Mechanical and Electrical Technology IV

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Authors: Wen Zhong Ma, Wei Zhang, Zhi Wang, Yao Rong Li
Abstract: The principle of the GPS pseudorange relative positioning is analyzed. The carrier phase smoothing algorithm which combines the measured pseudorange and carrier phase components is studied. The accuracy of the pseudorange observables is improved by the algorithm, the ambiguity determination problem is skipped and the solution process is simplified while ensuring the positioning accuracy. A comparison between the result which takes before the smoothing algorithm and the one after the algorithm is made and the validity of the carrier phase smoothing algorithm is proved.
Authors: Wen Zhong Ma, Zhi Wang, Yao Rong Li, Wei Zhang
Abstract: An acquisition and tracing algorithm of GPS receiver is introduced. The shortage of time domain acquisition algorithm is pointed out by analyzing the composition of GPS signal and C/A code’s correlation property. Then the frequency domain acquisition algorithm is discussed. The carrier wave track loop and C/A code track loop are designed and the algorithms of them are determined. Using these two loops can get the navigation message, etc that used for positioning and navigation. The GPS raw intermediate data is processed and the satellites signals are acquired and traced in MATLAB, then obtain the navigation message verified the feasibility and availability of the acquisition and tracing algorithm.
Authors: Min Chen, Wen Bing Lu, Chong Zhang, Liang Zhang
Abstract: TWACS (Two Way Automatic Communication System) has advantages such as economical and practical use, strong interference capability, long transmission distance and so on. But the noise in China's industrial distribution power grid owns the characters of strong interference randomness and even annihilation of the modulated signal. So the noise has a negative impact on power line communication performance. While the adaptive filter does not need to know in advance on the statistical characteristics of the input signal and noise, and has nothing to do with the spectral characteristics of the input signal. Based on this, it’s premised that the modulation signal is basically known, and the signal beyond modulation domain is regarded as reference signal to design an adaptive filter applied to TWACS by referring to the block diagram of the adaptive filter model to adjust the variable parameters of the RLS algorithm. Finally, the field test signal simulations show good effect of the adaptive filter design
Authors: Dan Li, Ying Qing Xia, Peng Jun He, Juan Xiao
Abstract: The device has the 13.56MHz radio frequency identification (RFID) reader feature, and it can be used in the reading and writing in the aspect with purchase secure access module (PSAM) card, embedded secure access module (ESAM) card and dual-interface user card in the Electronic Toll Collection (ETC) industry. This article focuses on the design of the antenna and external matching circuit of the contactless IC card reader, lists software architecture and communication process, and obtains the optimum matching circuit through analyzing the data got from Agilent vector network analyzer
Authors: Ran Li, Rui Ding, Zi Jian Min, Hui Mei Yuan
Abstract: Taking into account the efficiency, cost-effectiveness and reliability of power supply, redundant parallel power supply controlled by microcontroller could be a good solution for us. This paper analyzes principles and traits of parallel current sharing structure. Then a design of redundancy parallel current sharing structure is introduced, which is based on integrated buck chip LM2678 and microcontroller MSP430. The design has good fault-tolerant ability, and its output voltage can be adjusted easily. The capability and feasibility of this design has been verified by the simulation and experiment.
Authors: Xue Yang, Jian Ping Xiong, Cheng Ma, Hui Bo Jia
Abstract: Guided scrambling is an example of multimode coding technique, which belongs to line code. This technique uses scrambling polynomials to form selection sets, by using proper selection criteria, the codeword with least contribution to DC (direct current) content will be chosen for transmitting. This paper designs this kind of GS (guided scrambling) line code which is suitable to be transmitted in long-distance UTP channel. According to the requirement of the real channel, this technique optimizes the design parameters, such as augmenting bits, scrambling polynomials, bit rate and selection criteria, to achieve the high bit rate of 64/67. The simulation experiment shows that this scheme is efficient in suppression of low frequency, and its PSD characteristics meet the requirement of transmission in long-distance UTP channel.
Authors: Zhi Gang Wang, Fang Wang
Abstract: In order to acquire a kind of high accuracy multi-beams direction-finding method, this paper proposes a sort of 2-D multi-beams direction-finding method based on surface fitting. Three main factors influencing direction-finding accuracy are summarized in this paper, and the specific influence of these three factors to direction finding accuracy are analyzed by simulation experiments. The result of simulation experiments analysis shows that this method has higher steadiness and better direction-finding accuracy.
Authors: Xi En Ye, Yin Feng Zhu
Abstract: This paper describes a video signal processing system, based on the research of DirectShow streaming media processing platform, H.264/AVC video coding technology and multi-channel video encoding chip SC8919 which includes H.264 hardware video encoder. This system can compress four channel D1(720*576) size of the image data collected by camera at the rate of 30fps into standard H.264 stream, and upload it to the control room to store and decode broadcast through existed campus Ethernet without additional laying line.
Authors: Yan Zheng Zhang, Shi Lin Zhang, Lu Hong Mao, Sheng Xie
Abstract: In recent years, radio frequency identification (RFID) microwave technology receives great attention because of its advantages, e.g. long identification distance, small size of antenna, high identification speed and strong anti-collision ability. RFID tag plays one of the most important roles in logistics, and therefore special attention should be paid to tag design. In this paper, we present a 2.45G semi-active tag design, which is compatible with ISO 18000-4. The proposed tag can switch the manners of working between active and passive. When the generated RF-power is sufficient to operate, the tag works as a passive tag, and low noise amplifier (LNA), oscillator (OSC) and power amplifier (PA) are cut off to save the whole chip power consumption mostly. Otherwise it operates in active mode using battery power, and the working distance is greatly increased as a result of using PA.
Authors: Xiang Ning Fan, Bin Li, Wei Wei Zhu, Lu Yu, Yu Jie Wang
Abstract: In this paper, a fractional frequency divider (FFD) is designed for Phase-Locked-Loop (PLL) based Frequency Synthesizer, which can be used for GPS/Galileo and WCDMA dual-mode receivers. Based on a dual-modulus prescaler (DMP) and a programmable frequency divider (FD), the integer part can cover from 513 to 760. The fractional part is realized by improved MASH1-1-1 Delta-Sigma (Δ-Σ) modulator (DSM). The whole fractional frequency divider is implemented in TSMC 0.18μm CMOS process, occupying a chip area of 0.714mm2. With the voltage supply of 1.8V, the operating frequency range of the fractional frequency divider is 0.5-5.3GHz; and its supply current is about 5.9mA.

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