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…     

浅析卫星地球站上行信号对微波站干扰的计算

由于卫星通信系统与微波接力系统共用频段，会产生同频干扰。为了避免新建卫星地球站建成后的上行频率对地球站周围微波接力系统造成有害干扰，依据中华人民共和国信息产业部第21号令《建立卫星通信网和设置使用地球站管理规定》[2002．6．211和《建设卫星通信网和设置使用地球站的暂行规定》[国无管（1995．1）4号]，要求建站单位在卫星地球站确定站址之前，在申报有关技术资料的同时，提供数据要准确、论证要充分、分析要科学、结论要明确的卫星地球站对微波接力站的干扰分析报告。无线电管理部门根据建站单位提供的拟建站址电磁环境测试报告和干扰分析报告，     

浅谈卫星地球站对微波站干扰分析的一些因素

卫星通信和微波通信都是当令重要的无线电通信系统。由于卫星通信与微波通信都是使用微波频段，它们使用的频率就有存在重叠、相互干扰的可能，建站前必须考虑到这方面的因素，避免不必要的经济损失。因此，建立卫星地球站和微波站之前需要做电磁环境测试和干扰分析，保证新建的台站能     

卫星通信地球站电磁环境的测试

在设计一个卫星通信系统时,必须对地球站的站址进行合理的选择和布局,站址位置是否合适将关系到地球站能否正常通信,关系到地球站与微波站等地面无线电干扰的影响。本文论述了地球站站址电磁环境的测试方法。     

卫星地球站选址电测

目前，卫星通信在各个领域、各个部门得到越来越广泛地应用。随着卫星地球站的迅速增加，各级无线电监测站也就会越来越多地遇到地球站选址电测问题。在卫星系统的工程设计、电磁兼容分析、干扰协调等工作中常常需要进行现场电测。卫星地球站电测是使用电子仪器和部件组成的测试系统对卫星地球接收站的电磁环境进行测试，给出可能出现的干扰信号强度的测量结果，进而从电磁环境上判断预选站址的可用性。通过电测可以达到两个目的：一是把工程设计（或可行性论证）与实际测试结果相对照，为进一步修订设计方案提供依据；二是根据测到的干扰信…     

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...     

浅析卫星通信地球站电磁环境测试系统组成及测试方法

电磁环境测试是卫星通信地球站建设的前提条件,随着国家经济和信息化水平的提升,用频设备越来越多,电磁环境越来越复杂,电磁环境的好坏、干扰强度的大小将直接影响卫星通信系统效能的发挥。本文首先给出了地球站电磁环境测试系统的组成,其次分析了地球站干扰信号电平值指标,再次阐述了电磁环境的测试方法,最后对全文进行总结。     

卫星通信地球站的电磁环境测试

讨论了设置卫星通信地球站前进行电磁环境测试所需进行的有关工作,即确定测试系统的构成、测试系统灵敏度、测试系统输入端允许干扰电平和测试方法等,最后举例说明。     

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。     

船载卫星通信地球站跟踪精度分析

跟踪精度是评价卫星通信地球站质量的重要指标,但对船载卫星通信地球站的精度,目前还没有系统的分析方法,论述了船载卫星通信地球站的跟踪精度指标,分析了影响船载卫星通信地球站跟踪精度的误差源.采用分析最恶劣工作环境条件同时,给出了均方根误差估算分析方法,以7.3 m船载卫星通信地球站为例进行跟踪精度指标的确定及分析估算.实践结果表明:对船载卫星通信地球站跟踪精度的分析估算方法满足工程需要.可作为船载卫星通信地球站跟踪精度指标的确定及精度分析估算的参考.     

Swap your boiler for a power station

From autumn 2003, householders will be able to save money by generating their own electricity. The author looks at whether they will invest in CHP units. Whispertech and Microgen, have been running in-home trials of CHP units that can replace a standard gas-fired central heating boiler and also generate electricity. Both models will have an electrical output of just over a kilowatt contributing to baseload needs, with any extra requirement drawn from the grid as usual. Any surplus can be sold back to the electricity company. The Whispertech and Microgen units both generate electricity using Stirling engines, which produce little noise or vibration and take up the same space as a boiler.     

