无线寻呼发射机产业的发展和壮大

一、无线寻呼发射机的技术指标根据信息产业部司局文件信无（1999）12号“关于发布《无线寻呼发射机技术指标》的通知,为加强对无线寻呼发射设备的管理,避免寻呼发射台站对航空、水上导航和通信等无线电业务产生有害干扰,促使电磁环境根本好转,确保无线电台站正常工作,现将如下《无线寻呼发射机技术指标》予以发布,即日起在无线电发射设备检测工作中执行,凡不符合上述指标的寻呼发射机不得进口、生产、销售和使用,不核发电台执照。（1）频率容限：150MHz频段：5×10－6（单基站）,1×10－7（多基站）280MHz频段：3×10-6（单基站…     

调幅广播发射机技术指标的分析和解读

本文对广播发射机几项重点技术指标进行了分析和解读,同时还根据自己的工作积累,介绍了提高广播发射机技术指标的实际经验和测试技巧.     

大功率多注速调管发射机的小型化设计

车载和大功率机载雷达对真空管发射机的体积和质量提出了严格要求,发射机的小型化很有必要。文中介绍了一种大功率多注速调管发射机的小型化设计,叙述了发射机的主要技术指标和系统组成;阐述了高功率密度高压电源、小型化固态调制器、高压一体化设计和末级组件热设计等发射机小型化关键技术。实验表明:小型化发射机达到预期设计要求。文中对该小型化发射机的实际应用情况和使用前景进行了介绍。     

浅谈100kW PSM短波发射机的杂音问题

随着我国科学技术的不断发展,对100kWPSM短波发射机的改进问题也进一步加强,在100kWPSM短波发射机使用的过程中,暴露出的最突出问题就是杂音,严重影响了音质效果。文章通过对DF100A型的100kW PSM短波广播发射机杂音问题的分析,探索出杂音问题的解决方法,同时介绍几种改善杂音效果的方法,以及在实际维护中使用的维修措施。     

浅谈100kW PSM短波发射机的杂音问题

随着我国科学技术的不断发展,对100kWPSM短波发射机的改进问题也进一步加强,在100kWPSM短波发射机使用的过程中,暴露出的最突出问题就是杂音,严重影响了音质效果。文章通过对DF100A型的100kW PSM短波广播发射机杂音问题的分析,探索出杂音问题的解决方法,同时介绍几种改善杂音效果的方法,以及在实际维护中使用的维修措施。     

雷达发射机脉冲保护的优化设计

脉冲雷达发射机对脉冲的技术指标要求非常严格.在实际使用中,脉冲宽度和脉冲工作比是必须加以实时监控和保护的.文中介绍了雷达发射机脉冲保护设计的重要性及其硬件组成,着重叙述了应用复杂可编程逻辑器件进行过工作比保护的优化设计.该优化设计已在多项发射机控保系统产品中获得成功的应用.     

美国1973年通信设备数字估计

1971年实际数}1972年预计数}1973年估计数使用中的电话机电话设备的经费无线电台电视台电缆电视系统使用中的收音机使用中的电视机家庭用电视机家庭用电缆电视汽车用收音机产量调幅收音机销售数调频收音机销售数黑白电视机产量彩色电视机产量民用无线电发射机业余无线电发射机航空无线电发射机工业无线电发射机公用事业安全用无线电 发射机船用无线电发射机运输用无线电发射机 (万部)(亿美元) (个) (个) (个) (万部) (万部) (万部) (万部) (万部) (万部) (万部) (万部) (万部) (万部) (万部) (万部) (万部) 12,551 97 6593 892 2570 35,叨0 …     

CATV光发射机的工作原理与使用维护

简要介绍光发射机的组成、工作原理、技术指标，以及如何合理选择、使用和维护光发射机。     

短波发射机技术指标的调整

在进行短波发射时,短波发射机的一些技术指标由于一些原因的影响会偏离正常的状态,当发现这些技术指标有所偏离的时候,就一定要对这些技术指标进行调整,如果不对它们进行调整的话,那么短波发射机发射出去的短波就会出现问题,与要求的不一致。短波发射机技术指标容易发生问题的一般都是信噪比、失真度、频率响应等,只有将这些技术指标问题解决好了短波发射机才能正常的进行工作,但是如何进行调整是一个问题,因此本文就针对这个问题对短波发射机技术指标的调整进行了阐述。     

