抗干扰通信卫星星上处理技术研究

针对卫星通信中干扰和抗干扰的特点,研究了其抗干扰体制和技术,提出了一种采用星上信号处理和扩频等多种技术实现的具体较强抗干扰能力的卫星通信系统方案,对一些关键技术进行了实验和仿真。该系统在通常情况下都具有３５ｄＢ的最低抗干扰容限,其最高干扰能力可达６０ｄＢ以上。     

GEO移动通信卫星星上处理交换技术

提出了一种新的星上处理交换技术方案,并对不同配置方式给出了性能分析和数值计算结果。分析表明,这种透明转发与星上处理相兼容的星上处理交换技术方案,只需要较少规模的星上处理单元,就能以较高的概率满足话音一跳通信的需求,相比于星上全处理降低了复杂度,相比于透明转发提高了通信质量,且适用于多种通信体制。     

数字信号星上再生处理技术

扩展射频信号带宽使其远大于发送信号所需最小宽可以增强通信信号在传输中的反对抗能力，解调／调制可以清除干扰、噪声对上行信号的影响并增强下行信号的抗干扰能力，基带处理可以进行一步提高信息传输的可靠性。通信卫星上采用这些再生处理技术可以提高卫星通信系统的反侦察、抗干扰能力。     

通信卫星星上处理技术发展现状简析

除了增加信号增益、消除＂双跳＂、IP多址,以及不用远程端口站（Teleport）的网状组网等能力外,有什么能够比星上处理对卫星通信造成的影响大呢？星上处理拥有以下潜力：实现视频的点播、容量的增加以及地面与空间网络的融合。因此,正如我们所理解的那样,卫星的革命一定到来。     

卫星移动通信中星上再生处理技术的实现方法

本文在分析几种星上处理技术性能和发展的基础上，讨论了它们在卫星移动通信中的应用及实现方法，分析了再生转发器的性能。最后讨论了采用ＤＳＰ芯片实现ＤＱＰＳＫ数字调制信号再生处理的方案，给出了框图。     

OVATION系统运行典型故障及处理方法

在总结西屋公司WDPF系统使用经验的基础上,推出了OVATION系统。文中结合该系统在本企业的实践应用,针对运行过程中出现的几种典型事故进行了分析,并提出了相应的处理方法。     

SAR 的海洋动力探测研究及应用浅析

该文在深入研究海面微波散射特性及其SAR 海面成像机理的基础上,阐述了基于 SAR 图像的海洋动力探测的探索工作。主要是从内波、水下地形波和船只尾迹产生机理的统计和水动力分析出发、研究了它们的SAR成像特征和相应的物理参数反演,以此拓展SAR 的海洋观察应用。      

一种海洋可控源电磁发射拖体姿态及海洋环境参数在线监测的方法

近年,海洋可控源电磁法(Controlled-Source Electromagnetic Method,CSEM)在海底油气资源探测中有了更进一步的应用,其中,深海拖曳式CSEM的应用更为广泛。文章把CDTV(声速剖面仪和温盐深仪)和离底高度计安装到可控源拖体上,开发了基于RS232串口数据传输的实时监测程序,进行设备数据采集,通过拖缆把参数上传,在甲板上对水下拖体姿态、离底高度和海洋环境参数进行实时监测。     

数字机顶盒常见故障及处理方法研究

文章对数字电视机顶盒的工作原理进行了介绍,并对机顶盒的各种常见故障及产生原因进行分析。最后,在故障原因分析的基础上,提出了具体的故常处理方法。     

Retrieval of Ocean Surface Parameters from the Scanning Multifrequency Microwave Radiometer(SMMR) on the Nimbus-7 Satellite

Sea-surface temperature retrievals have been tested on 2 months of Nimbus-7 scanning multichannel microwave radiometer data. Using the prelaunch versions of the instrument calibration and geophysical parameter retrieval algorithms the initial results were poor. Improved algorithms produced substantially better results. It appears that at least for the night-Southern Hemisphere portion of the Nimbus-7 orbit, a rms measurement accuracy of 1.45°C has been achieved. Similar tests with wind speed retrievals yield an accuracy of 2.7 m/s rms with no substantial differences between day and night measurements but limited by availability of surface observations to the Northern Hemisphere. Moreover, it appears that the retrieved wind speed is more nearly related to the square of the wind observed at the surface than to the wind itself.     

Retrieval of Ocean Surface And Atmospheric Parameters from Multichannel Microwave Radiometric Measurements

This paper discusses the retrieval from Scanning Multichannel Microwave Radiometer (SMMR) data of ocean surface temperature, surface wind speed, rain rate, cloud height, and the amount of water vapor and nonprecipitating liquid water over the ocean. The sensitivity of the algorithms that retrieve the wind speed and seasurface temperature in the absence of rain to the (undetected) presence of rain, and the accuracy of a more general method that retrieves rain rate along with other meteorological parameters are discussed. These investigations are based on models of the microwave emission from the Earth's atmosphere over the ocean in the presence of rain. The modeling technique and the retrieval methods are also discussed.     

