Interference Rejection Techniques to Aid Coarse Acquisition in Direct-sequence Spread-spectrum PDF Download

Author: Lynn Denise Gottesman
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ISBN:
Category :
Languages : en
Pages : 304

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Author:
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Category : Communications, Military
Languages : en
Pages : 0

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Spread-spectrum signals are used widely in military and commercial communication systems due to their interference rejection capability and their lower probability of interception. In military applications the effects of intentional interference (jamming) are mitigated by the processing gain of the spread-spectrum system. In many spread-spectrum systems, processing gain alone is not sufficient to achieve satisfactory system performance and additional interference rejection techniques need to be employed. The interference suppression circuit is placed prior to the spectrum despreader with the goal of reducing the jammer/interferer energy to an adequately low level that can be handled by the system processing gain. We have presented a novel knowledge-based interference cancellation scheme for direct sequence spread-spectrum systems. This innovative approach utilizes: (1) IPUS, an expert system for the Integrated processing and Understanding of signals, to monitor the communication signal environment in order to determine the parameters of interfering signals within a pre-specified accuracy, and (2) Expert system rules to select from a library of preselected techniques, suitable interference rejection schemes based upon the knowledge obtained from monitoring the signal environment. The effectiveness of this novel interference rejection capability is demonstrated by considering a number of interference scenarios and using the software package SPW(copyright), a time-domain Signal Processing Worksystem.

Author: Ronald Athelstan Iltis
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Category : Line receivers (Integrated circuits)
Languages : en
Pages : 328

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Category : Military research
Languages : en
Pages : 248

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Author: Carlos Jaime Chávez
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Category :
Languages : en
Pages : 86

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A direct-sequence spread-spectrum (DSSS) receiver is vulnerable to being desensitized by high-power narrowband signals within its wide received bandwidth. A solution to this problem is to detect the interfering signals and remove them from the received bandwidth in a process called narrowband interference excision. This can be achieved through a number of existing techniques. However, a hybrid system that utilizes both DSSS and frequency-hopping spread-spectrum (FHSS) techniques complicates the solution. This thesis investigates one technique for narrowband interference excision in the context of such a hybrid frequency-hopping/direct-sequence spread-spectrum (FH/DSSS) system. This technique is based on the discrete Fourier transform (DFT). An overview of DFT-based excision employing an overlap-and-add architecture is given. The critical properties of the window function used are examined, including windowing loss, excision lass, and interference rejection. Finally, the application of DFT-based excision in a hybrid FH/DSSS system is explored.

Author: Cheryl L. Stutzmann
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Category : Adaptive filters
Languages : en
Pages : 156

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Author: Katherine Jauregui Lovette
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Category :
Languages : en
Pages : 108

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Author: Yuejin Huang
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ISBN: 9781374763180
Category :
Languages : en
Pages :

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This dissertation, "A Multiple Access Interference Rejection Technique Using Weighted Despreading Functions for Direct-sequence Code Division Multiple Access Communications" by 黃耀進, Yuejin, Huang, was obtained from The University of Hong Kong (Pokfulam, Hong Kong) and is being sold pursuant to Creative Commons: Attribution 3.0 Hong Kong License. The content of this dissertation has not been altered in any way. We have altered the formatting in order to facilitate the ease of printing and reading of the dissertation. All rights not granted by the above license are retained by the author. DOI: 10.5353/th_b3123707 Subjects: Wireless communication systems Code division multiple access Spread spectrum communications

Author: Krishna Rama Narayanan
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ISBN:
Category :
Languages : en
Pages : 190

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Author:
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Category : Spread spectrum communications
Languages : en
Pages : 400

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