查询词典 radio-frequency spectrum

For example, in a cellular telephone network with frequency reuse, spectrum spreading and forward error correction reduce the spectral efficiency in/Hz but substantially lower the required signal-to-noise ratio in comparison to non-spread spectrum techniques.

例如，在一个频率复用的移动电话网络中，扩频和前向纠错对于非扩频技术来说，虽然减少了频谱效率，但是充分地降低了所要求的信噪比。

In order to avoid spectrum error due to energy leakage, the thesis research on identification of parameters of two close frequency components in discrete spectrum analysis, and simulation result shows the validity of the method.

针对由于能量泄漏造成的频谱误差，深入研究了密集频谱的频域参数识别法，从理论上加以推导，并通过仿真证明了该方法的有效性，可以识别1个频率分辨率以内的两临近频率分量。

This paper points out that as the peak of the first order wind spectrum situated at a region of very low frequency, the contribution of the sum_frequency part to the second order wind spectrum is no longer negligible.

本文指出，由于风速谱与波浪谱不同，它的能量峰值位于极低频率处，因此二阶风速谱中和频项的贡献不能忽略，为此本文首先导出了保留和频项情况下的二阶风速谱表达式，并将和频项与差频项在数值上作了比较。

The fast Fourier transform frequency spectrum of the output wave contained no 50 Hz spectrum line.

放大器的输出结果为50mV峰峰值；输出波形的快速傅立叶变换频谱中没有50 Hz谱线。

The sensor's signals in flowmeter are processed digitally by means of the power spectrum analyzing method based on the periodogram spectrum method. The real frequency of signal is calculated, and the accurate volumetric flow is measured.

它采用周期图谱分析方法对涡街流量计中传感器的信号进行数字处理，准确计算出信号的频率，测出准确的体积流量。

Based on frequency spectrum of each point, amplitude spectrum of structure-borne noise and testing results of air-borne noise, the authors analyze the vibration characters and latent faults of double-ring gear reducer, coming to the value and the cause of the noise, providing theoretical basis f...

结合各测点频谱图、结构噪声幅值图谱和空气噪声测试结果，分析了双环减速器振动特性及可能存在的故障，得出其噪声值和噪声产生的原因，为设计双环减速器，减小其振动噪声提供理论依据。

By producing pseudorandom number series, we rectify the power spectrums of normal random inputs in the same shape as power spectrums of simulating signals. Through Laplace transformation, we can acquire the frequency response functions of rectifier. Two simulating examples were presented. The power spectrum curves based on one peak function model were almost coincided with the power spectrum curves of simulating loads shown in the figures. Simulating results of input loads had good accuracy. Creating a simulating method and program of input load in this paper was effective.

本文利用随机过程仿真的一般理论在已知随机载荷的分布特性、均值、方差和功率谱函数以后，实现随机载荷的计算机仿真，即利用仿真技术得到符合已知载荷的分布特性和功率谱特性的随机载荷的时间序列。1 产生伪随机数序列及分布整形采用乘同余法产生伪随机数的递推公式为[2 ] ：yi+1 =λyi ( 1 )式中M =2

Gabor-ring is often used in texture feature extraction, but it is based on the assumption that texture is narrowband signal and can not applied to most actual textured images that have more than one center frequency in power spectrum. To overcome the limitation of existing method, an improved method is proposed. According to this method, Gabor filters are constructed in accordance with the spectrum feature vector of texture, and a relaxation parameter is used to determine the effect of difference filters so as to integrate the frequencies and phases into the process of extraction.

Gabor环（即在频率域成环形分布的Gabor滤波器组）常被用于提取图像纹理特征，但它是以"纹理是窄带信号"为基础的，实际的纹理图像并不能很好地满足"窄带信号"的假设，用一个中心频率来描述一种纹理对能量集中在多个频率点的纹理图像往往不能取得理想的效果，而根据频谱特征值向量构造Gabor环的改进方法，通过松弛因子的加入改变不同滤波器的作用强度，综合考虑了多频率多相位对纹理特征提取的影响。

The frequency shifts and relative intensity configuration of multidegree stokes spectrum were measured and a simple analysis of spectrum characteristics using the concepts of effective scattering cross-section and differences of vibrational e...

测试了两类光纤的多级Stokes谱的频移分布与相对强度分布，并从等效散射截面的相对大小和赈动能级差的相对大小对话的特征进行了初步的分析。目的是在实验研究的基础上探索刊用这两类常用光纤构成光纤拉曼激光器以及利用光纤拉曼散射谱的可能性。

In this paper, total logistics amounts are chosen as evaluation index, and artificial time series are designed to solve the shortness of statistical data in Chinese logistics. Spectrum estimation theory depicts time characteristics in frequency domain thus has such benefit than time domain methods. This paper evaluates the period of Chinese logistics using spectrum estimation. Stationarity of artificial series is verified, parameter sensitivity of truncation point is analyzed, six periods with different delay window are compared, and significance of period evaluated is tested.

中国物流统计数据缺乏，客观上限制了对其周期规律的研究，本文选取社会物流总额作为测度指标，设计了一种人工序列，解决了统计数据过短问题；谱估计法从频域角度揭示客观事物的时间特性，在研究时间序列周期波动方面具有时域分析法所不具备的优势，作者采用谱估计法对中国物流发展周期进行测定，检验了指标序列平稳性，分析了截断点参数灵敏度，比较了6种不同滞后窗下周期值，并检验了所测得周期的显著性。

We got alerted a couple of times while we were down south that HETs were on the way to bring us back up north because things were going to go hot again, but it was just rumors.

南下的途中我们不只一次得到警告说重型装备运输车将拉着我们重新北上，因为局势正在变得重新紧张起来，但这只是谣传。

It's the one where they find the ghost in the salt mine.

这一集是演他们在盐矿找到鬼