为满足无线网络技术具有低功耗、节点体积小、网络容量大、网络传输可靠等技术要求，设计了一种以MSP430单片机和CC2420射频收发器组成的无线传感节点。通过分析其节点组成，提出了ZigBee技术中的几种网络拓扑形式，并研究了ZigBee路由算法。针对不同的传输要求形式选用不同的网络拓扑形式可以尽大可能地减少系统成本。同时针对不同网络选用正确的ZigBee路由算法有效地减少了网络能量消耗，提高了系统的可靠性。应用试验表明，采用ZigBee方式通信可以提高传输速率且覆盖范围大，与传统的有线通信方式相比可以节约40%左右的成本。 Abstract: To improve the proposed technical requirements such as low-ower， small nodes， large capacity and reliable network transmission， wireless sensor nodes based on MSP430 MCU and CC2420 RF transceiver were designed. This paper provided network topology of ZigBee technology by analysing the component of the nodes and researched ZigBee routing algorithm. Aiming at different requirements of transmission mode to choose the different network topologies form can most likely reduce the system cost. And Aiming at different network to choose the correct ZigBee routing algorithm can effectively reduced the network energy consumption and improved the reliability of the system. Results show that the communication which used ZigBee mode can improve the transmission rate， cover more area and reduce 40% cost compared with traditional wired communications mode.
上传时间： 2013-10-09
上传用户：robter
针对UHF读写器设计中，在符合EPC Gen2标准的情况下，对标签返回的高速数据进行正确解码以达到正确读取标签的要求，提出了一种新的在ARM平台下采用边沿捕获统计定时器数判断数据的方法，并对FM0编码进行解码。与传统的使用定时器定时采样高低电平的FM0解码方法相比，该解码方法可以减少定时器定时误差累积的影响；可以将捕获定时器数中断与数据判断解码相对分隔开，使得中断对解码影响很小，实现捕获与解码的同步。通过实验表明，这种方法提高了解码的效率，在160 Kb/s的接收速度下，读取一张标签的时间约为30次/s。 Abstract: Aiming at the requirement of receiving correctly decoded data from the tag under high-speed communication which complied with EPC Gen2 standard in the design of UHF interrogator， the article introduced a new technology for FM0 decoding which counted the timer counter to judge data by using the edge interval of signal capture based on the ARM7 platform. Compared with the traditional FM0 decoding method which used the timer timed to sample the high and low level， the method could reduce the accumulation of timing error and could relatively separate capture timer interrupt and the data judgment for decoding， so that the disruption effect on the decoding was small and realizd synchronization of capture and decoding. Testing result shows that the method improves the efficiency of decoding， at 160 Kb/s receiving speed， the time of the interrogator to read a tag is about 30 times/s.
上传时间： 2013-11-09
上传用户：liufei
At recent major international conferences on wireless communications, there have been several sessions on beyond third generation (3G) or fourth generation(4G)mobilecommunicationssystems,wheremodulation/demod- ulation and multiplexing/multiple access schemes related to multicarrier techniques have drawn a lot of attention. We often met at the conference venuesandrealizedthatnobookcoveredthebasicsofmulticarriertechniques to recent applications Aiming at the 4G systems. Therefore, we decided to write a book on multicarrier techniques for 4G mobile communications systems.
标签： Communications Multicarrier Techniques Mobile for 4G
上传时间： 2020-05-30
上传用户：shancjb
This paper presents a Hidden Markov Model (HMM)-based speech enhancement method, Aiming at reducing non-stationary noise from speech signals. The system is based on the assumption that the speech and the noise are additive and uncorrelated. Cepstral features are used to extract statistical information from both the speech and the noise. A-priori statistical information is collected from long training sequences into ergodic hidden Markov models. Given the ergodic models for the speech and the noise, a compensated speech-noise model is created by means of parallel model combination, using a log-normal approximation. During the compensation, the mean of every mixture in the speech and noise model is stored. The stored means are then used in the enhancement process to create the most likely speech and noise power spectral distributions using the forward algorithm combined with mixture probability. The distributions are used to generate a Wiener filter for every observation. The paper includes a performance evaluation of the speech enhancer for stationary as well as non-stationary noise environment.
标签： Telecommunications Processing Signal for
上传时间： 2020-05-31
上传用户：shancjb
We are very pleased to introduce the proceedings of the First EAI International Conference on Smart Grid Inspired Future Technologies (SmartGIFT 2016). This was the first SmartGIFT conference, Aiming to create a forum for researches, developers, and practitioners from both academia and industry to publish their key results and to disseminate state-of-the-art concepts and techniques in all aspects of smart grids. The 37 scientific participants had many fruitful discussions and exchanges that contributed to the success of the conference. Participants from 12 countries made the conference truly international in scope.
标签： Technologies Inspired Future Smart Grid
上传时间： 2020-06-07
上传用户：shancjb
针对交流电路过零检测电路存在结构复杂、过零点检测不准确、编程繁琐等问题，设计了一种基于LM339的硬件结构简单的过零检测电路。通过仿真软件Mulisim对该设计电路进行了仿真，实验证明了该方案过零检测的可行性、稳定性和可靠性，可直接作为交流电路中CPU的过零信号。Aiming at the problems of AC cilsuit zero crossing detection circuit such as complex structure, zero crossing detection and cumbersome programming, a zero crossing detection circuit with simple hardware structure based on LM339 was designed. The design circuit was simulated by simulation software Mulisim, and the feasibility, stability and reliability of zero crossing detection were proved by experiments, which can be used as zero crossing signal of CPU in AC circuit directly.
上传时间： 2022-05-03
上传用户：joshau007