Computing Coastal Ocean Surface Currents From Infrared and Ocean Color Satellite Imagery

Many previous studies have demonstrated the viability of estimating advective ocean surface currents from sequential infrared satellite imagery using the maximum cross-correlation (MCC) technique when applied to 1.1-km-resolution Advanced Very High Resolution Radiometer (AVHRR) thermal infrared imagery. Applied only to infrared imagery, cloud cover and undesirable viewing conditions (gaps in satellite data and edge-of-scan distortions) limit the spatial and temporal coverage of the resulting velocity fields. In addition, MCC currents are limited to those represented by the displacements of thermal surface patterns, and hence, isothermal flow is not detected by the MCC method. The possibility of supplementing MCC currents derived from thermal AVHRR imagery was examined, with currents calculated from 1.1-km-resolution Moderate Resolution Imaging Spectroradiometer (MODIS) and Sea-viewing Wide Field-of-view Sensor (SeaWiFS) ocean color imagery, which often have spatial patterns complementary to the thermal infrared patterns. Statistical comparisons are carried out between yearlong collections of thermal and ocean color derived MCC velocities for the central California Current. It is found that the image surface patterns and resulting MCC velocities complement one another to reduce the effects of poor viewing conditions and isothermal flow. The two velocity products are found to agree quite well with a mean correlation of 0.74, a mean rms difference of 7.4 cm/s, and a mean bias less than 2 cm/s which is considerably smaller than the established absolute error of the MCC method. Merging the thermal and ocean color MCC velocity fields increases the spatial coverage by approximately 25% for this specific case study     

星载GNSS-R海面风速反演方法研究

星载GNSS-R因其时延-多普勒相关功率(DDM)波形对风速的敏感性较低,采用理论与实测波形匹配的方法所得风速精度较差。针对这一问题,该文采用一种直接建立相关功率值与风速之间联系的方法获取风速信息。基于相关功率模型对散射功率进行了归一化修正及其简化处理,利用UK TDS-1卫星试验数据和散射计(ASCAT)同比观测风速分别建立归一化散射功率及其简化式与海面风速之间的经验模型。与ASCAT观测风速对比结果表明：在0~20 m/s的风速范围内,采用归一化散射功率反演风速的均方根误差为2.11 m/s;两种方法的反演精度相近,简化修正方式避免了复杂的积分运算更适用于实时处理。     

星载激光测高仪海洋表面回波计算的理论模型

不同地表目标的模拟回波波形对测高仪系统参数设计具有重要意义,而海洋回波参数在Tsai之后很少被研究。根据菲涅耳衍射理论、海洋表面镜面反射性质以及海洋表面波高和斜率的统计规律,推导出与Tsai结果不同的近天顶方向入射时星载海洋测高仪探测器输出的回波解析表达式和回波总光子数;并用该推导结果建立了适用于激光测高仪亚毫弧度量级发散角的回波解析式。将模拟波形与地球科学激光测高系统(GLAS)真实海洋回波做对比,其能量、脉宽、振幅和形状都非常接近,误差均小于6%;分析得出海洋测高仪回波与测高系统参数和海平面上方平均风速有关,以GLAS参数为例,在风速大于12m/s的条件下将很难收到有效海洋回波。该结论对海洋激光测高仪的系统设计参数及海平面上方风速的反演提供了重要的理论依据。     

A Stable Iterative Procedure to Obtain Soil Surface Parameters and Fluxes from Satellite Data

Two general methods recently proposed to obtain the thermal inertia, the sensible heat flux, and the evapotranspiration flux from satellite data are summarized. In these methods, stable algorithms were used, but the stabilization coefficients presented were empirical. In this paper, it is shown that optimal coefficients exist and can lead to an iterative process to calculate the thermal inertia and the fluxes with improved accuracy despite of errors of measurements. Some applications using in situ data and theoretically simulated data are given as an example.     

海洋监视卫星对水面舰艇电子侦察效能分析

监视海上舰艇活动的海洋监视卫星对我水面舰艇作战行动的隐蔽性造成了严重影响。基于海洋监视卫星工作原理的分析,建立了卫星对水面舰艇覆盖判定算法、卫星波束覆盖特性分析以及卫星电子侦察效能分析等模型,并对海洋监视卫星对水面舰艇电子侦察效能进行了仿真分析,提出了几种水面舰艇反卫星侦察方法。     

利用星载ERS-2 SAR进行长江口海面风场反演研究

基于SAR图像反演原理,提出一种后向散射系数反演海面风场的新方法,以相关长度确定风向,再利用随机粗糙海面理论模型反演风速.并以ERS-2 SAR为数据源,以长江口海区为研究区,获取了海面风场，反演结果和浮标测量风场对比,相符得很好,证明了该方法的可行性。     

海洋卫星及其应用

本文首先介绍了海洋卫星的概念,工作原理及分类．接着分析了国外海洋卫星的发展历史和我国海洋卫星的发展概况．最后指出了海洋卫星在突发事件中的应用情况。     

顺轨干涉SAR海洋表面流场迭代反演算法

该文在分析传统顺轨干涉SAR表面流场速度分离方法不足的基础上,根据海面微波成像仿真模型建立了顺轨干涉SAR海洋表面流场迭代反演算法。利用该迭代反演算法对JPL AIRSAR获得的机载顺轨干涉SAR数据进行流场反演,并将反演流场与普林斯顿海洋模型(POM)的输出流场进行对比,两个流场具有很好的一致性,证实了该迭代反演算法的有效性。