最小噪聲帶寬 的英文怎麼說
中文拼音 [zuìxiǎozàoshēngdàikuān]
最小噪聲帶寬
英文
minimum noise bandwidth-
In the terms of interpolation, the image reconstructed from nearest interpolation or linear interpolation has good edge but serious noise ; reconstruction from 4 * 4cubic interpolation or three b - spline or three - order lagrange interpolations has better local character. 2 x 2cubic interpolations which has both better edge and local character is the ideal interpolation, the following is the basic principle during reconstruction : ( 1 ) the more width of interpolation, the more number of summation and the more order of interpolation polynomial, the higher of density resolution ; ( 2 ) the more of interpolation polynomial and width of interpolation, the more of reconstruction time simultaneously, aimed at eliminating the effects of noise contained in projection data, in this paper, author analysis cause and effects of common artifacts. importantly, discusses convolution back - projection reconstruction algorithm with a shift axis of rotation has been derived for correcting images that acquired with a divergence axis of rotation using the fan beam geometry with an angle - equaled detector
在ct圖像重建時，選擇有限帶寬窗有較好的空間解析度，三角形窗有較好的密度解析度，選擇餘弦窗則使得空間解析度與密度解析度的折衷；從窗函數的頻譜角度來講，可以用於圖像重建的一個良好的卷積窗函數應該具備以下條件： （ ? ）小的3db帶寬b ，即最小的主瓣寬度； （ ? ）最小的旁瓣最大峰值a ； （ ? ）最大的旁瓣峰值衰減速度d ；就內插函數而言，臨近點內插與線性內插重建圖像噪聲大，但有較好的邊緣與細節； 4 4三次內插、三次b -樣條與四次拉格朗日多項式內插圖像平滑，局部特性較好。In order to measure the characteristics of such semiconductor optical amplifier, we adopted a set of measurement system. this measurement system can be used to measure the characteristics of all kinds of active or inactive optical passive components. such device presents good polarization insensitivity ( < 0. 9db ), wide 3db bandwidth ( > 33nm ) at 0 - 200ma and different input signal light wavelength and power, the maximum fiber - to - fiber gain of 10db, lossless operation current of 50 - 75ma for different input signal light wavelength and power, large extinction ratio ( > 50db ) and lower noise figure ( nf ) ( < 8db )
與張瑞英博士一起，首次利用該種有源區結構制備出偏振不靈敏半導體光放大器，並在0 - 200ma注入電流范圍內獲得33nm的3db帶寬，在不同信號波長，不同信號功率0 - 200ma的注入電流范圍內，偏振相關損耗均《 0 . 9db ，在耦合差損為7db / facet的條件下，最大fiber - to - fiher增益達10db ，無損操作電流為50 - 70ma ，消光比達50db以上，而噪聲指數則低於8db ，最小可達4 . 6db 。So, the emphases are put on this part. first, all sources of noise are analyzed and calculated to determine the parameter of component and estimate the feasibility of the system. second, on the one hand, low noise wideband and high gain amplifier is detailed particularly in the design of hardware, on the other hand, several mathematical methods are introduced to reduce the noise further in the design of software
首先，詳細分析了整個系統的噪聲來源，計算可能出現的噪聲，在器件的選擇上對參數提出要求，並分析方案的可行性；其次，在硬體設計上，兼顧帶寬，噪聲與放大倍數；在軟體設計上，採用累加平均，最小二乘擬合等信號處理方法，進一步降低噪聲。
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