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101.
相控震源对水平层状地下介质的高信噪比检测 总被引:4,自引:0,他引:4
为提高可控震源地震勘探数据的信噪比,采用能够产生定向地震波的相控震源,针对水平层状地下介质模型,给出了不同信噪比条件下的单震源、相控震源信号检测结果。使用单震源时不能分辨的目标层反射波信号,在相控震源地震记录中清晰可见;通过定量计算,用12单元的相控震源地震与单震源情况相比,反射波信噪比平均提高了19.25dB;与12单元的组合震源地震相比,反射波信噪比平均提高了8.46dB。可见,相控震源应用于水平层状地下目标体的高信噪比探测是可行的。 相似文献
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针对国产化大面阵红外器件技术缺乏,用红外焦平面探测器获取图像时难以消除自身的非均匀性以及信噪比低,航空航天成像应用中的图像采集、传输、存储成本越来越高等问题.论文引入了像面编码计算成像,首先分析了这种成像系统的原理模型,然后将压缩感知理论应用于计算成像中,搭建成像原理样机,进行非压缩和压缩的计算成像实验.最后在重构的图像质量评价中引入了信号子空间分析方法,进行重构图像的信噪比估计,实验结果表明,这种信噪比估计方法更加准确有效,并且可以以此作为实验结论给出实际压缩成像时需要的合理采样次数. 相似文献
104.
为分析高空紫外光通信性能,建立了高空太阳辐射分布模型;研究了不同波长紫外光的高空散射系数和吸收系数;考虑太阳辐射的背景光和接收端散粒噪声,对紫外光直视与非直视链路的损耗和信噪比进行了仿真分析.结果表明:在高空30 km以下,由太阳辐射产生的背景光远小于接收端散粒噪声;在7 km的高度上280 nm的信号光可实现距离为5 km、速率为10Mb/s的直视通信和距离1 km、速率50 kb/s、收发端仰角为20°的非直视通信.直视与非直视通信可以通过选择波长在“日盲区”两端的信号来减小臭氧对紫外光的吸收作用,提高信噪比;非直视通信还可以选择“日盲区”波长短的信号来增强散射效应,改善通信性能. 相似文献
105.
A novel architecture of a pipelined redundant-signed-digit analog to digital converter(RSD-ADC) is presented featuring a high signal to noise ratio(SNR), spurious free dynamic range(SFDR) and signal to noise plus distortion(SNDR) with efficient background correction logic. The proposed ADC architecture shows high accuracy with a high speed circuit and efficient utilization of the hardware. This paper demonstrates the functionality of the digital correction logic of 14-bit pipelined ADC at each 1.5 bit/stage. This prototype of ADC architecture accounts for capacitor mismatch, comparator offset and finite Op-Amp gain error in the MDAC(residue amplification circuit) stages. With the proposed architecture of ADC, SNDR obtained is 85.89 dB, SNR is 85.9 dB and SFDR obtained is 102.8 dB at the sample rate of 100 MHz. This novel architecture of digital correction logic is transparent to the overall system, which is demonstrated by using 14-bit pipelined ADC. After a latency of 14 clocks, digital output will be available at every clock pulse. To describe the circuit behavior of the ADC, VHDL and MATLAB programs are used. The proposed architecture is also capable of reducing the digital hardware. Silicon area is also the complexity of the design. 相似文献
106.
《Food Control》2016
High speed data processing for online food quality inspection using hyperspectral imaging (HSI) is challenging as over hundred spectral images have to be analyzed simultaneously. In this study, a real-time pixel based early apple bruise detection system based on HSI in the shortwave infrared (SWIR) range has been developed. This systems consists of a novel, homogeneous SWIR illumination unit and a line scan camera. The system performance was tested on Jonagold apples bruised less than two hours before scanning. Partial least squares-discriminant analysis was used to discriminate bruised pixel spectra from sound pixel spectra. As the glossiness of many fruit and vegetables limits the accuracy in the detection of defects, several reflectance calibrations and pre-processing techniques were compared for glare correction and maximizing the signal to noise ratio. With the best combination of first derivative and mean centering, followed by image post-processing, this system was able to detect fresh bruises in thirty apples with 98% accuracy at the pixel level with a processing time per apple below 200 ms. 相似文献
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109.
针对图像降噪中的不连续性、存在恒定偏差等问题,在Dohono等提出的硬、软阈值法基础上,提出了一种改进的指数函数阈值降噪算法。与传统阈值降噪法相比,该方法不仅克服了传统方法的不足,且具有更好的灵活性。仿真实验结果表明,该改进阈值法的降噪效果无论在信噪比增益及均方误差上,或是在视觉效果上,均优于传统阈值降噪法。 相似文献
110.
Nonlinear least squares regression for single image scanning electron microscope signal‐to‐noise ratio estimation 下载免费PDF全文
A new method based on nonlinear least squares regression (NLLSR) is formulated to estimate signal‐to‐noise ratio (SNR) of scanning electron microscope (SEM) images. The estimation of SNR value based on NLLSR method is compared with the three existing methods of nearest neighbourhood, first‐order interpolation and the combination of both nearest neighbourhood and first‐order interpolation. Samples of SEM images with different textures, contrasts and edges were used to test the performance of NLLSR method in estimating the SNR values of the SEM images. It is shown that the NLLSR method is able to produce better estimation accuracy as compared to the other three existing methods. According to the SNR results obtained from the experiment, the NLLSR method is able to produce approximately less than 1% of SNR error difference as compared to the other three existing methods. 相似文献