最高基帶頻率 的英文怎麼說
中文拼音 [zuìgāojīdàibīnlǜ]
最高基帶頻率
英文
top baseband frequency-
According to the guidline, two nd : yag lasers have been designed and set up, one is end - pumped by lower output power ld using a selfoc micro lens, and the other is end - pumped by high output power ld using a pair of lenses are designed, and the characteristics such as output power and power stabilization of both solid - state lasers are investigated. thirdly, when an empty liquid crystal cell is inserted in the cavity of the nd : yag laser pumped by high power ld, the laser can operates in single axial mode. finally, according to the relationship between the laser output power and the longnitudinal a ld - end - pumped nd : yag laser sensor for displacement measurement has been investigated theoretically and demonstrated experimently, the results indicate that when the mean radius of pumping inside the laser cavity is far less than that of the oscilating laser mode, the exponential of the output power is a gauss function of the longitudinal positon of focused spot of ld pumping beam, both the measurement range and the sensitivity are dependent on the incident pumping power, as the incident pumping power is increased, the measurement range is enlarged and the sensitivity is improve d
本文首先介紹了ld泵浦nd ： yag激光器的發展狀況、主要特性及其應用，從四能級速率方程出發，推導了ld泵浦nd ： yag激光器的閾值、輸出功率和斜效率的表達式，並簡述了激光器的工作原理、結構型式和倍頻方法；其次，以空間相關的速率方程為基礎，提出了ld端面泵浦nd ： yag激光器的設計方法，給出了一定泵浦耦合方式下，振蕩光模尺寸、最佳輸出耦合率、泵浦光模尺寸、泵浦光焦斑位置等參數的選取依據，以此為依據，設計了自聚焦透鏡耦合小功率ld泵浦nd ： yag激光器和透鏡組耦合高功率ld泵浦nd ： yag激光器，對激光器的輸出功率和功率穩定性等特性進行了實驗研究；再次，在帶尾纖輸出的高功率ld泵浦nd ： yag激光腔內插入一隻空液晶盒，觀察到了激光器以單縱模運轉；最後，根據泵浦光焦斑端面位置對激光輸出功率的影響規律，提出了ld端面泵浦nd ： yag激光位移傳感新方法，並進行了理論和實驗研究，研究結果表明：當激光晶體內泵浦光平均光斑半徑遠小於振西安理工大學碩士學位論文蕩光束腰半徑時，激光輸出功率的自然指數與泵浦光焦斑的縱向位置成高斯變化規律，測量范圍和靈敏度依賴于泵浦功率，隨著泵浦功率的增加，測量范圍擴大，靈敏度提高，當端面泵浦功率為7 . 24w （最大輸出功率為1 . 926w ）時，激光位移傳感器的測量范圍和靈敏度分別是13 . 045mm和0 . 148mw / pm 。In packet based wireless video communications, when best band distribution, not only source distortion should be considered, but also channel distortion caused by channel errors. the existing macroblock - layer rate control schemes calculates quantization parameters of all macroblocks ( mb ) in a frame in a raster scan order, and then encodes the mbs in the same order. actually, the quantization distortion is heavily dependent upon the coding order of mbs
在基於包的無線視頻傳輸中，最佳帶寬分配時，不僅要考慮信源編碼失真，也要考慮由於通道差錯引起的通道失真；已有的宏塊層碼率控制演算法以矩陣掃描的順序計算一幀中所有宏塊的量化參數，事實上量化失真與宏塊的編碼順序有很大關系，改變宏塊的編碼順序，使復雜的宏塊分配到更多的比特數，顯然能大大提高編碼效率。Secondly, the dissertation proposes a novel blind symbol - timing scheme for ofdm systems based on cyclostationarity feature of received symbols. the proposed schemes also exploits the periodicity of ofdm symbol introduced by cyclic prefix, by applying 2 - dimentional fourier transformation and choosing the appropriate correlation peak value as the symbol start location, the precision of this scheme is higher than previous conventional method. thirdly, the dissertation presents analysis with regard to channel estimation of ofdm systems. several interpolation algorithm in ofdm systems which based on pilot sequence have been analyzed in the first instance, and the influence of the channel noise on interpolation precision has discussed. the theoretic analysis and simulation results show that : the interpolation error induced by the precision of interpolation procedure itself has out weight
