共查询到19条相似文献,搜索用时 140 毫秒
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部分相干光通过强湍流对通信系统误码率的影响 总被引:1,自引:0,他引:1
为研究部分相干光通过强湍流对系统误码率的影响,借助对激光在大气湍流场中的传输方程进行解析求解(忽略系统中其他噪声,仅考虑由大气湍流引起的系统误码率),得到不同湍流内尺度、传输激光波长和光源相干参数条件下,系统误码率和传输距离的关系.结果表明:在强湍流条件下,当发射天线数目达到一定时,随着传输距离的增加,系统误码率逐渐增大,但增大到一定程度后趋于饱和;光源相干参数越大,系统误码率越低;湍流内尺度越大,系统误码率越高;传输激光波长的变化对系统误码率无明显影响. 相似文献
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多发射机在大气激光通信中的应用 总被引:3,自引:3,他引:0
大气湍流引起的光强闪烁会严重影响大气激光通信系统的性能,使误码率增加。研究表明误码率随对数振幅方差(湍流强度)的增加而上升,为了减小误码率,可以采用多点发射以减小大气湍流对系统的影响,从而提高系统的可靠性。 相似文献
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大气激光通信中多光束传输性能分析和信道建模 总被引:32,自引:6,他引:26
多光束传输技术是克服大气激光通信中大气湍流效应的有效途径之一。首先从理论上分析了大气湍流对多光束大气激光通信系统性能的影响和多光束大气传输的光强起伏特性,然后利用统计分析的方法,建立了一个以传输距离z、光束数目n、发射孔径之间的距离St、接收孔径Dr等为参量的多光束大气传输信道模型。最后,结合相关文献提供的实验结果对该信道模型进行了实验验证和误码性能分析。结果表明,当S1≥√λz或Dr远大于大气湍流相干长度ρo时,随着n的增大,接收光强将趋于对数正态分布.降低了大气激光通信系统的误码率,从而验证了多光束传输对于克服大气湍流影响的有效性。 相似文献
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基于大气湍流效应的双波长激光传输特性实验研究 总被引:1,自引:0,他引:1
为研究大气湍流作用下不同波长激光信号的传输特性,建立了基于双波长条件下的激光光束传输实验测试系统,在此基础上进行了室外实验测量,得到了双波长光束同信道传输时的光束漂移和光强起伏变化的测试数据。实验结果表明,大气湍流对激光信号的传输具有较大的影响,且光强的闪烁系数与波长有很大的关系,选择波长较长的激光束可减少湍流对光强起伏的影响;光束质心漂移具有很大的随机性,且其质心变化与波长之间无明显的直接联系。实验测试数据结果与大气湍流理论相符合,对空间大气通信具有一定的参考价值。 相似文献
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多光束发射对湍流效应下激光传输的影响 总被引:2,自引:0,他引:2
大气湍流引起的光强起伏会导致大气闪烁、光束漂移、到达角起伏和波前畸变等效应.多光束发射技术是克服激光大气传输中光强起伏的有效途径之一.以单光束、双光束、四光束以及八光束发射为例,通过计算峰值光强、环围功率半径以及像散参数等光束质量参数,得到单光束和多光束大气传输的光强起伏特性.结果表明:随着光束数目的增加,峰值光强显著... 相似文献
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This paper shows the impact of atmospheric turbulence-induced fading on the symbol decision position in the on-off keying (OOK) and the binary phase shift keying (BPSK) subcarrier intensity modulated (SIM) laser communication link. Weak turbulence is simulated in the laboratory using a chamber equipped with heating elements and fans. We have shown that in atmospheric turbulence, it is advantageous to employ modulation schemes such as pulse time and subcarrier intensity modulations that do not directly impress data on the optical irradiance as is the case with the OOK. For the OOK-modulated laser communication system, atmospheric turbulence imposes complexity on the symbol decision subsystem and by extension places a limit on the achievable bit error rate (BER) performance. 相似文献
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Pointing errors caused by the atmospheric turbulence will degrade the performance of free space optical (FSO) communication systems, especially the bit error rate (BER). In this paper, we innovatively analyze the relationship between BER and pointing errors by the probability density functions (PDFs) and intensity displacement in focal plane under the On-Off Keying (OOK) modulation conditions. The closed-loop experimental system is set up in laboratory, where the fast steering mirror (FSM) is real-time controlled by embedded controller with the parallel processing technology and the atmospheric turbulence is simulated by a turbulence simulation box. The results of repeated experiments show that the method of pointing errors correction we proposed is efficient under the conditions of atmospheric turbulence. By utilizing our method, the BER can decrease from nearly 10−3 to nearly or even below 10−9, thus improving the performance of FSO communication systems significantly. 相似文献
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Wenhe Du Feizhan Chen Zhongmin Yao Ruibo Ai Daosen Liu Quanling Cui 《Journal of Russian Laser Research》2013,34(4):351-355
In satellite–ground laser communications, atmospheric turbulence in the link degrades the performance of the system, so it is very important to estimate its influence on the performance of the system. The bit-error rate (BER) is an important parameter to indicate the communication performance of the system, which is directly used to judge the quality of the communication system. Using the results of our two previous papers, we analyze the joint influence of Kolmogorov turbulence from the ground up to 6 km and non-Kolmogorov turbulence above 6 km on the BER. These kinds of turbulence are associated respectively with the uplink and the downlink propagation channels for the geosynchronous orbit satellite communication system. 相似文献
