波道頻率 的英文怎麼說
中文拼音 [bōdàobīnlǜ]
波道頻率
英文
channel frequency-
Shortwave channel is time varying transmission channel. it has dispersion in frequency and time domains. this characteristics hinds the data transmi - ssion at high speed and the correction of received data. in this dissertation i have analyzed the statistic characteristic of shortwa - ve channel, established the model of shortwave channel and simulated the rayl eigh fading distribution. the technology of spreading spetrum has been proved that it has the capability for anti - multipath and discerning multipath
在短波通信中，由於通道的時間色散和頻率色散，引起多徑展寬和多徑衰落，前者限制了數據的傳輸速率，後者造成短波數據通信中出現突發錯誤，為了解決多徑效應對短波通信的影響，本文所做工作如下：首先詳細分析了短波通道的統計特性，建立其數學模型；其次分析了擴頻通信的特點，從理論上證明擴頻技術不僅具有抗多徑干擾能力，而且具有分離多徑的能力；介紹了傳統的rake分集合併技術的特點。In this thesis, for the merits of high frequency spectrum utility factor and high - speed data communication, the ofdm is introduced into the underwater acoustic communication. combined with fec to combat the frequency - selective fades and isi in the underwater acoustic channel, high speed data transmission is realized by employing ofdm technology
本研究嘗試將ofdm技術引入水聲通信領域，利用該技術頻譜利用率高，多載波并行傳送的特點，結合通道編碼，以克服水聲通道多徑干擾引起的頻率選擇性衰落和碼間干擾，獲得高速率數據傳輸。The conventional sphere model of earth and circle model of orbit are discarded, and the ellipsoid model and the ellipse model are selected for further research, which achieves a method to determine the target position through the antenna pointing direction. and the spaceborne sar system design and simulation software is brought forth. this software accomplishes sar system coefficients design for antenna area, pulse repetition frequency, signal bandwidth, downlink data rate, radar transmitter power and satellite platform yaw steering
本文從星載雷達的星地幾何關系入手，舍棄傳統星載合成孔徑雷達研究中的球地球模型和圓軌道模型，研究了在地球橢球模型和橢圓軌道模型下由雷達天線確定目標坐標的方法，並在此基礎上研製了星載合成孔徑雷達系統設計與模擬軟體，完成雷達系統天線尺寸、脈沖重復頻率、信號帶寬、雷達信號數據率、雷達發射功率、衛星平臺的偏航牽引等幾個方面的系統參數設計以及雷達多普勒特性、雷達系統模糊、雷達定位及精度的分析，最後完成雷達回波信號的模擬。In view of this situation this article has conducted research to the design of metallurgy auxiliary biography with the frequency conversion table electrical machinery first multianalysis to the frequency changer and the frequency conversion table electrical machinery movement characteristic is carried out, the voltage waveform harmonious which the frequency changer outputs is big, attacks in a big way, and the voltage climbing rate reaches as high as 6600v / mu s which is 20 times ordinary sine alternating voltage, the rolling mill auxiliary biography table set the extremely strict request to the electrical machinery ; its movement frequency is very low, rate frequency in 8 - 20hz ; the velocity modulation scope is wide, the lowest movement frequency lowers to 1hz, and the starting number of times is quite frequently, each hour reaches as high as 600 - 800 time, the impact shoulders in a big way, the overload capacity request is high
針對這一情況本文對冶金輔傳用變頻輥道電機的設計進行了系統研究。首先對變頻器和變頻輥道電機的運行特性進行詳細分析，變頻器輸出的電壓波形諧波大，沖擊大，電壓上升率高達6600v / s ，是普通正弦交流電壓的20倍;軋機輔傳輥道對電機提出了十分嚴格的要求:其運行頻率很低，額定頻率在8 - 20hz ;調速范圍寬，最低運行頻率低到0 . 5hz ，起動次數相當頻繁，每小時高達600 - 800次，沖擊負荷大，過載能力要求較高。The carrier wave is modulated directly by the baseband signal at several frequency point in l band and s band. firstly, this paper clarifies the theory of i / q modulation, elaborates evm and acpl, and analyzes the effect of amplitude and phase unbalance and dc offset on evm. secondly we review the basic principle of phase locked loop and it ’ s composing parts, including the basic conception and design method of pll frequency synthesizer, especially introduce the charge pump pll frequency synthesizer in detail
首先，在闡述i / q正交調制基本原理的基礎上，通過對誤差矢量和鄰近通道功率泄漏的詳細分析，定性、定量地討論了各種非理想電路因素（如相位不平衡、幅度不平衡、直流偏差等）對調制器性能的影響;其次，介紹了鎖相環的工作原理和基本組成部分，包括鎖相環的設計和環路濾波器的設計，特別詳述了電荷泵鎖相頻率源;第三，介紹了採用直接調制技術模擬衛星信號的射頻前端的設計;最後，對整個直接射頻調制系統進行測試，結果基本上達到了課題要求。Under the condition that the carrier frequency is the only prior knowledge, various feature abstraction methods and amr algorithms are analyzed, integrated and compared for the awgn and non - awgn channels
