ITU-R SM.2149-0建议书探析及其应用研究

随着国际无线电干扰频发,各国愈发频繁地通过国际电信联盟(ITU)干扰协调机制解决干扰问题、主张本国权益。研究并掌握相关ITU建议书,有助于提高国际规则运用能力,更好地维护国家频谱使用权益。本文对ITU-RSM.2149-0^[1]建议书进行探析,并结合监测实践提供应用示例,为无线电管理领域技术人员提供参考。     

ITU-RP.1546-3建议书的相关修正方法

国际电联ITU-R P.1546建议书为我们提供了大量建立在实验数据统计分析基础之上的场强预测数据和推测方法,旨在为VHF和UHF波段地面无线广播电视规划工作及其它无线电规划提供指导;同时为提高场强预测的精度提供了地形起伏、接收环境、接收地点概率变化等因素对场强预测影响的修正方法,在2007年修正的1546-3版本中还加入了有关大气散射对电波传播影响的场强修正方法.本文汇总了该建议书2001～2007年4个版本中提供的几种场强修正方法,并对其进行详细ITU-R P.1546介绍和分析.     

ITU-R P.1546-3建议书的相关修正方法

国际电联ITU-R P.1546建议书为我们提供了大量建立在实验数据统计分析基础之上的场强预测数据和推测方法,旨在为VHF和UHF波段地面无线广播电视规划工作及其它无线电规划提供指导;同时为提高场强预测的精度提供了地形起伏、接收环境、接收地点概率变化等因素对场强预测影响的修正方法,在2007年修正的1546-3版本中还加入了有关大气散射对电波传播影响的场强修正方法。本文汇总了该建议书2001～2007年4个版本中提供的几种场强修正方法,并对其进行详细ITU-R P.1546介绍和分析。     

海面环境700MHZ频段传输特性测试与模型校正

在海面环境下通过船-岸测量方式对700 MHz频段的无线传输特性进行测量.基于实测数据分析,引入海面双径传输损耗模型对ITU-R P.1546-5标准传输模型进行校正,该校正模型可实现700 MHz频段无线传输损耗预测.在仿真中,分别利用自由空间模型、ITU-R P.1546-5模型和ITU-R P.1546-5校正模型对700 MHz频段的海面无线传输损耗进行预测,通过与实测数据对比分析,证明ITU-R P.1546-5校正模型预测结果准确性更高,能够为海面无线通信系统的设计提供重要依据.     

用于原子干涉重力仪的小型频率合成器设计与实现

在原子干涉重力实验中,拉曼激光制备常采用光学锁相环方法,即先将主从激光器拍频信号与6.8 GHz微波信号源进行混频,再与直接数字频率合成信号发生器进行鉴频鉴相,得到的反馈信号用以控制激光器实现低噪声拉曼光输出,而拉曼光相噪将直接影响原子干涉重力仪的灵敏度。本设计采用STM32F103C8T6单片机对LMX2594数字锁相环芯片进行编程控制,通过锁相环频率合成技术,最终获得6.8 GHz的微波信号源。测试结果表明,该微波信号源相位噪声分别为-65.2 dB@1 Hz、-95.3 dB@1 kHz,频率稳定度为2.72×10^-11@1 s,输出功率大于10 dBm。在脉冲间隔时间为100 ms时,信号源对原子干涉重力仪灵敏度的影响为8×10^-8 m/s²/Hz^1/2,分辨率影响为2×10^-8 m/s²@600 s,具有频率稳定度高、相位噪声低等优点,可以满足原子干涉重力实验。     

碘酸锂晶体腔内上转换

这里报道的是用碘酸锂晶体和氩激光器进行的连续腔内上转换。3.4微米处的噪声等效功率为5×10^-14瓦/赫^1/2。测定并叙述了上转换器的噪声性质。     

一种宽温高精度温补晶振的研制

介绍了一种新型宽温微机补偿晶体振荡器。文中使用微处理器对专用集成电路芯片设计了温补晶振,分别在高低温区段对输出频率进行分段补偿;增加了噪声处理电路,滤除补偿电压跳变引入的噪声,避免相噪恶化;用二次分段补偿的方法,将补偿温度范围拓展到-55~+105 ℃。试验结果表明,使用该方法研制的10 MHz温补晶振,其频率温度稳定性在-55~+105 ℃范围内,优于±1.0×10^-6,相位噪声优于-140 dBc/Hz@1 kHz。     

