A New Type of Digital Compensatory Millimeter Wave Radiometer

System gain and receiver noise are two main impact factors of total power millimeter wave (MMW) radiometer output. In this paper, a new method of using software to compensate system gain and receiver noise fluctuation is introduced. This method can keep the long-term stability and accuracy of the radiometer. At the same time, only one matching load is used as the reference source, which can prevent the trouble caused by using two cold and hot calibration sources in ground-based or airborne radiometer. The preliminary experiment proves the efficiency of the method.     

利用毫米波辐射计探测金属目标的研究

基于物质辐射原理和毫米波无源探测技术,设计一套毫米波辐射计系统。根据实际运用需要,提出了目标信号波形特征提取与对目标中心进行定位的方案。通过建立天线温度模型和系统工作模型,进行了相应的仿真分析。最后通过设计实验,得到了十分有用的实测实验数据,验证了系统工作原理。     

Key Indexes Analysis of Three Beams Conical Scan MMW Radiometer

Building on a mathematical model of a single beam millimeter wave (MMW) radiometer on a hi-tech bomb, system parameters are proposed and simulated for a three beam MMW radiometer. Scanning rate, falling rate and other parameters are put forward in the context of a novel conical scan MMW detector. The demodulated signals of detecting a target are simulated. With this approach the target radial center positioning accuracy can be improved. The simulation results indicate that the radiometer has favorable performances, such as a wide range of detection, high radial positioning accuracy and reacquisition target ability in the most adverse condition that the target’s radial movement is outwards.     

The Performance Analysis of Digital Millimeter-Wave Radiometer

Digital millimeter-wave radiometer (DMMWR) has advantages such as simple structure and good stability, of which a wide-band, high speed analog-to-digital converter (ADC) is the key component. However the unavoidable impairments of ADC in DMMWR degrade the sensitivity and accuracy, the main performance parameters of DMMWR. This paper investigates the sensitivity of DMMWR by deriving an expression for the noise-equivalent sensitivity based on the signal statistical property. Also, it analyzes the accuracy of DMMWR by establishing the calibration equation between output signal power and system noise temperature. During the experiment, the methods of multi-point calibration and curve fitting are introduced to calibrate the nonlinearity and fit the calibration equation of DMMWR, respectively. The experimental results show that the sensitivity expression gives predictions in agreement with experimental results and multi-point calibration can improve the measurement accuracy of DMMWR. The work was supported by the National Nature Science Foundation of China (No. 60772090)     

Imaging Simulation for MMW Synthetic Aperture Radiometer

A synthetic aperture radiometer is a new type of passive remote sensing instrument that can reach high spatial resolution. Restricted by antenna element size and operating wavelength, however, the system design is difficult at MMW band. In this paper, main technical parameters optimization of a synthetic aperture radiometer is discussed. Based on low-redundancy linear arrays, a millimeter wave synthetic aperture radiometric imaging scheme is presented. The simulation experimental results show that the system imaging effect depends on the synthetic aperture antenna pattern.     

雷达全脉冲的数字分析方法研究

提出了一种雷达全脉冲分析算法——极值序列分析法。该算法能够分析雷达脉冲的载频、脉冲幅度、脉冲宽度、信噪比、脉冲到达时间、脉冲包络特征参数和脉内调制参数。该算法的特点是：参数测量精度高;识别信号类型准确率高;算法速度快和所需存储空间小。     

Sensitivity of the Total Power Radiometer with Periodic Absolute Calibration

The total power radiometer is an attractive choice for imaging applications due to its high sensitivity and simple configuration. However, available theoretical results are inadequate to allow an accurate radiometer performance prediction in the presence of receiver gain fluctuations and other receiver characteristics with nonuniform fluctuation power spectra. An improved analysis of the total power radiometer Delta T is presented in terms of the receiver output fluctuation power spectral density and a transfer function due to postdetection filtering and periodic calibration. Verification of this analysis is obtained by measuring the fluctuation power spectrum of a 94-GHz receiver and comparing the predicted Delta T with a direct measurement. Numerical results including application to an example radiometer system are presented. These results indicate that the total power radiometer should function well in short integration time, periodically calibrated radiometer systems.     

省级CDR全数字音频广播试验分析

随着我国广播电视无线数字化的不断推进,调频广播也逐渐进入数字化进程,开展全数字音频广播试验工作,符合未来广播业务发展的方向.本文结合河北广播电视台全数字音频广播试验,对全数字音频广播节目集成平台、传输系统、发射系统的搭建步骤进行了总结,对全数字音频广播实地路测数据、收听效果对比测试数据、实际覆盖效果进行了重点分析,为今...     

对频率步进毫米波导引头的干扰研究

研究毫米波成像导引头的干扰途径和方法,分析了毫米波导引头制导的特点和主要抗干扰措施,重点分析不同的干扰措施对毫米波导引头的干扰效果,仿真结果证明了分析的正确性。     

Full Vectorial 3-D Sensitivity Analysis and Design Optimization Using BPM

We present a novel approach to the sensitivity analysis of 3D structures using the full vectorial beam propagation method (FVBPM). Using no extra simulations, the sensitivities of the response with respect to all design parameters are obtained regardless of their number. Our approach is exploited to calculate the sensitivities of the propagation constants of multimode waveguides. It is also applied to the 3D imaginary distance FVBPM (ID-FVBPM) and utilized to extract the sensitivities of the mode parameters. The calculated sensitivities are then utilized within a gradient-based optimization algorithm to illustrate the application of the obtained sensitivities. The accuracy of our approach is verified through a comparison with the expensive central finite difference applied directly at the response level.     

