查询词典 frequency modulation

Laser technique ; modulation-free laser frequency locking ; acousto-optic modulation ; molecular absorption line

激光技术；无调制锁频；声光调制；分子吸收线

But, in the natural and artificial signal, a lot of signal phases don\'tvary linearly with time, for example, we usually use chirp signal in the radar technology,frequency step signal, linear modulation component of the ground echo in the SARtechnology, linear modulation component of the moving target echo, linear modulationcomponent while the airborn radar detecting the moving target, etc.

在自然界和人工信号中，许多信号的相位变化并不是随时间一次方变化，如雷达技术中常用的线性调频信号，频率步进信号，另外，SAR 技术中，地面回波所含有的线性调频分量，ISAR技术中，运动目标的回波所含有的线性调频分量，机载雷达探测运动目标时的线性调频分量，等等；傅里叶变换对此类信号分析所得的结果是信号在不同频率点上的能量分布，即信号在基函数上的投影。

Based on surveying the development of variable frequency power supply and analyzing its development tendency, and considering the practical features of the assignment, the conversion system is designed as follows: it selects the 3-phase Pulse Width Modulation Engine SA4828 as the PWM control signals generator; it chooses the single-chip-computer PIC16F877 as the microcontroller, which integrated the A/D modulation, which cuts down the complexity of the hardware system and strengthens the dependability of the system.

在论述和分析了变频电源及其控制技术发展的概况和趋势的基础上，结合本课题任务的实际要求，设计了一套中小功率的逆变电源。系统中PWM控制信号采用专用集成芯片SA4828生成，减轻了控制器的工作量也提高了系统的可靠性。控制器选用集成了A/D转换器的单片机，使得系统的硬件复杂性降低，提高了可靠性。

Theoretical analysis of and experiments on the fundamentals, efficiency, cross-modulation, inter-modulation and spectrum analysis of multiple-frequency acousto-optic Bragg diffraction are made and its application in laser high-speed printer illustrated.

本文对多频声光布喇格衍射的原理、效率、交叉调制、互调制、频谱分析等进行理论分析和实验研究，并阐明其在激光高速印字机中的应用。

The high efficiency transistor development causes the frequency changer the construction cost more and more to be also low, from the cost and the performance considered selects PLC to the frequency changer control realization frequency conversion velocity modulation.

大功率晶体管的开发使变频器的造价也越来越低，从成本和性能考虑选用PLC对变频器控制实现变频调速。

In the past, the high frequency resonance technique is usually applied in the envelope detection for a vibration signal with amplitude modulation. When applying the Hilbert transform in the high frequency resonance technique for the envelope detection of vibration signals, the computing burden is very high. On the other hand, when applying the linear least squares analysis method, the computing burden is lower. When applying the envelope detection in the lowest vibration mode, an accelerometer with the low-pass filtering cutoff frequency at 4kHz should be choose.

在过去的研究方法中，振动讯号之振幅调变通常以高频解调分析法应用於包络讯号侦测，而高频解调方法应用希尔伯特转换的包络分析，所需要的计算量是非常的高，若以线性最小平方分析法应用於高频解调分析法中，则所需要的计算量较小，如果以最低模态来估测包络讯号时，可以适当的选取加速规来代替低通滤波器，而加速规的截止频带必须在4kHz左右。

The calls of non-passerine are some kinds of monotonous dull vocalizations with the characteristics of low and deep frequency, single syllable, low basic frequency and with no ability of modulation in frequency and amplitude. Most of the calls are monotonous and low quality mainly based on the basic song. Compare the vocal of sub-oscine passerine with non-passerine, they have some similar aspects, but the former possesses of stronger capability of vocal control.

非鸣禽的叫声低沉而单调，音节种类单一，基本音频率低，缺乏频率调制以及幅度调制的能力，叫声的品质因数很低，不悦耳，大多为以基本音为主的单音调低音品叫声，亚鸣禽的叫声与非鸣禽近似，但在控声能力方面又有所提高。

Mechanical strains also regulated the protein and mRNA expression of several differentiation markers, as well as the activation of extracellular signal-regulated kinases, p38 MAP kinase and protein kinase B in a frequency-dependent manner. Furthermore, the inhibition of p38 pathway could block the strain-frequency induced the phenotype modulation of VSMCs, neither ERKs nor Akt. Frequency of mechanical strain, not conditioned medium, regulated the phenotype of VSMCs in a frequency-dependent manner. Rho-GDI alpha was suppressed by the mechanical strain at 1Hz.

采用免疫细胞化学法检测VSMCs形态和排列的变化；RT-PCR和Western blotting检测表型标志分子α-肌动蛋白、肌球蛋白重链(SM1/2)、肌动蛋白相关蛋白SM22α和调宁蛋白(h1-calponin)的mRNA和蛋白水平的变化；抑制剂或RNA干扰阻断可能的信号调节分子的活性或表达，包括p38、细胞外信号调节激酶1/(2extracellular signal-regulated kinases， ERK1/2)、蛋白激酶B和Rho-鸟苷酸解离抑制因子(Rho-guanine nucleotide dissociation inhibitor， Rho-GDI alpha)，研究了不同频率张应变对VSMCs表型转化的影响及其调节机制。

This paper mainly analyses dispersion frequency signals time and frequency property of triangle wave modulation. Real 5mm dispersion frequency signal is collected. The theory data and real data are compared and analyzed. It shows 5mm radar forepart is practicable, it also supplies theory base to design back signal processing circuit.

主要完成了三角波调频体制下的差频信号在时域和频域两方面的特性分析，并采集了5mm波段实际的三角波调制差频波形，通过将理论值与实测值的比较分析，表明5mm样机前端部分的可靠性，为后面的信号处理电路设计作准备。

Using upper sideband also allow the actual carrier frequency to be determined easily simply by adding the dial frequency to the audio modulation frequency.

使用上边带还允许实际载波频率确定仅仅通过增加拨号频率的音频调制频率容易。

Breath, muscle contraction of the buttocks; arch body, as far as possible to hold his head, right leg straight towards the ceiling (peg-leg knee in order to avoid muscle tension).

呼气，收缩臀部肌肉；拱起身体，尽量抬起头来，右腿伸直朝向天花板（膝微屈，以避免肌肉紧张）。

The cost of moving grain food products was unchanged from May, but year over year are up 8%.

粮食产品的运输费用与5月份相比没有变化，但却比去年同期高8％。