摘要：All digital implementation of receiver is a main topic on digital communication recently. The design of interpolation filter is one of the important problems for all digital implementation of receiver. In this paper, for full response linear modulation signal, a interpolation criterion is proposed. An interpolation formula is presented on bandwidth-limited transmission signal. For example, using the raised cosine roll off function as the system pulse response, the feasibility and effectiveness on the interpolation formula are certified by theoretical and numerical analysis. The computer simulation result on 16-QAM signal is given.

摘要：This paper presents a thorough design and comparative study of two popular control techniques, i.e., classical Proportional Integral (PI) and RST, for Matrix Converters (MCs) in terms of tracking the reference and robustness. The output signal of MCs is directly affected by unbalanced grid voltage. Some research works have attempted to overcome this problem with PI control. However, this technique is known to offer lower performance when it is used in complex and nonlinear systems. On the other hand, RST control offers better performance, even in case of highly nonlinear systems. Therefore, the RST can achieve better performance to overcome the limitation of PI control of nonlinear systems. In this paper, a RST control method is proposed as output current controller to improve the performance of the MC powered by unbalanced grid voltage. The overall operating principle, Venturini modulation strategy of MC, PI control and characteristics of RST are presented.

摘要：极式调变并不是什么新的技术,早在1930年,就已被普遍地用在AM广播发射器的设计中。而在EDGE手机的应用上,除了可以利用到Polar modulation适用各种调变技术的优点之外,也因为其Polar的架构,使EDGE的高Peak to Average Ratio在功率放大器端得到最佳化的表现。

摘要：AC motors, especially the squirrel cage induction motors have the advantages of simple structure, good reliability and low cost. They are more suitable to be used as electrical dynamometers to provide dynamic load for bench test systems. But, the speed and torque of induction motors are not easy to be controlled accurately. In this work, an electrical dynamometer based on the induction motor is proposed. In order to get better control performance of torque and speed of induction motor, an improved direct torque control method(DTC) is also developed based on the space vector modulation(SVM) technique. The performance of the proposed dynamometer system is validated in the Matlab/Simulink platform. The simulation results show that the new dynamometer has good torque and stator flux response. And the torque and stator current ripples of it are reduced significantly compared with using the conventional DTC method.

摘要：Transmittance and chromaticity are essential requirements for optical performance of thin-film transistor(TFT)***,it is still a challenge to get high transmittance and excellent chromaticity at the same *** this paper,optimized optical design by using antireflection film theory and optical phase modulation is demonstrated in low temperature poly-silicon(LTPS)TFT *** realize high transmittance,the refractive index difference of adjacent films is modified by using silicon oxynitride(SiOxNy)with adjustable refractive *** realize excellent chromaticity,the thicknesses of multilayer films are precisely regulated for antireflection of certain wavelength *** results show that the transmittance and chromaticity have been improved by about 6%and 18‰,respectively,at the same time,which is a big step forward for high optical performance of TFT *** device characteristics of the TFT arrays with the optimal design,such as threshold voltage and electron mobility,are comparable to those of conventional TFT *** optimized optical design results in enhanced power-conversion efficiencies and perfects the multilayer film design on the basic theory,which has great practicability to be applied in TFT arrays.

摘要：An optimized design of laser range finding system using the self-mixing effect in a single-mode verticalcavity surface-emitting laser （VCSEL） is proposed. In order to improve the ranging accuracy and expand dynamic measurement range, we apply difference frequency analog phase-locked loop （PLL） instead of fast Fourier transform （FFT） to process signal, and choose the optimum triangular wave frequency .fm= 500 Hz and small modulation current △Ip p = 0.28 mA to modulate single-mode VCSEL. The experiment results show that, without controlling the laser＇s temperature, the ranging accuracy is better than 2 mm and the measurement dynamic range is as large as 50-500 mm when the sampling time is 0.1 s and the room temperature is 0--55℃.

摘要：A new SO1 high-voltage device structure with nonuniform thickness drift region （n-uni SOl） and its optimiza- tion design method are proposed. Owing to the nonuniform thickness drift region, the electric field in the SOl layer is modulated and the electric field in the buried layer is enhanced, resulting in an enhancement of breakdown voltage. An analytical model taking the modulation effect into account is presented to optimize the device structure. Based on the analytical model, the dependencies of the electric field distribution and breakdown voltage on the device parameters are investigated. Numerical simulations support the analytical model. The breakdown voltage of the n-uni SOl LDMOS with n = 3 is twice as high as that of a conventional SO1 while its on-resistance maintains low.

摘要：This paper extends the work on cross-layer design which combines adaptive modulation and coding at the physical layer and hybrid automatic repeat request protocol at the data link layer. By contrast with previous works on this topic, the present development and the performance analysis as well, is based on rate compatible punctured turbo codes. Rate compatibility provides incremental redundancy in transmission of parity bits for error correction at the data link layer. Turbo coding and iterative decoding gives lower packet error rate values in low signal-to-noise ratio regions of the adaptive modulation and coding (AMC) schemes. Thus, the applied cross-layer design results in AMC schemes can achieve better spectral efficiency than convolutional one while it retains the QoS requirements at the application layer. Numerical results in terms of spectral efficiency for both turbo and convolutional rate compatible punctured codes are presented. For a more comprehensive presentation, the performance of rate compatible LDPC is contrasted with turbo case as well as the performance complexity is discussed for each of the above codes.

摘要：Recently, many studies propose the use of ultra-wideband technology for passive and active radio frequency identification systems as well as for wireless sensor networks due to its numerous advantages. By harvesting these advantages of IR-UWB technology at the physical-layer design, this paper proposes that a cross layer architecture platform can be considered as a good integrator for different wireless short-ranges indoor protocols into a universal smart wireless-tagged architecture with new promising applications in cognitive radio for future applications. Adaptive transmission algorithms have been studied to show the trade-off between different specific QoS requirements, transmission rates and distances at the physical layer level and this type of dynamic optimization and reconfiguration leads to the cross-layer design proposal in the paper. Studies from both theoretical simulation and statistical indoor environments experiments are considered as a proof of concept for the proposed architecture.

摘要：In recent years, underwater acoustic (UWA) communications have received much attention as their applications have begun to shift from military toward commercial. Digital communications through UWA channels differ substantially from those in other media, such as radio channels, due to severe signal degradations caused by multipath propagation and high temporal and spatial variability of the channel conditions. This paper describes a project designed, based on the results obtained from extensive laboratory and field experiments on sound speed profile in different depths of the Persian Gulf, to investigate and demonstrate an underwater acoustic communication system. Transmitted data are acoustic signals to which for more safety in transmission and low frequency bandwidth, Rivest cipher cryptography algorithm and linear prediction coding are applied, respectively. In transmitter, Quadrature Phase Shift Keying (QPSK) signaling is employed to make efficient use of the available channel bandwidth. In the channel, a comprehensive model for short-range shallow water multipath acoustic channel is presented. The mathematical modeling of the multi-path effects is based on the ray tracing and the image method. Also, the attenuations due to wave scatterings at the surface and their bottom reflections are accounted for. In addition, we consider the loss due to the frequency absorption of different materials and the presence of ambient noises such as the sea state noise, shipping noise, thermal noise and turbulences. In the receiver, to overcome the difficulties of inter symbol interference, adaptive equalization using Decision Feedback Equalizer (DFE) is applied.