共查询到20条相似文献,搜索用时 93 毫秒
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在对红外热像仪的测量中,噪声是评价红外热像仪性能的主要参数。噪声参数包括时间域噪声和空间域噪声,时间域噪声可分为高频时间噪声和低频时间噪声(即1/f噪声);空间域噪声可分为高频空间噪声(即固定模式噪声FPN)和低频空间噪声(非均匀性噪声)。对高频时间噪声和低频时间噪声进行了严格的区分和定义;给出了在短时间内忽略低频时间噪声时高频噪声NETD的计算模型;在不忽略低频时间噪声时计算高频噪声等效温差的数学计算模型和测量方法;对高频时间域NETD测量结果进行了不确定度分析与评价。 相似文献
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简述了电机噪声的作为电机技术指标的重要和电机噪声的研究发展历程,分析了直流电机噪声产生的成因,对这些噪声进行了分类,分析并总结了直流电机的电磁噪声、机械噪声、空气动力噪声的产生原因和机理,提出了在电机设计、制造和应用中降低和抑制直流电机噪声的方法,这些方法可以有效地在电机研发和制造中实际应用和借监。 相似文献
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介绍了开关电源的噪声形成原因,分析了差模干扰噪声及共模干扰噪声的干扰途径,指出了减小差模干扰噪声及共模干扰噪声的具体方法,同时说明了EMI电源滤波器的工作原理,最后给出了国内外对干扰噪声所采用的一些规范和标准。 相似文献
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研究了基于调制解调的硅微陀螺仪检测信号提取原理,推导了开环检测传递函数。根据调制解调的频谱转移特性,提出了有效位移噪声是高斯窄带噪声。推导了开环检测时位移噪声的等效角速度公式,分析表明,要提高噪声性能可以减小噪声功率密度、带宽和增加陀螺仪机械灵敏度。同时还推导了闭环检测时位移噪声的等效角速度公式。通过比较开环检测和闭环检测情况下由接口位移噪声导致的噪声等效角速度表明:闭环检测并不能减少由接口位移噪声导致的平均噪声等效角速度。据此设计实际电路,试验结果表明在100Hz频段内,闭环检测噪声谱密度基本等于开环检测噪声谱密度,验证了理论的正确性。 相似文献
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基于电子元器件低频噪声特性测试中,针对影响低频噪声测量系统准确性的因素,提出了一种改进型的低频噪声测量方法,优化设计电子元器件低频电噪声测试系统,放大噪声测试部分噪声,并可以分析电子元器件低频噪声测试过程中的低频噪声特性,从而可以有效证实通过测试低频噪声,就能够验证电子元器件质量是否缺陷,分析电子元器件的使用可靠性。在本文之中,将会基于电子元器件介绍其低频噪声特性和相关测试技术方案。 相似文献
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A Systematical Approach for Noise in CMOS LNA 总被引:1,自引:0,他引:1
A systematic approach is used to analyze the noise in CMOS low noise amplifier(LNA),including channel noise and induced gate noise in MOS devices.A new analytical formula for noise figure is proposed.Based on this formula,the impacts of distributed gate resistance and intrinsic channel resistance on noise performance are discussed.Two kinds of noise optimization approaches are performed and applied to the design of a 5.2GHz CMOS LNA. 相似文献
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采用系统研究方法来分析包括MOS器件的沟道噪声和感应栅噪声在内的CMOS低噪声放大器中的噪声,并提出了一个新的噪声系数解析式.基于此解析式,讨论了分布栅电阻和内部沟道电阻对噪声性能的影响.对噪声性能进行了两种不同的优化,并应用于5.2GHz CMOS低噪声放大器的设计. 相似文献
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While some denoising methods based on deep learning achieve superior results on synthetic noise, they are far from dealing with photographs corrupted by realistic noise. Denoising on real-world noisy images faces more significant challenges due to the source of it is more complicated than synthetic noise. To address this issue, we propose a novel network including noise estimation module and removal module (NERNet). The noise estimation module automatically estimates the noise level map corresponding to the information extracted by symmetric dilated block and pyramid feature fusion block. The removal module focuses on removing the noise from the noisy input with the help of the estimated noise level map. Dilation selective block with attention mechanism in the removal module adaptively not only fuses features from convolution layers with different dilation rates, but also aggregates the global and local information, which is benefit to preserving more details and textures. Experiments on two datasets of synthetic noise and three datasets of realistic noise show that NERNet achieves competitive results in comparison with other state-of-the-art methods. 相似文献
