一种弹载超宽带共形天线

介绍了一种可以用于弹载被动制导系统的、可以减小空间占用面积的超宽带共形对数周期折合槽天线。给出了单个天线的仿真和实测结果,以及这种天线安装于共形平台上的测试结果。该型天线采用了共面波导馈电方法,具有抗振动、抗冲击、短时耐高温等特性。此外该型天线还具有低剖面、易于安装于大型金属表面等特点。     

提高DCPR接收系统信噪比和抗干扰能力的方案

文章介绍了风云二号卫星地面应用系统工程高速数据收集平台报告信号（ DCPR）接收系统在北京气象站系统预交付联试中表现的天线频繁跟踪以及经过接收变频后的90.9MHz中频信号信噪比测试结果较差问题排查过程和有效的解决方案。问题排查过程主要针对DCPR接收系统射频接收机多个关键检测点进行测试,从测试结果和系统链路组成分析问题原因,并制定了四个具有针对性解决方案,主要是：DCPR接收系统射频接收机自带5MHz锁相晶体振荡器、加强手机信号干扰抑制、降低变频前链路增益、增加变频后链路增益以满足系统使用要求。最终将以上解决方案应用到风云二号卫星地面应用系统工程高速数据收集平台报告信号（ DCPR）接收系统中,问题得到了很好解决。     

子信道功率控制在Ka频段DT-OFDM系统中的应用研究

文章提出了子信道功率控制在Ka频段卫星通信信道DT—OFDM系统中应用的方案,给出了系统模型的组成和差分软检测方法,并根据系统模型进行了仿真。仿真结果表明应用子信道功率控制的DT—OFDM方案与传统的CC．OFDM方式相比,在10。误码率时能得到4dB的信噪比增益。     

一种有源高带外抑制导航天线设计

设计了一种有源高带外抑制导航天线,能够有效抑制弹上数据链天线的高功率干扰,适应弹上复杂电磁环境。     

An extended chirp scaling algorithm for spaceborne sliding spotlight synthetic aperture radar imaging

A system impulse response with low sidelobes is critical in synthetic aperture radar（SAR） images because sidelobes contribute to noise and interfere with nearby scatterers. However,the conventional tricks of sidelobe suppression are unable to be exactly applied to the case of spaceborne sliding spotlight SAR due to great azimuth shifts in both time and frequency domains. In this paper, an extended chirp scaling algorithm is presented for spaceborne sliding spotlight SAR data imaging. The proposed algorithm firstly uses the spectral analysis（SPECAN） technique to avoid the azimuth spectrum folding effect and then employs the chirp scaling（CS） algorithm to achieve data focusing, i.e., the so-called two-step approach. To suppress the sidelobe level, an efficient strategy for the azimuth spectral weighting which only involves matrix multiplications and short fast Fourier transformations（FFTs） is proposed, which is a post-process executed on the focused SAR image and particularly simple to be implemented. The SAR image processed by the proposed extended CS algorithm is very precise and perfectly phase-preserving. In the end, computer simulation results verify the analysis and confirm the validity of the proposed algorithm.     

有线电视HFC网络与光纤链路设计

本文论述了双向传输有线电视ＨＦＣ网络结构并比较了其优缺点，文中还就工程应用的实例讨论了光纤链路的设计问题。     

Integration and calibration of a multi slit spectropolarimeter

Multi-slit spectropolarimeter is a next-generation spectropolarimeter to obtain vector magnetic field information at high spatial, spectral, and temporal resolution for studying the magnetic structures on the Sun. Once developed, it can be used as ground based instrument at solar observatories, also as a space payload for various solar missions. A high spectral resolution is invariably an important parameter for accurate vector magnetic field measurements and faster cadence is required for the study of dynamical evolution of structures (e.g., solar flares, sunspots etc.) on the Sun and hence better understanding on the physics behind their evolution.     

超声检漏系统的研究

本文介绍了一种新型窄频带超声检漏系统，它能明显地区分环境干扰噪声与泄漏信号，其性能明显优于宽频带系统，在泄漏检测中更具实用价值。     

Identification of a 2D turbulent wind spectrum

Turbulent wind spectrum models usually involve nonrational terms. For such models the development of a Markovian time simulator relies on a rational approximation obtained by the way of an identification stage. This paper presents a general method to manage this identification stage, that provides us with a family of stable rational approximations which is proved to converge towards the true model as the dimension increases. We first give an exact but infinite dimensional state space representation of the spectrum. It is based on the use of a diffusive equation. For bi-dimensional (2D) signals it also uses decoupling by spatial Fourier transformation. Then the discretization of this exact model leads easily to stable finite dimensional approximations over a prescribed frequency range. This approach is applied to the identification of a theoretical 2D turbulent wind spectrum, and of a 1D turbulent wind spectrum estimated from in flight recorded data.     

Stability of relative equilibria of the full spacecraft dynamics around an asteroid with orbit–attitude coupling

The full dynamics of spacecraft around an asteroid, in which the spacecraft is considered as a rigid body and the gravitational orbit–attitude coupling is taken into account, is of great value and interest in the precise theories of the motion. The spectral stability of the classical relative equilibria of the full spacecraft dynamics around an asteroid is studied with the method of geometric mechanics. The stability conditions are given explicitly based on the characteristic equation of the linear system matrix. It is found that the linearized system decouples into two entirely independent subsystems, which correspond to the motions within and outside the equatorial plane of the asteroid respectively. The system parameters are divided into three groups that describe the traditional stationary orbit stability, the significance of the orbit–attitude coupling and the mass distribution of the spacecraft respectively. The spectral stability of the relative equilibria is investigated numerically with respect to the three groups of system parameters. The relations between the full spacecraft dynamics and the traditional spacecraft dynamics, as well as the effect of the orbit–attitude coupling, are assessed. We find that when the orbit–attitude coupling is strong, the mass distribution of the spacecraft dominates the stability of the relative equilibria; whereas when the orbit–attitude coupling is weak, both the mass distribution and the traditional stationary orbit stability have significant effects on the stability. We also give a criterion to determine whether the orbit–attitude coupling needs to be considered.