direct sequence 中文意思是什麼
direct sequence
解釋
直接序列-
Then studies a peculiar multi - carrier direct sequence spread spectrum ( mc - ds - cdma ) technology, analyzes the methods of processing multi - carrier signals and study the mathematical module of multi - carrier communication system receiver
然後對本文所研究的這種特殊的多載波直接序列擴頻技術進行闡述，分析了多載波信號處理的方法和研究了多載波接收機的數學模型。 -
After establishing the model of intermediate frequency direct sequence spreading spectrum ( if dsss ) receiver, comparing and analyzing several conventional code acquisition methods, code and carrier two - dimension fast acquisition scheme based on two - dimension fft is proposed. finally, the situation for two targets is analyzed
首先在建立了中頻直擴接收機的模型之後，本文對常用的偽碼捕獲方法進行了詳細地分析和比較，然後提出了本文的基於二維傅立葉變換技術的快速捕獲方法，並且分析了兩個目標時的情況。 -
A novel communication receiver which uses lapped transform ( lt ) incorporating modified median filter ( mmf ) algorithm is designed for narrow - band interference excision. the lt domain mmf algorithm takes full advantages of the direct sequence spread spectrum signal, as well as the characteristics of lt, performing the transform domain filtering twice. the first filtering locates the position of interference and mitigates most of them. the second filtering is performed in a small neighborhood of the located interference. so lt domain mmf algorithm can completely mitigate the interference without distorting the desired signal. simulation results demonstrate the improved ber performance and increased robustness of our receiver
本文採用改進的重疊變換域中值濾波演算法進行變換域抗干擾處理.該演算法既考慮到直接序列擴頻信號的特點，同時又利用重疊變換的特性對變換域系數進行了二次濾波.該演算法節省處理時間，並且不需要有關干擾的先驗知識，系統性能不會隨干擾頻率變化而變化，因而是一種很穩健的處理方法 -
This paper mainly focuses on the noise limiting by means of the direct sequence spread spectrum ( dsss ) and the analysis of the transmission performance of the plc and some digital modulation technology. the contents of the paper is as follows : 1 ) the technical feasibility is proved after simulating noise limiting principle of dsss by means of systemview, the simulation software ; 2 ) a kind of band pass filter ( bpf ) is realized according to the requirement of filter and the principle of butterworth approximation, which satisfies the index of performance of dsss. 3 ) the low voltage plc system includes the sc1128, the specific modulation / demodulation ic, the bpf filter and other circuit components, furthermore, the control function of system is realized by means of the personal computer and the microcontroller
本課題在對低壓電力線的傳輸特性和數字調制技術進行分析的基礎上，將通信理論中的直接序列擴頻技術（ dsss ）用於解決低壓電力線通信的干擾問題，主要研究內容如下： （ 1 ）用通信模擬軟體systemview對dsss技術的通信和抗干擾原理進行模擬分析，分別對時域和頻域下採用dsss技術前後接收信號的頻譜進行分析，驗證dsss技術在本系統中的可行性； （ 2 ）由dsss技術對濾波系統的要求，根據濾波理論分析了巴特沃思型濾波器的逼近原理並設計了合適的濾波電路； （ 3 ）用調制解調晶元sc1128和自行設計的濾波器加之輔助外圍電路，構造出低壓電力線載波通信系統，並採用atmel公司的單片機設計了接收和發射電路的微控制器； （ 4 ）分別對採取抗干擾措施前後輸入和輸出信號進行對比實驗，並對結果進行分析，驗證了dsss技術對干擾信號的抑制作用。 -
The parallel combinatorial spread spectrum provides high spectral efficiency and the data rate of the parallel combinatorial spread spectrum is higher than that of the direct sequence spread spectrum. this thesis studies on the mapping between data and spread sequence in the parallel combinatorial spread spectrum system and presents a mapping method based on the lexicographic order. the mapping method resolves the many to one mapping problem of the past method
本文研究了并行組合擴頻中數據和擴頻序列之間的映射方法，指出了已有的一種不定方程求解演算法中存在的映射不唯一問題，應用組合數學中的相關理論，將映射問題轉化為廠組合問題，提出了基於字典順序的并行組合擴頻數據映射演算法，該演算法具有普遍性，解決了原有演算法中的多一映射問題。 -
Direct sequence - code divition multiple access ( ds - cdma ) technology is achieved easily and used widely at present its receiver capability is confined by two factors, one of which is the multiple access interference ( mai ) which makes the capacity low, another of which is the near - far problem
直接序列擴頻-碼分多址（ ds - cdma ）技術是最易實現、也是目前應用最廣的一種方式，它的接收性能受到兩個主要的限制：一個是多址干擾造成的性能下降；另一個則是遠近效應問題。 -
For wireless communications, direct sequence code division multiple access ( ds - cdma ) techniques have received a great deal of attention due to the expectation of capacity increase, interference rejection capability, security, and so on. in a high data rate application such as multimedia services, however, the capacity of ds - cdma systems is limited by both the inter - chip, or inter - symbol interference
Cdma技術以其高抗干擾能力、高容量、高保密性等技術優勢在第三代移動通信系統中被廣泛應用，然而在高速數據業務中，嚴重的碼間干擾和符號間干擾會導致系統性能明顯下降。 -
The theory of direct sequence and cck is described. the mechanism of tdm is established. then, a method to maintain the synchronization of the tdm is proposed
在介紹了ieee802 . 11協議的物理層用到的直序擴頻技術和補碼鍵控技術后，對系統的時分雙工工作機制的建立與維護進行了詳細的分析。 -
