功率合成技术在全固态发射机中的应用实例

在全固态发射机中,功率合成技术得到了广泛应用。结合六盘山电视调频转播台使用的TBV332型全固态调频广播发射机。简述了功率合成器的概念,分析了3种功率合成器在全固态调频广播发射机中的基本原理和应用．同时介绍了对发射机功率合成网络的要求。     

调频发射机掉功率报警器设计与制作

１概述 天津广播电视塔调频发射机房共播出３套调频立体声节目。其中包括２台电子管发射机和４台全固态发射机。调频立体声节目在播出过程中需要设置预监（发射机输入端信号）及主监（发射机输出的经调频立体声收音机接收的信号）,从而达到调频广播监听的目的。当调频发射机过荷而发生掉高压（电子管发射机）或掉功率（全固态发射机）的故障时不易被发现,因为此时往往预监、主监都正常显示（激励器输出的功率仍可满足主监信号的接收）。原先天塔发射机房使用电子管发射机时为解决发射机掉高压不易被发现的问题,制作了调频发射机高压状态…     

Wilkinson合成器浅析及其应用

全固态大功率发射机中必须采用具有隔离作用的功率合成技术,将中小功放的输出功率合成额定的输出。本文介绍了HARRIS Z10CD 10kW全固态调频发射机中大量使用的Wilkinson合成器原理,并进行了简单定量分析。     

广播与电视

通过卫星的可靠点对多点通信(见0213154)基于无绳电话原理的调频广播调制器(见0212917)全固态中波广播发射机中的功率合成网络分析(见0212913)UPS 在现代广播、电视领域的应用(见0212602)     

调频广播发射机功率合成器

简要概述了全固态调频广播发射机基于微带线的功率合成器的原理及测量指标分析。     

PDM全固态中波广播发射机的开发与应用

10kW以上大功率中波广播发射机的技术近3O年来发展很快，7O代末，随着半导体器件的发展，MOS场效应管的出现，射频功率合成技术的成熟和保护电路的不断完善，用功率合成方式研制的大功率全固态发射机其高效率和高可靠性博得用户的极大兴趣。PDM全固态发射机采用功率合成技术，用MOS场效应管作为最基本的功率器件，由多个基本功率单元进行功率合成的方式构成不同功率等级的整机。采用PDM脉宽调制技术的全固态中波发射机，整机效率可达75％以上。电声指标远优于电子管整机。SO年代后，上海市广播科学研究所在消化吸收了加拿大Nautel公…     

全固态广播发射机大功率场效应管的维护浅谈

广播发射机的全固态化技术发展依赖于大功率场效应管制造技术的突破,全固态广播发射机的功放级广泛地采用了金属氧化物半导体场效应管即:MOS-FET.固原市广播电视台引进的海纳公司1kW系列全固态广播发射机的功率放大器采用4块场效应管放大,引用先进的功率合成技术,使单台发射机实现kW级功率输出,本文结合该机运行5年来情况,阐述一下维护大功率场效应管的经验. 1 激励器 激励器是意大利RVR公司生产的30W原装激励器,可以在87.5～ 108MHz之间间隔0.01 MHz任选规定频率,直接频率合成,保证高质量的线性偏差和极小的失真;激励器具有驻波比保护电路,在驻波比高于要求或锁相电路失控时,无功率输出.     

全固态广播电视发射设备故障检查方法

全固态电视和调频广播发射机的工作原理虽有所不同,但其操作维护和故障的分析方法却基本相同。电视发射机、调频广播发射机虽有功率等级之分,但其工作原理是基本相同的。因此,工程技术人员只要认真学习、掌握一种类型设备的故障分析与维护方法,就可以对其它功率等级的发射设备进行操作与维护。     

全固态数字调幅中波广播发射机原理与维护

本文介绍全固态数字调幅（DAM）中波广播发射机原理与维护,重点介绍全固态数字调幅中波广播发射机的两个关键技术：调制编码和功率合成。     

全固态调频广播发射机常见故障分析和检查流程

全固态调频广播发射机相比电子管调频广播发射机而言,具有的特点有:理论寿命无限,不必定期更换电子管;无直流高压,工作安全;并联冗余工作方式,降低停播率;功放模块及其供电单元标准化,便于备份;采用直流开关电源,调整率好;利于改善低频信杂比等。由于该类型发射机存在上述优点,并且体积小,噪声小,便于维护,是安全播出工作正常进行的重要保障,因此现在国内调频发射台基本均使用该类型设备。目前,我台所有调频广播频率均使用全固态调频广播发射机作为主机播出,备机也基本使用该类型发射机。该类型设备在多年的运行中,比较突出的特点就是运行稳定、故障率较低。在多年的一线工作中,本人也积累了一     

