频率调制

Measurement ; sinusoidal phase modulating interferometer ; spectrum leakage ; discrete Fourier transform ; measurement accuracy ; frequency changes

测量；正弦相位调制干涉仪；频谱泄漏；离散傅里叶变换；测量精度；频率变化

By using the numerical calculation results of the density matrix equations of motion of a closed Λ-type inversionless lasing system, the effects of the propagation of light fields on the gain of lasing without inversion, Rabi frequencies of the probe and driving fields, and the modulation role of spontaneously generated coherence on the effects were investigated when the Doppler broadening presents.

利用封闭Λ型三能级无粒子数反转激光系统密度矩阵运动方程的数值解，研究了存在Doppler展宽的情况下光场的传播对LWI增益、探测场和驱动场Rabi频率产生的影响以及有自发辐射诱导相干对这个影响的调制作用。

According to singular entropy and Percent of contribution to total energy, the de-noising rank is obtained and the signal is reconstructed. The thesis compares reconstruct wave form of different reconstruct rank and the error of original signal and reconstruct signal is contrasted.According to voltage flicker measurement, voltage flicker detection method based on Mathe Matical filtering and Teager Energy Operator is proposed. The multiple MM filter filters out pulse noise and white noise contained in fliker signal, then the filtered signal is tracked accurately and quikly via TEO.

提出了基于数学形态滤波和TEO能量算子的电压闪变快速测量方法，含噪电压闪变信号经过多结构元素复合数学形态滤波后，采用TEO能量算子计算跟踪电压闪变信号的包络，得到的包络信号用Pisarenco谱分析方法获得闪变调制信号的幅值频率等参数，对不同情况下的电压闪变信号进行了仿真验证。

It is based on the method of modeling mobile voice channel and system identification is made so that the waveform samples are designed in frequency domain with less signal distortion.Then the waveform codebook is gotten by a genetic algorithm which has the maximum Euclidean distance.Thus,the modulation and demodulation are equivalent to the mapping from index to waveforms and from waveforms to index.

提出了对移动话音业务信道建模的思想，通过系统辨识获得模型的频率响应特性，在波形畸变较小的频带范围设计波形频谱，采用遗传算法在时域样本空间全局寻优获得欧几里德距离最大的波形码本，通过码本索引值和波形矢量的映射和解映射来实现数据的调制和解调。

The wavelength of an actively mode-locked fiber laser based on erbium doped fiber amplifier was stabilized in the experiment.

在实验中对基于掺铒光纤放大器的主动锁模光纤激光器进行波长稳定，激光器的调制频率为10.06 GHz，观察到了良好的稳定效果。

A low in-band phase noise FM frequency synthesizer has been depicted in this paper. It bases on the fraction N PLL frequency synthesizer, and the THD of the system has been improved greatly by this closed loop modulation mode.

研制一种低带内相位噪声的立体声FM频率合成器，该合成器基于小数分频锁相环技术，利用闭环方式对载波信号进行调制，显著提高系统的THD。

Meanwhile, circuit is similar to reversing xm's phase after full-wave rectification.

同时，电路在a~b段相当于对 39 全波整流后反相，解调后的频率为原调制波的二倍。

Based on the characters of long rang underwater acoustic channels and MFSK modulation, a new Frequency Group Coding method is proposed in this paper.

本文针对远程水下信道和MFSK调制的特点，提出了一种新的频率分组编码方法。

And in the chapterⅢ,we locked the laser to the hyperfine transition of atoms with super-stability by the means of RF-modulated saturated absorption.

第三章中，通过射频调制的饱和吸收稳频方法，使激光器的频率锁定到十分稳定的原子的超精细跃迁线上。

The results of CFTanalysis of experimental CER spectra presented an indirect proof of the dynamics model.

实验研究了SIN+GaAs结构CER谱及其CFT谱，由CFT谱中四个特征频率随调制电压的变化关系间接地证明了理论模型的正确性。

According to the clear water experiment, aeration performance of the new equipment is good with high total oxygen transfer coefficient and oxygen utilization ratio.

曝气设备的动力效率在叶轮转速为120rpm～150rpm时取得最大值，此时氧利用率和充氧能力也具有较高值。

The environmental stability of that world - including its crushing pressures and icy darkness - means that some of its most famous inhabitants have survived for eons as evolutionary throwbacks, their bodies undergoing little change.

稳定的海底环境─包括能把人压扁的压力和冰冷的黑暗─意谓海底某些最知名的栖居生物已以演化返祖的样态活了万世，形体几无变化。