Complexity of a software GSM base station

There is increasing interest in developing radio-based applications in software. The new architecture for implementing mobile telephony base stations has the potential of offering many benefits: great cost savings by using one transceiver per base transceiver station (BTS) instead of one per channel, tremendous flexibility by moving system-specific parameters to the digital part, and allowing the support of a wide range of modulation and coding schemes. A very important problem in designing software radio applications is the need to estimate the required complexity of processing to dimension systems. For example, with a software GSM BTS it is critical to estimate the number of channels that can be supported by a given processor configuration, and to predict the impact of future processor enhancements on its capacity. This article focuses on the design of a software implementation of a GSM BTS and proposes a platform-independent evaluation of its computational requirements based on SPEC benchmarks. It focuses on the design and performance of a library of software modules. Portability and computational requirements are discussed     

Applying photovoltaic power to a petrol service station

This paper considers the use of photovoltaics to power rural petroleum service stations, or as a back-up for urban service stations where power supply from the national grid is rather erratic in a developing country like Nigeria. Issues concerning system design, choice of components and the economic considerations of such a conceptualized system are also discussed. the payback period based on simple payback analysis is about 5 years. It is envisaged that the service station will also provide facilities such as cathodic protection for storage tanks, battery charging and distilled water production.     

Base station location in a cellular CDMA system

We consider a cellular CDMA system in which blocking is enforced when the relative interference exceeds a certain threshold level. This paper addresses a radio network design problem in such a CDMA system. Given the data of call‐traffic distributed over the service area and potential sites of base stations, the objective of the problem is to locate base stations so as to minimize the associated cost for establishing base stations while keeping the probability of blocking under control. We develop an efficient algorithm for solving the design problem. Computational experiments with real‐world data are conducted to show both the efficiency and the practicality of the proposed design method. This revised version was published online in August 2006 with corrections to the Cover Date.     

八0四高山台数字电视覆盖分析和技术方案探讨

通过对八〇四发射台发射地面数字电视的覆盖分析,论证了在牡丹江地区特定的山地条件下,采用高山台站大功率覆盖的可行性。八〇四台发射相对高度950 m左右,采用3 kW数字功率,理论上可有效覆盖60 km半径,在该范围内牡丹江地区的11个乡镇和90多个行政村可良好接收8套左右的本地数字电视节目,接收点理论场强可达到55~66 d BμV/m。与常规中小功率、多点发射相比,该大功率、单点发射方案可以大大减少林口县、海林市境内的11个乡镇设备投入,为国家节省大量资金。     

Toward the software realization of a GSM base station

Advances in processor and analog-to-digital conversion technology have made the software approach an increasingly attractive alternative for implementing radio-based systems. For mobile telephony base stations, the advantages with the new architecture are obvious: great cost savings by using one transceiver per base transceiver station (BTS) instead of one per channel, tremendous flexibility by moving system-specific parameters to the digital part, and allowing the support of a wide range of modulation and coding schemes. This paper considers the software implementation of a GSM BTS, and analyzes the performance of each of its radio interface modules. The performance of each software module is evaluated using both a % CPU metric and a processor-independent metric based on SPEC benchmarks. The results can be used to dimension systems, e,g., to estimate the number of software-based GSM channels that can be supported by a given processor configuration, and to predict the impact of future processor enhancements on BTS capacity. Two novel aspects of this work are the portability of the software modules and the platform-independent evaluation of their computational requirements     

Performance evaluation of a cellular base station multibeam antenna

Experimental test results are used to determine the performance that can be achieved from a multibeam antenna array, with fixed-beam azimuths, relative to a traditional dual-diversity three-sector antenna configuration. The performance tradeoffs between the hysterisis level, switching time, and gain improvement for a multibeam antenna are also examined. The multibeam antenna uses selection combining to switch the signals from the two strongest directional beams to the base station's main and diversity receivers. To assess the impact of beamwidth on overall system performance, the following two multibeam antennas were tested: a 12-beam 30° beamwidth array and a 24-beam 15° beamwidth array. Both multibeam antennas were field-tested in typical cellular base station sites located in heavy urban and light urban environments. Altogether, the system performance is evaluated by investigating three fundamental aspects of multibeam antenna behavior. First, the relative powers of the signals measured in each directional beam of the multibeam antenna are characterized. Then, beam separation statistics for the strongest two signals are examined. Gain improvements achievable with a multibeam antenna compared to the traditional sector configuration are determined in the second phase of the analysis. Results indicate that in excess of 5 dB of gain enhancement can be achieved with a 24-beam base station antenna in a cellular mobile radio environment. Finally, the effects of hysterisis level and switching time are characterized based on gain reductions relative to a reference case with no hysterisis and a 0.5-s switching decision time. Useful approximations are developed for the gain effects associated with varying hysterisis levels and switching times. The resulting design curves and empirical rules allow engineers to quantify multibeam antenna performance while making appropriate tradeoffs for parameter selection