查询词典 frequency bandwidth

The receiver's high-current capability enables it to effortlessly drive even difficult loudspeaker loads, while ultrawide bandwidth provides far superior phase linearity, lower distortion, greater high-frequency headroom, and more accurate frequency response in the audible frequency range.

接收器的高电流能力，使它能够毫不费力地驱动扬声器甚至难以负荷，同时提供超带宽远远优于阶段线性度，低失真，更多的高频率余量，以及更准确的频率响应的发声频率范围。

to reduce the impact of carrier frequency offset in ofdm system,this thesis designs a new carrier frequency offset estimation scheme for ofdm system.the carrier frequency offset estimation includes acquisition and tracking.we adopt variable step size adaptive algorithm.the acquisition range of the proposed algorithm is as large as one half of the overall signal bandwidth.through this method we can not only avoid the feedback by using forward error correction,but also reduce the times of complex multiplication in order to reduce the power consumption of the system.this algorithm not only has low complexity and fast convergence nut also can improve the demodulation performance of ofdm system.computer simulation illustrates the superior performance of the proposed algorithm with regard to estimation accuracy in both awgn channel and multi—path channel.

摘 要：为了减小正交频分复用系统受频率偏差的影响，在ofdm系统中设计了一种新的载波频偏估计算法。频偏估计包括跟踪和捕获两个阶段，文中采用变步长自适应算法来进行跟踪，这个跟踪算法的捕捉范围是整个信号带宽的一半。通过此方法，不但可以利用前向纠错的方式来避免反馈，而且可以缩减复数乘法的次数以降低计算复杂度和系统功耗。该方法运算复杂度低，并具有较好的收敛性，能改善odfm的解调性能。从计算机的仿真效果可以看出无论是在awgn信道上还是在多径信道上都表现出了卓越的性能。

In this paper, the frequency spectrum and the bandwidth of the frequency shift signal with continuous and discontinuous phase are analyzed.

分析了相位连续与不连续移频信号的频谱并比较了它们的带宽。

The low/mid crossover frequency is sweepable from 60Hz to 1KHz providing an ideal frequency split between your subs and mid drivers and the mid/high crossover point is sweepable from 1KHz to 9KHz giving you enough range to effectively send an appropriate bandwidth to your mids and tweeters.

低/中交叉频率sweepable从60赫兹到1kHz时提供之间的潜艇和中司机和中/高的交叉点，是理想的频率从1kHz分裂sweepable到9KHz给你足够的范围，有效地发送一个合适的带宽和您的中频高音喇叭。

ABSTRACT:The half-power bandwidth method is the commonly used method at home and abroad, the authors discover that factors, such as the sampling frequency, the frequency resolution, the ratio of the sampling frequency to the signal frequency, the analyzed width and the damping ratio, make the estimated damping ratio fluctuate vastly. Mostly the result is incredible except for some conditions, the error is sometime amazing, which is not acceptable.

半功率带宽法是国内外常用的测试阻尼的方法，笔者发现半功率带宽法由于受到信号处理中的①采样频率SF②频率分辨率△f③采样频率与信号频率之比K ④采样分析的长度T和⑤阻尼比D的大小等因素的影响使得测得的阻尼比值波动很大，除少数状态是可信的外，多数状态是不稳定的，有时误差惊人，得到的测试数据不能使用，易导致错误的结论。

A charge pump phase locked loop based on self biased technique is presented. In this technique, the operating bias levels are essentially established by the operating frequency of the voltage controlled oscillator, namely, all bias voltages and currents are determined by VCO controlling voltage. Thus, a fixed damping factor and a fixed ratio of the bandwidth to operating frequency are obtained, which are defined by th...

给出了基于自偏置技术的电荷泵锁相环电路，压控振荡器的工作频率动态地建立了电路内部所有的偏置电压和电流，从而实现了固定衰减因子，固定环路带宽与工作频率之比，这二者由电容的比率决定，极大地实现了电路设计的工艺无关性，同时也得到了小的相位抖动，最后，对这种锁相环的稳定性进行了一定的分析。

Secondly, according to the spectral correlation theory of second order cyclostationary processes, maximumlikelihood filters are used to estimate the cyclic spectra. By estimating the crossspectra of the two frequency shifted versions of cyclostationary signal, the cyclic spectra can be obtained. The analysis effective bandwidth of maximumlikelihood filters is studied in details. In case of cross-spectra estimation, the analysis effective bandwidth of maximum-likelihood filters is not correct. A new method to calculate the analysis effective bandwidth is presented.

