互调干扰在移动通信中的危害及处理

互调干扰是无线通信系统中的衍生物,无处不在。移动通信系统中的上行干扰故障导致无线网络质量下降,严重影响用户的感知。文章分析互调干扰的成因,指出三阶和五阶产物对现网运行的巨大危害。通过对现网故障处理的总结分析,给出互调干扰排查思路和处理方法,使此类故障的处理清晰明了,有章可循。用现网故障处理案例给予详细说明。     

基于无源互调测试仪在互调干扰排查方面的应用

本文通过最新的PIM Mastar互调分析仪快速定位和排查在天馈系统中互调干扰硬件故障,有效地提高网络维护中处理这类故障的效率,提升通信网络优化的指标和用户感知.     

移动通信网络干扰与基站天线的关系研究

多个信号通过天线向外辐射时，将会产生互调信号；当天线自身互调较差时，落入上行频带内的互调信号将会产生严重干扰，影响通信质量。文章通过测试统计，阐明互调与通信质量的关系，给出了一种发现设备存在互调故障的方法。     

用场强仪检修交互调干扰故障

在有线电视网络维护工作中,会遇到各种各样的故障,其中网络中出现交调干扰、互调干扰的故障也较常见。网络中出现交、互调干扰的原因很多：一是放大器工作电平过高,这可通过场强仪测试得知,经适当调整后即可解决;另外,当放大器出现故障时（如电源故障、放大模块故障等）,也有可能出现仅管增益正常、工作电平正常,却发生强烈的交互调干扰的现象。如故障放大器在村中,还可通过各村放大器所服务的电视机画面情况加以对比来区分判断故障;若故障放大器是野外干放,特别是多级干放线路,检测判断就更为麻烦。当然用监视器检查是比较直观…     

甚高频无线通信系统发射机互调干扰研究

在甚高频（VHF）无线通信系统中,发射机互调干扰已成为一个影响通信质量和通信安全的重要因素。互调干扰不仅污染了周边电磁环境,还会干扰正常通信,降低通信质量。文中研究了互调干扰的形成与危害;分析了互调干扰的测试方法;并利用搭建的互调干扰测试系统对甚高频无线发射机互调干扰进行了测试与分析;讨论了降低和消除互调干扰的措施。研究成果对于提高甚高频通信系统的抗干扰能力,实现甚高频无线通信设备科学合理的频谱规划,提高系统间电磁兼容具有重要的应用价值。     

室内分布系统无源互调干扰问题排查与整治

室内覆盖系统无源互调干扰已经成为影响客户感知的重要因素,文章简要介绍了无源互调干扰的概念,以及无源互调干扰的三种判断方法,举例分析了无源互调干扰问题站点的排查与整治,提出了降低室内覆盖无源互调干扰的三点建议。     

有线数字电视网络噪声干扰原因与对策分析

有线数字电视网络噪声干扰原因较多,主要干扰因素有外界电磁波侵入、网络失配、有线数字电视网络的互调、差拍干扰以及HFC系统本身带来的电路噪声干扰。针对引起有线数字电视故障的各种噪声干扰原因的分析,提出相应的解决和预防措施。     

移动通信系统中三阶互调干扰的研究和分析

文章从三阶互调干扰形成的一般机理入手,研究和分析了移动通信系统中三阶互调干扰的成因和危害性,介绍了接收机输入互调、发射机输出互调和无源器件互调的测试方法,详细给出了减小移动通信系统中三阶互调干扰的方法.     

天馈系统互调干扰的工程处理方法探讨

文章分析了无源互调干扰的产生机理与三阶和五阶互调产物的影响范围,阐述了工程实际中互调干扰的成因及其对现网指标的影响,给出了互调干扰排查流程及实际经验。     

移动通信互调干扰抑制

叙述了移动通信电路设计、天线安装和频率选配不当会引起互调干扰，分析了三阶互调干扰和高阶互调干扰，指出电路的非线性是产生收发信机互调干扰的重要原因之一，提出了对收、发信机、天线、馈线及频率配置不当时产生的互调干扰进行抑制的方法。最后叙述了用人工倒叠法对无三阶互调的频率序列进行选择和检验。（ｅｄ）     

Analysis of Inter-Modulation Interference for MM-Wave Receiver

The problem of inter-modulation interference is an important problem in super-heterodyne receiver. In the past, the analysis about it was carried out for the lower frequency communication for example the short wave communication. In this paper, the analysis about inter-modulation interference and the output signal of frequency mixer will be carried out for MM-wave communication according to the features of MM-wave multi-channel communication. Then, the corresponding methods to reduce or avoid mixer output interference and inter-modulation interference are recommended.     

一种单通道自适应零位天线系统的研究与设计

在自适应阵列天线系统中,通常的多通道接收机电路复杂,难以保证各通道性能的一致性,以及使用的可靠性.文中对HF自适应三元阵列零位天线系统提出了一种单通道检测接收机方案,并分析了实现的可行性,给出了具体的实现方法,同时讨论了相关矩阵的算法.为了降低镜频干扰、交调和互调干扰,接收机采用了双中频方案.模拟测试结果证明了该方案的可行性.     

