共查询到20条相似文献,搜索用时 31 毫秒
1.
CAI Xiping ZHAO Yuan QIAO Lijie LIU Jianbo 《Chinese Journal of Lasers》2000,9(4):313-318
1 Introduction Inalaserradarsystem ,theratioofthepeakpowerofsignaltotheaveragepowerofnoise,i.e.,signaltonoiseratio (SNR)isanindextoindicatetheperformanceofthereceivingsystem .ItisbeneficialtoincreasetheSNRofthesystemforthediscriminationofthesignalfromtheb… 相似文献
2.
基于FPGA的红外焦平面成像条纹噪声逐帧抑制算法的研究 总被引:1,自引:0,他引:1
红外焦平面阵列是当今红外成像技术发展的主要方向,随着器件工艺的进步,红外焦平面阵列探测器有了长足的发展,然而红外图像普遍具有信噪比低的缺点,这大大限制了红外焦平面的应用。与固定图案噪声(FPN)相比,随机噪声的最大特点是每帧均不同,因此去除该类型噪声的算法必须在一帧之内完成。提出了一种新型的单帧去除此类条纹噪声的算法并加以硬件实现,在单帧内设置适合的校正参数和阈值,达到在单帧图像内有效去除条纹噪声的目的。通过算法处理前后的图像对比以及客观的MSE、PSNR测试数据对比,证明了该算法能够有效地改善焦平面器件成像质量。 相似文献
3.
Improvement of signal-to-noise ratio by stochastic resonance in sigmoid function threshold systems, demonstrated using a CMOS inverter 总被引:1,自引:0,他引:1
Michihito Ueda 《Physica A》2010,389(10):1978-2862
Stochastic resonance (SR) has become a well-known phenomenon that can enhance weak periodic signals with the help of noise. SR is an interesting phenomenon when applied to signal processing. Although it has been proven that SR does not always improve the signal-to-noise ratio (SNR), in a strongly nonlinear system such as simple threshold system, SR does in fact improve SNR for noisy pulsed signals at appropriate noise strength. However, even in such cases, when noise is weak, the SNR is degraded. Since the noise strength cannot be known in advance, it is difficult to apply SR to real signal processing. In this paper, we focused on the shape of the threshold at which SR did not degrade the SNR when noise was weak. To achieve output change when noise was weak, we numerically analyzed a sigmoid function threshold system. When the slope around the threshold was appropriate, SNR did not degrade when noise was weak and instead was improved at suitable noise strength. We also demonstrated SNR improvement for noisy pulsed voltages using a CMOS inverter, a very common threshold device. The input-output property of a CMOS inverter resembles the sigmoid function. By inputting the noisy signal voltage to a CMOS inverter, we measured the input and output voltages and analyzed the SNRs. The results showed that SNR was effectively improved over a wide range of noise strengths. 相似文献
4.
部分相干信息处理系统的噪声演绩(Ⅱ)——时间部分相干照明 总被引:1,自引:0,他引:1
本文研究了时间相干性对光学信息处理系统噪声演绩的影响。以输出信噪比作为信息处理系统噪声演绩的度量,系统中任意平面上的颗粒噪声及相位噪声作为主要的噪声源。结果表明,时间部分相干照明可以提高系统的输出信噪比,对系统的装置噪声有明显的抑制作用。 相似文献
5.
噪声对星载大气痕量气体差分吸收光谱仪信噪比具有重大影响,其是衡量光谱仪成像质量和痕量气体反演能力的标准。为量化并去除光谱仪系统噪声从而提高信噪比,分析了光谱仪噪声来源并给出了相应噪声模型,在此基础上建立了光谱仪信噪比模型。研究了入射光强度、积分时间和系统增益对系统信噪比的影响。通过光谱仪辐射定标试验数据对不同工作模式和不同参数与信噪比的关系进行了对比验证。并提出主要系统噪声的处理方法:利用线性拟合取截距法确定系统偏置噪声;在地面利用暗电流温度相关性获得温度修正因子实现载荷在轨暗电流校正;在探测器响应线性范围内利用两点校正法对PRNU噪声进行修正。结果表明:全幅成像模式下,可见1通道电子学偏置噪声响应DN值2 625,可见2通道电子学偏置噪声响应DN值2 763;暗电流噪声在CCD成像面温度高于0 ℃时占主要部分,温度下降至-20 ℃时其余噪声起主导作用,验证了CCD最佳制冷温度;光谱仪信噪比随着入射光响应和积分时间的增加而增大,系统增益不会影响信噪比;PRNU噪声通过校正得到明显改善,由3.32%下降到0.47%,提高了光谱仪成像质量。该噪声分析和处理方法对后期光谱数据的痕量气体反演提供帮助。 相似文献
6.
7.
Signal to noise ratio (SNR) is an important parameter in the output signal of the pulse replicator. We propose a novel new method to improve this parameter. Instead of focusing on lowering the noise level of the optical amplifier and limiting the accumulation of amplified spontaneous emission (ASE) noise in the loop, we consider the optimization of other system parameters. By modeling with a predefined implementation of the pulse replicator, an evaluation function of SNR is constructed, with variables such as the coupling ratio, the optical fiber length. In this paper, we will construct the quantitative function between SNR and the coupling ratio. According to the evaluation function, we can determine the optimal value of the coupling ratio for the coupler to obtain the best SNR within the predefined parameters. The experiment will prove that the SNR in the output signal of the pulse replicator has been increased while using the optimal coupling ratio. This will contribute greatly to future work on improving SNR of the pulse replicator. 相似文献
8.
