数字音频工作站系统的应用与改造

结合天津人民广播电台的实际应用,简要介绍了数字音频工作站系统的物理与逻辑结构,重点介绍了在实际使用中遇到的问题和相应的解决方法,并详细地描述了对系统原有节目审听系统的改造。     

Coherence theory of a radio telescope

A new theory is developed to describe the operation of a radio telescope consisting of an array of two-element interferometers. The theory is based on recent developments in the theory of partial coherence, which employs an expansion of the scalar field amplitude into an angular spectrum of plane waves. Expressions are found describing the correlation of the field amplitudes in the antenna plane which are more general than usually obtained, and which suggest a simplified data processing procedure which might yield improved images. The usual quasi-monochromatic approximation is made and the conditions under which it is valid are discussed in detail. Finally the theory is connected with the usual procedure for producing images of the radio sources and the existence of an obliquity factor is shown which could affect images over a large field of view.     

基于广义低秩矩阵分解的分离字典训练及其快速重建算法

针对传统压缩感知重建算法存在重建质量偏低、重建时间偏长等问题,本文提出了一种基于分离字典训练的快速重建算法.首先选取某类图像作为训练集,建立其广义低秩矩阵分解模型;其次采用交替方向乘子法求解该模型,训练出一组分离字典;最后将该分离字典用于图像重建中,通过简单的线性运算实现图像的快速重建.实验结果表明,本文算法相比于传统的重建算法,针对训练集同类图像,具有十分显著的重建性能,对于其他不同类型的图像,依然有不错的重建质量,极大地降低了重建时间.     

太阳射电Ⅱ型爆发中频率分裂现象的特征自动提取研究

在射电动态频谱图上,太阳射电爆发中的Ⅱ型暴通常具有缓慢漂移的基频和二次谐频辐射带,这些辐射带又具有带分裂结构。Ⅱ型射电暴的频率分裂现象是太阳射电频谱图像研究的重要现象之一。本文首先采用通道归一化方法和大津法对频谱图像进行预处理,然后通过形态学开闭重建定位出爆发区域。确定爆发区域后,采用高斯卷积平滑爆发,并运用边缘指示函数实现太阳射电暴的边缘检测,最后基于距离正则化水平集方法提取出频率分裂现象。成功提取出频率分裂现象后简要介绍了特征参数的统计与分析方法,以便为进一步理解Ⅱ型射电爆发的机制提供依据。     

Image reconstruction in optical interferometry

Since the first multitelescope optical interferometer [1], considerable technological improvements have been achieved. Optical (visible/infrared) interferometers are now widely open to the astronomical community and provide the means to obtain unique information from observed objects at very high angular resolution (submilliarcsecond). There are numerous astrophysical applications, such as stellar surfaces, environment of premain sequence or evolved stars, and central regions of active galaxies. See [2]-[4] for comprehensive reviews about optical interferometry and recent astrophysical results. As interferometers do not directly provide images, reconstruction methods are needed to fully exploit these instruments. This article aims at reviewing image reconstruction algorithms in astronomical interferometry using a general framework to formally describe and compare the different methods. The challenging issues in image reconstruction from interferometric data are introduced in the general framework of inverse problem approach. This framework is then used to describe existing image reconstruction algorithms in radio interferometry and the new methods specifically developed for optical interferometry.     

基于配准的肺4D-CT图像超分辨率重建

肺4D-CT数据在肺癌治疗中有重要意义.但肺4D-CT数据纵向(Z方向)分辨率低,为显示正确比例图像需进行插值运算,由此带来图像的模糊.本文提出了一种基于Active Demons配准的超分辨率重建技术来提高肺4D-CT图像分辨率.我们将不同相位同一位置的低分辨率图像视为不同"帧"图像.首先采用Active Demons配准方法得到不同"帧"图像之间的运动估计;而后采用凸集投影(Projection Onto Convex Set,POCS)超分辨率算法重建高分辨率肺图像.实验结果表明,与三次样条插值和反投影方法相比较,我们的方法能得到更清晰的肺图像,明显增强图像结构.     

