大型船载测控雷达船摇隔离度的分析

分析了船摇扰动对大型船载测控雷达两轴稳定系统的影响，提出了隔离船摇的几种方法，并用工程实例验证了方法的正确性。     

大型船载测量雷达天线的两轴稳定

给出某大型测量船实测船摇频谱，讨论了大型船载测量雷达天线两轴稳定的隔离效果及实测结果。     

船载测量雷达稳定回路作用分析

分析了船载测量雷达陀螺稳定回路的作用机理,以及稳定回路作用前后雷达跟踪稳定性。用Matlab对稳定回路作用前后跟踪回路进行了仿真,对分系统误差分量和随机误差分量进行了跟踪精度分析,并通过两次测量任务数据处理结果的比较,证明船摇较小时,加入稳定回路会造成跟踪精度的降低。     

船载天线伺服系统抗摇摆方案研究

提出了四种切实可行的抗摇摆方案,包括坐标变换法、具有陀螺环的零值自跟踪方案、四轴稳定体制、X—Y天线座。从机械到电气方面详细分析了各方案的工作原理、设计要点、特点及适用场合。     

速率陀螺应用方法研究

详细分析、计算了速率陀螺在反馈稳定环和补偿环中的应用效果。补偿环优于反馈环。     

控制系统中前馈控制与反馈控制的区别

文中主要阐述在自动控制系统中前馈控制与反馈控制之间的区别以及内在的联系。     

船载卫星通信地球站跟踪精度分析

跟踪精度是评价卫星通信地球站质量的重要指标,但对船载卫星通信地球站的精度,目前还没有系统的分析方法,论述了船载卫星通信地球站的跟踪精度指标,分析了影响船载卫星通信地球站跟踪精度的误差源.采用分析最恶劣工作环境条件同时,给出了均方根误差估算分析方法,以7.3 m船载卫星通信地球站为例进行跟踪精度指标的确定及分析估算.实践结果表明:对船载卫星通信地球站跟踪精度的分析估算方法满足工程需要.可作为船载卫星通信地球站跟踪精度指标的确定及精度分析估算的参考.     

舰载测量雷达船摇稳定回路设计

速率陀螺敏感于天线空间运动角速率,故可将陀螺感受的角速率信息作为反馈信息构成负反馈回路,通过加入船摇扰动前馈补偿环节,实现稳定回路的复合控制。再通过误差校正后将船摇补偿输出到功放,驱动天线方位及俯仰运动,达到隔离船摇扰动对天线指向影响的目的。设计已成功应用于舰载测量雷达的研制中,经对雷达性能测试,船摇隔离度达到50 dB。     

船用数字两轴稳定控制系统

本文在推导两轴稳定控制理论数学模型的基础上，独立地提出了工程适用的稳定控制公式，阐述了控制特点，介绍了速度控制，瞬时位置外推控制两种方法，给出了控制精度的试验结果。     

船载角跟踪系统船摇模拟器设计

舰船等航海设备在大海中航行会受到海洋气象环境的影响发生摇荡,其角跟踪性能会受船摇影响,可能难以跟踪目标,需要预先进行模拟分析以减小危害.角跟踪系统模拟船摇时,根据船摇信息,通过对无船摇影响的位置矢量进行欧拉角旋转,得到受船摇影响的位置矢量;利用矩阵变换解算出受船摇影响的轨道参数,进而推导出受船摇影响的和差支路信号功率及...     

A shipborne fading reduction antenna system for maritime satellite communications

Multipath fading due to reflected waves from a sea surface is serious in maritime satellite communications. A shipborne antenna system which reduces the fading by using the cross-polarized component of the reflected waves is presented.     

Intelligent antenna technology for mobile satellite communications

Intelligent antenna is important for mobile satellite communications because it can increase the channel capacity, spectrum efficiency and coverage range of the communication systems. This paper overviews the technology for intelligent arrays with design examples. A detailed list of references is given in the end of this paper.     

The design of the mechanically despun antenna for the Intelsat III communications satellite

The use of a spin-stabilized communications satellite of large channel capacity requires a high-gain antenna which may be despun, mechanically or electronically, with respect to the satellite. The design of a mechanically despun antenna system for the Intelsat-III communications satellite is discussed. The communications signals utilize a high-gain directive antenna which is mechanically despun while an omnidirectional antenna is used for the telemetry information. Positional control of the directional antenna is provided by the control electronics subsystem such that the antenna is always pointed directly at the earth. Satellite-borne infrared earth sensors provide earth reference pulses to the control electronic subsystem for antenna despin stabilization and pointing. Also discussed is the bearing and lubrication system for the antenna drive assembly. In-orbit performance of the two systems launched is also given.     

