查询词典 spectrum

It has not given India's mobile operators enough space on the radio spectrum to carry calls crisply and reliably.

遗憾的是政府对此准备不足，没有为移动运营商提供充足的无线频谱来确保清晰流畅的通话。

Based on the superposition principle, how to determine the critical angle of input seismic wave for complicated structures is discussed in detail by using response spectrum method.

因此，本文首先探讨应用弹性反应谱法确定最不利输入方向的基本原理及其在实际结构中的影响；其次在回顾前人研究的基础上，通过对最不利输入方向标准的探讨，提出一些建议。

Because the spread spectrum code of the users is known, the cross correlation coefficient between the users is known.

多用户检测技术是研究人员较为认可的抑制多址干扰的方法。

By means of signal processing techniques such as the power spectrum function, the auto correlation function and cross correlation function, two kinds of ECG signals when AF does or does not happen were successively analyzed, showing the evident differences between them.

提出了一种简便有效的、由心电图曲线提取QRS -T复合波的新方法，从而获得P波或f波；利用功率谱、自相关、互相关等信号处理技术，对它进行了处理和分析，特别是，比较了未房颤时和发生房颤时的相关信息的显著差别。

Auto-focusing algorithm based on cross correlation ;2. By means of signal processing techniques such as the power spectrum function, the auto correlation function and cross correlation function, two kinds of ECG signals when AF does or does not happen were successively analyzed, showing the evident differences between them.

提出了一种简便有效的、由心电图曲线提取QRS -T复合波的新方法，从而获得P波或f波；利用功率谱、自相关、互相关等信号处理技术，对它进行了处理和分析，特别是，比较了未房颤时和发生房颤时的相关信息的显著差别。

And the cross correlation function is approximately zero, which makes them suppress the disturbances due to the other users. After describing some basic knowledge of chaotic theory in chapter 2, we interview and classify the applications of chaos in communications including chaos secure communication, chaotic spreading codes for multi-user access in spreading spectrum system and chaotic modulation and demodulation in chapter 3. FM-DCSK system with non-coherent demodulation offers the best performance in chaotic modulation schemes.

在混沌调制方案中， FM-DCSK调制是一种极具竞争力的混沌调制方式，它克服了CSK、COOK、DCSK解调中存在的估计问题的缺点，在无线信道的传输过程中，可以很好的抑制噪声干扰与多径衰落，并且能获得非常优越的解调性能，加上混沌信号本身优越的保密性能，该调制方式在未来的无线通信领域存在着巨大的潜在优势。

Information of system auto and cross spectrum, auto and cross correlation. coherent function, signal to noise ratio, frequency response and impulse response was established to help the study and arrangement of the module components.

由力规及加速规两量测之时域讯号，经快速富利叶转换，计算其自频谱及互频谱，再经反富氏转换回时域之自相关及互相关函数、相通函数、讯噪比、频率响应函数、脉冲响应函数。

A method of time delay estimation by two times spectral analysis, where the time delay is the time interval between peaks of spectrum of the cross power spectral density, is proposed in the paper. It can be used to estimate time delay of not only single target but also multi-target without unwrap.

本文提出了两次谱分析时延估计方法，即将互功率谱函数再次进行谱估计，二次谱峰值位置间距即为时延估计，这种方法既能够估计单目标时延，又能够估计多目标时延，并且不用相位解绕。

The main job and contribution of this paper are as follows:Based on narrowband signal processing, we propose a new method for FH signal blind detection and blind parameter estimation. Firstly, compute the cross-correlation function of FH signals from multichannels, then we get the cross power spectral density matrixCSDM Secondly, select the hops of FH signals from the CSDM via processing and analyzing the CSDM, meanwhile reduce the influence coming from noise, fixed frequency signal and other interferences; Lastly, estimating the DOA of every hop and according to the DOA, we can separate the hops, get the number of FH signals and their parameters. Propose a new method for designing the threshold in FH signal detection. This method makes it easy to get the threshold by theoretic computing and it can extremely reduce the interference of non-FH signals.Based on broadband signal processing, we propose a new method for FH signal blind detection and blind parameter estimation. Firstly, get the DOA of the signals by wideband spatial spectrum estimation; secondly, separate the signals by spatial filtering using wideband beamformer; Lastly, we propose two methods for FH signal blind detection and blind parameter estimation, one is for several constant hop-rate FH signals whose dwell-time are different and another is for a single FH signal whose hop-rate is alterable.By employing spatial interpolation in broadband signal beamforming, it can reduce the number of antenna elements and corresponding RF modules, A/D converters, etc. It can also eliminate the mutual coupling between antenna elements while getting the narrower main beamwidth and lower sidelobe level.

本文的主要研究工作和贡献如下：●提出了一种基于窄带处理的FH信号盲检测和参数盲估计的实现方法，即首先求出多路信号之间的互相关，进而得到互功率谱密度矩阵，然后通过对CSDM进行对折处理来抑制噪声、定频信号及其他干扰的影响，并将所有属于FH信号的hop(每一跳的驻留时间在时频图上持续的线段)从CSDM中筛选出来，最后用阵列信号处理中的到达方向估计理论在频域中估计出各个hop的方向参数，利用方位信息完成FH信号分离并得到FH信号的数目及其各自的参数集；●提出了一种确定FH信号检测门限的策略，该策略不仅使得检测门限能够通过理论计算得到，而且还显著地抑制了非跳频信号的干扰，从而能有效地检测出FH信号；●提出了一种基于宽带处理的短波FH信号盲检测和参数盲估计的实现方法，即首先利用宽带空间谱测向技术得到接收信号的DOA，然后采用宽带波束形成技术对特定方向进行空间滤波，实现多个信号的分离，最后分别提出了两种FH信号的盲检测和参数盲估计方法，第一种方法适用于空间某个特定方向上存在着几个驻留时间不同的恒跳速FH信号和其他干扰信号的混合信号，第二种方法适用于空间某个特定方向上仅含一个可变跳速的FH信号和噪声的混合信号；●将空间插值的概念和宽带波束形成技术结合起来，提出了一种基于频域处理的宽带恒定束宽的波束形成方法。

In this paper, the application of sun-blind-region ultraviolet spectrum in short-range cryptical communication is discussed, and an experimental system of ultraviolet communication is constructed.

本文对紫外日盲区光谱在近距离、保密通信中的应用进行了探讨，并建立了紫外光学通信原理实验系统。

As of Tuesday, Google's results were still censored in China.

截至周二，谷歌的搜索结果仍受中国审查。

In order to make the positive action increase and negative one decrease, the sub-forces of the social factors must be adjusted to form a centripetal force.

在这一过程中，人的主体性发挥是社会有机体健康发展的灵魂。