Advances in Mechanics Engineering

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Authors: Zhu Lei, Ying Mei Chen, Ling Tian, Li Zhang
Abstract: A Front-End Amplifier for the STM-64(10Gb/s) optical receiver in SDH system has been proposed in TSMC 0.18 μm CMOS technology. The common-gate feedforward configuration with an active inductor is employed in the input stage of transimpedance amplifier to increase the bandwidth. A 3-order interleaving active feedback configuration is employed to expand the bandwidth in the gain stage of transimpedance amplifier and limiting amplifier. Simulation results show that the output swing is 190mV (Vpp) when the input current varies from 20μA to 400μA. The power consumption is only 98.2mW with 1.8V power supply and the chip area is 496μm×480μm.
Authors: Ying Si, Ya Dan Zheng, Shu Bo Ren, Jian Jun Wu
Abstract: Reference Signal (RS) is used for channel estimation and sounding in LTE uplink of terrestrial system to accomplish data demodulation. However, the situation in multiple-beam mobile satellite communication system is different. The Uplink Reference Signal (UL-RS) designed in terrestrial LTE doesn’t fit the satellite environment and may result to system performance degradation. In this paper, the UL-RS pattern used in GEO multiple-beam mobile satellite communication system is proposed, as well as two enhancement techniques, i.e., full bandwidth sounding, retransmit and combined receive. System performance index calculation and simulation results prove the effectiveness of the proposed design.
Authors: Chuan Wen Chang, Wen Shen Mao
Abstract: In the narrow band data communication system, there are such problems as long time delay and random loss of data resulted by large amount of data from data source. The delay of a typical data transmission system consisted by DTE and DCE is resulted by several factors. Through the analysis of these factors, this paper presents a low-cost and open-loop software method to control the speed of the signal source. By increasing the interface speed and reasonably estimating the data package delay, this method can make the delay and the loss of data package controllable and prevent the random loss of data. This method can be applied to those low-speed communication transmission situations which have special requirement of the delay, such as short wave, ultra short wave, dial-up network, a line for special use and so on.
Authors: Fei Xu, Le Nian He
Abstract: A high efficiency step-up White Light Emitting-diode (WLED) driver with PWM dimming is presented in this paper. An integrated current sensing technique is used to improve system efficiency. Meanwhile, a novel PWM(pulse width modulation) dimming scheme is proposed to achieve wide range dimming frequency, which can be adaptive to dimming frequency from 200Hz to 200 KHz. The proposed driver is designed with CSMC 0.5um 40V bipolar-CMOS-DMOS process. Simulation results verify the functionality of the design and high efficiency is realized, with a peak value of 94.12% at 5.5V-input and 200mA-load.
Authors: Bo Zhang, Jing Zhao, Wen Wei Duan, Long Yang Yu
Abstract: A novel method of analyzing the visibility of GNSS satellites in mountainous area is proposed by taking advantage of target area’s digital elevation model (DEM) data and GNSS almanac. The key point is calculating the obstacle elevation on the basis of target points’ visible range. Simulation results show that both different target points at the same time and same point at different time have different situation of visible satellites on the condition with or without obstacle. On the other hand, this method contributes lots to determine the distribution of pseudolites in mountainous area.
Authors: Zhen Juan Liu, Wei Jiang Wang, Hui Bo Niu, Ting Zhi Shen
Abstract: In order to resist the Single Event Upset(SEU)in outer space so that the camera focal plane array system could work in a long time, a design and improvement method for the selection of host and backup based on FPGA was introduced. VHDL was used to do the design and simulation, FPGA developed by Altera company was chosen as the hardware design platform. The results of experiment showed that the improved module could reliably get a group of effective data from the two in all cases and the camera focal plane array system could produce reliable driving timing for the CCD camera.
Authors: Jia Qiang Li, Xing Juan Chen, Jin Li Chen
Abstract: As a new type of Doppler wind radar, Wind profiler radar often suffers from a variety of meteorological factors. These interferences have great effect on the detection data precision, which leads to radar data quality problem. A data processing method based on Extended Kalman Filter (EKF) is presented in this paper, which focuses on the nonlinear problems of wind data of wind profiler radar. This method is the development of traditional Kalman Filter (KF) in practical engineering applications. To verify the validity of this first-order EKF from different situation, one day’s and one moment’s wind data are selected respectively, as examples for filtering. EKF is better for data processing of wind profiler radar and has some engineering application prospects.
Authors: Ya Fang Yin, Long Hui Duan, Yan Na Liao
Abstract: This paper presents a micro-wideband radar experimental system design. Wideband signal source and high-speed data sampling and processing module of the system is discussed in detail. Designed radar experimental system weighs 4.5Kg, with signal bandwidth of 1GHz and effective distance of 5km. The system can realize wideband radar echo real-time sampling and processing functions. On-board Synthetic Aperture Radar (SAR) imaging experiment is done. The imaging resolution of the system is 0.3m, this result is satisfactory. It shows that the system can meet the requirements of a unmanned aerial vehicles (UAV) platform. The design and test results are significant to miniaturization of wideband radar system.
Authors: Qiang Zhao, Shi Rui Peng, Bing Qie Wang, Chang Wen Zheng
Abstract: Aiming at electromagnetism efficiency evaluation of large ground interference antenna is complex, the paper proposes to model and simulate it by FEKO and then the radiation pattern of the antenna can be obtained. The simulation result is conform to the fact. In view of the large power of the vice and back orientation of antenna from the simulation, adopt the method of installing electromagnetism shield wall to solve. Through the simulation shows the efficiency of electromagnetism shield wall in improving antenna’s electromagnetism compatibility.
Authors: Bo Lu, Jian Ping Jin, Wen Yi Duan, Liang Jin Chen, Hong Ye Guan
Abstract: GPS multipath disturbance is a bottleneck problem that limits accuracy of GPS positioning. The function of single epoch kinematic positioning of GAMIT TRACK is used to study GPS signal multipath effects. A filtering method for separating signal and noise based on the wavelet analysis is established. The decomposition level for wavelet filter is confirmed according to the high correlation of the multipath effects between adjacent sidereal days by using the maximum correlation coefficient method. The accurate multipath corrections in GPS coordinate series are acquired with the proposed method making use of TRACK and the repeating property of multipath effects is used to weaken multipath effects in subsequent days, and therefore improve the precision of the GPS positioning.

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