2005/1
http://hdl.handle.net/11012/57986
2019-09-23T05:18:59ZStatic and Dynamic Nonlinearity of A/D Converters
http://hdl.handle.net/11012/57990
Static and Dynamic Nonlinearity of A/D Converters
Halamek, J.; Viscor, I.; Kasal, M.; Villa, M.
The dynamic range of broadband digital system is mostly limited by harmonics and spurious arising from ADC nonlinearity. The nonlinearity may be described in several ways. The distinction between static and dynamic contributions has strong theoretical motivations but it is difficult to independently measure these contributions. A more practical approach is based upon analysis of the complex spectrum, which is well defined, easily measured, and may be used to optimize the ADC working point and to somehow characterize both static and dynamic nonlinearity. To minimize harmonics and spurious components we need a sufficient level of input noise (dither), which destroys the periodicity at multistage pipelined ADC, combined with a careful analysis of the different sources of nonlinearity.
2005-04-01T00:00:00ZEstimation of Spread Spectrum Signal Parameters Utilizing Wavelet Transform Analysis
http://hdl.handle.net/11012/57992
Estimation of Spread Spectrum Signal Parameters Utilizing Wavelet Transform Analysis
Leonis, N.; Katsoulis, G.; Amditis, A.; Uzunoglu, N.
This paper investigates the application of wavelet transform (WT) to the extraction of particular features of direct sequence spread spectrum signals. The WT is exploited to the point that not only its capabilities but also its limitations are exposed to achieve the specific task of identifying spread spectrum signal parameters. The capabilities focus on the detection of the chipping sequence, while the limitations refer primarily to the advent of direct sequence CDMA signals. In the latter case no progress has yet been made to distinguish the different chipping sequences by the WT, whose resultant effect on the carrier appears as a single-phase change.
2005-04-01T00:00:00ZAn Adaptive Block-Based Eigenvector Equalization for Time-Varying Multipath Fading Channels
http://hdl.handle.net/11012/57993
An Adaptive Block-Based Eigenvector Equalization for Time-Varying Multipath Fading Channels
Landquist, R.; Mohammed, A.
In this paper we present an adaptive Block-Based EigenVector Algorithm (BBEVA) for blind equalization of time-varying multipath fading channels. In addition we assess the performance of the new algorithm for different configurations and compare the results with the least mean squares (LMS) algorithm. The new algorithm is evaluated in terms of intersymbol interference (ISI) suppression, mean squared error (MSE) and by examining the signal constellation at the output of the equalizer. Simulation results show that the BBEVA performs better than the non-blind LMS algorithm.
2005-04-01T00:00:00ZIntelligent FDSS Overlay on GSM System (Uplink Analysis)
http://hdl.handle.net/11012/57999
Intelligent FDSS Overlay on GSM System (Uplink Analysis)
Taha-Ahmed, B.; Calvo-Ramon, M.; Haro-Ariet, L. D.
The overlay of an intelligent frequency diversity spread spectrum system (FDSS) on the (GSM) system is studied. The uplink capacity of both systems is given using a model of 36 hexagonal macrocells. Performance of GSM and FDSS users is investigated. An original GSM system with 48 users/macrocell can be substituted by a mixed system, which has GSM system capacity of 48 users/macrocell and FDSS system capacity of 128 users/macrocell.
2005-04-01T00:00:00Z