ATS mechanically despun communications satellite antenna

The antenna system described is one of the experiments on NASAs ATS-III spin stabilized satellite that was launched on November 5, 1967. It was put into synchronous orbit shortly thereafter and has been operating satisfactorily since. Using a line source feed illuminating a parabolic cylindrical reflector, a linearly polarized gain over 17 dB is achieved. The antenna is positioned by means of a vernier type stepping motor-drive system that points the antenna beam towards earth within approximatelypm0.7degree in accordance with instructions received on the satellite from the ground control station. Prior to launch, the antenna system was subjected to extensive qualification testing. Confidence in a desired five-year life in orbit for the motor-drive system was obtained by testing the lubrication system and bearings for 7800 hours at temperatures ranging from-80degF to+120degF at vacuum pressures as low as1 times 10^{-8}torr.     

Simple, small antenna terminal for maritime satellite communications

A simple printed antenna that can be utilised for maritime satellite communications is presented. The antenna is based on a dual linearly polarised proximity coupled microstrip antenna on an extended hemispherical dielectric lens. The resulting small printed antenna is impedance matched over both the transmit (14.0-14.5 GHz) and receive (12.25-12.75 GHz) bands and has a gain of 21 and 20 dBi, respectively, over these frequency ranges.     

Dual offset reflector multibeam antenna for international communications satellite applications

Dual offset reflector antenna systems offer exciting possibilities for achieving both low scan losses and low cross polarization in geosynchronous communications satellite antennas providing narrow (100 leq D/lambda leq 400) and multiple beam frequency reuse coverages over an18degconical field of view. Novel geometrical configurations for the reflectors are characterized by simultaneously achieving: 1) blockage free apertures for all element beams within the18degconical field of view, 2) compatibility with large planar feed arrays, 3) additional degrees of design freedom by orientation and shaping of reflector surfaces for depolarization and scan loss optimization, and 4) large effectivef/Dratio achieved in compact and foldable geometries. A comparison of new front-fed offset Cassegrain (FFOC) and side-fed offset Cassegrain (SFOC) systems is made.     

基于Simulink仿真的用户星天线控制系统分析

为满足中继卫星系统对天线指向精度的要求,首先描述了天线指向控制概念,对用户星与中继卫星星间链路的建立过程进行了分析,并且设计了星上自主控制方案,在Simulink环境下对所设计的天线指向控制系统进行了数学仿真,最后通过对仿真结果的分析验证了用户星天线控制系统的跟踪性能。     

耐高温卫星导航天线

设计了一种陶瓷基底的右旋圆极化微带天线,能够满足高温环境下卫星导航系统的应用.天线设计特点有以下四点:天线外形具有低轮廓特性, 适合高速运动飞行器表面的贴装; 采用钛合金材料和高温陶瓷材料, 能够在400 ℃高温环境下正常工作, 具有优异的耐热性能; 加工装配流程均无焊接工艺, 确保天线组件的电连接在高温冲击下的可靠性; 采用中心短路销钉设计, 减少同轴馈针的感抗, 获得优异的阻抗匹配特性.通过仿真优化和实际测试, 验证了该天线性能优异, 满足高温环境下的卫星导航系统的使用要求.     

L频段低仰角覆盖机载前舱卫通天线

目前用于机载前舱卫星通信的L频段终端系统设备,全部是由国外厂商提供,且多采用平面阵或机械扫描的方式.提出"屋顶"形天线阵列来实现超低仰角覆盖,设计并研制了L频段机载前舱卫通相控阵天线样机.地面静态对星试验结果表明,天线样机可与海事卫星实现稳定通信,通信速率为310 kb/s,通信质量良好.相比于以往的平面布阵或机械扫描...     

Dual-band circularly polarized equilateral triangular-patch array antenna for mobile satellite communications

The Japan Aerospace Exploration Agency will launch the Engineering Test Satellite VIII (ETS-VIII) in 2006 to support the next generation of mobile satellite communications covering the area of Japan (beam coverage El=38/spl deg/ to 58/spl deg/). In this paper, a satellite-tracking left-handed circularly polarized triangular-patch array antenna is developed for ground applications. The targeted minimum gain of the antenna is set to 5 dBic at the central elevation angle (El=48/spl deg/), in the Tokyo area, for applications using data transfer of around a hundred kbps. The antenna is composed of three equilateral triangular patches for both reception and transmission units operating at 2.50 and 2.65 GHz frequency bands, respectively. The antenna was simulated by method of moments (MoM) analysis, and measurement of the fabricated antenna was performed to confirm the simulation results. The measurement results show that the frequency characteristics and the 5-dBic gain coverage in the conical-cut plane of the fabricated antenna satisfy the specifications for ETS-VIII. A prototype of the proposed antenna system is employed in outdoor experiments using a pseudosatellite and shows good performance from El=38/spl deg/ to 58/spl deg/.