Design of tube power amplifiers for optimum FM transmitterperformance

Tube amplifiers are extensively used in modern high-power FM broadcast transmitters. The power amplifier bandwidth affects not only the modulation performance, but also the transmitter's immunity to RF intermodulation. The tradeoffs involved and the choice of bandwidth are discussed. The design of tube power amplifiers for optimum FM performance requires careful considerations in the selection of input-matching and output-coupling circuit topologies, due to their effects on the transmitter amplitude and group delay responses. Results of computer circuit analysis and of measured amplitude and group delay responses are compared for different circuit topologies. Modulation performance data of a typical 20 kW FM transmitter are also presented to illustrate the effects of tube power amplifier input and output circuits     

中波广播发射机功放问题处理与发射机维护研究

传统广播发射机存在着功能不足、耗电较大等缺陷,随着科技的发展,数字调幅中波发射机取得了较大的发展,取代了传统广播发射机。但中波广播发射机的功放问题,会影响了广播节目的播出质量。文章围绕中波广播发射机功放问题进行分析,并总结了发射机的维护技巧。     

调频段DRM数字广播信道技术研究

2009年8月ETSI颁布的DRM(Digital Radio Mondiale)标准将调频段DRM数字广播囊括其中,介绍该标准中调频段DRM数字广播的优势与信道部分的技术特性。调频段DRM数字广播通过信道编码技术、信道复用、OFDM调制等技术,实现调频段广播信号的传输,与DAB相比可快速而平滑地实现FM波段广播由模拟向数字的过渡。     

Combining digital and analog signals for US IBOC FM broadcasting

IBOC DAB (In-Band On-Channel Digital Audio Broadcasting) requires the simultaneous broadcast of an analog and a digital signal within one channel of the FM band. Because broadcasters are adding IBOC to their existing systems, it is vital that they achieve maximum power efficiency while working within their existing space and power limitations. There are currently three different strategies proposed for accomplishing this goal, each having its own advantages and disadvantages. One strategy is to establish a separate, second antenna for the digital service. The other two strategies involve combining the analog and digital signals, either in a single hybrid transmitter or at the output of separate analog and digital transmitters. This paper discusses the equipment required for accomplishing this last strategy.     

小型电台转播车的设计实践与思考

广播转播车是一个综合的广播业务技术系统,设计制作涉及到车型选择、车身布置、设备选择、供配电以及数字化播出系统的衔接等功能实现方法。详细介绍了珠海广播电视台广播转播车的设计实践。     

IF Modulation of VHF Television Transmitters

The important phases of the engineering work that produced the new color transmitters are described. The subjects include intermediate frequency (IF) modulation, visual and aural exciter design, active group-delay compensation, power tube development, and solid-state control logic. They reflect the advanced technology employed in the transmitters. The resulting engineering work has one ultimate objective: unsurpassed color transmission.     

Low-power radio-frequency ICs for portable communications

The contributions of integrated circuits to the RF front-end of wireless receivers and transmitters operating in broadcast and personal communications bands are surveyed. It is seen from this that when ICs enable a rethinking of the RF architecture, the wireless device can sometimes become significantly smaller, and consume much less power. Examples are taken from FM broadcast receivers, pagers, and cellular telephone handsets. Many semiconductor technologies are competing today to supply RF-ICs to cellular telephones. The various design styles and levels of integration are compared, with the conclusion that single-chip silicon transceivers, combined with architectures which substantially reduce off-chip passive components, will likely dominate digital cellular telephones in the near future. The survey also projects future trends for ICs for miniature spread-spectrum transceivers offering robust operation in the crowded spectrum. With sophistication in baseband digital signal processing, its increasing interaction with the RF sections, and with increasing experience in simplified radio architectures, all-CMOS radios appear promising in the 900 MHz to 2 GHz bands. A specific CMOS spread-spectrum transceiver project underway at the author's institution is discussed by way of example     

基于自适应分数延迟估计的FM广播辐射源雷达直达波对消

在连续波体制的双基地雷达中一个重要的问题是存在直达波干扰,传统的解决方法是通过自适应天线的干扰置零技术,但这对警戒雷达来说置零的深度有限。该文首先对基于FM广播辐射源的双基地雷达中的直达波干扰进行了分析;然后提出了基于自适应分数延迟估计直达波干扰抑制算法;最后给出了基于FM广播照射源的一个双基地实验系统,利用该实验系统采集的数据进行仿真,仿真结果验证了该方法的有效性。     

Sweep-Frequency Oblique Ionospheric Sounding at Medium Frequencies

An experimental ionospheric sounder has been constructed for vertical-incidence or oblique sounding in the frequency range 600 kHz to 2 MHz. The equipment employs an FM linear frequency sweep transmission generated by direct synthesis from a frequency standard; an identical sweep is used for demodulation at the receiver. Sounding records, made at night over a 2000-km path, exhibit 10-?s resolution and show no interference from broadcast stations. Radiated power ranged from 25 to 250 watts. The advantage of good time delay resolution, together with suppression of interfering signals, makes possible ionospheric sounding of greatly improved quality in the MF range.