查询词典 radio frequency

According to the mine shaft tunnel to the microwave frequency band in the certain degree to the channel characteristic, the radio frequency selects the microwave frequency band 433MHz to make the carrier, enables the wireless signal to carry on the effective dissemination in the line of sight distance, has the transmission stability to be good, external interference small merit.

根据井下隧道对微波频段在一定程度上相当于通道的特点，射频选用微波频段的433MHz做载波，使无线信号能够在视线距离内的进行有效传播，具有传输稳定性好，受外界干扰小的优点。

RF modules covering GSM, CDMA, TD-SCDMA, WCDMA, WLAN and Wimax wireless communications systems, active modules include power and frequency of the linear power amplifier, transceiver components, modules and integration of selected frequency modules, Passive radio frequency modules, including various types of filters, diplexers, a road, splitters and couplers; wireless network optimization campaign整机including PHS, GSM, CDMA, TD-SCDMA and WCDMA straight-machine, RF Rafah Yuan and indoor distribution systems, digital television, including digital TV mobile wireless transceiver modules, wireless transponders, digital mobile TV repeater, and so on.

射频模块涵盖了GSM、CDMA、TD-SCDMA、WCDMA、WLAN和Wimax等无线通信系统，有源模块包括各种功率和频率的线性功率放大器、收发组件、选频模块和一体化模块等，无源射频模块包括各类滤波器、双工器、合路器、功分器和耦合器等；无线网络优化系列整机包括PHS、GSM、CDMA、TD-SCDMA和WCDMA直放机、射频拉远和室内分布系统等；数字移动电视包括数字电视无线收发模块、无线转发器、数字移动电视直放站等。

Each House Detective installation kit comes with three primary test instruments; a frequency agile signal level meter, a frequency agile radio frequency leakage detector, and a zero foot dead zone time-domain reflectometer; all three housed together in a durable hard case.

每家侦探安装套件具有三个主要的测试仪器，一个频率捷变信号电平表，一个频率捷变射频泄漏探测器和一个零脚死区时域反射计；所有三个关在同一个持久的疑难案件。

Wavelet modulus maxima with high frequency and low frequency coefficients were obtained firstly through multiscale decomposition of well logging data;then important wavelet coefficients were chosen according to the fusion principle where high frequency coefficients were taken as maximal absolute values and low frequency coefficients were selected by edge detection principle;finally alternating projection algorithm was applied to reconstruct the fusion curve.

首先对原始测井曲线进行多尺度分解，得到不同尺度下的小波低频系数和高频模极大值；然后选用高频系数取绝对值极大、低频系数采用边缘法的融合规则，选取重要的小波系数；最后利用交替投影算法重构融合曲线。

The excellent agreements between simulated and measured results prove the accuracy of the established circuit model. Moreover, the varactor was added to the resonator to adjust its resonant frequency. As expected, the reactance introduced by the varactor indeed affects the net inductance and capacitance obviously. It is noted that, not only the shift with the center frequency, the inductive or capacitive of the reactance can also provide a parameter to switch its frequency toward the two directions away from the one without varactor. As a consequence, a wideband tunable band-pass filter is achieved. Although the bad quality factor with the diode strongly increases the insertion loss, this concept was proved to be available for effectively tuning the center frequency of such a class of band-pass filter.

另外，在共振器上的varactor是用来调整共振器的共振频率，如预期的，由varactor所造成的电抗确实的影响到共振器的总电感和电容值，值得一提的是，不仅滤波器的中心频率可以被改变，这电抗是电感性或是电容性也将决定滤波器的中心频率将大於或小於未加varactor时滤波器的中心频率，利用这个结果，我们也实现了一个宽的可调频率带通滤波器，虽然不理想之二极体的Q值增加了滤波器的介入损失，但这原理是被证明可有效的用於调变带通滤波器的中心频率。

Experiments shows that it can detect the carrier frequency and the low frequency of modulation signal as expected, the resolution of the carrier frequency is 0.3Hz,the detecting error is within ±0.5Hz, and the resolution of the low modulation frequency is 0.07Hz, the detecting error is within ±0.05Hz.

