基于C8051F045单片机的轮速测量电路设计

介绍了基于C8051F045单片机的轮速测量电路,该电路采用磁敏式传感器SDI-H采集脉冲信号,将经信号处理电路处理后的2路脉冲方波鉴向后送入单片机计数,得出轮速信息,最后通过CAN总线通信在上位机上显示。实际应用表明,该测速电路具有良好的稳定性。     

Performance analysis of amplify-and-forward relaying with hybrid-ARQ in Rayleigh fading channels

Hybrid automatic repeat request (HARQ) is a well-known technique for improving system throughput and link performance of wireless communication systems, including cooperative communication systems. The amplify-and-forward (AF) relaying method is one of the most attractive cooperative diversity schemes because of its low complexity. In this article, the end-to-end performance in terms of block error rate (BLER) and normalized throughput of AF relaying with HARQ transmission under the Rayleigh fading channel is analyzed. Numerical results validate the proposed analysis and demonstrate the gain of HARQ schemes in AF relaying systems. This analytical method can be extended to the systems with other HARQ protocols and other cooperative relaying schemes.     

基于S3C44B0嵌入式系统的SCCB设计与实现

随着现代图像采集技术的迅速发展,CMOS图像传感器正在得到越来越广的应用。但目前绝大多数控制器没有SCCB总线接口,给其应用带来一定的不足。在介绍OmniVision公司的CMOS图像传感器中的SCCB总线的规范及总线构成和数据传输形式特点后,并针对低成本、低功耗的要求以基于ARM 7内核的三星公司的S3C44B0X平台上利用通用I/O接口与CMOS图像传感器OV7660芯片为例,说明了SCCB总线在嵌入式系统中的软硬件设计实现方法。     

Shorted spiral-like printed antennas

We present two electrically small printed antennas suitable for mobile communication handset terminals. The conductor shapes of the proposed shorted patch antennas maximize the length of the current path for a given area thereby significantly reducing the resonant frequency of the antenna. Reductions in operating frequencies of the order of seven to ten have been achieved     

移动IPv6概述

文章分析了IPV6支持移动性的优势，概述了移动IPv6协议，并对一些热点问题，如快速切换、平滑切换、移动管理、AAA和服务质量等进行了探讨。     

噪扰下数字化多频连续波雷达的测距模糊问题

数字化多频连续波测距雷达是一种新体制雷达.它具有能同时测定多个目标、便于同时得到目标多个运动参数等突出优点.为了解决增大最大测距不模糊距离与提高测距精度之间的矛盾,我们将会在多频雷达中采用参差频差关系进行测距,这样我们可以大大提高测距最大不模糊距离.但此时噪声对测距结果有着各种有待讨论的影响,包括:能否正确解模糊;对输入信号信噪比有何要求;理论测距精度有何变化;直至对参差系数有何要求等.数字化多频雷达的这些问题,本文对这些问题进行了详细的讨论,并给出了本文结论的计算机仿真结果.从而在理论上为这种雷达的深入研究提供了一个很好的基础.     

A 2 V 1.8 GHz fully integrated CMOS dual-loop frequency synthesizer

A 2 V 1.8 GHz fully integrated CMOS dual-loop frequency synthesizer is designed in a standard 0.5 /spl mu/m digital CMOS process for wireless communication. The voltage-controlled oscillator (VCO) required for the low-frequency loop is designed using a ring-type VCO and achieves a tuning range of 89% from 356 to 931 MHz and a phase noise of -109.2 dBc/Hz at 600 kHz offset from 856 MHz. With an active chip area of 2000/spl times/1000 /spl mu/m/sup 2/ and at a 2 V supply voltage, the whole synthesizer achieves a tuning range from 1.8492 to 1.8698 GHz in 200 kHz steps with a measured phase noise of -112 dBc/Hz at 600 kHz offset from 1.86 GHz. The measured settling time is 128 /spl mu/s and the total power consumption is 95 mW.     

H原子在Si(111)-7×7表面吸附的STM研究

利用超高真空扫描隧道显微镜(UHV-STM),在液氮(78K)及液氦(4.2K)低温条件下研究了H/Si(111)-7×7吸附体系.H原子易于吸附在表面增原子(adatom)以及剩余原子(rest atom)的位置,导致表面局域电子态密度(LDOS)和STM图像发生明显的变化.利用扫描隧道谱技术(STS)测量获得了H吸...     

Service function chain embedding algorithm with wireless multicast in mobile edge computing network

To resolve the excessive system overhead and serious traffic congestion in user-oriented service function chain (SFC) embedding in mobile edge computing (MEC) networks,a content-oriented joint wireless multicast and SFC embedding algorithm was proposed for the multi-base station and multi-user edge networks with MEC servers.By involving four kinds of system overhead,including service flow,server function sustaining power,server function service power and wireless transmission power,an optimization model was proposed to jointly design SFC embedding with multicast beamforming.Firstly,with Lagrangian dual decomposition,the problem was decoupled into two independent subproblems,namely,SFC embedding and multicast beamforming.Secondly,with the L_p norm penalty term-based successive convex approximation algorithm,the integer programming-based SFC embedding problem was relaxed to an equivalent linear programming one.Finally,the non-convex beamforming optimization problem was transformed into a series of convex ones via the path following technique.Simulation results revealed that the proposed algorithm has good convergence,and is superior to both the optimal SFC embedding with unicasting and random SFC embedding with multicasting in terms of system overhead.     

噪扰条件下数字式多基线相位干涉仪解模糊问题

数字式多基线相位干涉仪具有能被动测向、且测向精度高的优点。为了解决增大最大无模糊角度与提高测向精度之间的矛盾,将会在多基线干涉仪中采用参差基线关系进行测向,这样可以大大增加最大无模糊角度。但在噪扰条件下,还有一些有待讨论的问题,包括:正确解模糊的条件,对输入信号信噪比的要求,理论的测向精度以及参差系数的选取等。对以上这些问题进行了深入的研究,给出了正确解模糊允许的最大噪扰、最低信噪比和可以正确解模糊的角度范围,仿真结果表明了理论分析的正确性。