A real-time algorithm is proposed for pointing, acquiring, tracking and predicting the laser spot in intersatellite optical communications (IOC) system. Since the approximate position of laser spot was acquired by grid scanning in the max interest area of CCD, a tracking window was covered with the target. The best image segmentation threshold was generated based on the Ostu image segmentation algorithm. Due to the threshold, the centric theory was used for calculating the exact position of laser spot within an image of tracking window. In case of attaining the actual location data of the target, the coming position of the laser spot can be provided. This drives the system to operate on predicting the state and improving the responsive bandwidth. The results show that the speed of image processing is up to 625 frames/s when the tracking window is set to 100 × 100.

Kun Yu Tao;Fu Wang;Yan Ping Zhou;晶 马

Harbin Gongye Daxue Xuebao/Journal of Harbin Institute of Technology

2008-11

A truncated ellipse Gaussian model to express localized distortion is developed to a transmission-type optical antenna, based on which the effects of localized deformation on pointing and tracking errors are researched. It is shown that localized distortion has the greatest influence on pointing and tracking errors when distortion deepness h ≈ 0.8λ, which does not depend on other distortion parameters. To reduce the impact of localized deformation on pointing and tracking errors, the machining precision of the objective lens of the transmission-type antenna should be much better than 0.8λ. The requirement of the machining precision for lenses is lower than that for mirrors. The maxima of pointing and tracking errors due to the localized distortion with different radii are given. We hope the results can be used in the design of intersatellite optical communication systems.

Yuqiang Yang;Liying Tan;晶 马

Applied Optics

2009-2-1

This paper studied the influence of neutron irradiation on the characteristics of 980nm pumped erbium-doped fiber amplifier(EDFA). After 7 days neutron irradiation, with the total fluence of 1.5×10¹³n/cm², radiation induced loss changed little compared with pre-irradiation, maximum difference of single signal and WDM signal between pre-irradiation and post- irradiation are 0.5dB and 0.6dB, respectively. EDFA affected by neutron irradiation got less loss when the input signal power is higher.

晶 马;Qing Feng Liu;Li Ying Tan

2013

Based on the characteristics of the laser device and the inevitable error of the processing technique, a laser beam emitted from a communication terminal can be represented by the Gaussian Schell model (GSM). In space-to-ground link laser communications, the optical intensity is affected by the source coherence parameter and the zenith angle. With full consideration of these two parameters, the statistical distribution model of the optical intensity with a GSM laser in both downlink and uplink is derived. The simulation results indicate that increasing the source coherence parameter has an effect on the statistical distribution of the optical intensity; this effect is highly similar to the effect of a larger zenith angle. The optical intensity invariably degrades with increasing source coherence parameter or zenith angle. The results of this work can promote the improvement of the redundancy design of a laser communication receiver system.

Mengnan Li;Liying Tan;晶 马;Siyuan Yu;Qingbo Yang;Jiajie Wu

Journal of Modern Optics

2016-5-30

In this paper, burst errors in uplink communication due to lags of the tracking system control in Satellite to Ground optical link was analyzed in detail. In order to make sure how about these bursts in uplink communication are affected by control frequency can, system model of the satellite terminal was founded, parameters of a satellite in sun synchronous Low Earth Orbit and detectors were set to initialize the simulations. The zenith angle of the link was set in the range of [0°, 70°]. The simulation results showed that the bursts due to lags of the tracking system control were different for communication links, but the bursts can be avoided by raising the control frequency to a certain level if it accessible.

Qiwen Ran;Zhonghua Yang;晶 马;Liying Tan;Shichen Wu;Qingfeng Liu;Huixi Liao

2012

Heterodyne efficiency in free-space optical communications based on heterodyne detection is degraded by the aberrations of the optics antenna used for reception of optical beams. The evolution of heterodyne efficiency with the change of rms of primary aberrations is investigated. It is shown that heterodyne efficiency decreases gradually with increasing primary aberrations. The comparison shows that different aberration types have variant influence on heterodyne efficiency. In addition, obscuration ratio of receiver antenna has a noticeable but relatively minor influence on heterodyne efficiency. We hope this work can benefit system design of heterodyne receiver in free-space coherent communications.

Qingbo Yang;Liying Tan;晶 马

2011

The quantum bit rate is an important operating parameter in free-space quantum key distribution. We introduce the measuring factor and the sifting factor, and present the expressions of the quantum bit rate based on the ideal single-photon sources and the single-photon sources with Poisson distribution. The quantum bit rate is studied in the numerical simulation for the laser links between a ground station and a satellite in a low earth orbit. The results show that it is feasible to implement quantum key distribution between a ground station and a satellite in a low earth orbit.

晶 马;Guang Yu Zhang;Li Ying Tan

Chinese Physics Letters

2006-6-1

We report on a novel technology for high-speed inter-satellites optical communication by bidirectional beam tracking. By establishing the relation between the compensation effect and the parameters of response time and overshoot situation, the stability can be well compensated simply by the control system. Thus the relation between compensation effect and maintain time can be predicted from ground tests, and the certain evaluation standard could be established to meet the requirements of system. The other critical factors, such as signal-to-noise ratio and pointing angle error, have also been considered to improve the stability. The general approach can provide us a powerful path to overcome the performance limitation of bidirectional beam tracking, which can be expected to be widely applied in Free Space optics communications in future.

Siyuan Yu;Feng Wu;Liying Tan;Pengzhen Guo;晶 马

Optics Express

2015-10-19

A method of compensating the satellite vibrations in intersatellite laser links was presented. The satellite vibrations were detected by a CCD instead of the traditional angular sensors, so the tracking system was simplified. The angular errors from the satellite vibrations influence the beam tracking, while these errors can be well compensated by a feedforward control system. An experimental study on the vibration compensation technology was performed, and a vibration simulation device and a feedforward compensation system were built in the lab. Using a CCD with the sampling frequency of 1 kHz, tracking errors can be reduced by 71% after vibration compensation when the frequency of angular vibrations is 100 Hz.

Si Yuan Yu;Li Ying Tan;晶 马;Jun Wang

Guangdianzi Jiguang/Journal of Optoelectronics Laser

2004-4

We present a simple and systematic way of designing stabilization fuzzy PID (Proportional-Integral-Differential), PI (Proportional-Integral), and PD (Proportional-Differential) controllers for the T-S fuzzy model. The state space representations of the fuzzy PD, PI, and PID controllers are firstly presented. Then we equivalently transform the fuzzy PID (PI, or PD) control system into the fuzzy static output feedback control system. The fuzzy static output feedback controller design for the latter system can be efficiently solved via the existing numerical optimization methods with some conservatism. Consequently, the fuzzy PID (PI, or PD) controller can be derived due to the one-on-one correspondence between the fuzzy PID controller and the fuzzy static output feedback controller. We use a numerical simulation example to show the effectiveness of our proposed methods.

Kairui Cao;X. Z. Gao;Xing Wang;H. K. Lam;晶 马

2016-1-13