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提出地对地链路的云散射模型,用于分析不同类型云对给定波长信号光的信道传输特性。通过模型仿真,定量分析不同通信几何结构条件下,三种云的路径损耗预测,分析了发送、接收仰角、发送光束束散角等因素对路径损耗的影响。结果表明,当接收视场角固定时,最佳通信距离随着发送、接收仰角的增大而减小;当发送光束束散角很小(1°以下)时,需要调整发送仰角使得信号光源在云层下界形成的光斑位于检测器垂直上方,以达到接收能量的最大值;当发送光束束散角较大时,应调整发送、接收仰角使一次有效散射体积最大,使得接收能量最大。通过实验测量云散射链路的路径损耗,验证了结论的正确性。结论与波长相关,选用620nm和808nm两种波长激光二极管作为实验及仿真的光源。
This paper proposes a cloud-to-ground link scattering model to analyze the channel transmission characteristics of different types of clouds for a given wavelength of signal light. Through the simulation of the model, the path loss prediction of three kinds of clouds under different communication geometries is quantitatively analyzed, and the influence of sending, receiving elevation angle and sending beam angle on the path loss is analyzed. The results show that when the receiving angle is fixed, the optimal communication distance decreases with the increase of transmitting and receiving angles. When the transmitting beam angle is very small (less than 1 °), the elevation angle needs to be adjusted so that the signal light source The light spot formed in the lower boundary of the cloud is located vertically above the detector to reach the maximum value of the received energy. When the transmitted beam angle is larger, the transmit and receive elevation angles should be adjusted to maximize the effective scattering volume so as to maximize the receiving energy. By experimentally measuring the path loss of the cloud-scattered link, the correctness of the conclusion is verified. The conclusion is wavelength-dependent. The two wavelength laser diodes, 620 nm and 808 nm, are chosen as experimental and simulation light sources.