航天微波辐射计

介绍六种形式的航天微波辐射计的工作原理和各种技术参数，并给出相应的方框图，阐述各种形式的微波辐射计的灵敏度和噪声温度的计算方法，比较这些微波辐射计的优缺点及其适用的场合。     

微分变压器用于宽频数字信号隔离

用微分变压器取代积分变压器实现数字信号隔离，不仅有利于箭上设备小型化，还可提高隔离性能，改善电磁兼容（ＥＭＣ）性。文中分析了积分变压器隔离电路的缺点和局限性。展宽频域下限的一种有效途径是使用微分变压器，它的工作条件易于满足，可小型化，且频率下限低至毫赫级。文中给出了计算公式和电路。为了恢复变形的波形，给出了迟滞整形电路，本方案优点是增强了抗干扰能力，提高测量精度，延长传输距离。     

基于IP网络的测试研究

为实现IP语音测试的专项研究,介绍了基于VOIP(Voice over IP IP语言)的信令及语音测试相关技术实现方案,系统硬件及功能实现框图。对IP语音测试平台的硬件设计方法及语音质量测试(VQT),信令流及媒体流的测试模型进行了研究。     

信号传输中的驻波处理

给出了驻波处理的简便方法,考察了有关的理论,给出了新的计算公式。     

导弹目标ISAR成像的仿真

在逆合成孔径雷达（ISAR）成像基本原理及信号处理过程的基础上，根据导弹的飞行弹道、自转和进动模型建立导弹飞行模型，采用自相关快速运动和累积相关运动两种补偿方法，对导弹目标的ISAR二维成像进行了仿真研究。结果表明，导弹的自旋时成像结果及积累时间的影响较大，模型不同，积累时间也不同。     

基于自适应修正曼哈顿距离的室内定位方法

在室内WiFi环境下,针对常见指纹匹配算法所忽略的信号波动问题,提出了一种基于自适应修正曼哈顿距离和AP选择的指纹匹配算法,并结合加权K近邻方法实现定位。首先采用AP选择算法获取部分受干扰程度小和出现频率高的AP,在指纹匹配时仅使用该部分AP的接收信号强度进行计算;在分析WiFi信号传播衰减公式和信号波动的基础上,提出了将自适应修正曼哈顿距离作为指纹匹配的度量距离,使用该距离旨在平滑信号波动对指纹相似度计算的影响;最后采用加权K近邻方法估计测试点的坐标。实验结果表明,在加权K近邻方法的框架下,基于自适应修正曼哈顿距离的定位算法在定位精度上优于基于欧氏距离、曼哈顿距离、余弦距离和Sorensen距离的定位算法。     

序列凸优化的小天体附着轨迹优化

针对小天体附着多约束轨迹优化问题，提出一种基于序列凸优化的轨迹优化方法。首先采用内球谐引力场模型对目标小天体附近的不规则引力场进行精确建模，内球谐引力场模型是对经典球谐系数法的改进，形式简单，计算量小，并且克服了经典球谐系数模型在形状不规则的小天体附近不收敛的问题。对于小天体附着多约束轨迹优化问题，通过约束松弛、线性化、离散化过程，转化为一个可以迭代求解的二阶锥规划问题（SOCP），进而采用内点法进行解算。数学仿真结果显示，优化结果符合各项约束条件，以零速度到达了目标着陆点，且符合燃耗最优的优化目标。利用序列凸优化算法进行小天体附着燃耗最优轨迹设计，推导简便，计算速度快，精度高，具有应用价值。     

A novel signal processing approach for LEO space debris based on a fence-type space surveillance radar system

The increase in space debris can seriously threaten regular activities in the Low Earth Orbit (LEO) environment. Therefore, it is necessary to develop robust, efficient and reliable techniques to understand the potential motions of the LEO debris. In this paper, we propose a novel signal processing approach to detect and estimate the motions of LEO space debris that is based on a fence-type space surveillance radar system. Because of the sparse distribution of the orbiting debris through the fence in our observations, we formulate the signal detection and the motion parameter estimation as a sparse signal reconstruction problem with respect to an over-complete dictionary. Moreover, we propose a new scheme to reduce the size of the original over-complete dictionary without the loss of the important information. This new scheme is based on a careful analysis of the relations between the acceleration and the directions of arrival for the corresponding LEO space debris. Our simulation results show that the proposed approach can achieve extremely good performance in terms of the accuracy for detection and estimation. Furthermore, our simulation results demonstrate the robustness of the approach in scenarios with a low Signal-to-Noise Ratio (SNR) and the super-resolution properties. We hope our signal processing approach can stimulate further work on monitoring LEO space debris.     

A novel LAAS pseudo-range error over-bound method based on improved pseudo-range error distribution model

The high level of safety demand of civil aviation requests local area augmentation system (LAAS) extremely high navigation integrity performance. A new LAAS pseudo-range error overbound method is proposed in this paper to improve the integrity of LAAS. Firstly, a more practical pseudo-range error distribution model is established. Then, by calculating the relationship between the statistical uncertainty of the model parameter and the integrity risk, a new method is proposed to calculate the pseudo-range error over-bound model. This method can effectively reduce the inflation factor and the resulting conservativeness of the over-bound model. Comparative experiments show that the method proposed in this paper performs better and satisfies the requirements of real applications.     

Time and phase synchronization using clutter observations in airborne distributed coherent aperture radars

Airborne Distributed Coherent Aperture Radar(ADCAR) is one of the most promising next-generation radars to significantly improve target detection and discrimination abilities. However, time and phase synchronization among unit radars should be done before an ADCAR is intended to cohere on a potential target. To address this problem, a time and phase synchronization technique using clutter observations is proposed in this paper. Clutter returns from different azimuths and elevations on the surfac...