实验结果表明该检测仪能很好地检测出信号的载频和信号的低频调制信息，其中信号载频的分辨率为0.3Hz，误差范围在±0.5Hz 以内，低频信息的分辨率可达0.07Hz，信号的误差在±0.05Hz。

A new frequency estimation algorithm for Time Domain Synchronization OEDM system is proposed, which utilizes the time domain circular characteristic of PN sequences to adjust frequency offset and then uses a variable step frequency scan scheme to estimate large frequency offset.

提出一种新的适用于TDS-OFDM系统的频偏估计算法，利用PN序列的时域循环特性进行预频偏调整，然后用变步长扫频进行大频偏的估计，定时同步之后再利用PN的时域循环特性进行细偏估计。

Below us Divider VHDL description of the source code for the completion of the clock signal CLK frequency of 2 hours, 4 frequency, frequency of 8 hours, 16 minutes frequency.

下面我们介绍分频器的 VHDL 描述，在源代码中完成对时钟信号 CLK 的 2 分频， 4 分频， 8 分频， 16 分频。

To review the basic terminology in data organization and data presentation 2 To learn frequency distribution and cumulative frequency distribution 3 To construct the graphical representations: histogram, frequency polygon, and culmulative frequency polygon

回顾数据组织及数据表达的基本用语。学习频数分布及累积频数分布。绘制如组织图、频数多边形及累积频数多边形等的图示。

The effect of tribology factors on bearing vibration is studied experimentally. AR model and WPT are used to processing the normal arid abnormal signals. The results are as follows:1. The vibration of ball bearings is caused by the tribology action of contact pairs of ball and ring races and has the essential of tribo-dynamics. Any factors affecting the tribology characteristics of contact pairs will affect vibration and noise of bearings consequently.2. Vibration characteristics of bearing keep almostly unchanged with the increasing of axial load expecting the increasing of nature frequencies. When radial load increasing with axial load unchanged, nature frequencies keep unchanged but some new vibration peaks appears in the spectrum.3. Vibration amplitudes are damped and nature frequency are enhanced with sufficient lubrication. Vibration and noise of bearings increase obviously and roar can happen and the contact surfaces scratch slightly under insufficient and unclean lubrication state. Bearing will be disabled in a few minutes without any lubrication.4. Bearing vibration is unstable under low speed. With the speed increasing, the vibration become stable and natural frequencies increase slightly but the amplitudes increase apparently.5. Bearing vibration can be excited only by some harmonics ofwaviness without lubrication and by all harmonics with lubrication based on the theoretical analysis.6. The nature frequencies of ball bearings decrease with the increasing sizes. When international clearance increasing, nature frequencies decrease in radial and increase in axial and angular and the amplitudes increase in radial and decrease in axial and angular. When the number of balls increasing, nature frequencies increase and amplitudes decrease. When the pitch diameter increasing, axial nature frequency increase and others nearly keep no change. When outer race groove curvature radius increasing, nature frequencies increase in radial and decrease in axial and angular and amplitudes keep no change in radial and increase in axial and angular. When inner race groove curvature radius increasing, nature frequencies decrease and amplitudes increase.7. The distortion in amplitude and frequency components of bearing vibration signals picked up by the present probe measurement method is founded and right conclusions cannot be achieved by the signals. When accelerometer is rigidly screwed with steel stud onto a flat outer surface of a ball bearing, vibration signal can be got without distortion and the reliability of research on bearing vibration is assured.8. AR model is suitable for large samples of bearing vibration signals, square root of length of samples can be used as the upper limitation of order determination and the FPE order selection criterion is effective. Many advantages of AR spectrum are founded over the classical based on FFT.9. Time-Frequency analysis is necessary for abnormal noise of ball bearings. WPT overcomes the principle shortcomings of STFT and proved to be a best tool to process the abnormal signals.

