time-frequency code 中文意思是什麼
time-frequency code
解釋
時間頻率編碼-
The pulse code modulation / frequency modulation ( pcm / fm ) is widely used in most reentry remote sensing ( rrs ) system at the present time in our country
目前我國再入遙測系統主要採用脈沖編碼調制/調頻（ pcm / fm ）體制。 -
In the fourth chapter, firstly, the fsk / psk signal function is presented, then, the signal which frequency and phase are modulated by costas code and barker code for each are analyzed at the same time. after that, the target returns and clutter returns are analyzed and modeled. at last, both of the time correlation characteristics and space correlation characteristics are theoretically analyzed
在第四章中，首先給出fsk / psk信號的表達式，並對一種分別採用costas碼和barker碼進行頻率和相位調制的fsk / psk信號進行分析，然後對fsk / psk信號的目標回波和雜亂回波進行分析與建模，接著，對雜波信號的時間相關性和空間相關性進行理論分析，由分析結果可知， fsk / psk雷達雜波的時間相關性不變、空間相關性增強。 -
( 3 ) the features of the low frequency time - code receiver are digital, high performance and high precision. on the basis of the testing flat of low frequency time - code, we designed a low frequency time - code receiver based on software radio
在前面已經實現的低頻時碼信號測試平臺的基礎上，對設計一種基於軟體無線電模式的低頻時碼接收終端作了初步的探討，為今後的全數字化接收機的實現打下一定的基礎。 -
Comparing with the system which does not space - time code, space - time coding can obtain transmit diversity and increase channel capacity without frequency bandwidth loss
與空間未編碼系統相比，空時編碼可以在不犧牲帶寬的情況下起到發射分集和提高功率增益的作用。 -
This system can process linear frequency modulation signals ( lfm ), nonlinear frequency modulation signals ( nlfm ) and taylor quadriphase code signals with time width under 42 s and band width under 5mhz. the experimental results demonstrate that the specification characteristics meet the requirements of practical radar systems
該系統可處理時寬在42 s以內?帶寬在5mhz以下的線性調頻信號（ lfm ） ，非線性調頻信號（ nlfm ）和taylor四相碼信號，且技術指標完全滿足實用系統的設計要求。 -
In order to meet to the higher timing precision of the low frequency time - code timing terminal, the applications of dsp ( digital signal processing technology ) in the time service is researched in this paper. the main works and contributions can be summarized as follows : ( l ) the low frequency signal transmission and dsp technology are discussed. according to the system needs, a testing flat of low frequency time - code based on dsp is built up
本論文的工作針對低頻時碼授時高端用戶的定時需求，對數字信號處理（ dsp ）這一新型技術在該領域應用進行了探索性研究，主要完成和開展了如下工作： （ 1 ）研究分析了低頻通道和dsp技術，根據系統要求，從硬體上實現了基於dsp晶元的低頻時碼信號的採集測試平臺。 -
Pcma is a fundamentally new technique for two - way satellite and a novel method for frequency re - use which allows two different earth stations to use the same frequency, time slots and / or cdma code at the same time
Pcma技術是用於雙向衛星通信的一種嶄新技術，是一種全新的頻率復用方式，它允許兩個不同的衛星地面站同時使用完全相同的頻率、時隙或擴頻碼字。 -
Construction and characteristic analysis of a frequency - hop time - spread code
一種跳頻擴時碼的構造及性能分析 -
Due to the data transmission characteristics between tags and reader, space division multiple access ( sdma ), frequency division multiple access ( fdma ) and code division multiple access ( cdma ) are applied in a limited way in rfid system. therefore, time division multiple ( tdma ) has been generally accepted. according to tdma, there are aloha protocol, s - aloha, binary - tree protocol, clipped binary - tree protocol and others
解決這個問題必須要用到多路存取法，針對射頻識別系統中閱讀器與應答器之間的通信特點，空分多路法、頻分多路法、碼分多路法在rfid系統中應用都受到一定的限制，只能應用到一些特定的場合，一般採用時分多路法，按照時分多路法的演算法有aloha演算法、時隙aloha演算法、二進制樹型搜索演算法、修剪枝的二進制樹型搜索演算法等防碰撞演算法協議，分析了各自特點以及存在的缺點。 -
In this paper, bit - error rate performance analyses are presented for coded and un - coded frequency hopping m - ary frequency - shift keyed systems under the condition of additive white gaussian noise ( awgn ) and partial band noise jamming and multitone jamming. the use of error - correct codes provide a way to improve the performance of frequency hopping system, particularly the use of reed - solomon code in a fh system under the condition of partial band noise jamming can greatly improve the performance of system. so we provide the way of coding and decoding of rs code in c language. in the end, we offer the simulation of the performance of time diversity fh / 2fsk system over partial band jamming noise channels
第一章為緒論，敘述跳頻通信的發展趨勢，以及基本概念，第二章及第三章介紹提高抗部分頻帶干擾的前向糾錯碼reed - solomon碼的原理和實現方法。第四章研究跳頻通信系統在各種干擾條件下的性能。最後在第五章以fh mfsk系統為例，探討在部分頻帶干擾下的系統性能，並進行計算機模擬，模擬結果表明採用分集技術和各種編碼技術對于系統的性能改善具有明顯的效果。 -
