查询词典 frequency histogram

This paper bases on frequency-hopped and frequency synthesis theories, and through demonstrating three schemes of frequency synthesis, the paper selects one of these schemes that uses DDS spiriting up PLL and improves on the method according to the practical target and synchronously, the paper analysis the capability of the output signal and the conversion time of the frequency.

本文在对跳频理论及频率合成理论分析的基础上，在讨论三种频率合成方案后，设计完成了一种适于本课题的DDS激励PLL的混合方案，并对频率合成器主要性能中的输出信号的噪声特性和频率转换性能做了研究分析。

According to the field variation with frequency in the test volume, the work frequency of GTEM cell can be divided into three frequency areas, namely, quasi-static area, high frequency area and out of the vertical polarization area.

根据测试区场分布随频率的变化情况，可将GTEM传输室的工作频率分为三个特征频段，即：准静态区、高频区和非垂直极化区。

Based on the requisition of wireless system debugging, this paper develops a novel radio-frequency beaconing. Design method and system constitution of a novel beaconing based on PLL IC PE3336 are given, and the accomplish method of the system's hardware and software arc expounded. The test results show that the beaconing adopted in this method has a reliable and stable frequency conversion features. The more applications in the wireless system find that the users can set necessary frequency conveniently. Especial1, the friendly man-machine interface makes the operation is more flexible. It is as excellent performance-price-ratio beaconing, and as a signal source, it can be used in the research and the debug procession of variable radio-frequency components.

根据无线电数据链系统及部件的调试需要，研制开发了一种新型的以锁相环为核心、由单片机控制的射频信标机；文中给出了基于锁相环芯片PE3336的新型信标机的设计方法与系统组成，阐述了系统硬件及软件的具体实现为法；测试结果表明，利用该方法设计的信标机具有稳定、可靠的变频特性，且各项指标均达到了要求；进一步在某无线电系统中的应用发现，用户可方便地设置所需频点；特别是友好的人机界面，使用户操作更为灵活方便，是一种性能价格比优良的信标机；并可作为信源用于不同的射频部件研制与调试过程中。

Taking the development platform of HVDC power transmission for example, the calculation result of impedance-frequency characteristic of traditional line commutated converter and that of FCC are compared. Simulation results show that the impact of impedance-frequency characteristic of converter on the resonance frequency of AC system is not negligible, and FCC can enhance the strength of AC system in a certain extent, improve system stability and effectively reduce AC equivalent impedance under resonance frequency, thus the harmonic instability of HVDC power transmission system can be avoided.

以直流输电开发平台为例，对传统电网换相换流器(line commutated converter，LCC)与FCC的阻抗频率特性计算结果进行对比，仿真结果表明换流器的阻抗频率特性对交流系统的谐振频率有着不可忽略的作用，FCC在一定程度上提高了交流系统强度，改善了系统稳定性，有效降低了系统谐振频率下的交流等值阻抗，从而更好避免直流输电系统谐波不稳定现象的发生。

According to the method, model dimension is contracted to five by the way of selecting the unit in which amount of I/K is m inimal. Then sensitivity of frequency to stiffness is calculated. After the diff erence between measured frequency and calculated frequency have been got, the ad justed amount of stiffness is calculated by the using of the sensitivity and the frequency difference.

该方法按照I/K最小优先合并原则，将轴系模型自由度数缩聚为5，分析该模型4个刚度对前4阶频率的敏感度，算出实测的前4阶频率和模型计算频率之间的差值，利用敏感度和频率差值计算出刚度的调整量。

In shoaling process, the main peak frequency of broken wave spectra moves to lower frequency. With decreasing relative water depth, both the ratios of wave spectral energy at twice and triple peak frequency to main peak frequency increase. and when the value of the nonlinear parameter increases, both the ratios increase, too. The Stokes third order wave theory has the same tend but overestimates the value quantitatively.

波浪浅化时，碎波后主频频率有往低频移动之现象，且波浪进入浅水区，相对水深减小，非线性参数Ursell number越大时，二倍主频及三倍主频与一倍主频能量比值均有增加之现象，与 Stokes三阶理论有相同之趋势，但实验之比值在定量上小於Stokes三阶理论值。

Namely in high-frequency unit use gradually incisive time resolution and lower frequency resolution, in order to moves the near observation signal quickly to change the part; In low frequency partially has the higher frequency resolution and the lower time resolution, in order to moves the far observation signal slowly to change partially, the wavelet this kind of signal analysing expression characteristic to analyzes the non- steady signal is extremely effective, suits the transient state anomaly very much which smuggles in the survey normal signal and demonstrates its ingredient, therefore by reputation for analysis signal microscope.

即在高频部分使用逐渐尖锐的时间分辨率和较低的频率分辨率，以便移近观察信号的快变部分；在低频部分具有较高的频率分辨率和较低的时间分辨率，以便移远观察信号的慢变部分，小波这种信号分析表示特征对分析非平稳信号是非常有效的，很适合于探测正常信号中夹带的瞬态反常现象并且展示其成分，所以被誉为分析信号的显微镜。

By locking laser frequency to atomic absorption spectrum through current negative feedback and locking microwave frequency to electromagnetic induced transparency resonance peak through voltage negative feedback, it is realized to lock the clock frequency of this laboratorial desktop experimental CPT frequency standard.

通过采用电流负反馈将激光频率锁定在原子对激光的吸收峰上，电压负反馈将微波频率锁定在电磁感应透明共振峰上，用该物理系统实现了闭环锁定的实验室桌面CPT频标实验系统。

By locking laser frequency to atomic absorption spectrum through current negative feedback and locking microwave frequency to electromagnetic induced transparency resonance peak through voltage negative feedback respectively, the locking of the clock frequency of this laboratorial desktop experimental CPT frequency standard is realized.

介绍了相干布居囚禁原子频标的小型、低功耗物理系统，并应用它开展实现了CPT原子频标的激光锁定、微波锁定方案的实验室研究。通过采用电流负反馈将激光频率锁定在原子对激光的吸收峰上，电压负反馈将微波频率锁定在电磁感应透明共振峰上，用该物理系统实现了闭环锁定的实验室桌面CPT频标实验系统。

With the development of semiconductor devices, the switching frequency of PWM converters becomes higher, which makes PWM converters (mainly high-frequency transformers, inductors and capacitors in converters) smaller, and this will benefit design and application of them. Whats more, higher switching frequency will reduce the audio-frequency noise and improve dynamic response of PWM converters.

随着半导体器件技术的不断发展，PWM变换器所能达到的开关工作频率越来越高，使得变换器(主要是变换器中的高频变压器、电感等磁性元件和电容)的体积和重量越来越小，这有利于PWM变换器的设计及推广应用。

You can do some assertiveness training.

你可以进行一些自信训练。

We were well on the path to making a rear-wheel-drive global platform," says Mays."

我们正致力于建立一个后轮驱动的平台，"Mays这样说道。"