谈谈微波传输中的越站干扰问题

在微波线路上传输的信号，往往迭加上不希望的信号，我们习惯上称之为干扰信号。干扰源随着各种通信系统的发展而日趋复杂。微波接力通信系统中除外部系统的干扰，如雷达干扰、卫星通信干扰、电视广播干扰及其它专用的微波系统干扰外，还存在着本系统内部干扰，如天线前对背干扰、分支线路干扰、越站干扰、中频耦合干扰及天馈系统回波干扰等。其中越站干扰在二频制的微波通信系统中最为常见。如果在电路设计中站址选择不当，就会造成越站干扰，从而影响信号的传输质量。     

8GHz微波系统中频率组合干扰的分析

８ＧＨｚ微波系统中频率组合干扰的分析丁正，许力，颜景瑞山东省淄博市广播电视局采用８ＧＨｚ微波设备传送电视已多年，但自从增容至４个双向波道且满负荷工作后，电路中的西山微波站经常出现干扰，使传输的电视质量降低，严重时，无法收看。西山微波站在其微波线路中所...     

微波射频直放站越站干扰的考虑

本文对微波射频直放站越站干扰进行了详细分析，给出了几种防止越站干扰的措施。     

为林南仓微波站排忧解难

今年1月，河北唐山传输局玉田县林南仓微波站受到不明信号干扰。林南仓微波站是河北省电信局SDH北部传输干线的重要接力站，如果该微波站受到干扰，将直接影响省会到唐山和秦皇岛两地的SDH数据传输。接到报告后，唐山无线电管理处领导立即召集唐山传输局有关技术人员了解情况，     

电视信号的微波传输概论

介绍微波传输的特点，微波站主要设备和微波中的中继系统，并且剖析了电视信号微波调制传输理论以及ＣＡＴＶ系统应用的微波联网原理。     

防雷接地在广播电视微波站的运用

广州市广播电视微波总站担负着中央一套、广州电视台主频道（34频道）和广州电台96．2MHz信号的传输，通过数字微波传送到从化、增城、花都、番禺、南沙和萝岗等区市的微波站，白云山微波站是无人值守站，是广州市数字微波传输线路中的中继站，担负着整个微波线路的交叉连接和转发，地位相当重要，必须建立一套完整的防雷系统，以保证整个微波网络线路的传输安全。     

地球站与微波站间的干扰计算

由于卫星通信系统与地面微波中继系统共用频段，所以会产生同频干扰。干扰可分为两类，一类是卫星转发器（空间电台）与地面微波站间的干扰，可通过限制微波站的全向等效辐射功串和空间电台在地球表面产生的最大功串通量密度等加以解决，如CCIR建议358，387，406，报告790，393等都作了规定。另一类是地球站与地面微波站间的干扰，必须慎重选择站址。认真核定系统多数，进行严格的干扰分析等加以控制，把干扰控制在允许标准之内，使地球站和微波站，不管是先建还是后建，都能不受有害干扰影响。这就要求设计部门要认真科学地做好建站前的…     

广播电视地面微波传输系统与卫星传输系统相互间干扰的测量及其防护

本文根据微波测量原理，提出了卫星传输系统与地面皮传输系统相互间干扰的测量方法。并根据实际工程建设，进一步地阐述了各种系统干扰系统源的测量方法。最后通过参加地面微波传输系统和卫星传输系统的工程实践，提出了抗干扰的具体方法。     

微波射频直放站的工程设计

介绍了微波射频直放站的工程设计,包括站址选择及越站干扰、电源系统、天线系统、直放站系统的计算等等。     

SDH微波交叉极化传输系统的几个问题

本文以ＳＤＨ微波交叉极化传输系统在实际应用中的问题，诸如系统的性能指标预测、系统内的干扰、ＸＰＤ恶化等进行了分析。     

卫星通信地球站微波干扰计算与分析

总结了微波接力通信站对卫星通信地球站的同频干扰的计算步骤和方法.首先计算地球站的工作方位和仰角,分析地球站和微波站的相对位置关系；然后,在得到卫星站和微波站相互间的干扰鉴别角的基础上,分别计算两站在干扰方向的天线增益；最后,计算卫星站接收机输入端的干扰信号允许电平和实际的干扰信号电平,通过对比两者的关系,可以判断预选站...     

Tunable microwave photonic filter for noise and interference suppression in UMTS base stations

A design of a tunable microwave photonic filter for noise suppression and channel interference mitigation in the front-end stage after the receiving antenna of an UMTS base station is presented. The filter provides a tunable and very high selective performance (5 MHz along the 1935-1977 MHz band) with 14 dB suppression in the stopband using 30 fibre Bragg gratings and a reconfigurable dispersive delay line.     

