查询词典 chirp

It′s found that the GVD-caused chirp in the exponential type of DDF is least likely to be affected by the initial chirp,the GVD-caused chirp in exponential, linear,Logarithm and Guassian types of DDF has the synchronous character of saturation as the nonlinear-effect-caused chirp ,and the two kinds of chirp are found to counteract to balance, which makes the sum chirp tend to be zero.

发现指数型色散缓变光纤中初始啁啾对GVD所致啁啾的影响最小，在指数型、线型、对数型和高斯型色散缓变光纤中GVD所致啁啾具有同非线性效应所致啁啾相似的饱和性，二者相消，使净啁啾趋于零。

a system of along-track mode sar based on the gps is established.by seeing the gps signal as a chirp,chirp scaling algorithm of this mode with large squint angle is investigated.chirp scaling algorithm is considered more efficient and widely applicable when the bistatic sar system is in side-look or small squint angle mode,but in large squint angle case,the errors caused by taylor expansion are so large that the algorithm could lose its precision.in such a case,an equivalent mono-static sar range mode which has fewer errors than taylor expansion with large squint angle is proposed to substitute the range history of bistatic sar.then bistatic sar images with large squint angles are gotten by common nonlinear cs algorithm.the effectivity of the method is verified by matlab simulation.

摘 要：建立了基于gps的顺轨sar系统模型，通过将gps信号等效为chirp信号，研究了在该模式下的大斜视角chirp scaling算法。在正侧视或小斜视情况下，cs算法具有较好的聚焦性能和广泛的适用性，但在斜视角较大的情况下，该算法将散焦而不能成像，因而提出了用等效的单基地距离模型来代替双基地距离历史的方法，解决了大斜视角情况下距离模型二阶近似误差较大的问题，并结合单基地非线性cs算法，实现了在大斜视角情况下的基于gps反射信号的双基地sar高精度成像，最后通过matlab仿真进行了验证。

When the chirped pulse with area smaller than propagates in the medium, splitting doesn't occur and the chirped pulse evolves gradually to an approximate normal Gaussian pulse (C=0), and this characteristic doesn't vary when the chirp coefficient; however, variation of the chirp coefficient will change amplitude and group velocity of the pulse.

面积小于的啁啾脉冲，在介质中传播时不发生分裂，且啁啾脉冲逐渐演化为一个近似的无啁啾(C=0)脉冲，这一特点不随啁啾系数的改变而改变；但啁啾系数的变化将改变脉冲的振幅和群速度。

Goes based on the connected domain image chirp is through carries on to the image corrosion and the inflation has the choice to go chirp.

基于数学形态学的图像去除噪声是通过对图像的开、闭操作有选择的去噪。

This month Boyun the chirp sends out diphthong, this time we duplicate him "the chirp" to make the response, and "converses" with lip shape must obviously and her.

这个月的柏妘会咿咿啊啊地发出双元音，此时我们多重复他的「咿咿啊啊」去做回应，并且用唇形要明显地和她「对话」。

We compare the effect of eliminating the chirp by means of linearly chirp fiber Bragg grating, normal dispersion fiber and F-P cavity.

因此我们认为光纤光栅消啁啾是消除脉冲中心部分的啁啾，脉冲前后沿啁啾消除情况，决定于啁啾的类型。

As an example of the Gaussian pulse and soliton,the effect of quintic nonlinearity on the chirp was found to depend on the initial chirp,the fiber loss,and the peak power of the light field.

而现在诸多学者研究的热点课题之一的光孤子通信，由于其绝热保形的传输特性，为将来实现高速率、远距离的通讯提供了新的手段[1]。

Nasutus lasts 4.5 ms,consisting of 4 pulse-strings with an inter-chirp interval of 1.8 ms,and the frequency of highest power peak is about 11.37 kHz. The chirp of the songs of E.

鼻优草螽鸣声的每个脉冲组由4个脉冲串构成，脉冲组持续时间4.5 ms，脉冲组间隔为1.8 ms，主能峰频率为11.37 kHz。

Many new detection techniques are proposed, that include: To overcome the faults of cross-terms and short unambiguity range for the common Wigner-Ville Distribution , short-time Fourier transform and Gabor transform are applied to SAR moving target detection. To improve the detection performance of WVD in noise environment, a new technique based on the Cross-WVD is proposed. The application of fractional Fourier transform to chirp signal detection is analyzed and extended to SAR moving target detection. To eliminate the restriction of chirp-Fourier transform, a new modified definition is proposed and applied to SAR moving target detection. To detect multiple moving targets whose scattering intensities are different heavily, the CLEAN technique is combined with the above techniques and the ideal detection performance is achieved. At last, the whole dissertation is concluded.

具体的研究成果如下：针对常用的Wigner-Ville分布在多目标情况下存在交叉项，并且多普勒不模糊范围小的缺点，提出将短时Fourier变换和Gabor变换应用于SAR运动目标检测，分析了其优势所在；为进一步提高Wigner-Ville分布低信噪比条件下的信号检测能力，提出基于互Wigner-Ville分布的运动目标检测方法；分析了分数阶Fourier变换在线性调频信号检测中的应用，提出基于分数阶Fourier变换的运动目标检测算法；对离散Chirp-Fourier变换的定义进行了修正，提出修正的离散Chirp-Fourier变换，克服了限制其应用的约束条件，并用于SAR运动目标检测当中；强度相差较大的多运动目标检测历来是机载SAR技术的一个重点和难点，我们将CLEAN思想融入上述多种算法当中，良好地解决了该问题。

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。

Among which is the mindset, perceptions and moralities of those who accept mini- military tasks for economic gains.

其中最重要的是心态，观念和道德的人谁接受小型军事任务的经济收益。

In time course imaging, activity peaked 2 days after coronary ligation.

在时程成像检测，活性峰值在冠脉结扎后2天。