In掺杂CdMnTe晶体的Te气氛退火研究

Thermal annealing in Te vapor atmosphere was adopted to improve the properties of indium-doped Cd_1-xMn_xTe（x=0.2,CdMnTe） wafers grown by the vertical Bridgman method.The wafers before and after annealing were characterized by measuring the Te inclusions,etch pit density（EPD）,Mn composition,resistivity, and impurity.IR transmission microscopy and EPD measurements revealed that the densities of Te inclusions reduced from（5-9）×10⁴ cm^-3 to（2-4）×10⁴ cm^-3 and EPD from 10⁵ cm^-2 to 10⁴ cm^-2 after annealing. NIR transmission spectroscopy showed that the Mn composition increased by 0.002-0.005 mole fractions during the annealing.The resistivity of the wafers improved from（2.0-4.5）×10⁸Ω·cm to（1.7-3.8）×10⁹Ω·cm,which suggested that the deep-level donor of Te antisites was successfully introduced after annealing.Inductively coupled plasma-mass spectrometry（ICP-MS） revealed that the concentrations of impurities in the wafer decreased,which indicated the purifying effects of Te vapor annealing on the wafers.All the results demonstrate that the Te vapor annealing of the indium-doped CdMnTe crystal has positive effects on the crystallinity,resistivity and purity of CdMnTe wafers.     

国外动态

ITU建议书将推动3D电视发展国际电信联盟(ITU)日前公布了一系列的建议书,将给筹备中的3D电视广播带来福音。这项新标准(或者说建议书)是由ITU的无线电通讯部门(ITU-R)第六研究组编写的,并被该机构称作一项"巨大飞跃"。新公布的ITU-R建议书集中对世界范围使用的两种制式(720p和1080i/p高清电视)下,3D电视节目制作和播出进行规范。     

超薄柔性硅CMOS器件及无源元件性能退化仿真研究

基于150 mm 0.35μm CMOS工艺,利用Silvaco TCAD软件,针对50μm厚硅基上NMOS与PMOS器件、多晶硅-介电层-多晶硅(PIP)电容和N⁺型多晶硅电阻,在单轴状态不同弯曲半径下,仿真了压缩与拉伸对器件电学参数变化的影响程度。结果表明,单轴拉伸与压缩弯曲使NMOS的阈值电压最大漂移0.46 mV,使PMOS阈值电压最大漂移0.33 mV。漏极电流随变形量线性变化,NMOS压缩时系数为-0.132 95,NMOS拉伸时系数为0.006 01。PMOS拉伸时系数为-0.104 47,PMOS压缩时系数为-0.110 7。电阻阻值随变形量呈线性变化,当掺杂浓度分别为1×10¹⁹,2×10¹⁹,3×10¹⁹,4×10¹⁹,5×10¹⁹时,系数分别为247,498,766,1 016,1 301。电容最大变化值和初始值不超过0.5%,结论归纳为无失配影响。这些结果与实验吻合,验证了模型的正确性,为研制降低退化的柔性硅基集成电路打下基础。     

Verification of background noise in the short wave frequency range according to recommendation ITU-R P.372

The so-called background noise level is a very critical figure in many EMC problems, especially when sensitive radio services are involved. In order to provide a sufficient signal-to-noise ratio (SNR) the minimum signal strength is most commonly calculated on the basis of existing noise levels. On the other hand, if the impact of unwanted emissions on radio services is studied, background noise takes on the function of a reference level. An extensive database of noise levels to be expected is available in the recommendation ITU-R P.372. However, most data concerning man-made noise were already measured in the 1970s. Thus, the significant increase of use of electrical devices with fast digital circuits and various communication systems gives reason to question the validity of the ITU recommendation for today's EMC purposes. This paper deals with different measurement techniques with respect to their suitability for measuring extremely low field strengths in the short wave range and presents measurement results for selected environments. Although the measurements are performed with the constraint of using a mobile measuring setup a considerable sensitivity is reached, leading to the conclusion that the ITU-R P.372 still seems to be valid for estimating noise levels.     