第二，根据二阶周期平稳随机信号的谱相关理论，提出了循环谱密度估计的最大似然滤波器法，即采用最大似然滤波器估计出周期平稳信号的两个频移分量之间的互谱密度，从而得到了循环谱密度的估计；对最大似然滤波器的有效分析带宽做了详细的分析，指出了在互谱密度估计时以往的有效分析带宽不正确，并提出了互谱密度估计时的有效分析带宽的新的计算方法。

The Hilbert amplitude envelope of the stator current includes the low frequency of fault characteristic, thus it can reduce the signal length by resample the Hilbert amplitude envelope of the stator current by downsampling, which can avoid spectrum aliasing. Then it can reduce the computation time of the MUSIC Method for the spectrum analysis to the resampled signals for the given bandwidth. Meanwhile combining continuous subdivision Fourier transform and rotor slot harmonics based slip estimation it can in advance estimate the concrete values of the fault characteristic frequency, and then inquiry purposely the fault feature component information in the stator current spectrum in order to accomplish the broken rotor bar fault with high sensitivity and h reliability, which eliminates adverse effect of issuable false peaks to the fault detection and formed a novel scheme to detect broken rotor bar fault.

定子电流Hilbert幅值包络信号包含了低频的故障特征频率调制信号，故通过对定子电流Hilbert幅值包络信号进行降采样率重采样、减少分析信号长度，可避免低频段频谱混叠，再对减少的重采样数据进行具有超分辨率的MUSIC低频段估计，可大大降低MUSIC算法频谱估计时间；运用连续细化傅里叶变换和转子齿槽谐波转差率估计技术，可预知故障特征频率精确值，从而可有目的地查询故障分量，消除MUSIC虚假波峰对故障检测混淆的影响，大大提高了故障检测的灵敏度和可靠性，以此形成异步电动机转子断条故障检测新方法。

With fault signals of vibration tested in practice, this paper takes frequency-domain half-power bandwidth Gauss wavelets of continuity, index wavelets decomposition and equivalent bandwidth equivalent sampling discrete bi-orthogonal wavelets decomposition as basis, presents scaling correlated analysis correspondingly toward wave making vibration signals, and accurately realizes to decompose different stress wave speeds, and provides a method of analysis and calculation for accurated location and recognition of the polygenetic faults.

根据上述故障力学模型，我们提出并设计了相应的测试系统，对实测的故障振动信号，以频域半功率带宽连续高斯小波、指数小波分解和等带宽等采样离散双正交小波分解为基础，提出了相应的对波致振动信号的尺度相关分析，准确地实现了分离不同的应力波速，为多源故障的精确定位识别提供了分析和计算方法。

The proposed antenna consists of a rectangular metal patch on a printed circuit board fed by a 50- coplanar waveguide. By cutting a C-shaped slot in the rectangular radiating patch,a frequency band notch will be created. The proposed antenna yields an impedance bandwidth of 3.1-10.6GHz with VSWR,except the bandwidth of 5-6GHz for WLAN.

天线采用印刷电路板上的矩形贴片作为辐射单元，并由同一面上的共面波导馈电，通过在矩形贴片上开一个C形槽来实现陷波功能，电磁仿真软件Ansoft HFSS10的仿真结果显示，合适地选择C形槽的尺寸可以调整陷波的中心频率和带宽。

Objective To investigate the effects of interleukin-1 β converting enzyme gene on the biologic characteristics of ovarian cancer cells.

目的 探讨白细胞介素-1 β转换酶的表达，对卵巢癌细胞生物学特性的影响。

Campylobacter: This illness is the most commonly identified cause of diarrheal illness in the world.

弯曲：这种病是最常见的原因查明腹泻病，在世界上。