东芝TV/TU3000A型10KWUHF电视发射机的使用及维护方法

对发射机的技术指标、激励器各单元的作用、整机特点逐一进行介绍和分析,科学正确的维修维护方法,对实际工作中遇到的故障进行分析和处理。     

Resolution Enhancement Technology:Integrated Process Solutions using OPC

DUV lithography, using the 248 nm wavelength, is a viable manufacturing option for devices with features at 130 nm and less. Given the low kl value of the lithography, integrated process development is a necessary method for achieving acceptable process latitude. The application of assist features for rule based OPC requires the simultaneous optimization of the mask, illumination optics and the resist.Described in this paper are the details involved in optimizing each of these aspects for line and space imaging.A reference pitch is first chosen to determine how the optics will be set. The ideal sigma setting is determined by a simple geometrically derived expression. The inner and outer machine settings are determined, in turn,with the simulation of a figure of merit. The maximum value of the response surface of this FOM occurs at the optimal sigma settings. Experimental confirmation of this is shown in the paper.Assist features are used to modify the aerial image of the more isolated images on the mask. The effect that the diffraction of the scattering bars (SBs) has on the image intensity distribution is explained. Rules for determining the size and placement of SBs are also given.Resist is optimized for use with off-axis illumination and assist features. A general explanation of the material' s effect is discussed along with the affect on the through-pitch bias. The paper culminates with the showing of the lithographic results from the fully optimized system.     

Cost-effective test solutions for smart card and other integrated flash applications

From its emergence in the late 1980s as a lower cost alternative to early EEPROM technologies, flash memory has evolved to higher densities and speedsand rapidly growing acceptance in mobile applications.In the process, flash memory devices have placed increased test requirements on manufacturers. Today, as flash device test grows in importance in China, manufacturers face growing pressure for reduced cost-oftest, increased throughput and greater return on investment for test equipment. At the same time, the move to integrated flash packages for contactless smart card applications adds a significant further challenge to manufacturers seeking rapid, low-cost test.     

An improved parallel thinning algorithm with two subiterations

The parallel thinning algorithm with two subiterations is improved in this paper. By analyzing the notions of connected components and passes, a conclusion is drawn that the number of passes and the number of eight-connected components are equal. Then the expression of the number of eight-connected components is obtained which replaces the old one in the algorithm. And a reserving condition is proposed by experiments, which alleviates the excess deletion where a diagonal line and a beeline intersect. The experimental results demonstrate that the thinned curve is almost located in the middle of the original curve connectivelv with single pixel width and the processing speed is high.     

Theoretical analysis of the relationship between the Brillouin gain coefficient and the strain in the optical-fiber sensors

The relation between the power of the Brillouin signal and the strain is one of the bases of the distributed fiber sensors of temperature and strain. The coefficient of the Bfillouin gain can be changed by the temperature and the strain that will affect the power of the Brillouin scattering. The relation between the change of the Brillouin gain coefficient and the strain is thought to be linear by many researchers. However, it is not always linear based on the theoretical analysis and numerical simulation. Therefore, errors will be caused if the relation between the change of the Brillouin gain coefficient and the strain is regarded as to be linear approximately for measuring the temperature and the strain. For this reason, the influence of the parameters on the Brillouin gain coefficient is proposed through theoretical analysis and numerical simulation.     

Novel fiber-optical interferometer with miniaturized probe for in-hole measurements

Today, micro-system technology and the development of new MEMS （Micro-Electro-Mechanical Systems） are emerging rapidly. In order for this development to become a success in the long run, measurement systems have to ensure product quality. Most often, MEMS have to be tested by means of functionality or destructive tests. One reason for this is that there are no suitable systems or sensing probes available which can be used for the measurement of quasi inaccessible features like small holes or cavities. We present a measurement system that could be used for these kinds of measurements. The system combines a fiber optical, miniaturized sensing probe with low-coherence interferometry, so that absolute distance measurements with nanometer accuracy are possible.     