一种通过PCI总线配置FPGA的设计方法

在软件无线电领域中,系统必须具有较强的动态重构能力。这里讨论PCI协议特点和FPGA配置过程．给出一种通过PCI总线配置卡上FPGA的设计方法。硬件部分采用CPLD实现读写配置空间、PCI总线时序和FPGA配置时序,软件部分采用WinIO作为驱动程序。设计上简洁、灵活,不依赖专用PCI接口芯片,也不需要下载电缆。实践证明,这种方法便捷可靠。对PCI卡的设计具有很好的参考价值。     

Reconstruction of subsurface radio holograms fully and partially measured by different methods

Reconstruction of measured holograms is performed by the backward propagation method and by means of a preliminary measured instrument function (IF). It is shown that the results of the reconstruction can be improved by reducing the IF measuring error, e.g., by averaging over a ring. It is established that images of a part of subsurface radio holograms can be obtained not only if the known part of a hologram is an entire fragment but also if the measured points of the hologram are not nearest neighbors of each other.     

基于GPU的太阳图像斑点重建技术实现

在地基太阳观测中,光线在穿越大气层时会受到大气湍流的影响而导致图像扭曲、变形以致质量下降。为了消除或降 低大气湍流的影响,事后图像处理技术被用来获得高分辨力的太阳图像。基于斑点干涉法和斑点掩模的事后重建算 法可以获得高分辨力的图像,但由于计算复杂度高,难以满足实时性的要求。在讨论了算法原理的基础上, 使用CUDA并行计算架构实现了太阳斑点重建算法并行化。实验结果表明,在GPU环境下,一张TiO通 道2304 pixel$\times$1984 pixel像素大小的图像,可以在70 s内完成重建,相比运行在CPU上的串行程序,加速比可达7以上。     

县级高山广播电视发射台综合防雷改造

本文首先介绍雷电的危害及南岳山广播电视发射台的防雷现状,然后概述对其进行综合防雷改造方案设计、施工、检验全过程,最后对改造中新技术的应用、施工细节、注意事项进行总结。以期能为县级广播电视发射台综合防雷新建或改造工程提供参考借鉴。     

SCA架构软件无线电台设计与实现

为提高数字通信电台的通用性、灵活性和重构性,提出了一种基于软件通信体系结构（SCA）的软件无线电台的设计方案,给出该方案的工程实现方法,并以超短波跳频波形为例讲述了基于该软件无线电台的应用波形和组件的开发过程。该方案可为基于SCA架构的便携式软件无线电台的设计和开发提高参考。     

Terahertz Computed Tomography Using A Continuous-Wave Gas Laser

A 3D continuous-wave (CW) terahertz computed tomography (CT) system employing a gas laser operating at 2.52 THz is presented. To shorten acquisition time on the premise of guaranteeing the image quality, the modified simultaneous algebraic reconstruction technique (MSART) coupled with image processing operations like the Gaussian low-pass filter (GLPF), open operation and close operation has been adopted in the paper. With the 2D results the 3D images of the samples have been also obtained. The reconstruction results illustrate the promising application prospects of this CW THz CT system.     

红外运动目标轨迹重构动态仿真平台

提出了一种红外热成像视频中运动目标识别追踪以及轨迹重构的动态仿真方法。通过仿真环境中虚拟红外图像的生成方式与成像的基本模型,对得到的图像进行一系列预处理。以空对空场景搭建了基于Gazebo与OpenCV的动态仿真平台,利用平滑约束算法对追踪目标进行实时动态轨迹重构,提出了误差分析模型,并分析出轨迹重构算法的性能以及仿真平台的效能。实验结果表明,该方法针对空对空场景下的红外运动目标轨迹重构具有较好的精度与鲁棒性,对目标的运动模型基本没有约束,同时仿真平台具有较高的运行效能与实时性,普通家用电脑即可实现高于60 fps的实时动态仿真,满足轨迹重构算法性能测试与训练的需求,其核心算法亦可迁移至机载计算平台实现真实场景下的实时轨迹重构。所提出的单路热成像视频中运动目标轨迹重构动态仿真方法对空间目标三维轨迹重建与动态测距定位的研究具有重要意义。     