第三，論文在ofdm系統的通道估計方面，先對基於導頻的ofdm通道估計中的多種插值方法進行了分析，討論了噪聲對插值精度的影響，指出插值本身的精度所造成的插值誤差遠大於噪聲所帶來的插值誤差，從而階次更高的插值演算法在實用中並非最優的;並指出插值濾波法比變采樣率演算法對噪聲的影響更為敏感，在信噪比較高時插值濾波演算法比變采樣率演算法更優。Based on the research of videoconference systems of h. 323 protocol over ip networks and the author ' s experiences of implementing h. 323 videoconference systems in remote education area, in this thesis the main factors that affect videoconference quality are analyzed, and a dynamic bit rate allocation model is proposed and partly implemented. this model is designed to dynamically allocate bit rate for multi - media data flow ( including audio data and video data ) in fixed bandwidth network environment. when continuous multi - media packet losses are detected in ip based h. 323 videoconference system, the bit rate of video data is adjusted meanwhile the bit rate of audio data remains unchanged, and the bit rate allocation of multi - media data ( including audio data and video data ) is optimized as a whole effect
本文結合作者在h . 323視頻會議系統應用於遠程教育的經驗，通過對現有的基於ip網路的h . 323協議視頻會議系統的研究，分析了影響視頻會議質量的原因，提出並部分實現了在固定帶寬的網路環境下，基於ip的h . 323視頻會議的多媒體數據包發生丟包、抖動或延時時，保持音頻數據位速率不變，通過對視頻數據的位速率的進行調整，最終實現旨在提高視頻會議語音質量的多媒體數據位速率動態調整的模型。Broadband source location method is investigated by using signal - phase - matching principle, and simulations and experiments are carried out to show the validity of the method ; two high resolution algorithms of broadband signals are proposed, which are the dft interpolation algorithm and the frequency invariant beam space algorithm. the proposed algorithms have no requirement for prior information of source locations, so the results of doa estimation can be unbiased ; a method of temporal - spatial averaging, which can improve the performance of doa estimation for uniform linear arrays, is given. this method can be applied in the most narrowband or broadband eigen - structure based high resolution algorithms
提出了利用信號相位匹配法的寬帶信號方位估計方法並從模擬和實驗兩方面對其進行了驗證；提出了基於dft插值的和基於頻率不變響應波束域的兩種寬帶信號高分辨方位估計演算法，這兩種方法在進行方位估計時均不需要進行方位預估，從而避免了因角度預估可能帶來的估計偏差；最後提出了一種提高均勻線列陣方位估計性能的時空平均法，該方法可適用於多數窄帶或寬帶的特徵結構類高分辨方位估計演算法中。The thesis is composed of 9 parts : the background, significance, main topics and innovations in the thesis are introduced in chapter 1 ; in chapter 2, the main function and performance of interface circuits are described from the view of system by using the example of gigabit ethernet ' s transceiver ; the transmission media ' s frequency characteristics and model are analyzed for the high - speed data transmission system in chapter 3 ; the line driver is presented in chapter 4 ; the equalization principles for high - speed data transmission system are introduced in chapter 5 ; a novel adaptive equalizer for 1000base - cx transceiver is presented in chapter 6 ; in chapter 7, a fixed equalizer for 2. 5gbps transceiver is described ; in chapter 8, layout design and measured results are discussed ; at last, the conclusions are drawn in chapter 9. during period of finishing the thesis, i read lots of literatures about the interface circuits in high - speed data transmission system, studied their principles and design techniques, and designed : 1 、 the line driver for 2. 5gbps baseband copper cable transceiver ; 2 、 the fixed equalizer for 2. 5gbps baseband copper cable transceiver ; 3 、 the fixed equalizer for 1. 5gbps sata ( serial at attachment ) transceiver ; 4 、 an adaptive equalizer for 1000base - cx transceiver
論文由9部分組成：在第一章引言中介紹了論文的背景、意義、國內外研究現狀，以及論文的主要內容和創新；第二章以千兆位以太網為例，從系統的角度介紹了高速數據傳輸系統介面電路的主要功能和性能指標；第三章分析了高速數據傳輸系統的傳輸介質的頻率特性和模型；第四章描述了線驅動器的設計原理及其電路實現；第五章描述了高速數據傳輸系統的均衡原理；第六章描述了適用於1 . 25gbps基帶銅纜收發器系統的自適應均衡器的設計原理和電路實現；第七章描述了適用於2 . 5gbps基帶銅纜收發器系統和1 . 5gbps串列硬盤介面（ sata ）收發器系統的固定均衡器的設計原理及其電路實現；在第八章中分析了電路的版圖設計及晶元測試結果；最後，第九章總結了全文。在完成論文期間，查閱了大量的有關高速數據傳輸系統介面電路方面的文獻，較系統地學習了線驅動器、傳輸線和均衡器等方面的理論知識和電路設計原理，設計了用於： （ 1 ） 2 . 5gbps基帶銅纜收發器系統的線驅動器； （ 2 ） 2 . 5gbps基帶銅纜收發器系統的固定均衡器； （ 3 ） 1 . 5gbpssata系統的固定均衡器； （ 4 ） 1 . 25gbps基帶銅纜收發器系統的自適應均衡器。分享友人