Study of waveguide coupling efficiency in hybrid silicon lasers

This paper presents a new method to increase the waveguide coupling efficiency in hybrid silicon lasers. We find that the propagation constant of the InGaAsP emitting layer can be equal to that of the Si resonant layer through improving the design size of the InP waveguide. The coupling power achieves 42% of the total power in the hybrid lasers when the thickness of the bonding layer is 100 nm. Our result is very close to 50% of the total power reported by Intel when the thickness of the thin bonding layer is less than 5 nm. Therefore, our invariable coupling power technique is simpler than Intel＇s.     

Curved crystal spectrometer for the measurement of X-ray lines from laser-produced plasmas

In order to diagnose the laser-produced plasmas, a focusing curved crystal spectrometer has been developed for measuring the X-ray lines radiated from a laser-produced plasmas. The design is based on the fact that the ray emitted from a source located at one focus of an ellipse will converge on the other focus by the reflection of the elliptical surface. The focal length and the eccentricity of the ellipse are 1350 mm and 0.9586, respectively. The spectrometer can be used to measure the X- ray lines in the wavelength range of 0.2-0.37 nm, and a LiF crystal （200） （2d = 0.4027 nm） is used as dispersive element covering Bragg angle from 30° to 67.5°. The spectrometer was tested on Shengnang- Ⅱ which can deliver laser energy of 60-80 J/pulse and the laser wavelength is 0.35 μm. Photographs of spectra including the 1 s2p ^1P1-1s^2 ^1S0 resonance line（w）, the 1s2p ^3P2-1s^2 1S0 magnetic quadrupole line（x）, the 1s2p ^3P1-1 s^2 ^1S0 intercombination lines（y）, the 1 s2p ^3S~1-1 s^2 ^1S0 forbidden line（z） in helium-like Ti Ⅹ Ⅺ and the 1 s2s2p ^2P3/2-1 s622s ^2S1/2 line（q） in lithium-like Ti Ⅹ Ⅹhave been recorded with a X-ray CCD camera. The experimental result shows that the wavelength resolution（λ/△ 2） is above 1000 and the elliptical crystal spectrometer is suitable for X-ray spectroscopy.     

Preparation and Characterization of TaN ALD Precursors

High purity organic-tantalum precursors for thin film ALD TaN were synthesized and characterized.Vapor pressure and thermal stability of these precursors were studied.From the vapor pressure analysis,it was found that TBTEMT has a higher vapor pressure than any other published liquid TaN precursor,including TBTDET,TAITMATA,and IPTDET.Thermal stability of the alkyl groups on the precursors was investigated using a 1H NMR technique.The results indicated that the tertbutylimino group is the most stable group on TBTDET and TBTEMT as compared to the dialkylamido groups.Thermal stability of TaN precursors decreased in the following order:TBTDET ＞ PDMAT ＞ TBTEMT.In conclusion,precursor vapor pressure and thermal stability were tuned by making slight variations in the ligand sphere around the metal center.     

Electronic Structure of Semiconductor Nanocrystals

This paper reviews our recent development of the use of the large-scale pseudopotential method to calculate the electronic structure of semiconductor nanocrystals, such as quantum dots and wires, which often contain tens of thousands of atoms. The calculated size-dependent exciton energies and absorption spectra of quantum dots and wires are in good agreement with experiments. We show that the electronic structure of a nanocrystal can be tuned not only by its size,but also by its shape. Finally,we show that defect properties in quantum dots can be significantly different from those in bulk semiconductors.     

A rigorous proof of MIMO channel capacity’s increase with antenna number

It is well known that adding more antennas at the transmitter or at the receiver may offer larger channel capacity in the multiple-input multiple-output（MIMO） communication systems. In this letter, a simple proof is presented for the fact that the channel capacity increases with an increase in the number of receiving antennas. The proof is based on the famous capacity formula of Foschini and Gans with matrix theory.