查询词典 narrow frequency

This paper proposed a new method of distance measurement named the continuous wave narrow bandwidth frequency modulation method.

本文提出了一种连续窄带调频的超声波测距方法。

A 40Hz event related potentialdetecting system is introduced here. The system employs the elliptic—type filters which have excellent edge features to extract signals of narrow band frequency . It exploits the correlation—threshold method proposed by us to cancel the musc1e artifacts.

详细介绍了我们建立的一套 40 Hz ERP(4 0 Hz事件相关电位)信号检测系统，该系统使用边缘特性最好的椭圆窄带滤波器提取窄带信号，采用我们提出的相关域值法很好地剔除了肌电干扰，并在微机上实现了实验自动化和结果自动统计。

However,for free decay method,its range of changing frequency is very narrow and the initial states of samples are not easily repeated because of the effect of crystallization;for forced oscillation method,the measuring results are seriously affected by crystallization,which is caused by slow heating rates.

然而，自由衰减法有限的变频范围，以及由于受晶化的影响，使两次升温测量时样品的初始状态不易重复；用强迫振动法测量时，同步变频条件限制了升温速率，造成金属玻璃的晶化过程严重影响了测量结果。

One of the most important requirements is a very narrow linewidth and high frequency stability.

最重要的一个要求是很窄的线宽以及很高的频率稳定度。

These applications call for higher requirements of the laser frequency stabilization, narrow linewidth, phase stabilization and other properties.

这些应用对于激光器的频率稳定性，线宽，位相稳定性等性能提出了更高的要求。

Due to existing signal processing technology's shortage such aslow measurement, narrow measurement range precision and other poor performance, we introduced a high-precise signal processing technology:firstly,to get power spectrum with Hanning windowed Welch modified periodogram, search its peak value frequency;secondly, to apply zooming analysis via Goertzel algorithm;at last,to get a highly precise doppler frequency with energy centrobaric rectifying algorithm.

针对存在的缺点，本文提出了一种应用于激光多普勒测速的高精度信号处理技术，即首先利用加Hanning窗的Welch修正周期图算法得到信号功率谱，搜索其谱峰值频率，接着利用Goertzel频谱细化算法对搜索的谱峰进行细化分析，再引入能量重心频谱校正算法对细化后的谱峰进行校正分析，从而将离散频谱分析算法、频谱细化算法和频谱校正算法三者有机结合起来，充分发挥各自的优点：通过加Hanning窗的Welch修正周期图算法快速得到功率谱及峰值频率，通过Goertzel算法获得分析频带的高分辨率频谱，然后通过能量重心校正算法对细化后的频谱进行高精度校正，这样不仅保证了算法的高效性，而且大大提高了分析的精度。

Some methods, in which synthesized theoretical seismogram of high frequency is taken as record signal and 20%random noise is superimposed on the seismogram, are used to analyze the theoretical seismogram. The digital experiment shows that in the correlating frequency range, Green's function method can measure precisely interstation phase velocity, but the results obtained by correlation and narrow band-pass filtering correlation methods are more dispersed.

以合成的高频理论地震图作为记录信号，并在理论地震图上叠加了20％的随机噪声，利用这些方法分析理论信号，数字实验表明：在相干频率范围内，格林函数方法能够精确测量台间相速度，而互相关法和窄带通滤波互相关法所得结果较为离散。

The echolocation signals of Rhinolophidae and Hipposideridae are both long CF-FM with 1 harmonic and narrow FM bandwidth. But Rhinolophidae has longer duration, higher duty cycle and lower dominant frequency than Hipposideridae. All the echolocation signals of Vespertilionidae are short FM with 2-6 harmonics and wide FM bandwidth. Vespertilionidae has shorter duration and lower duty cycle than the other two families. There are obvious differences in dominant frequency between different species in this family.

菊头蝠科和蹄蝠科回声定位信号均为长CF-FM型，一般具有1个谐波，调频带很窄，但菊头蝠科的持续时间和能率环明显高于蹄蝠科，蹄蝠科能量最大处频率高于菊头蝠科；蝙蝠科回声定位信号均为短FM型，具有2～6个谐波，持续时间和能率环比其他两科低，调频带很宽，能量最大处频率在种间变化较大。

However, various intrinsic problems exist in a conventional DLL such as narrow operation frequency range, harmonic locking, lack of frequency synthesis function, mismatch among delay stages, and unsuppressed VCDL noise.

但是，传统延迟锁相回路却有著较小操作频率范围、缺乏频率合成弁遄B压控延迟线中相位间不匹配、及压控延迟线的杂讯不能被压制等缺点。使得延迟锁相回路的应用范围受到限制。

For narrow-band signals, three uniform linear arrays, whose grating lobes are not overlapped by setting the angles between the arrays and the same pointing of main-lobes, are used and then multiplication of three patterns is operated to reduce the grating lobes of large-spaced array, which makes the array operate in broad band. For wideband or ultra-wideband signals, array pattern in the whole frequecy band is identical by designing the frequency-dependent weighting coefficients based on the Bessel function, and therefore grating lobes in high frequency parts are suppressed.

对于窄带接收信号，利用三个相交的大间距均匀线阵，通过设置它们之间的角度和主瓣指向相同使各自的栅瓣位置错开，然后把三个方向图相乘从而抑制大间距阵列栅瓣，因而适用于宽频带工作；对于宽带接收信号，利用Bessel函数设计与频率有关的加权系数，产生整个信号带宽内恒定的方向图，从而抑制了高频部分的栅瓣。

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。