系統噪聲帶寬 的英文怎麼說
中文拼音 [xìtǒngzàoshēngdàikuān]
系統噪聲帶寬
英文
system noise bandwidth-
Frequency response, quantization noise, reconstruction error and its sensitivity to mismatch among adcs are studied at length in prqmf banks adc system, and the theoretic results include : ( 1 ) the distortion / aliasing functions of hybrid filter banks adc system is similar with that of switch capacitor filter banks adc system ; ( 2 ) for wide or narrow band input signal, the effective resolution of the two adc systems is 0. 51og2m bits higher than their adc ; ( 3 ) reconstruction error ' s sensitivity to mismatch among adcs of the two adc systems is reduced effectively than time interleaved adc system
2對prqmf濾波器組adc系統的頻響、量化噪聲特性、重建誤差特性以及重建誤差對adc間的失配敏感性進行了理論分析研究，所得到的理論結果為： （ 1 ）混合濾波器組adc系統與開關電容濾波器組adc系統的失真/混迭函數一致； （ 2 ）無論輸入寬帶還是窄帶信號，這兩種adc系統的有效解析度均比其adc提高了0 . 5log _ 2m比特； （ 3 ）這兩種adc系統的重建誤差對其adc間的失配敏感性均明顯低於時間交織adc系統。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。The conclusions are as follows : the ultrasonic intensity is proportion to the laser intensity ; the ultrasonic induced by a laser line source has much more advantages than by a laser point source, such as stronger energy, higher snr, more directivity and shape ; the intensity of cfpi ' s output signal is linear with ultrasonic vibration velocity, and is effected by incidence angle and scattered angle ; snr will increase by reducing cfpi ' s bandwidth, reducing incidence angle, increasing cavity ' s length and reflectivity
在分析點光源激勵聲表面波機理的基礎上，求出了線光源激勵的超聲振動的位移表達式，發現線光源激勵的近場區表面波具有波形好，信噪比高，指向性好，幅度強等特點。通過理論推導，得出共焦fabry - perot干涉儀的輸出光強除了與樣品表面的振動速度成正比，並與入射角和散射角有關；適當減小cfpi的帶寬，增加腔長，增大鏡面反射率，或者減小檢測入射角都可以提高系統的信噪比。The fiber raman amplifiers ( fras ) are more and more attractive for its particular virtues such as on - line, wide band, and low noise etc, and they are very fit for dense wavelength division multiplexing ( dwdm ) system of next generation charactered by its super large capacity and long transmission distance. fras are unsubstitutable in the fields such as optical fiber communication over the ocean, long haul transmission and exploitation of the entire low - loss band of fiber
光纖拉曼放大器因其特有的在線、寬帶、低噪聲等特點而越來越被人們關注，是一種非常適合下一代超大容量、超長距離dwdm系統的光放大器，尤其是在海底跨樣光纖通信、超長距離光纖通信以及開發整個光纖低損耗窗口等方面有著不可替代的優勢。Secondly, ground on the duct noise control, the delayed - lms algorithm, which is actulized easily, is brought forward, then the simulation on pc is achieved. it is shown from the computer simulation that for the single frequency noise, there will be a good effect when choosing the suitable parameters ; but for the narrowband noise, the effect will become worse with increasement of the bandwidth. this result is helpful to analyze the parameters influencing anc
結果表明： （ 1 ）隨著濾波器長度的增大，系統收斂速度變快； （ 2 ）隨著值的增大，系統的收斂速度增大，但是當值超過某一范圍時會引起系統的發散； （ 3 ）次級通路的延遲數與初級噪聲頻率有關； （ 4 ）對于窄帶信號， dlms演算法可以取得一定的降噪量，但是隨著窄帶信號帶寬的增大，降噪效果明顯變差。With the advantages of high gain and output power, low noise, wide bandwidth as well as no relation with polarization, edfa changes the traditional optical - electrical - optical relay mode step by step in many fields, and becomes an indispensable device in modern optical communication systems. it saves the expensive cost in optical - electrical transition, makes equipment easy to operate and maintain
由於其本身具有高增益、高輸出功率、低噪聲、帶寬寬、與偏振無關等優點，在很多領域和場合， edfa正逐步取代傳統的光-電-光中繼模式，省去光電/電光轉換的昂貴成本，便於設備的運行維護，成為現代光纖通信系統中不可缺少的關鍵部件。Firstly, the system has a good snr and high accuracy, which is owed to wideband operational amplifier being used, accurate adjustment by da, 12 - bit high sampling ad converter being applied. secondly, data transmission becomes less by using forecasting code technology and dictionary compress technology, which are run by dsp on board
本採集系統採用400mhz增益帶寬積的運算放大器，運用da高精度校準技術，並選用高采樣率低噪聲的12位ad轉換晶元進行模擬電路和ad轉換電路設計，既保證了數據採集系統的信噪比，又提高了系統測量精度。The simulated results show that we can improve the sensitivity by setting the optical bias at / 2, reducing the gap of electrode, increasing the overlap integral factor, reducing the insert lose, adopting suitable segmentation number, increasing the electrode length, increasing the optical power, reducing the wavelength and the relative intensity noise and reducing the receive bandwidth ; obtain the wider bandwidth utilizing reducing the electrode length and the capacitance of modulator, segmentation the electrode ; increase the dynamic range using lowering noise, increasing the optical power at the detector and lower optical bias