Radio tomography of the ionosphere

An overview of tomographic approaches to ionospheric remote sensing in the radio-wave range is provided. Tomographic methods are divided into deterministic and statistical ones. Deterministic tomography problems can be subdivided into ray radio tomography and diffraction radio tomography. The statistical radio tomography approach is used when it is necessary to reconstruct the statistical structure of a great number of inhomogeneities, on the basis of measurements of field statistics (instead of one realization of the reconstruction of an inhomogeneity). Methods of solving radio tomography problems, and their connection with inverse scattering problems, are considered. The results of some initial experiments that show the possibilities of the radio tomography approaches are described. Future applications and problems are discussed     

太赫兹计算机辅助层析图像重构算法仿真研究

由于太赫兹波具有独特的性质,使得太赫兹成像技术成为目前的研究热点。太赫兹层析成像可以获得物体横截面的分布信息并可获得物体的三维重构图像,因此也受到了广泛关注。文中对连续太赫兹层析成像进行了仿真研究。分别使用滤波反投影算法（FBP）和改进的联合代数重建算法（MSART）进行图像重构,并且分析比较了高斯低通滤波（GLPF）以及数学形态学等数字图像处理方法对改善重构图像质量的效果。仿真结果表明:在文中的仿真条件下,使用MSART算法及相应的图像处理方法所需的最少投影方向数可以达到9,与真实成像实验结果相吻合。     

宜兴本地高清互动增值业务BOSS系统的构建

BOSS系统是广电网络运营支撑综合平台的核心,是将客户服务、业务运营及账户管理作为核心,以服务及计费作为整个系统的主要功能,用来支撑广电运营商多种业务运营的系统。结合宜兴广电本地互动电视平台综合运营支撑系统（BOSS）的建设,介绍了BOSS系统的设计原则、系统架构、功能结构以及本地广电业务受理界面。     

基于改进地形重构的SSPE传播预测方法

针对复杂环境下电波传播预测分析难的问题,提出了一种基于地形重构的分步抛物方程(split-step parabolic equation,SSPE)传播预测方法.该方法采用具有广角传播因子且步长可变的双向SSPE解法,并利用基于改进地形重构的SSPE传播预测方法对真实地形的电波传播特性进行仿真分析和试验验证.与现有的电...     

圆锥扫描机制下的红外图像帧重建仿真研究

重点研究了圆锥扫描机制下,红外图像帧重建的仿真实现.在简要介绍圆锥扫描机制下基于变行频采样机理和红外图像完整重建技术的基础上,进行了大量的重建图像仿真研究.作为示例,文中列出第1、3、5、7、9场的扫描数据图像及其相应的场重建图像.从图像仿真结果可以看出这种技术能够完成红外图像的重建,重建的红外图像具有较高的分辨率,能够充分利用红外器件获得的扫描数据和相应的空间信息.     

Image reconstruction by convolution with symmetrical piecewisenth-order polynomial kernels

The reconstruction of images is an important operation in many applications. From sampling theory, it is well known that the sine-function is the ideal interpolation kernel which, however, cannot be used in practice. In order to be able to obtain an acceptable reconstruction, both in terms of computational speed and mathematical precision, it is required to design a kernel that is of finite extent and resembles the sinc-function as much as possible. In this paper, the applicability of the sine-approximating symmetrical piecewise nth-order polynomial kernels is investigated in satisfying these requirements. After the presentation of the general concept, kernels of first, third, fifth and seventh order are derived. An objective, quantitative evaluation of the reconstruction capabilities of these kernels is obtained by analyzing the spatial and spectral behavior using different measures, and by using them to translate, rotate, and magnify a number of real-life test images. From the experiments, it is concluded that while the improvement of cubic convolution over linear interpolation is significant, the use of higher order polynomials only yields marginal improvement.     

两种新的彩色图像(n, n)分存方案

提出了两种彩色图像的（n,n）．分存方案，解密过程仅需要执行XOR运算。这两种方案重构密图的复杂度与可视分存方案等价，更为重要的是该方案没有像素膨胀，并且重构密图的质量优于彩色可视分存方案。