通过高压变压器产生高压使气体间隙之间的空气击穿,并使之达到自持击穿导电状态,这时气体之间的等效阻抗比较小;为了提高耦合效率降低损耗,采用给接收线圈连接电容使它们达到谐振状态.通过这些手段就能实现电能在两个电极间无线传输.

采用高压击穿气体放电技术来传输无线电能.首先用击穿高压电使空气击穿放电,达到自持放电状态,接着采用相对较低的维持电压替换击穿电压使自持放电进入稳定状态.这时击穿的空气相当于一个良导体.通过理论分析,我们搭建了实验平台,试验数据显示此时电阻率比较低,能完成无线电能传输.

The system is combined with a calibrated digital output temperature sensor, DHT11, a low energy consumption, high-performance 8-bit microcontroller, AT89S51, a high integrated LCD1206 character LCD display module, and alarm buzzer. The user simply sets target temperature. The system detects the actual temperature value, which passesthrough the noise filtering, puts the target and actual temperature value involve fuzzy PID operation, and outputs control signal. The software part includes the main program, the display module subroutine and the temperature measurement subroutine.

The system is combined with a calibrated digital output temperature and humidity sensors,DHT11,a low energy consumption,high-performance 8-bit microcontroller,AT89S51,a high integrated LCD1206 character LCD display module,alarm buzzer.For physical manipulation,the user simply pull on a button to meet with their own temperature and humidity range.The actual temperature and humidity value is detected by the system,after the data processing system,and the temperature and humidity range of pre-setting value comparison,when the actual value exceeds the pre-settings,alarm module circuit will be work,that is audible alarm to alert user.The system need software part,which is comprised by the main program,(display module) and subroutine (temperature and humidity) subroutines.

This paper presented a design using full-duplex wireless signal inversion adaptive cancellation. Signal inversion using a transmitter based on balanced / unbalanced design was simple (Balun). The new design, different from the previous work in support of broadband and high-power systems. In theory, this new design was not limited in bandwidth and power. In practice, we found that the signal inversion can be canceled at least 36dB at 45MHz bandwidth. Further, the signal in the digital domain inversion cancellation of a combination of OFDM signal was 15MHz seventy-three db reduce self-interference.

In order to improve the transmission performance of wireless channels,the improved training sequence based channel estimation algorithm in MIMO-OFDM system was proposed.Using irrelevance of the training sequence and information sequence,the channel parameters was estimated.Even in the presence of channel mismatch errors and channel quantization error,quantitative feedback channel estimation training sequence can improve the performance of the system.10-bit quantizer can fulfill the general performance requirements.And then the design of the optimal pilot sequence using the channel to maximize the mutual information was discussed.

One of the biggest drawbacks of OFDM is its high peak to average power ratio (PAPR). High PAPR of OFDM makes it unusable in non-linear systems. So the clipping signals scheme is one useful and simple method to reduce the PAR. But because of the clipping process, the subcarrier's orthogonality is destroyed, the recovered signal is distorted at receiver, so the performances of bit-error-rate (BER) and channel capacity drop severely when clipping process is relatively severe. This paper presents a new receive algorithm for OFDM signals with limited dynamic range. The estimator is based on the distribution of the real and imaginary parts of the complex baseband OFDM signal. It recovers the original undistorted process by minimizing the mean-square estimation error. It is shown that the estimator significantly improves the error rate of OFDM systems impaired by clipping at the transmitter.

The multi-band orthogonal frequency division multiplexing (OFDM) UWB system is the new proposal for the IEEE 802.15.3a standard for wireless high bit-rate personal area networks. Pulsed OFDM is an enhancement to the multi-band OFDM system that offers better performance with lower complexity and correspondingly reduced power consumption. In this paper, the implementation issues and pipeline structures of a pulsed OFDM transmitter are presented. In particular, architectural features of the system and its components are described and analyzed.

For the selective fading problem of frequency in ultra-wideband channel,an anti-fading method based on the bit and power allocation algorithm is used in this paper.So as to aquire maximized system transmission rate,meanwhile,total transmission power and bit error rate need to meet the requirements.In the end,simulation results show that this can improve the transmission performance.