民用航空甚高频通信系统互调干扰分析与建模研究

本文分析了民航甚高频通信系统的干扰机制,建立干扰分析模型,对民航西安区管甚高频系统的实际干扰问题进行了分析,介绍了无线电频率管理的基本概念,讨论了电磁频谱的概念、特点,论述了电磁频谱检测分析和评估的重要性,并对国内外无线电频率管理的现状做了介绍,深入分析了互调干扰机理,总结了调频广播对民航甚高频系统干扰的类型和产生机制。最后,分别从频率和功率两个维度建立了互调干扰频率分析模型。为民航甚高频通信系统的规划和管理提出了有益的参考。     

GPS 接收机交调互调敏感度测试方法研究

GPS 卫星定位技术已广泛应用于航空航天系统。本文通过阐述GPS 接收机的工作原理及GPS 信号的特点,分 析了接收机交调互调传导敏感度测量原理,扩展了GPS 接收机交调互调传导敏感度的试验方法。该测试方法快捷、易 于掌握,便于得到接收机互调交调抑制比参数。     

OFDM系统中降峰均比研究及PTS改进算法

正交频分复用（OFDM）技术在解决无线移动通信系统中显示了许多特点,如抗多路径衰落和频际间的干扰等。然而,OFDM系统中一个最主要的瓶颈在于OFDM信号的峰均功率比（PAPR,Peak-to-Average Power Ratio）很大,因而容易导致OFDM信号的交调失真和系统性能的下降。如何有效地解决OFDM系统中的峰均功率比是亟待解决的问题。为此,提出一种新的PTS（部分传输序列）改进算法。     

基于参考信号的无源互调故障定位技术

研究了一种基于参考信号的无源互调故障定位技术.该技术比传统无源互调测量技术多了一个参考信道,提供参考信号,解调互调信号相位响应,同时引入校准技术,在测量端口构建参考平面,通过频时转换得到相对于参考平面的时域响应,有效地进行故障排查.在此基础上,仿真故障定位实验验证了理论的正确性,设计并制造相位参考板,测试结果与实际值比较表明：电缆上两个故障位置实际值与测量值之差的绝对值均≤1m,实际相对误差分别约为5.1%、2.4%,证明了这种方法的正确性和可行性.该技术将克服传统故障定位的不足,更适应于恶劣的地域环境.     

Superposition effect of passive inter-modulation for systems operating in multiple carriers

Nowadays, more carriers and components are used in cellular networks to satisfy the requirement of high-speed data service. The increase of carriers and components may result in serious problem of passive inter-modulation （PIM）. This paper investigates the superposition effect of 3rd-order and 5th-order PIM under multicarrier scenarios with the channelized scheme （CS） and the multiplexed scheme （MS）. We use the concept of ＇effective hit＇ and the cumulative inter-modulation factors （CIFs） to evaluate the cumulative PIM product strength on each individual carrier within the receive signal band. Furthermore, with the simulator based on Monte-Carlo method, the group inter-modulation factor （GIF） is calculated to measure the average superposition effect for multiple carriers compared with the benchmark case. The simulation results show that, compared with the CS, the strength of PIM product with the MS does not increases so greatly with the growth of the total number of the carriers. The results are useful for the component designers and the cellular network planners.     

Spurious Signal Response of Broadband Solid–State Frequency Multipliers at Millimeter and Submillimeter Wavelengths

Heterodyne instruments at millimeter and submillimeter wavelengths often use wideband fixed-tuned frequency multipliers, in conjunction with broadband power amplifiers driven by frequency synthesizers, as the local oscillator (LO) source. At these frequencies the multipliers use Gallium Arsenide (GaAs) based Schottky varactor diodes as the nonlinear element, and like most other harmonic generators are susceptible to spurious signal interference. The state-of-the-art LO sources at these wavelengths use high power MMIC amplifiers at the initial stages, and are used to drive the subsequent multiplier stages to have enough LO power to pump the mixers. Because of the high input power environment and the presence of noise in the system, the multipliers become vulnerable to spurious signal interference. As the spurious signals propagate through the receiver system, they generate inter-modulation products which might fall in the passband of the heterodyne instrument and seriously degrade its performance. In this paper spurious signal response of solid-state frequency multipliers at millimeter and submillimeter wavelengths is investigated. Results of numerical harmonic balance simulations and laboratory experiments, which were found to show good agreement, are presented here.     

SiGe HBT功率放大器基极偏置电阻的优化

模拟了基极偏置电阻对功率放大器参数的影响.在兼顾效率、S参数、电压驻波比、功率增益及稳定性等特性的同时,得到了三阶交调信号幅度为最小值时的优化基极偏置电阻.模拟结果表明,一个优化的基极偏置电阻,不仅能使功率放大器的直流偏置点不受影响,三阶交调信号幅度最小,功率增益平坦度得到改善,而且S参数也能满足功放的要求.     

Crosstalk due to optical demultiplexing in subcarrier multiplexed systems

We report an in-depth investigation of the inter-modulation crosstalk in subcarrier multiplexing (SCM) systems with optical demultiplexing (ODeMux). Both theoretical derivations and numerical simulations show that the crosstalk in ODeMux systems mainly comes from the nonlinear mixing of the baseband and subcarrier modulations inside the signal channels. Several key parameters are then studied to estimate their effects on the magnitude of the crosstalk. As a result, performance optimization strategies are proposed for ODeMux SCM systems. In order to further enhance the transmission performance of ODeMux SCM systems, we discuss two techniques to suppress the inter-modulation crosstalk and analyze their effectiveness with numerical simulations.