At the last we program the parameter detecting methods for frequency - shift track signal with c language and assembly language base on code composer studio of dsp. then we realize it on the dsp chip of tms320f2812. experiments shows that it can satisfy the demand of real time and precision
最後在dsp的集成開發環境ccs （ codecomposerstudio ）上採用c語言和匯編語言混合編寫移頻軌道信號的參數檢測演算法，並將該演算法移植到dsp晶元（ tms320f2812 ）上實現，測試結果表明上述演算法能夠滿足實時性和精度的要求。 -
However, multipath components can be resolvable due to the autocorrelation of the spread spectrum signal, thus the optimal receiver equals coherent rake reception, i. e. maximum ratio combining the independent components which endure flat fading or frequency non - selective fading. synchronization of pn code and separation of resolvable multipath components need to estimate the exact time delay among the multipath components
但是利用擴頻信號的自相關特性，可分辨多徑可以被有效分離，最優接收機等效為對多個具有獨立平坦衰落通道（或頻率非選擇性通道）特性的多徑信號進行最大比合併，即相干rake接收。 -
The main numerical method of this code is coming from scheme ( jameson, schimit and turkel ) : using cell - centered finite volume method as spatial discretization tools, and a system of ordinary differential equations for time variable is obtained, which is solved by utilizing five - step runge - kutta scheme as time marching method, introducing artificial dissipation to damp high frequency oscillations near the shock and stagnation point
本論文採用歐拉方程作為控制方程，利用中心有限體積法進行空間離散，得到對時間變量的常微分方程組，採用龍格庫塔多步法進行時間積分，加入人工粘性以消除激波和駐點附近的壓力振蕩等方法來對naca0012翼型的實際流動進行并行數值模擬。 -
In this thesis, a kind of 2 - dimention signal acquisition method is presented which combines parallel pn code phase and carrier frequency acquisition, as a result the acquisition time is shortened greatly. besides, according to the fact that the detection of spread spectrum signals is always the key point in the receiving system
在擴頻信號的捕獲過程中要求有較小的時延和較高的概率，本文介紹一種二維信號的捕獲方法，這種方法結合偽pn碼和載波頻率的獲取，捕獲時延將大幅度降低，實際上，擴頻信號的檢測是接收系統的關鍵。 -
It not only considers the effect of frequency error and data modulation, but also realizes code synchronization and frame synchronization at the same time. all these research work will give a valuable reference to the design of the new communication systems
本文對擴頻通信系統構成和原理，擴頻序列設計與優選，擴頻序列同步問題進行了研究，並進行了相應的模擬。 -
Because using ofdm, a frequency - selective fading channel can be transformed into multiple frequency - flat fading sub - channels, in the coding process, spatial diversity ( due to multiple antennas ) is integrated with frequency diversity ( due to delay spread ), therefore, the proposed code can provide higher diversity gain than space - time code alone
該編碼利用正交頻分復用把頻率選擇性衰落通道變換成平衰落通道的特性，同時引入了基於多天線的空間分集和基於時延擴展的頻率分集，比空時編碼具有更高的分集增益。 -
The generally an inside contain entrance for, using to be used asing the random access of two is. the repetition method can be an ip, ib, ibp, ibbp, and even and all is an i ? the repetition frequency of the basis means with m. the repetition frequency of different provides the rate of different exportation code, and affect the access delay at the same time
一般是一秒內有兩個i幀，用來作為隨機存取的入口。幀重復方式可以是ip ， ib ， ibp ， ibbp ，甚至全部是i幀。基準幀的重復頻率用m表示。 -
Multicarrier wireless communications have been widely investigated in the past decades. recently, two - dimensional spread spectrum ( 2d - ss ) system has drawn a lot of attention because of its full utilization of spreading characteristics in the frequency domain and time domain. compared with multicarrier code division multiplex access ( mc - cdma ), 2d - ss system can effectively mitigate multiple access interference ( mai ) due to spreading in the time domain
當前多載波無線通信技術得到了廣泛的研究，二維擴頻通信系統是近年來提出的新的擴頻通信方式，由於二維擴頻系統從時域和頻域上分別對數據信號進行頻譜擴展，因此它同時具有時域擴頻和頻率擴頻通信系統的特點，是對傳統的一維時域直接序列擴頻和多載波擴頻的推廣。 -
This method embarked from the practical application characteristic, carried on first the rank arrangement to multiple roi, and filtered the high frequency component that the background region outside the roi thus reduced the jpeg2000 code operand, reduced the production symbol stream code time
該方法從實際應用的特點出發，對多個roi進行優先級別的排列，對roi外的背景區域進行高頻分量濾除，從而減少了jpeg2000編碼的運算量，減少了生成碼流的編碼時間。
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