The development of a model to estimate the bistatic transmissionloss associated with intersystem interference

This paper presents a new method for evaluating transmission loss, which is a key factor used in determining the impact of interference between terrestrial radio relay systems and Earth-satellite systems operating at the same frequency. The current model used by the CCIR was developed in the early 1970's when system packing density was low and large earth station antennas allowed the consideration of narrow beam approximations, resulting in a small common volume of intersection of the two beams. The recent increase in microwave communications traffic and improvements in technology have meant that smaller earth station antennas, including very small aperture terminals (VSATs), can be employed and hence the model requires revision. Results from the new model proposed are compared with two experimental geometries and good agreement is found     

Evaluation of bistatic intersystem interference due to scattering by hydrometeors on tropical paths

Evaluation of bistatic transmission loss cumulative distribution is very useful in assessing the effect of interference due to hydrometeor scatter between the communication links operating at the same frequency. Out of the many factors that could be responsible for the intersystem interference between the microwave communication systems, this paper presents the result of computation of intersystem interference resulting from the hydrometeor scatter on tropical paths. Interference is computed in terms of the cumulative distribution of transmission loss. The effect of varying common volume formed by the intersection of the antenna beams on the transmission loss is investigated. Results show that at frequencies higher than 10 GHz, for antenna separation longer than 100 km, common volume will be in the ice region, leading to a higher interference level at the interfered terminal. Also, results obtained show that because total path attenuation at 30 GHz is lower than at 20 GHz (this is due to the decrease in water vapour attenuation in the 22·2–30 GHz window), transmission loss tends to be higher at 20 GHz than at 30 GHz. In addition, increasing the antenna gain of the interfering station will result in the increasing interference level at the interfered station. Evaluation of the effective transmission loss shows that this parameter gives a better assessment of interference on the tropical propagation paths noted for high-intensity convective precipitation. In this case, the effective transmission loss has been evaluated in terms of the joint occurrence of additional rain attenuation on the wanted path, and the cumulative distribution of transmission loss on the intersecting paths. Copyright © 1999 John Wiley & Sons, Ltd.     

移动通信微波部件无源互调干扰综述

在地面通信系统中,基站的微波部件长期暴露在外,受温度、湿度、污染等因素影响,原本洁净的部件表面受到氧化、沾污等,导致接触不良,产生无源互调(PIM),干扰通信系统,导致地面移动通信中PIM的干扰不可避免。卫星通信系统中,由于通信距离远、平台限制等,必须采用收发共用模式,随着接收机灵敏度提升,对PIM指标要求更高;因系统高可靠性要求,PIM成为系统成败的关键问题之一。本文介绍了地面移动通信和星载微波部件PIM干扰的特点和研究进展,以期对PIM研究提供参考。     

Remote Control of Standby Engine Generator Sets Over a Microwave System

Experience in actual operation of microwave relay systems throughout the country has shown that involuntary outages have been caused principally by failure of the input power to the microwave equipment. Where substantially continuous service is required of the microwave system the common practice is to have emergency standby power available. This emergency power is supplied by an emergency generator set at the microwave station site. Failure of the normal input power supply initiates starting the engine generator set to supply a particular microwave station with power. This paper describes the units used to improve reliability of engine generators in microwave applications.     

TD-LTE系统间干扰问题的分析与研究

本文主要对TD-LTE多频段组网中的干扰问题进行分析.论文首先对TD-LTE可能的共址共存异系统工作频段进行了分析,指出了可能产生干扰的异系统和频段.并对不同干扰产生的原因分别进行了研究.在此基础上,论文提出了TD-LTE干扰隔离分析方法以及TD-LTE宏基站与其他系统共址时干扰隔离距离要求.通过对干扰隔离的计算,本文最终给出了TD-LTE室外宏站(F频段)、室外宏站(D频段)以及室分系统与其他系统共站时的干扰隔离结论.     

Proposal of a Fixed Communication System Sharing the Bandwidth of an Existing Personal Communication Network

This paper deals with the proposal and performance evaluation of a fixed microwave communication (FMC) system that shares the same bandwidth with a wireless personal communication network. In particular, the focus here is on the case of an existing universal mobile telecommunication system (UMTS) network for which an FMC system is considered to provide a wireless connection between a remote base station not having the possibility of a wired connection to the core network and a base station having this possibility (a core network access point). This facility is of special interest in a dense urban environment or whenever a wired connection is prohibitive for service providers due to its implementation cost or lack of frequency spectrum. The mutual interference effects between the FMC systems and the existing UMTSs are investigated by focusing on typical application scenarios. A receiving scheme where interference signals are first detected and then canceled from the other received signals is proposed. The performance of the two interfering systems has been evaluated in terms of bit error rates (BERs) both by means of an analytical approach and computer simulations. The obtained results clearly demonstrate the effectiveness of the proposed method, in particular, by allowing efficient bandwidth sharing between the FMC system and the existing UMTS network.     

无源中继站在微波电路中的应用

介绍了设置背对背天线无源中继站应考虑的因素以及主要指标的计算,最后对无源中继站与微波站的建设费用进行了比较.