The design of direct sequence spread spectrum communication system for data transmission
直接序列擴頻數據通信系統的設計 -
In wcdma system which uses direct sequence to spread spectrum, the spread spectrum code ( pn code ) phase of the receiver must be synchronized with that of the received signal precisely to despread and demodulate the signal correctly. multipath channel exists in the mobile communication environment for the radio signal reflection by obstacles between transmitters and receivers. by using the autocorrelation of the spread sprectrum code, rake receiver can process received signals and therefore multipath components can be resolvable
在wcdma系統中，為正確解擴解調接收到的擴頻信號，接收機本地產生的擴頻碼（ pn碼）相位必須和接收信號中的擴頻碼相位完全同步;同時移動通信環境中的傳輸信號由於接收機和發射機之間的直達路徑有可能被建築物或其他障礙物所阻礙，總是經過折射或反射的多條路徑后才到達接收機，從而產生多徑通道。 -
The spread spectrum communication ’ s availably jamming becomes the key to get the electronic war ’ s victory, so it is very important to research the effectiveness of jamming and interference referred to the direct sequence spread spectrum ( ds - ss ) communication system
為取得現代電子戰的勝利，對擴頻通信的有效干擾成為關鍵。因此，研究直接序列擴頻通信干擾效能具有重要的現實意義。 -
Based on the analysis of vhf - rc, the method of applying chaos direct sequence spread spectrum communication ( cds - ssc ) to ahts has been studied and discussed in this thesis. in this method, cds - ssc, which combines chaos sequences ( cs ) of high rand quality with ds - ss excelling in resisting interferences, is used to realize the transmission of hydrologic data
文中所述方法利用混沌直接擴頻通信的通信方式來實現水文數據的傳輸，即將隨機性能較強的混沌序列作為擴頻碼與抗干擾性較強的直接擴頻通信相結合，應用於水文自動測報系統中去。 -
Secondly, this paper analyses data - delivering method, data - transmitting format and fault - control technology, studies and picks out direct sequence spread spectrum, accessing point network topology and the ieee802. 11b network rule, on the basis of which the harbor wireless communication system model is established. each composing part of the system ' s model is given out. the choice of hardware equipments and the design of communication software are expounded
其次，本文對通信技術中的數據傳送方式、數據傳輸形式和差錯控制技術進行了分析，研究了港口無線通信系統中的傳輸方式、拓撲結構和網路標準等關鍵技術，選取直序擴頻傳輸方式、接入型拓撲結構和ieee802 . 11b網路標準作為港口無線通信系統的技術基礎，建立了港口無線通信系統模型，闡述了該模型的實現方法，包括硬體設備選擇和通信軟體設計。 -
Aiming at the problem of intercepting the direct sequence spread spectrum communication signal, this paper makes full use of the wave characteristic of base - band signal after it is applied to shaping filter is made, and an algorithm which is based on the average power serial is given
摘要針對直接序列擴頻通信信號的偵察問題，充分利用擴頻基帶信號發送成型濾波后的波形特點，提出了一種基於最大平均功率序列的演算法。 -
Principle and application of direct sequence spread spectrum asic
直序擴頻晶元的原理與應用 -
The paper firstly analyses the fundamental principles of the direct sequence spread spectrum technique, the arithmetic in the frequency - domain by using the technology of the spectrum correlation adaptive filter
本文首先就設計中選擇採用的直接序列擴頻技術、以及在頻域中實現直序擴頻信號中多窄帶干擾抑制的自適應演算法的基本原理做了分析。 -
We analyzed the anti - jam and band inside anti - interfere performance of the system, and the low probability intercept ( lpi ) of the traditional direct sequence spread spectrum ( dsss ) modulations in the uav platform ' s applications. so a new modulation technique using a multi - level pseudo noise ( pn ) code has been presented. the new multi - level pn code is built from a high speed pn code through a low passed filter ( lpf )
分析了系統抗阻塞式干擾和抗帶內頻帶干擾的性能，以及常規bpsk qpsk - dsss調制在無人機通信中存在的安全隱患，提出了一種用多電平pn碼進行擴頻調制的方法：採用高速pn碼，經過低通濾波器，產生多電平pn碼進行直序擴頻調制，能在低信噪比情況下有效抵抗平方率檢測器對系統載波的檢測。 -
In addition, hybrid spread - spectrum communication system is propitious to enhance anti - jamming performance of the system that is make up of direct sequence ( ds ) and frequency hopping ( fh ), and it can satisfy the require of anti - jamming of systems. it concentrate their virtue and overcome shortage in single spread spectrum style. this paper discusses the aspect in detail
另外，將擴頻技術中應用最廣泛的兩項技術直序擴頻（ ds ）和跳頻（ fh ）結合在一起，構成混合擴頻通信系統，有利於提高系統的抗干擾性能，更能滿足系統抗干擾的要求，而且將跳頻系統和直擴系統的優點集中起來，克服了單一擴頻方式的不足。 -
In modern communication, direct sequence spread spectrum communications was widely used in the fields of telemetering and telecontrol systems, because of low interception probability, its high noise resistance and good security
在現代通信中，直接序列擴頻通信技術以其截獲概率低、抗干擾性強、保密性高等優點，在航天測控領域得到了廣泛的應用。 -
Spread spectrum communication technology can be classified into four catalogs : direct sequence spread spectrum, frequency hopping, time hopping and chirp
擴頻技術種類較多，主要包括直接序列擴頻、跳頻、跳時和線性調頻。
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