通過計算得知，使傳感器相位偏置為/ 2 ，減小電極間距，提高電光重疊因子，減小器件插入損耗，採用合適的分段數，增加電極長度，增大光功率，降低激光的波長，減小相對強度噪聲，減小接收帶寬，對提高靈敏度的效果是非常明顯的。而減小天線長度，降低調制器電容，電極分段，都可以獲取較大的帶寬。降低系統噪聲;增加到達探測器的光功率，採用較低的光學偏置，都可以增大線性動態范圍。Frequency - domain equalization. at the same time discusses some key problems in ofdm : high ratio of peak - to - average power of output signals, problem of synchronization, channel estimation, adaptive bit, power and subcarrier allocation. emphasize on channel estimation, and present a new algorithm which can filtering more interpolation errors and noise. for the sake of improve the performance of resist narrowband noise and make efficient use of the spectrum apply malvar wavelet division
同時就ofdm系統中的一些關鍵問題如峰值平均功率比（ papr ）太高，同步問題，通道估計，通道、比特與功率必須動態分配進行了研究，著重研究了通道估計問題並提出一種改進的方法，能濾除更多的噪聲分量和插值誤差，提高系統的性能；為了提高抗窄帶噪聲的性能和提高通道利用率，用malvar小波變換實現了不等帶寬分配。Embedded technologies, multi - way technologies and sampling technologies are used to reduce the sampling rate by software, so that the system can provide appropriate image format according to the condition of network and can eliminate aliasing noise. the system also uses motion detection to control the frame rate. therefore, the system can save transmission bandwidth effectively and design to provide multiple degrees qos according to the network condition
本方案採用了嵌入式技術和多路技術，並從采樣技術入手，軟體調整采樣率，使得系統能夠根據網路狀態提供適當格式的圖像，消除欠采樣噪聲，而且通過運動檢測來控制幀率，從而可以有效地節省傳輸帶寬，達到根據網路情況自適應地提供多種qos服務等級的目的。For the application of direct broadcast satellite ( dbs ), a ku - band high image rejection broadband mixer is designed using ads. it appears predominant performances when compared with common single balanced mixer
針對衛星電視直播接收系統，用ads設計了一個寬頻帶、高鏡像抑制度、低噪聲的ku波段鏡像抑制混頻器，並同普通平衡混頻器進行了對比分析，顯示了其優越的性能。Unlike pilots which are used for estimation of channel and must waste some useful bandwidth, the ppss, whose power can be boosted 3db or 6db to suppress efficiently the additive noise, is useful data transmitted, thus efficiency of the ofdm has been increased
與用於做通道估計的導頻符號不同， ppss傳輸的是有用的數據，因此提高了系統的帶寬利用率， ppss的平均功率增加3db或6db可有效抑制通道的加性高斯噪聲。Simulation results demonstrate theoretical derivation is correct and both sequences can be used in communication. based on the presented ds / sfh communication scheme, and employing msk as fh spread spectrum modulation, the performance is studied n the presence of partial band multitone jamming and additive white gaussian noise ( awgn )
根據所提出的混合ds sfh擴頻通信系統方案，採用msk相干調制，在假設直接序列擴頻后信號帶寬等於跳頻間隔的情況下，推導了系統在部分頻帶多頻干擾和加性白噪聲下的誤比特率公式。Meanwhile, with the development of wdm / dwdm communication systems, more and more attention is paid on the edfas with broader bandwidth, good gain and noise feature, and gain clamping, etc. according to the tianjin natural science foundation project : intelligent fiber amplifiers and light sources, the tianjin natural science foundation project : ( c + l ) broadband fiber amplifier and the nankai - delta ( tianjin ) project : development of gain flattened erbium - doped fiber amplifiers, this dissertation is mainly focused on the study of novel gain - clamped edfa, light sources, multi - wavelength fiber laser and variable optical attenuator for gain - clamped usage, gain and noise improvement of edfa, and broadband edfa
Wdm / dwdm通信系統的發展又需要edfa具有更大的帶寬、優良的增益和噪聲特性和增益控制等功能。基於上面的情況，並結合天津市重點基金項目? ?智能光纖放大器光源的研究、天津市重點基金項目? ? （ c + l ）超寬帶摻雜光纖放大器和南開-達爾泰（天津）項目? ?開發增益平坦的摻鉺光纖放大器等課題，論文主要圍繞新型增益控制edfa 、增益控制用光源、多波長激光器及可調光衰減器、 edfa性能優化和超寬帶edfa等方面進行了理論和實驗研究。But they have the disadvantages such as poor complexity, poor security and insufficient amount of sequence numbers among the family of codes, the chaotic signals have noise ? ike, broadband frequency spectrum, they can be used as spreading codes, furthermore, chaos system is extremely sensitive on initial conditions so that the various initial conditions given by chaos system can provide with large sum of spreading sequences and this can meet the demand of cdma, this thesis sets out to study on using chaos system to generate spreading sequence s, there are two parts is this paper : firstly, we study the basic theory of spread ? pectrum communication and the characteristics of chaos so as to prove the applicability of chaos system to be used in spread ? pectrum ii communication system
現在使用的擴頻碼有m序列， gold碼和r - s碼等，這些擴頻碼具有良好的隨機性，但普遍存在著復雜度低、保密性差以及同一碼族序列數目少等缺點。混沌信號具有類似噪聲、寬帶連續頻譜的特徵，正符合擴頻通信中對擴頻碼的要求，而且混沌系統對初始值極其敏感，可以通過給混沌系統賦予不同的初始值得到為數眾多、不相關的擴頻序列，這正好滿足碼分多址的要求。本文對利用混沌系統應用於擴頻通信作了一些研究工作，主要包括兩部分：第一部分：探討了擴頻通信的基本理論和混沌的基本特性，說明將混沌系統應用於擴頻通信系統的可行性。Microwave broadband low noise amplifier is the important part of the receiver system of radar, electron rivalry, remote measuring and remote control
微波寬帶低噪聲放大器是雷達、電子對抗及遙測遙控接收系統等的關鍵部件。分享友人