One of the biggest drawbacks of OFDM is its high peak to average power ratio (PAPR). High PAPR of OFDM makes it unusable in non-linear systems. So the clipping signals scheme is one useful and simple method to reduce the PAR. But because of the clipping process, the subcarrier's orthogonality is destroyed, the recovered signal is distorted at receiver, so the performances of bit-error-rate (BER) and channel capacity drop severely when clipping process is relatively severe. This paper presents a new receive algorithm for OFDM signals with limited dynamic range. The estimator is based on the distribution of the real and imaginary parts of the complex baseband OFDM signal. It recovers the original undistorted process by minimizing the mean-square estimation error. It is shown that the estimator significantly improves the error rate of OFDM systems impaired by clipping at the transmitter.

本文探讨了通信原理教学改革的途径,阐述了<通信原理>课程改革的思路,对如何正确处理好传统教学方法和互动教学方法,如何在课堂上激发学生的学期积极性、主动性提出了自己的观点和看法;同时进行了教学改革,经过实践取得了较好的成效.

Mainly introduces the estimation quality of classical PSD and modified Periodogram,and analyses the impact of window function on Welch method.Finally list several general selecting criterion,via emulation on matlab,selecting criterion.

第四代移动通信系统计划以正交频分复用(OFDM)为核心技术提供增值服务,在宽带领域的应用有很大的潜力。在正交频分复用(OFDM)系统中,对频率偏移敏感和峰均比相对较大是OFDM系统要解决的两个很重要的问题。针对针对正交频分复用(OFDM)技术具有较高的峰均功率比(PAPR)的缺点,分析了PTS算法降低OFDM系统PAPR的原理,并对其性能进行了仿真分析,仿真结果验证了算法的有效性。

A newly developed multimedia advertising system is introduced based on NiosⅡof Altera Company in this paper.We will introduce the composing of the multimedia advertising system and the common SOPC technology in embedded system.We have built the system with the DE1 board of Altera company.This system can lauch multimedia advertisement duly and exactly.

As a bottom industrial control network,the real-time performance influences the whole function of control system directly.So analyzing and counting of it is of great importance.While the message transaction cycle time is an important measurement to the realtime performance of Profibus.This article focuses on the multi-master system.Based on the analysis of different setting values of the targettoken rotation time,the method of calculating the message transaction cycle time is presented through the analysis of the application inproject.

The paper studied emphatically on two kinds of admission control plan.Due to the special breathing effect of 3G networks and various rates of user admission requests,the Quality of Service(QoS) guarantee becomes more difficult.As the cover and the optimization of GSM networks have become so mature at present that it is enough to meet user requirements of voice operation with a large expanding space.Multimedia operation of high quality and big flux,provided to high-class users,should be considered in the program tactics of 3G networks.But the spatial frequency resources are limited.Therefore,it becomes the designing goal to improve utilization rate and get as low CBP and CDP as possible.The non-real-time performance of Multimedia operation makes it possible to introduce new method for adjusting.

The reliability of PLC control system is judged between hardware and software.This paper introduces the request of its working power,the way of connection,redundancy design,I/O electric circuits of its control system and its software programming, etc,and presents some feasible methods and measures.

Orthogonal Frequency-Division Multiplexing(OFDM) system is very good for the high speed communication system,but the high Peak to Average Power Ratio(PAPR) is a very serious problem.Partial Transmit Sequence (PTS) scheme has been widely studied to reduce the high PAPR of OFDM signal since it is flexible and efficient.This paper proposes a new phase search algorithm that reduces the high PAPR.Our simulation results show that the proposed scheme provides significant computational savings while yielding a performance similar to that of the conventional PTS method.

文章首先介绍了WiMax和Wi-Fi技术基础IEEE802.16和IEEE802.11的系列标准及其论坛的发展现状,,对比介绍了WiMax和Wi-F技术,着重对两种技术的物理层技术特点和其对媒体访问的控制进行了分析,并对两种技术的技术标准做了对比研究.最后,作者描述了两种技术的应用前景和一些最新的政策,并对两种技术的前景进行了分析.

The concept of Orthogonal Frequency Division Multiplexing(OFDM) technology is introduced.The basic principle of OFDM technology and the research condition are narrated.The key techniques and the application in 4G of OFDM technology are discussed.Analysis indicates that OFDM technology can enhance the capacity of communication system while maintaining bandwidth,and OFDM is the key technology in the 4G mobile communication system.Research trend of OFDM technology in future is given finally.