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《Waves in Random and Complex Media》2013,23(2):224-234
AbstractDense wavelength division multiplexing (DWDM) has been widely applied in ground optical communication. However, the technology of DWDM is still not mature enough in the space optical communication system. In order to further advance the use of DWDM into space optical communication, the probability density function (PDF) and the bit-error rate (BER) performance of DWDM is investigated in uplink communications under the influence of atmospheric turbulence, consisting of intensity scintillation and beam wander caused by atmospheric turbulence. Numerical results show that the atmospheric turbulence has a great impact on BER and PDF, and wavelength, divergence angel, and other relevant parameters should be carefully considered in this DWDM system. This work can be conducive for improving DWDM design of space optical uplink communication systems. 相似文献
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In free-space optical communication links, atmospheric turbulence causes fluctuations in both the intensity and the phase of the received signal, affecting link performance.Influence of Kolmogorov and non-Kolmogorov turbulence statistics on laser communication links are analyzed for different propagation scenarios, and effects of different turbulence spectrum models on optical communication links are presented. Statistical estimates of the communication parameters such as the probability of fade (miss) exceeding a threshold dB level, the mean number of fades, and BER are derived and examples provided. The presented quantitative data suggest that the non-Kolmogorov turbulence effects on lasercom channels are more severe in many situations and need to be taken into account in wireless optical communication. Non-Kolmogorov turbulence is especially important for elevations above the boundary layer as well as for even low elevation paths over water. 相似文献
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In this paper, the effects of auto-tracking subsystems on the Bit-Error-Rate (BER) and reliability of free-space optical (FSO) communication links are investigated. Considering environmental influences on the laser beam intensity distribution in receiver, we study the propagation properties of Gaussian laser beams through a complete optical path. Then it is tried to derive an analytical formula for intensity distribution along the complete optical path as well as on the receiver's detector plane based on the Collins integral. Based upon the intensity formula, we calculate the values of signal to noise ratio (SNR), BER, and power while considering the effects of atmospheric losses due to absorption, scattering and turbulence on them. Using mentioned values, the role of auto-tracking subsystems on link reliability improvement in adverse weather condition is described. The related results are illustrated by graphs obtained by calculations and simulations. 相似文献
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Strong atmospheric turbulence is a major hindrance in wireless optical communication systems. In this paper, the performance of a wireless optical communication system is analyzed using different modulation formats such as, binary phase shift keying-subcarrier intensity modulation (BPSK-SIM), differential phase shift keying (DPSK), differential phase shift keying-subcarrier intensity modulation (DPSK-SIM), M-ary pulse position modulation (M-PPM) and polarization shift keying (PolSK). The atmospheric channel is modeled for strong atmospheric turbulences with combined effect of turbulence and pointing errors. Novel closed-form analytical expressions for average bit error rate (BER), channel capacity and outage probability for the various modulation techniques, viz. BPSK-SIM, DPSK, DPSK-SIM, PolSK and M-PPM are derived. The simulated results for BER, channel capacity and outage probability of various modulation techniques are plotted and analyzed. 相似文献