锁相调频中的噪声性能分析

本文分析了有噪调频锁相环的噪声种类,得出了有噪调频锁相环的相位模型,计算出了环路输出噪声相位方差。     

高精度锁相环调频电路

电路采用两次数字分频方法，仅采用４个普通的十六进制计数器，使得振荡电路的频率不再有跳变步长，其稳定度也可超过所采用的晶体振荡器，电路材料要求相当低，可靠性却相当好，非常适合于高精度射频信号发生器和射频调频发射电路。     

锁相环式调频立体声解码器LM1800

<正> LM1800是美国国家半导体公司推出的一种锁相环式调频立体声解码器单片集成电路。这种集成电路采用了先进的相位锁定技术,使得集成块内再现的38kHz开关信号与原主、副信道合成信号中的38kHz副载波信号之间的相移减至最小,并且保持严格同步,从而使其具有较高的分离度和稳     

用FPGA设计调频广播监测频率合成器

对调频广播无线电信号的监管工作中,需要用无线电干涉仪测定电台的方位.与节目内容收测工作只关心信号的振幅和频率参数不同,因为测向工作是测量信号的相位信息,所以作为本机振荡器的频率合成器需要有较高的相位噪声指标.用FPGA设计的频率合成器,采用了小数分频方式,结合FPGA内部设计的CPU软核组成调频广播监测设备.经过在广播电视监测设备中的实际应用,取得了良好的效果.     

数字式调频收音机设计

介绍利用数字锁相频率合成技术构成收音机的电调谐部分并阐述了收音机的调台、选台、搜索与存储等功能的电路设计原理，着重介绍了用收音机集成芯片CXA1019S构成的FM电路、频率合成器芯片BU2614构成的锁相环电路。     

室外广播用锁相环调频无线扩声系统

介绍一种采用锁相环（PLL）频率合成器BU2618FV和AVR单片机控制的室外调频广播用无线扩声系统，具有可选择的定时开头机和有广播自动开机的功能，详细介绍了锁相环集成电路BU2618FV的性能和典型应用。     

数字调频激励器

1引言近年来,山西省广播电视局先后购置5部10kW哈里斯全固态数字调频广播发射机,分别承担中央台、山西台多套调频广播节目的发射任务。经几年工作运行,机器性能稳定可靠,技术指标质量高,音质可与CD媲美,显示了数字化发射机的优越性。现对整个发射机的核心部分数字激励器的性能及原理作简要介绍。2数字激励器DIGITCD数字调频激励器是美国哈里斯公司上世纪末的最新产品。如果输入一个数字的或模拟的复合立体声信号,输出端就会得到一个调频功率电平达55W的载波信号,调频(FM)调制处理完全数字化。同时,它还具有捷变频率的功能,可用于发射…     

DMR终端锁相调频发射机设计

文章介绍了一种DMR数字终端锁相调频发射机的设计与实现,首先阐述了其设计原理,然后利用振荡器芯片设计宽带调频VCO,再与频率合成芯片构造锁相环调频器,最后利用RF2117进行功率放大,测试结果表明该设计具有良好的应用价值。     

Wideband FM Generation

An analysis is presented which demonstrates that an exact FM signal with no theoretical limits on its frequency deviation or modulation frequency may be obtained by wave shaping an FM triangular wave. A straightforward method of physically generating the FM triangular wave along with experimental data on the resultant circuit is also presented. These data indicate that for frequency deviations as high as 75 percent of the carrier frequency, overall transmitter-receiver system distortions are of the order of 0.2 percent.     

直接加间接锁相调频应用于TV伴音调频

本文分析了锁相调频的原理,指出了直接锁相调频应用于TV伴音调频的缺陷。同时分析了直接加间接锁相调频应用于TV伴音调频的优点,即既可以克服伴音漂移现象,又可以扩展调制频率下限。笔者最后给出了具体设计实例和测试参数。     

FM/FM Multiplex Radio-Telemetry System for Handling Biological Data

Multiplex systems are examined in the time and frequency domains for their utility in applications to biological studies. The continuous-wave FM is shown to fit best the requirements of genuine signal reproduction, reasonable construction and reliability.     

Frequency stabilization of the FM laser

A technique for the frequency stabilization of an FM laser is discussed. This technique employs a stabilization discriminant derived from a residual variation of the phase and amplitude of the small FM laser beat note at the modulation frequency, as the frequency of the FM carrier moves across the Doppler gain profile. A first-order analysis describes the dependence of that stabilization discriminant on δ, the mode coupling coefficient produced by the internal KDP phase modulator, and Γ, the resulting FM modulation index. Experimentally, a 50-mW He-Ne FM laser was frequency stabilized to better than one part in 10⁸on a long-term basis. In addition, the beat note at the modulation frequency was suppressed by 40 dB from its free-running value.     

New Concept in FM Exciters

A new approach is used for a frequency modulated Exciter: Modulation is accomplished through use of semiconductor capacitive diodes. The AFC System makes use of a counter-type discriminator to stabilize center frequency. A magnetic amplifier is utilized as stable, high gain dc amplifier in the AFC loop. These three novel approaches lead to a simplified reliable equipment.     

A point-contact transistor VHF FM transmitter

In extending the upper frequency of operation of point-contact transistors to the VHF region, the device development was paralleled by an investigation of CW oscillator circuitry. This was done because a CW oscillator is a self-contained system capable of accurate analysis. It is therefore a highly suitable tool for studying the electrical characteristics of the transistor in the VHF region. The concept of frequency modulation by alpha cutoff frequency shift originated as a result of this CW oscillator circuitry study. An experimental FM transmitter operating in the commercial FM band was built to demonstrate both this frequency modulation technique and also CW oscillation in the alpha frequency cutoff region. It is the purpose of this paper to describe this transmitter and to show how a single transistor can simultaneously perform all the functions required of a complete FM transmitter.     

哈里斯数字调频发射机频率切换电路

介绍了一款哈里斯DIGIT CD数字调频激励器频率显示切换装置.该装置的使用,很好地实现了哈里斯全固态调频发射机瞬时换频的功能,减少了因换频带来的停播时间;同时增加了工作频率显示及激励封锁,进一步完善了发射机的功能.     

Linearization of direct FM frequency modulators

Voltage controlled crystal oscillator (VCXO) frequency modulators have found increasing use in recent years in portable frequency modulation (FM) equipment as an alternative to a standard crystal oscillator followed by a phase modulator. The advantages of using a direct FM VCXO over an indirect FM phase modulator are considered. A model for the crystal and frequency control element will be developed and basic circuit design considerations will be presented. Conditions necessary to minimize audio distortion generated by the VCXO modulator will be dealt with in detail.     

Compound AFC-APC FM demodulators

In this letter two different types of FM demodulators, called compound AFC-APC (automatic frequency control--automatic phase control) FM demedulators, have been considered. It is shown that the tracking capability of either of the systems is much higher than that of an ordinary phase-locked demodulator. Experimental results are also presented in support of the conclusions of the analyses.