, produce the spot distortion and reduce the aim. The quasi capture tracking accuracy reduces the accuracy of the system detection, increases the aim deviation, reduces the receiving power, and increases the bit error rate, and even makes the establishment and maintenance of the satellite and ground laser links difficult. Holding is of great significance.
The problem is how to use the light intensity distribution of the incident laser beacon beam obtained by the receiving laser terminal CMOS, to suppress the influence of the atmospheric turbulence on the detection accuracy of the tracking deviation angle, and to find a method to obtain the high precision tracking deviation angle. This is the key problem for the rapid establishment and stability of the satellite ground laser communication link. 1.
First, the research progress of satellite and earth satellite laser communication technology at home and abroad is summarized. The basic theory and detection mechanism of tracking deviation angle are introduced, and the method of obtaining the angle of tracking deviation is analyzed. On this basis, the research work of this paper is further carried out.
In the process of filtering the noise of the distorted two valued spot image, the Euclidean distance from the bright pixel to the full image geometry center is used as a criterion to judge whether the pixel is a single point noise in the process of filtering the noise of the distorted two valued spot, and it is a criterion to determine whether the pixel is a single point noise. In the vertical direction, the light spot is reconstructed into a single connected convex image. The geometric center of the regenerated longitudinal and horizontal unidirectional convex image is close to the ideal spot center of the incident laser beam on the receiving laser terminal CMOS. The higher precision of the tracking deviation angle is obtained. The geometric meaning of the calculation formula of the regenerated longitudinal and horizontal unidirectional convex image centroid method is given. In addition to the filtering threshold of the single point noise in the distorted two valued spot image, combined with the influence of the changing atmospheric turbulence on the spot, the dynamic optimization method of the threshold length memory of the two value image single point noise filtering is proposed, and the comprehensive filtering threshold is proposed. The historical memory optimizes the current filter threshold by frame by frame.
An iterative spectrum phase distribution regeneration method obtained by high precision tracking deviation angle is proposed. The spectrum phase distribution is generated according to the diffractive optical theory. Only the light intensity distribution obtained by the long distance receiving laser terminal CMOS is used to form the light field distribution of the incident laser beam at CMOS, and the phase corrected spot is obtained after the approximate convolution processing. The distribution of light intensity is combined with the regenerated vertical and horizontal convex image centroid method, and the high precision tracking deviation angle is obtained. The calculation formula of the angle of tracking deviation is given after the phase correction of iterative spectrum. The selection of iterative initial value is determined by the iterative method of phase distribution regeneration of the iterative spectrum. To make the phase iterative initial value change with the atmospheric turbulence, the convergence rate of the iterative spectrum phase distribution regeneration method after the iterative initial value selection strategy is studied and compared with the traditional method. The error generated by the iterative method of the phase distribution regeneration of the iterative spectrum is analyzed, and the correction coefficient is determined.
According to the theory of light propagation under the atmospheric channel, a numerical simulation model is established to simulate the optical distortion field of laser beam after long distance transmission. The ground simulation experiment of the satellite ground laser link heel tracking deviation angle is carried out on a city link with distance of 11.2km. Through simulation and experiment, two optical terminals are used in the different atmospheric scintillation index. The static spot image and the dynamic spot image moving along a certain trajectory are studied.
In this paper, the image centroid method of regenerated longitudinal and horizontal unidirectional convex image and the method of regenerating the phase distribution of the iterative spectrum are proposed. The intensity distribution of the incident laser beam obtained by the satellite ground laser communication system received by the laser terminal CMOS is used to suppress the influence of atmospheric turbulence on the laser beam of the satellite and ground laser communication, and the high precision tracking deviation angle is calculated. In order to improve the performance of the satellite ground laser communication acquisition and tracking system, the satellite ground laser communication link is quickly established and maintained. These research work has important theoretical guiding significance and practical application value for the optimization design of the satellite and ground laser communication system and the improvement of the communication performance of the system.
【學(xué)位授予單位】：哈爾濱工業(yè)大學(xué)
【學(xué)位級(jí)別】：博士
【學(xué)位授予年份】：2014
【分類號(hào)】：TN929.1
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本文編號(hào)：2130993
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