查询词典 narrowband

Simple upper bounds of signal to noise ratio improvement factor are derived for the suppression of a narrowband first-order autoregressive process and analytical conclusions corroborated by numerical examples.

研究了判决反馈滤波器在直扩系统中估计和抑制窄带干扰的性能，给出了判决反馈滤波器抑制一阶自回归干扰时信噪比提高因子的闭合表达式的上界。

The traditional Givens rotation algorithm involves root computation that needs more hardware resources, a Givens rotation algorithm without root and division computation is presented. And, combined with special structure of input signal matrix, a interference suppression algorithm with low computation is proposed. The narrowband interferences are modeled as autoregressive process and digital signal.

传统Givens旋转算法涉及平方根运算，要消耗较多硬件资源或需要多次循环来实现，为此，提出一种无平方根与除法运算的Givens旋转算法，并结合信号输入矩阵的特殊结构，给出一种低复杂度的干扰抑制算法，将窄带干扰建模为自回归过程以及数字窄带信号。

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。

Despite the channel is not smoothly,but each sub channel is smoothly and the signal be transferred by narrowband in sub channel,which can avoid disturber between sigal wave.

本文的研究表明，如果采用新的正交基来取代这些子载波，可以在不加保护间隔的情况下减少ICI和ISI，从而改进正交频分复用技术的性能。

When the pump beams have either narrowband or broadband linewidth,it is found that the overall accuracy for the energy-level difference measurement is determined by the homogeneous linewidths of the optical transitions,and is independent of laser linewidth and Doppler broadening.

无论泵浦光束为窄带线宽或宽带线宽，它对能级差测量的总体精度仅仅取决于光学跃迁的均匀增宽，而与激光线宽和多普勒增宽无关。

Our study has the following findings: most of the network bandwidth is used by P2P software to transfer the files, approximately 34%. Among the P2P software, the largest service item is the eDonkey, approximately 24%. Most of the traffic in each group is used by only a few users. The behaviors of the broadband users are significantly different than the narrowband users. To download the files is the major purpose of the broadband users, but the narrowband users are used to get their Emails. The files with the video files extensions of dat、mpg、avi and with image file extensions of iso、mdf、img are the primary file types transferred by campus users.

本研究发现：占用频宽最大比例者为P2P软体之档案资料传输，约占总频宽34%，其中最大项目为eDonkey，占总频宽使用量约24%；群组的流量，大部分是群组内少数使用者所使用；宽频及窄频使用者行为有显著不同，其中，宽频使用者是以下载档案为主，而窄频使用者是以收信为主；在档案的传输中，以副档名为dat、mpg、avi等影片档及副档名为iso、mdf、img等光碟映射档为主要传输类别。

In Speex narrowband mode,the input data are exactly 160 samples with each sample consisting of 16 bits.It can create corresponsive compressed data by set quality.

於Speex narrowband中，每160个且为16 bits的样本中，设定相对应的品质可以得到相对应的压缩大小

However, upon detection of an incumbent narrowband signal in the channel, the WRAN endpoint forms a frequency usage map for transmission to another WRAN endpoint, wherein the frequency usage map identifies one, or more, of the subcarrier sets that would interfere with the incumbent narrowband signal.

然而，在检测到信道中在用窄带信号时，WRAN端点形成频率使用映射，用于向另一个WRAN端点传输，其中所述频率使用映射识别一个或者多个与在所述用窄带信号干扰的子载波组。

The communication technology used in GPS is a direct sequence spread spectrum structure. Using C/A Gold codes, it can cope with wideband noise (such as thermal noise and channel noise) or low power narrowband interference by its processing gain. But DS-SS can not reject high power narrowband interference completely. So we need an anti-jamming filter to reject the narrowband interference by using adaptive filters prior to dispreading.

它是利用直接展频的一种架构，因此，此系统能藉由C/A码的展频处理增益，来对付ㄧ些宽频的干扰或是低能量的窄频干扰，但是它无法应付高能量的窄频干扰，因此我们需要一个抗干扰滤波器在解展频之前来先将干扰去除。

There are few equivalent circuit modeling methods for UWB antennas. This thesis compares the characteristic of some existing modeling methods and presents a general and precise modeling method for UWB antennas. Firstly, establish the narrowband model of the antenna, and compute the difference between input admittances of the antenna and its narrowband model. Secondly, implement rational approximation of the difference to build the macromodel, and convert it into SPICE equivalent circuits. Lastly, combine the narrowband model and the macromodel to form the ultimate equivalent circuit model of the antenna.

本论文针对目前UWB天线等效电路建模方法比较少的现状，结合现有的天线建模方法的一些特点，研究了一种系统通用、模型精度高的新建模方法：首先建立超宽带天线的窄带模型，计算天线及其窄带模型导纳的差值；接着对差值进行有理多项式拟合，得到相应的宏模型，并转化为SPICE等效电路；最后合并窄带模型与宏模型电路，得到天线等效电路模型。

It is also known as one of the most poisonous naturally occurring substances.

它也被称为一个最自然发生的有毒物质。

The greatest stress is found at the location on the cross section where V is the largest.

最大应力出现在横截面上V为最大的地方。