Design and Simulation of Sub-Nanosecond Pulse Generator for Ultra-Wideband Communication

A new sub-nanosecond pulse generator scheme is proposed in the opinion of frequency field in this paper. The filtering techniques used in the UWB (ultra-wideband) generator make the circuit simple and suitable for integration. The theoretical analysis and simulation results show that monocycle form generated in the scheme have a good balance between positive and negative shape and small traipse by circuit parameter control and has improved the quality of UWB pulse form.

A STUDY OF METHODS FOR IMPROVING LEARNING VECTOR QUANTIZATION

Learning Vector Quantization(LVQ)originally proposed by Kohonen(1989)is aneurally-inspired classifier which pays attention to approximating the optimal Bayes decisionboundaries associated with a classification task.With respect to several defects of LVQ2 algorithmstudied in this paper,some‘soft’competition schemes such as‘majority voting’scheme andcredibility calculation are proposed for improving the ability of classification as well as the learningspeed.Meanwhile,the probabilities of winning are introduced into the corrections for referencevectors in the‘soft’competition.In contrast with the conventional sequential learning technique,a novel parallel learning technique is developed to perform LVQ2 procedure.Experimental resultsof speech recognition show that these new approaches can lead to better performance as comparedwith the conventional

OPTIMIZATION OF THE MAGNETIC DEFLECTION SYSTEM BY THE METHOD OF ORTHOGONAL DESIGN

By using the expressions of the field parameters and with the aid of the Orthogonal DesignMethod,we optimized the design of the saddle delection yoke with a ferromagnetic shield.The results ob-tained agree with the practical model.It is pointed out that the end ear and the distribution of the fieldparameter B0（z）have important effects on the deflection aberrations.An example is given,in which the elec-tron optical properties of the deflection coils having cosine distribution and finite length and that of the de-flection coils having distributed winding are compared.

Turbo-Coded Modulation of EVRC Speech Encoder with Unequal Error Protection for Fading Channels

The Enhanced Variable Rate Codec (EVRC) is a standard for the Speech Service Option 3 for Wideband Spread Spectrum Digital System, which has been employed in both IS-95 cellular systems and ANSI J-STC-008 PCS (Personal Communications Systems). This paper investigated the combination of turbo codes with Unequal Error Protection (UEP) and 16-QAM modulation for EVRC codec of Rate 1 to get power and bandwidth efficient coding scheme. The results show that the UEP system outperforms the Equal Error Protection (EEP) one by 1.45 dB at BER of 10 -5.

COMPUTATION OF EM FIELD DISTRIBUTION IN A BIOLOGICAL MEDIUM AND EXPERIMENTAL CONFIRMATION

Theory and numerical computation of EM field distribution rule in a biologicalmedium with irregular shape are described. Integral equations of induced EM field distributionin biological body are deduced from EM field scattering. Numerical computations are conductedby the moment method. In order to verify the effectiveness of the theory, a set of experimentalequipment is designed precisely. The results of numerical computation are compared with mea-sured values. It is shown that they are in good agreement. This theory can be used widely forits generality.

A DECISION FEEDBACK EQUALIZER FOR NON-LINEAR CHANNELS

A Simple and useful decision feedback equalizer used for non-linear channels with severe linear distortion and mild non-linear distortion is proposed. It is a combination of a nonlinear channel equalizer based on connectionist model and a common decision feedback equalizer for linear channels. For a typical non-linear channel model it is shown that the equalization performances of the proposed equalizer are improved significantly.

Multipath time delay estimation of underwater acoustic sinusoidal signals

To overcome the performance limitation of multipath time-delay estimation posed by underwater acoustic sinusoidal signals, an approach incorporating the frequency-domain weighting of the highly oscillatory Nonlinear Least Squares （NLS） cost function with the evolu- tionary optimization was proposed to facilitate the accurate estimation of the multipath timedelay of sinusoidal signals. In the described method, the number of the effective multipath signals, which is included into the parameter model as well as the multipath time-delay and amplitude factor, can be estimated simultaneously thus avoiding the requirement of additional computation. The experimental results performed with numerical simulation and sea-trial data are provided, demonstrating the effectiveness and precision enhancement of the proposed algorithm.