低噪音光折变体全息存储 总被引:4,自引:3,他引:1
光折变全息存储中,透过晶体的散射光会影响再现象的信噪比,本文基于两波耦合理论,对光折变存储中的散射噪音随光斑尺寸的变化作了简化计算和分析,结果表明减小辐照在晶体上的光斑尺寸能降低散射噪音,提高衍射效率和信噪比,采用球面参考波小光斑尺寸入射,在KNSBN光折变晶体中存储了傅里叶全息图,并得到了低噪音的再现象. 相似文献
9.
The signal to noise ratio (SNR) of a multiplexed fiber-optic sensor network can be improved by inserting fiber-optic amplifiers.
Several configurations of amplifiers in the sensor network are analyzed. A single fiber-optic amplifier used as a preamplifier
is a good solution with high SNR. However, by distributing amplifiers in the network even higher SNR can be obtained, and
identical couplers can be used throughout the network. 相似文献
10.
11.
Entropic stochastic resonance in a confined structure driven by dichotomous noise and white noises 下载免费PDF全文
The entropic stochastic resonance(ESR) in a confined system subjected to dichotomous noise and white noise and driven by a periodic sinusoidal force along the x axis of the structure and a time-dependent force in the declining direction,is investigated.Under the adiabatic approximation condition and based on the two-state theory,the expression of the output signal-to-noise ratio(SNR) is obtained.The results show that the SNR is a non-monotonic function of the strengths of dichotomous noise,white noise,and correlated strength of correlated noise.In addition,the SNR varies non-monotonically with the increase of the shape parameters of the confined structure,and also with the increase of the constant force along the y axis of the structure.The influence of the correlation rate of the dichotomous noise,and that of the frequency of the periodic force on the SNR are discussed. 相似文献
12.
13.
HAN Yin-Xia LI Jing-Hui CHEN Shi-Gang 《理论物理通讯》2005,44(2):226-230
The phenomenon of stochastic resonance (SR) in a bistable nonlinear system is studied when the system is driven by the asymmetric potential and additive Gaussian colored noise. Using the unified colored noise approximation method, the additive Gaussian colored noise can be simplified to additive Gaussian white noise. The signal-to-noise ratio (SNR) is calculated according to the generalized two-state theory (shown in [H.S. Wio and S. Bouzat, Brazilian J.Phys. 29 (1999) 136]). We find that the SNR increases with the proximity of a to zero. In addition, the correlation time T between the additive Gaussian colored noise is also an ingredient to improve SR. The shorter the correlation time T between the Gaussian additive colored noise is, the higher of the peak value of SNR. 相似文献
14.
Stochastic resonance in linear system driven by multiplicative noise and additive quadratic noise 下载免费PDF全文
In this paper the stochastic resonance (SR) is studied in an overdamped linear system
driven by multiplicative noise and additive quadratic noise. The exact
expressions are obtained for the first two moments and the correlation
function by using linear response and the properties of the dichotomous noise.
SR phenomenon exhibits in the linear system. There are three different forms
of SR: the bona fide SR, the conventional SR and SR in the broad sense.
Moreover, the effect of the asymmetry of the multiplicative noise on the
signal-to-noise ratio (SNR) is different from that of the additive noise and
the effect of multiplicative noise and additive noise on SNR is different. 相似文献
15.
改善光源光谱特性提高光学多道分析器用于吸收光谱测量的信噪比 总被引:2,自引:0,他引:2
本文报道通过改善热辐射光源光谱特性,相对提高短波辐射光强,以提高CCD光学多道分析器在可见区特别是短波段吸收光谱的信噪比。改善后光源的短波辐射信噪比比一般热辐射光源提高约8倍。实验证实用此光源易在整个可见光区得到高信噪比的吸收光谱曲线。 相似文献
16.
17.
18.
电荷耦合器件(CCD)是遥感成像系统的核心部件,为了在低照度、低量化位数的情况下获得高信噪比与大动态范围的遥感图像,首先根据CCD的结构与噪声物理性质给出了模拟增益、量化位数与CCD信噪比的关系,接着搭建了CCD的积分球标定系统,依据实验数据建立了散粒噪声、光子响应非均匀性噪声以及基底噪声的数学模型,然后着重分析了低照度情况下模拟增益与信噪比之间的关系,最后搭建了实际成像系统,获取了低照度情况下不同模拟增益系数的遥感图像.结果表明理论分析、实验室积分球标定数据与实际成像图像符合良好,即模拟增益提高1至2倍
关键词:
电荷耦合器件
模拟增益
信噪比
遥感成像系统 相似文献
19.
利用光锥耦合的ICCD系统探测荧光染料标记的生物芯片,并对CCD芯片和像增强器制冷,以提高探测灵敏度。基于实验分析结果,指出背景噪声的主要来源为杂散光和生物芯片基底所发的荧光,指出用镜头成像限制了系统探测灵敏度的提高,可采用低荧光物质作为生物芯片的基底对系统加以改进。 相似文献