在載波頻率是唯一先驗知識的條件下，本論文分別對awgn通道和非awgn通道下的調制類型特徵提取和自動識別演算法進行了分析、綜合、對比。The efficient sppc had been performed with 1 - hz - repetition - rate 532nm nanosecond pulses, in which phase conjugate reflectivity as high as 21. 5 % was obtained. when sppc were operated in ce : batio3 with 532nm, 632. 8nm and 790nm cw lasers, the maximum sppc reflectivity of 54. 1 %, 88. 2 % and 80. 5 % were obtained, respectively. unlike the results reported before that four - wave mixing by stimulated photorefractive backscattering ( spb - fwm ) only exists at short wavelengths while four - wave mixing by total internal reflection ( tir - fwm ) only exists at long wavelengths, both of these two mechanisms coexist at all wavelengths from 532nm to 790nm in our experiments
通過大量的實驗全面研究了ce ： batio _ 3自泵浦位相共軛特性：在低重復頻率（ 1hz ） 、 532nm調q激光泵浦時最高獲得了21 . 5的位相共軛反射率，而此前報道過的建立位相共軛脈沖光最低重復頻率是10hz ；實驗中發現在532nm 790nm波長范圍內，在不同的波長激光泵浦時，同時存在兩種自泵浦位相共軛機制：全內反射?四波混頻（ tir - fwm ）和受激背向散射?四波混頻（ spb - fwm ） ；在連續激光泵浦時，對532nm 、 632 . 8nm和790nm三種波長，最高分別獲得了54 . 1 、 88 . 2和80 . 5的位相共軛反射率；同時還研究了自泵浦位相共軛光的時間穩定性。The major job is manufactured a transmitter, which has three upmixer channels. its function is to up convert the signals from c - band to ka - band. the input local oscillator is provided by a low frequency crystal oscillator which has a good performance of phase noise, through 512 times multiply to ka band. this sysetem is used in the laboratory as transmitter source of the fuze, for the multidimensional objects in practise, which lead to the complexity of the reflect signal, so the amplitude, frequency and the phase of the transmit signals both have a key role in dealing with the reflection signals. therefore, this system requires for both the coherence of the single channel ’ s amplitude, phase and multi channels
本文的主要工作是應用戶要求製作一具有三發射通道的上變頻系統，可以將c波段的微波信號上變頻到ka波段的毫米波信號。系統的本振輸入基頻由一相位噪聲非常好的低頻率晶振提供，經過512次的倍頻放大至ka波段。本系統作為實驗室中引信的發射源，由於目標反射信號具有時變的多維性，反射信號變得極為復雜，在信號處理時，不僅信號幅值、頻率有決定意義而且相位關系也很有決定意義。Single carrier frequency domain equalization for high data rate transmission systems over frequency selective fading channels
頻率選擇性通道下高速數據傳輸中的單載波頻域均衡技術Channel frequency response
波道頻率響應Data used in this work are north pacific ssta, 160 stations precipitation of china, and ncep reanalysis data. main results are as follow : ( 1 ) it is found that a apparent transition of north pacific ssta in later 1970 ' s : eastern and middle - equatorial pacific ssta turns from cold to warm with area extending, and mid - latitude pacific ( west wind drift zone ) turns from warm to cold. during this transition of ssta, different characters also appear in el nino and la nina : before 1976, la nina happens more frequently, and its duration is longer, el nino zone develops from negative ssta in the early stage ; after 1976, el nino happens a little bit frequent and longer with more intensity than before, el nino zone develops from positive ssta in the early stage ; the course of ssta variation has an enso cycle of 2 - 6 years, annual oscillation of 8 - 9 years, and decadal variation of about 22 years
本文採用1950 - 1999年北太平洋海表溫度（ sst ） 、中國160站夏季降水和ncep再分析的歐亞500hpa高度場等資料，利用eof 、 svd 、小波分析、合成分析和相關分析等方法，在分析北太平洋海溫時空分佈特徵的基礎上，著重探討了海溫異常及其年代際變化對我國東部降水的影響，並對降水、高度場和海溫三者之間的關系進行了分析，以試圖尋找三者異常之間可能的聯系，主要結論如下： （ 1 ） 1976年前後，北太平洋海溫經歷了一次明顯的轉變，赤道中、東太平洋厄爾尼諾海區由冷轉暖，暖水范圍增大，中緯度西風漂流區海溫由暖轉冷；在這樣的年代際背景下，厄爾尼諾、拉尼娜事件在不同的時期也有不同的特徵：在76年前，拉尼娜事件發生頻率高，持續時間長，事件起始於負海溫距平；而76年後，則是厄爾尼諾事件發生頻率略高，持續時間長，強度增大，事件起始於正海溫距平。Transitional feature of the arc and metal droplet in the welding process with steam shielded arc is investigated by means of analysing the waveforms of welding voltage and current under different welding regimes and it is found that there are two types of arc process behavor ? " arc starting - arc blowing out - short - circuiting " and " arc - starting - short - circuiting ". under the condition of constant diameter of welding wire and its feeding speed, the arc process behavor can be changed by adjusting the inductance of welding circuit as well as the voltage of power supply. if arc process behaves as alternative process of " arc starting - arc blowing out - short - circuiting " with minimum time duration of arc blowing out and maximum frequency of short - circuit transition, the welding process will be stable with less spatter and smooth weld bead
