查询词典 frequency modulation

Molecular iodine has rich strong absorption lines near 532 nm that can provide the absolute references for frequency stabilization. A monolith solid laser was tuned at the spectrum of transition R (56) 32-0 of iodine molecule with new modulation frequency 375 kHz.

使用532 nm单块固体激光器，在375 kHz新的调制频率下，利用调制转移技术，将激光频率调谐到127I2的R(56)32-0跃迁的吸收谱线，并观察到该吸收谱线相应的15条超精细结构分量。

The result of frequency response analysis shows that when the modulation frequency of incident radiation increases, the phenomenon that the response of detector lagging behind the variation of radiation becomes evident, the temperature variation range in pyroelectric thin film decreases, but the variation velocity increases, so the current resulting from pyroelectric effect increases.

频率响应分析表明：随着入射辐射调制频率的增大，可以观察到探测器响应的滞后现象越来越明显，热释电薄膜中的温度变化范围减小，但变化速率增大，因此探测器的热释电电流增大。

A low in-band phase noise FM frequency synthesizer has been depicted in this paper. It bases on the fraction N PLL frequency synthesizer, and the THD of the system has been improved greatly by this closed loop modulation mode.

研制一种低带内相位噪声的立体声FM频率合成器，该合成器基于小数分频锁相环技术，利用闭环方式对载波信号进行调制，显著提高系统的THD。

By utilizing the cross-gain modulation effect and the period-one oscillation harmonic frequency-locked in an optically injected semiconductor laser, we can extract the wavelength conversional individual channel optical clock from the optical-time-division-multiplexing signal. In a FP-LD, we numerically simulate the extraction of 20 GHz optical clock at 1550 nm from the 2×20 Gb/s OTDM signal at 1555 nm, and experimentally obtain the -105 dBc/Hz phase noise frequency division clock of 12.36 GHz to 6.18 GHz with simultaneous wavelength conversion from 1550.24 nm to 1545.91 nm.

采用一个FP半导体激光器作为全光分路时钟提取及波长转换器，数值模拟实现了从波长为1555 nm、速率为2×20 Gb/s的光时分复用信号中提取出波长转换为1550 nm、重复频率为20 GHz的分路光时钟，实验完成了从波长为1550.24 nm、重复频率为12.36 GHz光脉冲信号中提取出相位噪声为-105 dBc/Hz的波长为1545.91 nm、重复频率6.18 GHz的分频光时钟。

Their vocal quality is better than non-passerine, but still much less than oscine passerine. Compared with non-passerine, they appeared longer syllable length, higher basic frequency and more viable frequency ranges. Though the amplitude modulation properties enhanced their vocal production, the type of syllable is still stable and less of variety. So thephrase consisted of syllables are comparatively few and changes of the tone are relatively less.

且表现出很强的频率调制特性和特有的幅度调制特性，相对的音节时程比较长，基频较高且频率变化范围较大，所特有的幅度调制特性更增加了其控声的能力，但其音节的种类仍很单一，缺乏变化，由音节所组成的句型较少，音调变化幅度不大，因此，其叫声质量尽管较非鸣禽有所改善，但相对鸣禽而言却又远远不如。

Altera Corporation system to the Cyclone FPGA series of digital platform, microprocessor, bus, Digital Frequency Synthesizer, memory and I / O interface hardware concentrated in an FPGA, the use of direct digital frequency synthesis technology and digital modulation waveforms required to achieve the rise, Using FPGA ROM storage of the DDS waveform table, and make full use of on-chip resources, improve the system's accuracy, stability and robustness.

系统以 ALTERA公司的 Cyclone 系列 FPGA 为数字平台，将微处理器、总线、数字频率合成器、存储器和 I/O 接口等硬件设备集中在一片 FPGA 上，利用直接数字频率合成技术、数字调制技术实现所要求波形的产生，用 FPGA 中的 ROM 储存 DDS 所需的波形表，充分利用片上资源，提高了系统的精确度、稳定性和抗干扰性能。

At the first step, time-frequency distribution (spectrogram or pseudo Wigner-Ville distribution) of the time-varying signal is adopted and a peak-tracking scheme is designed to obtain a coarse ionosperic modulation estimation from the time-frequency distribution.

在第一步校正中，首先分析这种时变信号的时频分布，并设计了一种谱峰追踪方法从时频分布中获得粗糙的电离层频率调制估计。

Main Products: Network Analyzer, integrated tester, spectrum analyzer, noise figure testers, receiver, telephone tester, high, low-frequency signal source, audio, video signal source, high, low-frequency oscilloscope, modulation device, the video analyzer and so on.

主要产品：网络分析仪，综合测试仪，频谱分析仪，噪声系数测试仪，接收机，电话测试仪，高、低频信号源，音、视频信号源，高、低频示波器，调制仪，视频分析仪等。

Used mainly engaged in Communications equipment Products: Network Analyzer, integrated tester, spectrum analyzer, noise figure testers, receiver, telephone tester, high, low-frequency signal source, audio and video signal source, high, low-frequency oscilloscope, modulation device, video analysis detector.

主要经营二手通信仪器产品：网络分析仪，综合测试仪，频谱分析仪，噪声系数测试仪，接收机，电话测试仪，高、低频信号源，音、视频信号源，高、低频示波器，调制仪，视频分析仪等。

The introduction of some products are as follows: First, Taiwan's electronic devices Aosta Product:(self-produced self-marketing) program-controlled voltage insulation tester, grounding resistance, leakage current, micro-resistance tester, electrical parameters of the test Transformer parameters meter, insulation resistance tester, electronic load, on-machine, cable tester, variable frequency power supply, LCR Bridge, frequency meter, mV table, the standard signal generator, oscilloscope, signal generator, signal generator, digital multimeter, distortion device, before shaking device, spectrum analyzer, capacitance meter, inductance meter, modulation device, Sweep Signal Generator, Telephone Analyzer, Calibrator Table III, EMC Electric Tester, regulated power supply and so on.

现将部分产品介绍如下：程控耐压绝缘测试仪、接地电阻、泄漏电流、微电阻测试仪、电参数测试变压器参数测量仪、绝缘电阻测试仪、电子负载、导通机、排线测试仪、变频电源、LCR电桥、频率计、毫伏表、标准信号源、示波器、信号发生器、信号源、数字万用表、失真仪、抖摆仪、频谱分析仪、电容测量仪、电感测量仪、调制度仪、扫频信号发生器、电话分析仪、三用表校准仪、EMC电测仪、稳压电源等。

Breath, muscle contraction of the buttocks; arch body, as far as possible to hold his head, right leg straight towards the ceiling (peg-leg knee in order to avoid muscle tension).

呼气，收缩臀部肌肉；拱起身体，尽量抬起头来，右腿伸直朝向天花板（膝微屈，以避免肌肉紧张）。

The cost of moving grain food products was unchanged from May, but year over year are up 8%.

粮食产品的运输费用与5月份相比没有变化，但却比去年同期高8％。