Extracting OSNR From Low-Resolution Optical Channel Monitors

Optical channel monitors (OCMs) that use scanning filters need to resolve the amplified spontaneous emission (ASE) noise floor between channels in order to determine optical signal-to-noise ratio (OSNR). We show how regularized least-squares can extract accurate OSNR values from raw spectra when the ASE floor is not visible because of insufficient resolution in the monitor. Our experimental results demonstrate OSNR measurement accuracy to within 0.6 dB from a spectrum of 50-GHz-spaced 10-Gb/s channels measured using a scanning Fabry-Peacuterot filter with 35-GHz bandwidth. The ability to use broader bandwidth filters in OCMs without sacrificing accuracy may reduce their cost and increase their robustness     

Sensorless Control of Induction Motors by Reduced Order Observer With MCA EXIN + Based Adaptive Speed Estimation

This paper presents a sensorless technique for high-performance induction machine drives based on neural networks. It proposes a reduced order speed observer where the speed is estimated with a new generalized least-squares technique based on the minor component analysis (MCA) EXIN + neuron. With this regard, the main original aspects of this work are the development of two original choices of the gain matrix of the observer, one of which guarantees the poles of the observer to be fixed on one point of the negative real semi-axis in spite of rotor speed, and the adoption of a completely new speed estimation law based on the MCA EXIN + neuron. The methodology has been verified experimentally on a rotor flux oriented vector controlled drive and has proven to work at very low operating speed at no-load and rated load (down to 3 rad/s corresponding to 28.6 rpm), to have good estimation accuracy both in speed transient and in steady-state and to work correctly at zero-speed, at no-load, and at medium loads. A comparison with the classic full-order adaptive observer under the same working conditions has proven that the proposed observer exhibits a better performance in terms of lowest working speed and zero-speed operation     

RS码参数的盲估计

提出了一种基于对偶码的RS码盲识别方法.建立接收序列的矩阵模型,通过统计该矩阵模型对应的低重量向量的数量,估计RS码的码长和分组起点.通过计算对偶码,估计校验矩阵、生成多项式、本原多项式等参数.实验表明在较高的误码率条件下也能达到较好的识别效果.     

使用6通道增量型编码器进行精确的轮椅电机控制

阿尔伯(Alber)公司为德国轮椅推动和刹车辅助的市场领先者,在推出新的Viamobil V25型轮椅时进行了多方面的改善,包括:·性能·使用的友善性·易于安装·使用锂离子电池和高效率驱动提高耐久性为了达成这个目标,需要使用高效率电机来降低功耗并减轻电池重量。     

Position Estimation of a Matrix-Converter-Fed AC PM Machine From Zero to High Speed Using PWM Excitation

This paper describes a sensorless position estimation method for a permanent-magnet (PM) motor fed from a three-phase matrix converter using only its space-vector pulsewidth-modulation (SVPWM) sequence. The scheme employs measurements of $di/dt$ of the motor line currents to construct orthogonal “resolverlike” position signals. In principle, the SVPWM waveforms provide sufficient excitation to extract the position signal from the motor current. However, in order to improve the signal-to-noise ratio of the $di/dt$ signals, a small modification to the SVPWM is required. Sensorless control of the PM synchronous motor at zero and high speeds is demonstrated experimentally. The use of alternative input voltage vectors is also investigated to reduce the current ripple.      

基于光电编码器的速度反馈与控制技术

对常用的速度反馈手段进行了分析比较，介绍了以光电编码器实现速度反馈的工作原理和控制方法，分析了高精度的M／T测速法。介绍了高性能单片ADUC824在数字控制系统中的应用。     

AVS编码器运动估计中内插的快速算法

为了降低AVS编码器在运动估计中进行像素内插的运算复杂度,通过对1/2精度像素进行整帧内插减少了总的内插运算量和内存存取量;提出了利用1/2精度像素的最终值代替中间值滤波的简化算法,进一步降低了运动估计中内插运算实现的复杂度.在PNX1500平台上实验表明在保证编码质量的情况下,运动估计时间得到了大幅度降低.     

旋转编码器在线速度检测控制中的应用

通过对盘绞式成缆机工作过程的分析,说明了对收线电机的控制要求,采用AT89C51单片机为控制核心,通过检测旋转编码器在单位时间内输出的脉冲数,与标准脉冲数进行比较,控制收线电机调速器的给定值,从而控制收线电机的旋转速度,实现了线缆的均匀走线速度控制。给出单片机与旋转编码器组成的闭环线速度控制系统的电路原理及主要控制程序的设计方法。其简洁的电路设计和典型的控制方法具有较高的参考价值。     

MPEG-2编码芯片中运动估计电路的设计

运动估计是视频压缩中最重要的环节，文章讨论了运动估计的基本原理并分析了其特点，采用了三步分层搜索算法．设计了一种基于MPEG-2的主档次标准的9PE全并行结构的高速运动估计电路，并通过FPGA验证，系统时钟频率达到35MHz，性能达到了实时编码的要求。     

Baseline Influence on Single-Frequency GPS Precise Heading Estimation

When using the signal from the Global Positioning System (GPS) for precise estimation of a vehicle’s heading, the main challenge is finding the integer ambiguities in the carrier phase measurements. If the distance between the receiver’s antennas, also known as baseline length, is used in the process of solving that challenge, the resulting solution’s stability and precision can be enhanced, particularly for single-frequency L1 receivers. This paper presents a study of the overall influence of this baseline length in the precision and accuracy of the heading estimation, using raw measurements from two GPS single-frequency L1 receivers. Conclusions are presented based on the results from field trials for baselines up to 8 m.     