大联盟全数字HDTV

本文综述了GA高清晰数字电视标准,并对GA全数字HDTV标准进行了较为详细的讨论和评价。该标准的制定为HDTV技术发展及产业化给出了一个可共同遵守的统一框架。     

毫米波无源对抗技术浅析

针对毫米波具有的多普勒分辨率高、等离子体穿透能力强等特点,着重分析了可用于毫米波无源对抗的11种措施,包括毫米波箔条与箔片、毫米波烟幕、毫米波吸收层和角反射器及毫米波雷达干扰物控制投放技术等,以实施对毫米波导引头有效的干扰．毫米波无源干扰技术使毫米波对抗上了一个新的台阶,同时由于毫米波制导波段已从8mm向3mm扩展,使人们不断开拓新的思路,寻求新的毫米波对抗方法．     

合成孔径辐射计多路高阶数字复相关器方案研究

本文针对目前合成孔径辐射计中存在的相关器单元过于复杂，难以星载应用的问题，提出了一种新的数字相关方法．借鉴了软件无线电中的数字接收机技术，利用大规模可编程门阵列(FPGA)，用一块芯片来实现功率分配和大量复相关器的工作，实现了片上系统(SOC)，解决了多天线单元合成孔径辐射计相关器系统中存在的体积、重量、功耗和硬件复杂程度过大的问题．通过仿真表明，多路高阶数字相关器系统得到的天线阵列的干涉方向图与模拟相关器系统得到的干涉方向图基本一致，证明该方案可行。     

高光谱微波辐射计宽带高速数字系统设计

高光谱微波辐射计是基于频谱分析技术的精细谱段微波辐射计,通过增加探测通道实现高垂直分辨率大气探测,解决传统微波辐射计通道数少,频谱分辨率低的问题.该系统采用高性能模数转换器(Analog-to-Digital Con-verter,ADC)实现对模拟输入信号进行10Gsps采样,8bit量化,并基于高性能现场可编程门阵列(Field Programming Gate Array,FPGA)芯片获取输入信号的功率谱.文章详细介绍了宽带高速数字系统设计、器件选型和测试方法,给出了测试结果,分析表明硬件系统设计符合设计要求.     

An Analysis of the Sensitivity of Digital Modulation Techniques to Frequency-Selective Fading

This Paper investigates the sensitivity to frequency-selective fading of different modulation techniques commonly used in digital radio systems. The modulation methods considered are phase-shift-keying (Mary PSK), nonoffset and offset quadrature amplitude modulation (M-ary QAM), and quadrature partial response signaling (QPRS). The performances of these methods during multipath fading are compared on the basis of the "signatures" calculated for idealized systems. Results are presented from which the relative outage probability was determined, assuming a propagation channel with frequency-selective Rician fading.     

数字视频的全面认识和分层测试

该论文由《广播与电视技术》2007年第6期、第7期、第8期刊出。主要内容包括：对数字视频的层次构架进行的全面分析,通过借用信息系统的层次模型,对高清、标清,压缩、无压缩的数字视频进行了层次模型解析,并通过对应于各层次的技术指标．针对实际工作中常见的问题和业内广泛存在的一些困惑,提出了对数字视频系统性能进行分层测试和全面考察的观点和技术思路。     

全数字电视制作系统的设计考虑

在全数字电视制作系统的设计中，选择数字编码方式和接口形成是关键。本文通过对分量数字与复合数字，串行数字传输与并行数字传输的分析比较，以及考虑到先建立的数字制作系统必须能与后建立的全台数字化大系统联网运行，最后选定了分量数字和串行数字接口方式。     

网络化的全数字图像监控系统

网络化的全数字图像监控系统是利用现代的计算机网络技术及多媒体信息压缩，解压技术实现的网络数字图像监控系统，实现了由模拟监控到数字监控质的飞跃，监控的视频，音频，告警，控制信号可传至网络所及的每一个节点，人们可以利用计算机网络在不同地点同时监视，控制远程某一或某些场所，同时具有移动图像探测功能，上报告警信息，并进行远程指挥，适用于电信，电力，交通，铁路，金融，水，大型公司等诸多行业的图像监控业务。     

毫米波气象雷达发射机的设计

某车载式毫米波气象雷达发射机,输出峰值功率600 W,脉冲宽度40μs,最大工作比可达20%,工作电压高达20 kV,发射机的工作环境为露天,需要做好野外防护工作,随天线转动,尺寸有严格限制,只允许风冷,发射机工作时处于无人值守状态.为了满足这些要求,在电路拓扑、结构及热设计、机内测试设备(BITE,built-in test equipment)等方面采取了模块化、冷板、灌封等措施,使该毫米波发射机电路简洁、布局巧妙、易于散热、可用性高,完全适合车载及野外工作.     

频率步进毫米波雷达假目标干扰仿真与分析

为了提高距离分辨力,弹载毫米波雷达常采用频率步进体制。雷达发射的一串相参的频率步进信号经过逆傅里叶变换可以得到目标高分辨距离像,对该种体制雷达采用传统的噪声干扰不能起到满意的效果,必须采用相参干扰技术。主要研究了复制转发假目标干扰和灵巧噪声干扰两种相参干扰技术,首先从理论上研究两种干扰技术的干扰机理,然后研究不同干扰参数的干扰性能,比较了两种干扰技术的优劣,提出了对频率步进毫米波雷达的有效干扰方法,最后仿真验证了理论分析结果。