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《Components and Packaging Technologies, IEEE Transactions on》2006,29(3):535-542
The noise produced by cooling air passing through electronics packages arises from two sources. One source is the noise of the air-moving fan of either an axial or centrifugal type. This noise may have both tonal and random components and is strongly dependent on the way that the fan is placed in the unit and on where its operation is on the fan's operating curve. Often, fans are the dominant noise sources. The flow of air produces random noise due to the turbulence generated throughout the unit. Because the turbulent airflow is also responsible for heat transfer between the components and the air stream, we can regard this part of the noise as the irreducible noise due to cooling. If fan noise were eliminated, this part of the noise would remain. There is a relation, therefore, between the irreducible noise and the cooling of the unit. But the fan noise must also be considered. The relation between total airflow related noise and cooling requirements is developed in this paper for the irreducible noise. 相似文献
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Y. Nemirovsky G. Asa C. G. Jakobson A. Ruzin J. Gorelik 《Journal of Electronic Materials》1998,27(6):800-806
The effect on energy resolution of dark noise currents experimentally observed in state of the art CdZnTe spectrometers is
quantitatively analyzed. Expressions for the energy resolution determined by shot noise, generation-recombination noise, and
1/f noise are discussed in turn and are compared with the linewidth due to incomplete charge collection. The effect of the
dark noise upon energy resolution is directly measured by monitoring the broadening of peaks provided by a pulser, due to
biased, non-irradiated CdZnTe spectrometers that are connected in parallel. The noise characteristics of the spectrometers
under study were measured separately and their dominant noise mechanism is characterized. In this manner, the effect on resolution
of the dark noise is correlated not only with the dc value of the dark current but also with the noise spectral behavior which
is determined by the noise mechanism. 相似文献
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光强闪烁激光雷达的背景噪声分析 总被引:1,自引:1,他引:0
介绍了光强闪烁 激光雷达回波信号中背景噪声的分类,通过某次实验中实验条件的变化,获得了采集卡本底噪声、放大器本底噪声、PMT本底噪声、自然背景光噪声和散粒噪声等不同背景噪声叠加在一起的大小和方差信息,以及不同噪声各自本身的方差信息。通过不同噪声之间的比较,发现在未接收激光大气散射回波信号时,放大器本底噪声占主导,自然背景光噪声相对于其他噪声是小量;在接收散射回波信号时,近距离内(低层通道2km,高层通道4km)散粒噪声占主导,远距离上处于弱势。实验结果确定了不同噪声对总背景噪声的贡献程度,为光强闪烁激光雷达从散射回波信号中提取大气湍流信息提供了依据,也为消除噪声对有效信号的影响提供了指导。 相似文献
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LinLin Li 《Quantum Electronics, IEEE Journal of》1991,27(2):174-177
A model of a self-heterodyne-type electrical feedback semiconductor laser is presented. The effects of electrical feedback on the AM noise of a semiconductor laser are discussed on the basis of the model. It is shown that the FM noise can be greatly reduced by electrical feedback. However, this reduction is always accompanied by AM noise enhancement. The AM noise can also be reduced by this scheme under some conditions with the enhancement of the FM noise. This means that AM noise reduction and FM noise reduction can be interchanged by using this method. The influence of feedback parameters on the noise is discussed 相似文献