Multiple accumulated-crossover parallel concatenated SPC codes

By constructing an accumulated-crossover relationship in multiple parallel concatenated single parity check (M-PC-SPC) codes, a class of error-correcting codes, termed multiple accumulated-crossover parallel concatenated single parity check (M-ACPC-SPC) codes, is proposed. M-ACPC-SPC codes possess linear encoding complexity and can be decoded iteratively with low complexity by the sum-product algorithm (SPA). Simulation results show that M-ACPC-SPC codes have lower error floors than M-PCSPC codes with the same dimension, and when the dimension is 5, M-ACPC-SPC codes achieve bit error rate (BER) better than (3, 6) regular low density parity check (LDPC) codes. Supported by the National High-Tech Research & Development Program of China (Grant No. 2007AA01Z288), the National Science Fund for Distinguished Young Scholars (Grant No. 60725105), the Program for Changjiang Scholars and Innovative Research Team in University and the 111 Project (Grant No. B08038)     

基于Visual C++.NET的GDI+技术的研究与应用

鉴于GDI技术具有功能简单、使用复杂的不足,使用GDI+技术进行图形图像处理会取得更好的效果。着重介绍GDI+技术的特点及其新特色,并总结得出在Visual C++.NET开发环境下使用GDI+开发图像处理软件的步骤和相应的程序代码。     

Surround structured lighting: 3-D scanning with orthographic illumination

This paper presents a new system for rapidly acquiring complete 3-D surface models using a single orthographic structured light projector, a pair of planar mirrors, and one or more synchronized cameras. Using the mirrors, we project structured light patterns that illuminate the object from all sides (not just the side of the projector) and are able to observe the object from several vantage points simultaneously. This system requires that projected planes of light to be parallel, so we construct an orthographic projector using a Fresnel lens and a commercial DLP projector. A single Gray code sequence is used to encode a set of vertically-spaced light planes within the scanning volume, and five views of the illuminated object are obtained from a single image of the planar mirrors located behind it. From each real and virtual camera we recover a dense 3-D point cloud spanning the entire object surface using traditional structured light algorithms. A key benefit of this design is to ensure that each point on the object surface can be assigned an unambiguous Gray code sequence, despite the possibility of being illuminated from multiple directions. In addition to presenting a prototype implementation, we also develop a complete set of mechanical alignment and calibration procedures for utilizing orthographic projectors in computer vision applications. As we demonstrate, the proposed system overcomes a major hurdle to achieving full 360° reconstructions using a single structured light sequence by eliminating the need for merging multiple scans or multiplexing several projectors.     

A wireless data clustering method for multipoint queries

By effective data clustering, the mobile clients can access the data objects of their interest in short latency. In this paper, we propose a clustering method of wireless data for multipoint queries, where wireless data objects are uniformly broadcasted.We first analyze the data clustering problem and propose a new measure, named the Query Distance, i.e., convenient to manipulate for the analyses of the average query performance. Then, we propose a clustering method that efficiently minimizes the Query Distance, based on the Gray coding scheme. We show that the Gray coding scheme has useful properties that can be utilized for clustering the data on the air. We also show the performance advantage of our method through experiments. Since, as far as we are aware of, there is no previous work that deals with multipoint queries in wireless data broadcasting, the experiments are in comparison with the random clustering method.     

Turbo码与TCM编码调制技术研究

本文研究了Turbo码与网格编码调制(Trellis Coded Modulation,TCM)相结合的编码调制技术,给出了Turbo码与TCM相结合的调制方案,对Turbo码与TCM调制方案进行了计算机仿真,仿真结果表明,其性能要优于传统的采用卷积码的TCM调制。     

数字磁光记录系统中的编码技术

在简述数字存储原理的基础上给出基本存储信道各种模型及其容量上下限。分析了两种检测技术 (峰值检测与部分响应最大似然Viterbi检测 )的优缺点 ,采用受限码的原因及其基本编译码器构成。     

联机手写维文字符的预处理和特征提取方法

根据维吾尔字符的特点,介绍了归一化,平滑处理,重采样等几种预处理方法。并结合统计特征和结构特征各自的特点,提出了不变矩,投影,方向码,环等特征,用来构造字符的特征向量,便于进行字符的训练和识别。     

Joint source channel VL coding/decoding for deep space communication networks based on a space trellis

This paper presents joint source channel variable length (VL) coding/decoding based on a space trellis.Through constructing a joint decoding plane trellis,better decoding performance can be achieved than by using the bit-level decoding algorithm.However,the plane trellis is complicated,which results in high decoding complexity for decoding VL turbo codes.To solve this problem,we construct a space trellis and design a low-complexity joint decoding algorithm with a variable length symbol-a posteriori probabil...     

用Verilog实现BCD码到余3码的转换

BCD码和余3码是串行通讯中比较常见的两种编码方式,二者的转换在不同的通讯场合中也经常用到,文章主要介绍二者之间的关系并用Verilog语言实现了二者之间的转换。