通過分析不同焊接規范下的焊接電壓和電流的波形.研究了水蒸氣保護下電弧及熔滴過渡的特點，發現其電弧過程行為有「燃弧?熄弧?短路」和「燃弧?短路」兩種形式.在焊絲直徑和送絲速度一定的情況下，通過調節焊接迴路中的電感量和電源電壓，可以改變電弧的過程行為形式.若電弧過程呈「燃弧?熄弧?短路」交替進行，並且熄弧時間最短時，短路過渡頻率最高，在這種情況下，飛濺小，焊道成型好，焊接過程穩定For example, carrier frequency offsets, which are caused by the inherent instabilities of the transmitter and receiver carrier frequency oscillators, can lead to severe system degradation due to inter - carrier interference ( ici ). symbol timing synchronization must also be achieved in order to avoid inter - symbol interference ( isi )
其載波頻率誤差會引入子通道之間的干擾（ ici ） ，而幀同步的誤差會引入符號間干擾（ isi ） ，同時還會對通道估計帶來嚴重的影響。They are the property of sum and difference beams, the errors of the elements and channels and different pulse repeating frequency ( prf )
這些因素包括和、差波束的特性、陣元和通道的誤差、不同的脈沖重復頻率（ prf ） 。These include the well - known am, fm, shortwave and citizens bands and vhf and uhf television channels, as well as hundreds of less familiar bands that serve cellular and cordless telephones, gps trackers, air traffic control radars, security alarms, radio - controlled toys and the like [ see box on page 71 ]
這些頻率包括眾所周知的am 、 fm 、短波、民用頻帶， vhf和uhf電視頻道，以及數百個較不為人知的頻帶，供行動電話、家用無線電話、 gps追蹤系統、航空管制雷達、安全警示與無線電遙控玩具等使用（見85頁無線電頻譜） 。The emphases of our research works are as follows : under ultra - low temperature ( about 0. 236k ) conditions, how the frequency and power of the saw and the source drain voltage influence the acoustic current ; and the relationship between the source drain current and the split - gate voltage ; and how to find the cut off voltage of the quasi - 1d electron channel ; and also the frequency character of the idt in the saw parts
研究的重點為，在甚低溫（ 0 . 236k ）下，通過實驗研究表面聲波的頻率和功率，源漏偏壓等因素對聲電電流的影響;研究準一維電子通道中不同源漏電流與分裂門負偏壓的關系，以找到分裂門的鉗斷點電壓;以及研究聲表面器件叉指換能器的頻率特性等。The advantages of using leo satellite are as following : on the one hand the satellite orbit is low, so the transmission delay is short, the power loss is small ; on the other hand the development of cell communication, multi - access, frequency multiplex and etc also provide a technique guarantee to the leo satellite - mobile - telecommunication. so the leo system is considered to be a satellite - mobile - communication system with a great future
低軌道衛星是一種運行於1000公里左右的高空中的人造衛星，利用leo衛星實現個人通信的優點在於：一方面衛星的軌道高度低，使得傳輸延時短、路徑損耗小，多個衛星組成的星座可實現真正的全球覆蓋，頻率復用更有效：另一方面蜂窩通信、多址、點波束、頻率復用等技術的發展也為低軌道衛星移動通信提供了技術保障。Aiming at the lower performance and floor effect of the traditional orthogonal frequency division multiplexing channel estimation, the ofdm channel estimation algorithm based on wavelet recursive least square support vector machine ( wrls - svm ) is proposed
摘要針對傳統多徑衰落下的ofdm導頻通道估計性能低下，地板效應的缺陷，提出了基於導頻的小波遞歸最小二乘支持向量機（ wrls - svm ）時變通道頻率估計演算法。Frequency using wavelet theory, another is multi - channels based on gray. the first method is based multi - scale decompression using wavelet theory, it extract gray feature from each channel to form feature vector, it can distinguish objects, but this method not have invariant property when object rotate
基於小波的頻率多通道是從小波多分辨分解的角度，提取各頻率通道的灰度特徵形成特徵向量，該方法可以很好的區分目標，但不具有旋轉不變性。In cellular envirorunents, because of the influence of several adverse factors, such as muitipath, non - line - of sight propagation, noise, interference and channel frequency characteristics, radio statistics measuremenis like tdoa, toa and aoa related to mobile position, the performance of location algorithms mny be significantly degraded and the position estimation of ms is inevitably biased
在蜂窩網路環境中，由於受多徑、非視距傳播、噪聲、干擾和通道頻率特性等多種不利因素的綜合影響，使tdoa 、 toa 、 aoa等與移動臺位置有關的電波特徵測量值不可避免地出現較大誤差，從而使各種定位演算法的性能顯著下降，造成移動臺位置估計出現較大偏差。分享友人