大气无线电噪声测量与分析

在中纬地区（河南省辉县）进行了冬季一个月的大气无线电噪声测量。对实测值分别与ＣＣＩＲ－３２２－２＾「１」及ＣＣＩＲ－３２２－３＾「２」报告书的预期值进行了分析比较,结果表明ＣＣＩＲ－３２２－３报告书的预期值较接近于实测值,但还存在一定的偏差,特别是白天偏差较大。     

数字音频广播设台对民航业务的干扰分析

随着数字技术的发展,数字化已经成为世界广播电视发展的必然趋势.基于ITU-R SM.1009-1建议书及国家标准G/B 6364-2013《航空无线电导航台(站)电磁环境要求》所给出的保护场强,并参考中国现行的数字音频广播台的典型参数,分析了数字音频广播设台对邻频民航地空通信的互调干扰,给出了干扰缓解建议.     

Wideband CDMA system for personal radio communications

This article describes a wideband spread code-division multiple access (W-CDMA) system for high-capacity and high-quality personal radio communication. This system has been authorized as an EIA/TIA Interim Standard IS-665, T1P1 Trial Use Standard J-STD-015, and ITU-R Recommendation M 1073. The system uses wideband spreading to accomplish good interference immunity, high-quality speech, and high-speed data transmission. The system uses coherent detection (CD) and an interference canceller system (ICS) to enhance the capacity. The CD and ICS use continuous pilot signals in the forward/reverse links to estimate the propagation path parameters. PN and Hadamard sequences are used as the spreading code for minimal mutual interference between traffic and pilot/sync/paging channels. A robust 32 kb/s waveform speech coder, ITU-T COM101+, has been developed to achieve toll-quality speech in the radio environment. This system provides up to 128 voice channels per cell and data transmission up to 64 kb/s by 5 MHz spreading. Unification of low- and high-mobility applications and reduced complexity of system and hardware configurations are accomplished     

External Noise Measurements in the Medium Wave Band

This paper presents an up to date study on external noise levels in the medium wave band based on field trials carried out in Spain and Mexico during years 2004 and 2005 respectively. External noise levels predicted by the ITU-R P.372 recommendation are based on measurements carried out more than 30 years ago and no updated results for the medium wave band have been published in this time. An increment on these noise levels have been measured, which leads to a significant impact on the minimum usable field strength requirements for the broadcasting systems used in this frequency band, such as the new Digital Radio Mondiale (DRM) and In-Band/On-Channel (IBOC) systems     

音频质量客观评价方法的综合与实现

以ITU—RBS．1387—1为基础，讨论了多种音频质量客观评价的改进方法。在此基础上提出了“对各种改进方法加以综合，可进一步提高相关度系数”的假设。结合国、内外相关文献，进行了试验性地优化，最终实现了可视化仿真程序OE（Objective Evaluation）设计，主、客观评价相关度达到了0．85以上。     

A 0.18μm CMOS Gilbert low noise mixer with noise cancellation

正This paper presents a broadband Gilbert low noise mixer implemented with noise cancellation technique operating between 10 MHz and 0.9 GHz.The Gilbert mixer is known for its perfect port isolation and bad noise performance.The noise cancellation technique of LNA can be applied here to have a better NF.The chip is implemented in SMIC 0.18μm CMOS technology.Measurement shows that the proposed low noise mixer has a 13.7-19.5 dB voltage gain from 10 MHz to 0.9 GHz,an average noise figure of 5 dB and a minimum value of 4.3 dB.The core area is 0.6 x 0.45 mm~2.     

CMOS宽带线性可变增益低噪声放大器设计

文章设计了一种48MHz~860MHz宽带线性可变增益低噪声放大器,该放大器采用信号相加式结构电路、控制信号转换电路和电压并联负反馈技术实现。详细分析了线性增益控制、输入宽带匹配和噪声优化方法。采用TSMC0.18μm RF CMOS工艺对电路进行设计,仿真结果表明,对数增益线性变化范围为-5dB~18dB,最小噪声系数为2.9dB,S11和S22小于-10dB,输入1dB压缩点大于-14.5dBm,在1.8V电源电压下,功耗为45mW。     

Evaluation of the Propagation Model Recommendation ITU-R P.1546 for Mobile Services in Rural Australia

In this paper, the validity of recommendation ITU-R P.1546 in a short-range terrestrial environment is analyzed. Its three versions (P.1546, P.1546-1, and P.1546-2) are compared against simple models and evaluated using measurement results that were obtained by utilizing the pilot signal of a commercial code-division multiple-access mobile telephone network. Measurement results show that P.1546-2, on average, underestimates the field strength by more than 10 dB for typical Australian rural areas. However, it improves the error standard deviation compared to previous versions. The causes of these effects and the suggestions for further development of the Recommendation are discussed and evaluated.