ds direct sequence 中文意思是什麼
ds direct sequence
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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。 -
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 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。 -
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。 -
Then, introducing something about spread spectrum technique. and deciding to select direct - sequence spread spectrum ( ds ) in underwater acoustic communications by comparing ds to fh according to the properties of underwater acoustic channels. after that, discussing something about rake receiver, simulating the path - search algorithms, synchronization circuits and rake receiver in low speed underwater acoustic communications and analyzing some major factors influencing the performance of systems
然後介紹了rake接收技術的基本原理，並對rake接收系統中的路徑搜索和同步系統進行了討論和模擬分析，另外還對rake接收技術在低速水聲通信系統中的應用作了模擬分析，並討論了一些影響rake接收系統性能的主要因素。 -
The system completes anti - jamming function of frequency - hopping ( fh ) and direct sequence spread spectrum ( ds - ss ) by exploiting dsps + fpga structure, so it is flexible and modular
它採用dsps + fpga的結構，實現跳頻擴頻和直接序列擴頻的抗干擾功能，因而結構靈活，適于模塊化設計。 -
Direct sequence spread spectrum ds
直接序列擴頻 -
In this thesis, the zero correlation zone ( zcz ) or generalized orthogonal ( go ) sequences are applied to direct - sequence cdma ( ds - cdma ) systems, and the corresponding system performance are analysed. topics on the correlation property analysis of hadamard walsh ( wh ) sequences, go sequences, and loosely synchronous ( ls ) sequences are performed, and the system model and performance evaluation of single - cell and multi - cell synchronous cdma ( s - cdma ) systems employing go sequences, and the applications of go sequences in quasi - synchronous cdma ( qs - cdma ) systems are elaborated
本文研究了零相關區（ zcz ）或廣義正交（ go ）序列在直接序列碼分多址（ ds - cdma ）系統中的應用並給出了系統性能分析結果，包括hadamardwalsh （ wh ）序列集、廣義正交序列集與鬆散同步（ ls ）序列集相關特性分析，採用廣義正交序列的單小區與多小區同步cdma （ s - cdma ）系統模型與性能分析，以及廣義正交序列在準同步cdma （ qs - cdma ）系統中的應用等問題。 -
Combining walsh sequence with direct spread spectrum sequence, we can construct hybrid ds - fh spread - spectrum communication mode. this is very important for the mode to have better performance on anti - multiple - access inference and anti - near - far inference
將walsh函數序列與直接擴頻序列相結合構成的ds - fh混合擴頻通信方式對于系統抗多址干擾和遠近效應具有重要意義。 -
Direct sequence spread spectrum ( ds ) signals have been widely used for secure communication and mobile communication known as code division multiple access ( cdma ) system. because ds signals have many advantages such as anti - jamming capability, low probability of interception, multiple access capability and so on
直接序列擴頻通信具有低截獲概率，抗干擾能力強以及實現碼分多址等優點，因而在抗干擾通信及民用移動通信中得到廣泛的應用。 -
Secondly, we analyse the anti - jamming performance of coherent csk system and non - coherent dcsk system under a narrowband sine wave jamming, and analyse the performance of chaotic communication system under coexisting with a conventional spread spectrum communication system, such as direct - sequence spread spectrum ( ds - ss ) system
其次，詳細分析了相干csk系統和非相干dcsk系統的抗窄帶正弦干擾能力，以及與傳統擴頻通信系統（以ds - ss為例）共存時，傳統擴頻通信系統對它們的影響。 -
By analyzing the spectrum feature and correlation feature of walsh sequence, we find that it has the spectrum feature of ds / fh ( direct spread / frequency hopping ) communication mode
我們分析了walsh函數序列的頻譜特性和相關特性，結果表明，該序列具有ds fh （直擴跳頻）的頻譜特性。 -
Secondly, in the research of communication, the direct - sequence code division multiple access ( ds - cdma ) is an important component of numerous recent communications systems, proposed and implemented
其次，在通信領域，本文主要針對當前研究的一個熱點問題? ? cdma多用戶檢測，展開研究。 -
The problem of signal processing for direct - sequence code - division - multiple - access ( ds - cdma ) signal over multipath frequency - selective mobile channels is considered. a new blind receiver is proposed. without the knowledge of the multiple - access interference users spreading code and the channel characteristics, the receiver achieves blind detection with prior knowledge of only the desired users spreading code and approximate timing. by using reduced rank adaptive decorrelating filter and adaptive multipath combiner which is based on decision - directed algorithm, the receiver gets the ability to combat both fading and the near - far effect at low cost. simulation results demonstrate that the proposed receiver offers high performance
本文研究多徑頻率選擇性衰落通道下直接序列擴頻碼分多址（ ds - cdma ）信號的處理問題，提出了一種新型的盲接收機.該接收機不需預知多址干擾用戶的擴頻碼，不需預知通道參數，只需已知期望用戶的擴頻碼和粗略的定時，就可以完成用戶的盲檢測.同時，該接收機通過降維自適應去相關濾波和基於判決指導的自適應多徑合併，來獲得低成本和良好的抗衰落、抗遠近效應性能.模擬結果驗證了本文提出的接收機的優良性能 -
A tdrss user transponder is a terminal of the user satellite in this system, in which qpsk or sqpsk modulation and direct sequence spread spectrum ( ds - ss ) are employed in the forward / backward links
Tdrss用戶應答機是該系統的用戶終端，其正反向鏈路的信號通常採用qpsk或sqpsk調制和直接序列頻譜擴展。 -
Concerning with the direct sequence ( ds ) cdma system, this thesis focuses on several issues related to orthogonal spreading sequences and amc, including correlation properties of orthogonal variable - length spreading sequences and their effects on ds cdma system performance, performance of multicarrier ( mc ) ds cdma system with generalized orthogonal ( go ) sequences, adaptive modulation with throughput maximization, performance of adaptive turbo - qam coded modulation in generalized fading channel and performance of amc in wcdma high speed downlink packet access ( hsdpa )
針對直接序列碼分多址（ dscdma ）系統，本文主要研究了正交擴頻序列和自適應調制編碼若干問題，包括正交變長擴頻序列的相關性及其對dscdma系統性能的影響、採用廣義正交（ go ）序列的多載波直接序列碼分多址（ mcdscdma ）系統性能、吞吐量最大化自適應調制、自適應turbo - qam編碼調制在廣義衰落通道中的性能，以及wcdma下行分組接入（ hsdpa ）中自適應調制與編碼性能五個方面。
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