查询词典 frequency bandwidth

On the basement of passband subsampling and digital downconvertion, according to QPSK with 30M carrier frequency and 8M bandwidth, digital IF channel is elaborately analyzed .In this module, multiple phase filters are elaborately designed .According to this module, IF digital signal is simulated .

以对中频为30MHz，带宽为±4MHz的输入QPSK信号进行带通欠采样和数字下变频为基础，提出和分析了中频数字化通道的实现方案，进行了相应的多相低通抽取滤波器的设计，并针对数字中频信号就数字下变频模块进行了仿真，从而验证了整个下变频系统参数设计的可行性。

The surface current distribution of patch is changed because of the stub, so the operating frequency is decreased, the bandwidth is broadened, the return loss in operating range is decreased.

由于短截线的存在，改变了贴片表面电流的分布，由此降低了天线的频率，增大了工作带宽，降低了天线工作频段内的反射损耗。

The study demonstrates that there are four ways to expand the bandwidth of servo control system of the electro-optical theodolite: 1 Improving the free vibrancy natural frequency of optical-electronic theodolite; 2 To compensate the structural syntony ; 3 Using electric current feedback; 4 Using acceleration and velocity feedback.

研究表明，提高光电经纬仪伺服控制系统带寛有4个途径：1）增大光电经纬仪固有频率；2）对结构谐振进行补偿；3）使用电流反馈；4）使用加速度和速度反馈等。

In order to widen the frequency bandwidth of piezoelectric vibration based generator, the structure with multi-beams and single mass is designed.

本文针对压电式振动发电机频带宽度过窄的问题，设计了多悬臂梁-单质量块结构的微型压电式振动发电机。

By using of the theory and simulation methods above, the inject cavity, buncher cavity and output cavity are analysed separably. With An annual electron beam of voltage 500kV, and current 3kA, average output microwave power 455MW and peak power 1.3GM is observed, bandwidth is 60MHz, the efficiency is 30.3%, the gain is about 36.8dB.and the frequency is 2.85GHz, The amplitude and phase of output microwave is stable.

最后运用上面所得出的一系列理论及模拟方法，分别对相对论速调管的注入腔、聚束腔和输出腔的工作特性进行了详细的分析和优化设计，我们采用3kA和500kV的环形强流相对论电子束，最后得到了工作频率为2.85GHz、饱和增益为36.8dB、效率为30.3％、带宽大约60MHz、平均功率为455MW，峰值功率可达1.3GW的微波输出的相对论速调管，输出微波的幅值平稳，相位稳定。

Three important conclusions are achieved: 1 By analyzing the demand for spatial resolution of recording medium in different digital holographic recording setups, it shows that lensless Fourier transform holography can relax the requirement of spatial resolution and use the full spatial bandwidth of the CCD sensor. 2 Because of the differences of spatial resolution of image planes in different directions, reconstructed images can be relatively extended in the direction of high spatial resolution and reduced in the direction of the low one. 3 Lateral resolution of the reconstructed images is mainly determined by the highest spatial frequency of digital holograms recorded by CCD, and increases with the larger CCD size, the higher spatial resolution of the CCD sensor, and the shorter recording distance.

通过分析几种不同数字全息记录光路对记录介质空间分辨率的要求表明，无透镜傅里叶变换全息光路对CCD的空间分辨率要求最低，最能充分利用CCD的带宽；再现像面的空间分辨率在不同方向上的不一致，会导致再现像在空间分辨率高的方向上相对展宽，而在空间分辨率低的方向上相对压缩；再现像的横向分辨率主要由CCD所能记录的物体的最高空间频率决定，它随CCD的尺寸和空间分辨率的提高及记录距离D的减小而提高。

In anFDD wireless system, the duplex spacing between uplink and downlink islarger than the coherence bandwidth of the mobile radio channel, thus theuplink and the downlink small-scale fading is uncorrelated. Moreover, thearray response is correlated with the frequency of the signal carrier. So it isimpossible to resue the uplink weights for downlink beamforming. As aresult, the application of smart antenna for the downlink is a difficult problem.

在频分双工系统中，由于上、下行载波的频率差大于相干频带，上、下行信道衰落是不相关的，而且阵列响应也与信号的载波频率有关，因此，上行信道不能直接用来估计下行信道，故智能天线应用于下行链路是一个难点。

Cyber cafe network applications type very diversification, face to face network bandwidth, transmission mass and network function have very high request, network applications essential points collection advanced, many business, extended and stability what an integral whole, not only satisfied customer broadband network upper at the same time transmission pronunciation, video frequency and data need, and hold out various new business data-handling capacity, get on the Internet high speed unobstructed, big data rate of flow lower no away gleam, be not at a standstill and so on.

网吧网络应用类型非常的多样化，对网络带宽、传输质量和网络性能有很高的要求，网络应用要集先进性、多业务性、可扩展性和稳定性于一体，不仅满足顾客在宽带网络上同时传输语音、视频和数据的需要，而且还支持多种新业务数据处理能力，上网高速通畅，大数据流量下不掉线、不停顿等。

From the view of antenna circuit point, this paper adopts the finite difference time domain to analyze the impact on the center frequency and the bandwidth, which introduces by the radome.

从天线电路特性的角度入手，采用时域有限差分方法分析了天线罩的引入对天线中心频率、带宽比的影响。

Bubble function is a band pass filter in the frequency domains, while it can't have the ability to adjust bandwidth of filter.

Bubble函数在频域里相当于一带通滤波器，它可以反映不同的时域、频域特性，但它不具有调节带宽的功能。

In the chapter 2, the theoretic knowledge about the photosensitive resin and the grinding tools was firstly introduced.

第二章阐述了光固化树脂结合剂磨具的相关理论研究。

Do not use the program's indenting or margin-setting features; these will be added during typesetting.

不要使用缩排，页面边缘设置之类的选项，偶看不大懂。