频率

In anFDD wireless system, the duplex spacing between uplink and downlink islarger than the coherence bandwidth of the mobile radio channel, thus theuplink and the downlink small-scale fading is uncorrelated. Moreover, thearray response is correlated with the frequency of the signal carrier. So it isimpossible to resue the uplink weights for downlink beamforming. As aresult, the application of smart antenna for the downlink is a difficult problem.

在频分双工系统中，由于上、下行载波的频率差大于相干频带，上、下行信道衰落是不相关的，而且阵列响应也与信号的载波频率有关，因此，上行信道不能直接用来估计下行信道，故智能天线应用于下行链路是一个难点。

The echolocation signals at flying, foraging behaviors and food types of 4 endemic species in China were studied. The results were described as followed:(1) Rhinolophus rex has long CF-FM signals, low dominant frequency with the range of 26. 8±0.2kHz, which is the lowest in the recorded Rhinolophidae.

2.4种中国特有蝙蝠飞行状态下的回声定位信号和根据回声定位信号推测出捕食策略和食物类型：（1）贵州菊头蝠回声定位信号为长CF-FM型，能量最大处频率非常低，为26.8±0.2kHz，是已有记载的菊头蝠科中回声定位频率最低的。

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。

By using the Ricker wavelet and thin inter-beds model data, taking Morlet wavelet, MSW wavelet (A mother wavelet which can match seismic wavelet) and three-parameters wavelet as mother wavelet respectively, the calculated instantaneous frequency is analyzed. Results show that the instantaneous frequency analysis based on three-parameter wavelet has good anti-noise ability and higher temporal resolution.

利用Ricker子波和薄互层模型数据，分析了以Morlet小波、匹配地震子波的小波及三参数小波为基本小波计算的瞬时频率，结果表明：基于三参数小波的瞬时频率分析方法具有良好的抗噪性能及较高的时间分辨率。

This paper introduces eight methods of tlme-frequency analysis, such as Hilbert transform, Hilbert-Huang transform, sine curve fitting, Ricker wavelet matching, short time Fourier transform, wavelet transform, S transform and Cohen methods, This paper explains the merits and defects of those methods from the time resolution, frequency resolution and the adaptive ability of multi-frequency signals.

本文介绍了Hilbert变换、Hilbert—Huang变换、正弦曲线拟合、雷克子波匹配、短时傅立叶变换、小波变换、S变换以及Cohen娄这八种方法，并从时间分辨率、频率分辨率，以及对多频率成份信号适应能力等各方面阐述了各种方法的优缺点，对其中的一些方法结合了理论记录进行了试算，进一步阐述了这些方法的长处和不足之处。

This paper introduces eight methods of time-frequency analysis,such as Hilbert transform,Hilbert-Huang transform, sine curve fitting ,Ricker wavelet matching,short time Fourier transform,wavelet .

本文介绍了Hilbert变换、Hilbert-Huang变换、正弦曲线拟合、雷克子波匹配、短时傅立叶变换、小波变换、S变换以及Cohen类这八种方法，并从时间分辨率、频率分辨率，以及对多频率成份信号适应能力等各方面阐述了各种方法的优缺点，对其中的一些方法结合了理论记录进行了试算，进一步阐述了这些方法的长处和不足之处。

Pavlov verified that "quality, rate and frequency of the salivation changed depending upon the quality, rate and frequency of the stimuli."

巴甫洛夫证实到&分泌唾液的质量、比率和频率依靠刺激的质量、比率和频率来改变。&

Methods Eight hundred metres fast walking on a flat ground and semisupine cycling exercise test were performed in 18 patients randomly programmed to VVIR or VVI pacing mode and compared.

18例老年患者分别在具频率应答与无频率应答状态下做800米快速行走及症状记分和半卧位踏车运动评价。

There is no significantly difference of the frequency of genotypes among the CAD cases with different numbers of stenosed coronary artery.

CAD组T等位基因频率显著高于对照组(p＝0.004)。1、2、3支冠脉病变组间各基因型频率均无显著差别。

In consideration of the in-pulse phase modulation and Doppler frequency rate-of-change's subtleness, a fast and accurate algorithm is proposed. The influence to parameter estimation with phase modulation is dismissed by time domain correlation between neighboring pulses. Signal noise ratio is increased by frequency domain accumulation.

该文针对信号脉内相位调制和多普勒频率变化率信息非常微弱的特点，提出了一种快速高精度估计算法，通过相邻脉冲间的时域相关消除了相位调制对参数估计的影响，频域积累增强了信噪比，利用脉冲间的相参特性进行频谱相关消除了相位模糊，并放大了多普勒频率变化率信息。

With Death guitarist Schuldiner adopting vocal duties, the band made a major impact on the scene.

随着死亡的吉他手Schuldiner接受主唱的职务，乐队在现实中树立了重要的影响。

But he could still end up breakfasting on Swiss-government issue muesli because all six are accused of nicking around 45 million pounds they should have paid to FIFA.

不过他最后仍有可能沦为瑞士政府&议事餐桌&上的一道早餐，因为这所有六个人都被指控把本应支付给国际足联的大约4500万英镑骗了个精光。