Speed and Load Torque Observer Application in High-Speed Train Electric Drive

This paper presents an application of induction motor mechanical speed and load torque observers in high-speed train drives. The observers are applied for a 1.2-MW electric drive with an induction motor. The goal of using such observers is to utilize computed variables for diagnostic purposes of speed sensors and torque transmission system. The concept of diagnostic system is presented in this paper, and proper criteria are proposed. The suggested system is designed to work without a speed sensor in the case of existing sensor faults. Monitored motor load torque is used to limit the maximum motor torque in the case of existing problems in the gearbox. The results of simulation and experimental investigations for a 1.2-MW induction motor drive are presented.      

High Speed 4-Symbol Arithmetic Encoder Architecture for Embedded Zero Tree-Based Compression

In state-of-the-art multimedia compression standards, arithmetic coding is widely used as a powerful entropy compression method. In the MPEG-4 standard a specific 4-symbol, multiple-context arithmetic coder is used for wavelet based image compression. In this paper we present a first-of-a-kind architecture capable of processing close to 1 symbol per cycle, managing multiple context in a simple, yet cost-efficient manner. We explain the need for such an architecture, develop the algorithm and propose an efficient implementation. The characteristics of the architecture are detailed and a comparison with other alternatives is presented. This architecture has been synthesized achieving a maximum speed of 170 MHz, equivalent to 340 Mbits/s.     

基于OFDM的联合信道估计的定时方法

针对正交频分复用(OFDM)系统中,传统的时域相关法无法满足定时同步精度的要求,提出了一种联合信道估计的同步算法,给出了理论推导,在得到信道估计结果的基础上对初始的定时同步结果进行修正,进而得到较为精确的定时位置,解决了同步头摆动等定时不准确的问题。用Matlab对提出的算法进行了仿真,仿真结果表明,此改进算法能满足低信噪比下的定时同步要求。     

Analysis of Optical Losses in a Photoelectrochemical Cell: A Tool for Precise Absorptance Estimation

Optical losses in a photoelectrochemical (PEC) cell account for a substantial part of solar‐to‐hydrogen conversion losses, but limited attention is paid to the detailed investigation of optical losses in PEC cells. In this work, an optical model of combined coherent and incoherent light propagation in all layers of the PEC cell based on spectroscopic measurements is presented. Specifically, photoelectrodes using transparent conductive substrates such as F:SnO₂ coated with thin absorber films are focused. The optical model is verified for hematite photoanodes fabricated by atomic layer deposition and successfully used to determine wavelength‐dependent reflection, transmission, layer absorptances, and charge generation rates. Furthermore, the calculated absorptances enable 20–30% more accurate calculations of the absorbed photon‐to‐current efficiency of PEC cells. Our optical model is a powerful tool for the optimization of the optical performance of PEC cells focusing on single absorber or tandem configurations and represents a cornerstone of a complete (optical and electrical) model for PEC water splitting cells.     

GMR-1 3G中LDPC高速编码器的设计与实现

针对GMR-1 3G标准中的LDPC码,设计实现了一种多码长、多码率的编码器,采用并行处理的方式,降低了编码的时延,提高了编码的速率。使用Quartus II工具进行功能仿真,验证了编码的正确性和有效性。     

用软件做一个正交编码器的解码

很多应用都用正交编码器来确定机械行程的位移量与方向。它们随设计而变化,但都做了相同的工作:提供一组相差为90°的方波。图1给出了典型的输出信号。     

Wind Speed Estimation Based Sensorless Output Maximization Control for a Wind Turbine Driving a DFIG

This paper proposes a wind speed estimation based sensorless maximum wind power tracking control for variable-speed wind turbine generators (WTGs). A specific design of the proposed control algorithm for a wind turbine equipped with a doubly fed induction generator (DFIG) is presented. The aerodynamic characteristics of the wind turbine are approximated by a Gaussian radial basis function network based nonlinear input-output mapping. Based on this nonlinear mapping, the wind speed is estimated from the measured generator electrical output power while taking into account the power losses in the WTG and the dynamics of the WTG shaft system. The estimated wind speed is then used to determine the optimal DFIG rotor speed command for maximum wind power extraction. The DFIG speed controller is suitably designed to effectively damp the low-frequency torsional oscillations. The resulting WTG system delivers maximum electrical power to the grid with high efficiency and high reliability without mechanical anemometers. The validity of the proposed control algorithm is verified by simulation studies on a 3.6MW WTG system. In addition, the effectiveness of the proposed wind speed estimation algorithm is demonstrated by experimental studies on a small emulational WTG system.     

动目标检测与速度估计仿真研究

介绍了雷达信号处理技术中的脉冲压缩、动目标检测、脉冲多普勒处理和恒虚警检测技术,并对雷达发射波形、目标回波、动目标检测进行了Matlab仿真。对脉冲回波信号进行脉冲压缩与动目标显示得到动目标脉压信号。利用动目标显示和脉冲多普勒处理实现脉压信号的动目标检测,并得到脉冲多普勒数据块。在数据块的距离维上进行恒虚警检测,检测动目标的距离,然后提取对应距离门的多普勒数据,检测动目标的速度。通过仿真建立了雷达信号处理的基本框架,为雷达系统建模及其仿真的深入研究提供了仿真支持。