扩频信号声光相关解调技术

声光相关技术在检测宽带微弱信号中有很大的潜力，提出在射频上用声光相关器对扩频信号做相关运算的方案，给出扩频信号的快速捕获、精密跟踪和信息解调的方法，并设计了实验系统，结果得到了验证。     

调频连续波无线电高度表的仿真研究

阐述了调频连续波无线电高度表工作原理和仿真模型，在分析中考虑了垂直速度形成的多普勒效应，文中给出几种仿真计算的结果，分析计算结果可得知高度表的工作稳定性以及多普勒效应引起的动态误差，仿真计算程序可以应用于优化伺服系统参量或制作高度表的数学仿真器等方面。     

雷达散射截面积的计算研究

 采用矢通量分裂法在网格加密后对电磁散射场和雷达散射截面积RCS进行了检验.根据矢通量分裂法将特征值分解为正负两部分,每一部分抑制了各自的误差.目前计算RCS大都采用频域方法,运用时域方法在实际网格下进行差分运算还较少见.计算结果与网格加密前的情况基本一致.     

等效地球半径法应用中的问题

为阐明等效地球半径法应用的范围和应用中应该注意的问题,从等效地球半径法的定义推导了等效地球半径模型与实际地球模型之间量的映射关系.给出并证明了等效过程中等效地球半径模型与实际地球模型下的射线高度、仰角、长度相等,而地心角在转换过程中约为3/4的映射关系.讨论了需要利用地心角映射关系进行计算时的两种情况,同时给出计算结果和误差分析.     

SSRT: First results of millisecond spike observations

We present the results of the first observations of spike-like phenomena with the Siberian Solar Radio Telescope (SSRT) in the one-dimensional mode at the frequency of 5.7 GHz with high spatial and temporal resolutions.     

基于直线形浮标阵的反潜巡逻机监听方案

针对反潜巡逻机监听直线形浮标阵的问题,在给出该问题的背景和特点的基础上,给出了平行监听直线形浮标阵和垂直监听直线形浮标阵时的监听通用模型,提出了 4种特殊的监听直线形浮标阵方案并进行了比较。最后,通过仿真对这几种方案进行了验证。对仿真结果的分析表明了这些方案的优劣,为指挥员执行航空反潜任务提供了有效的辅助决策依据。     

极区F层不规则结构的分形模型

本文利用1986年9—12月期间17个电离层吸收事件的Riometer资料计算了电离层闪烁强度的Fourier谱和Bessel谱。求出了谱遵从的k~(-β)型函数的β值,1.8<β<2.5,平均为2.1;求出了不规则结构的漂移速度平均为129m/s。计算了各个事件的闪烁指数S_4<0.4。求出相位涨落空间谱,且指出其也遵从幂型函数k~(-α)规律。根据上述结果,本文提出极区F层不规则结构为分立的分形,不是分立的“斑块”。利用β值求出分形的分数维D=2.45。给出了不规则结构的近似分形模型。     

Evolution of an electron beam pulse influenced by coulomb collision effects in the solar corona

Electrons accelerated in the corona during solar activity give rise to radio emission events that can be observed over a wide range of frequencies. Among different finer-scale structures in the dynamic spectra observed in the radio range, fast transients with extents of some milliseconds known as solar radio spikes are observed accompaning the background continuum emission. Fundamental to the generation of radio spikes is a propagating electron beam and following its evolution allows us to understand the physical processes occurring in the solar corona. With the use of a numerical Fokker–Planck code we follow a previous numerical study to simulate the propagation of an electron beam pulse injected in a small region at the top of a magnetic field and outwards the solar corona under typical flare conditions. It was found that in large ambient densities of ${10}^{10}$ cm⁻³ at the injection point, Coulomb collision effects have an important effect on the propagation of the electrons, causing that the injected electrons thermalize faster in a time of $0.1$ and $0.4$ s for an electron distribution with a low-energy cut off of 16 and 7 keV respectively and a spectral index of 3. For a tenous ambient medium of density ${10}^9$ cm⁻³ thermalization occurs only for an electron distribution with smaller low-energy cut off (7 keV) with a duration of $\approx$1.5 s, while for a larger low-energy cut off (16 keV) the loss of accelerated electrons is very slow, regardles of the spectral index ($3,7$). The electron loss time by Coulomb collisions, which depends on the low boundary ambient density, might be an important parameter that influences the generation of radio spikes due to the formation of instabilities in the corona.     

0.5—1.5GHz快速射电频谱仪研究中的几个科学问题

本文介绍了０．５－１．５ＧＨｚ频段上的研究课题和技术方案，主要科学目标是：粒子加速过程及加速区位置的研究；小惊讶磁流力管的振荡；射电爆发精细结构和ＨＸＲ事件的相关性研究等。