理论分析和试验研究表明： 1球轴承振动是钢球—滚道接触副中的各种摩擦学作用引起的，具有摩擦动力学的本质，任何对接触副的摩擦学特性有影响的因素都将对球轴承的振动和噪声特性产生影响； 2中心轴向载荷作用下，载荷增大使球轴承的固有振动频率升高，载荷越大同样的载荷增幅引起的频率升幅减小，足够大的中心轴向载荷作用下载荷的变化对球轴承振动的频率特性不会产生明显的影响； 3轴向和径向联合载荷作用下，径向载荷不大时球轴承振动的固有频率基本不变，但是可能引起变刚度激励的非线性振动，出现新的频峰，过大的径向载荷将使部分钢球脱离接触，使球轴承的振动和噪声呈现不稳定状态； 4润滑对球轴承的振动和噪声特性有重要的影响，良好的润滑对振动有明显的抑制作用，润滑不充分时，振动和噪声的水平会有明显增高，一定条件下还会激发接触副中的谐振，发出啸声，造成接触表面的伤害，无润滑干接触时，短时的运转就会损伤接触副表面，使振动和噪声迅速增大，并随时可能引发严重的磨损和卡滞失效；接触副润滑良好时，油膜的"刚化效应"使球轴承振动的固有频率有所提高，润滑剂中含有弥散性污浊时，振动的幅度总体升高，但弥散性污浊不会改变球轴承振动的频率特性；浙江大学博士学位论文：球轴承振动的研究 5低速时，球轴承振动的基本特征呈现不稳定状态，随着转速的提高，球轴承振动的频率特性趋于稳定，固有频率频峰升高； 6理论分析表明，干接触时钢球和滚道表面波纹度的某些谐波分量能激励球轴承的振动，振动的幅值与谐波幅值成正比，实际球轴承中钢球的分布不可能完全均匀，波纹度的激励作用会随时发生；润滑接触的分析表明，波纹度的任意谐波分量均能激励球轴承的振动； 7球轴承的几何和结构参数分析表明，球轴承尺寸越大，径向、轴向和角振动的固有频率越低；钢球中心圆直径增大，球轴承的径向和轴向振动的固有频率基本不变，角振动的固有频率有所上升，振动的幅频特性基本不变；径向游隙加大使球轴承的径向振动固有频率降低，轴向和角振动的固有频率有所升高，径向振动幅频特性的幅值升高，而轴向和角向降低；钢球的数量增多使球轴承振动的固有频率上升，幅频特性的幅值下降，径向振动的幅值下降最为明显；外圈沟曲率半径系数增大使球轴承径向振动的固有频率升高，轴向和角振动的固有频率降低，径向幅频特性基本不变，轴向和角向幅频特性幅值升高；内圈沟曲率半径系数增大使径向、轴向和角振动固有频率均下降，振动幅频特性的幅值均有升高； 8试验对比表明，传感器采用探针式安装时，由于探针接触副接触特性的影响，钡(量得到的球轴承振动信号有失真，采用专门设计和制作的试验球轴承，以固定式安装加速度计，首次测量得到了球轴承振动的真实信号，通过对振动信号的分析，验证了球轴承振动的理论模型； 9)基于时间序列分析的AR模型适用于大样本球轴承振动信号的分析，以样本长度的均方根值作定阶上界，FPE做判阶准则，给出的AR谱光滑，频率分辨率高，是球轴承振动分析的简便而可靠的手段； 10以时频域分析的小波包变换分析球轴承异音信号能够比较好地定位和聚焦异音发生的时间，时间间隔，频率范围，同样是球轴承振动分析的可靠的手段，可用作球轴承故障诊断技术。

Listen,point and check your answers.

听，指出并且检查你的答案。

Warming needle is one of effective treatment methods for knee arthralgia aggravated by cold,and it is simple,safety,so it should be developed in clinical acupuncture and moxibustion extensively.

但以本院科针灸门诊在2005年1月—2006年6月期间共收治膝痛患者100余例，经过临床的诊断后，其中施以温针治疗的48例，疗效显著，报道如下。1临床资料本组病例48