最佳三元序列偶理论研究

本文提出了一种新的具有良好循环自相关特性的离散信号,即最佳三元序列偶。给出了最佳三元序列偶的变换性质,研究了在伪随机二元序列、最佳二元序列偶以及最佳屏蔽二元序列偶基础上,通过插零法构造最佳三元序列偶的方法,从而可以利用现有的最佳信号生成最佳三元序列偶,大大拓宽最佳信号的存在空间,进一步丰富和完善了序列偶最佳相关信号理论。     

Revised analyses of postdetection switch-and-stay diversity in rician fading

The performances of dual-branch postdetection switch-and-stay combining (SSC) for noncoherent orthogonal binary frequency-shift keying and noncoherent orthogonal M-ary frequency-shift keying operating over slow, flat Rician fading channels are a topic of current interest. It is shown that recently published analyses obtain incorrect final results because some incorrect probability distribution parameters are used in the analyses. The previous results are corrected, and it is seen that the final results change significantly. The revised results are used to obtain optimum switching thresholds that minimize the average bit-error rate (BER) performance of these systems. Monte Carlo simulations are presented to verify the results, and it is shown that for a given BER, the signal-to-noise ratio difference of postdetection SSC and predetection SSC is much less than previously reported.     

Non Binary and Precoded Faster Than Nyquist Signaling

Faster than Nyquist (FTN) signaling is an important method of narrowband coding. The concept is extended here to non binary signal constellations; these are much more bandwidth efficient than binary ones. A powerful method of finding the minimum distance for binary and non binary FTN is presented. Preceding FTN transmissions with short linear filters proves to be an effective way to gain distance. A Shannon limit to bit error rate is derived that applies for FTN. Tests of an M-algorithm receiver are performed and compared to this limit.     

A method for increasing the number of majority multiplexed channels

A majority multiplexing method for multiplexing some moderately large number of binary data channels is proposed. It is shown that the number of channels can be increased if the transmitted signal is formed by using a two-stage transformation process. A suitable detection process for recovering the binary data elements is established. Results of computer studies on the performance of the method in additive white Gaussian noise are presented, and the method is briefly compared with TDM.     

A note on dichotomous feature extraction (Corresp.)

An error is corrected in an expression, for misclassification probability with dichotomous (binary) random variables, and the perils of dichotomous feature extraction are exhibited.     

Binary grayscale halftone pattern generation using binary artificial bee colony (bABC)

In grayscale context, digital halftoning can be considered as binary pattern generation task where 0- and 1-valued pixels represent black and white, respectively. This paper presents application of artificial bee colony (ABC) in its modified binary form called binary ABC (bABC) toward generation of optimized binary halftone patterns. The human visual system incorporated cost function formulation addresses the tonal and structural parity between the original and halftone images along with pleasant halftone appearance. A pattern look-up table (p-LUT) approach is investigated including edge enhancement in halftone images. The results are presented pictorially and evaluated objectively. Comparison between the presented method and established halftoning techniques is also drawn to judge the potential of the presented bABC generated p-LUT approach. The pictorial presentations as well as objective evaluation show that the presented method may be potentially useful in the field of digital halftoning.     

基于噪声谱约束的二值掩码估计语音增强算法

提出一种基于噪声谱约束的二值掩码估计语音增强算法,用以提高低信噪比情况下的语音可懂度。首先分析了低信噪比时,先验信噪比过估对噪声谱估计函数的影响;再分别对先验信噪比和噪声谱估计函数进行修正;最后,根据修正后的噪声谱估计函数和先验信噪比判断出噪声谱被欠估的时频单元,估计出二值掩码值,并对相应的增强后语音时频单元进行幅度谱约束。仿真结果表明,在几种常见背景噪声的低信噪比情况下,相比于传统维纳滤波法,本文算法效果更好,能有效的提高语音可懂度。      

Perfect pseudoperiodic binary arrays

Arrays with good correlation properties are required for code-departure imaging, as well as for other applications of two-dimensional signal processing. Since binary arrays with perfect periodic autocorrelation are rather sparse. `pseudoperiodic' binary arrays are discussed. The transmitted binary array is correlated in the receiver with the same array which is surrounded periodically by similar ternary arrays. A construction method is presented that permits the construction of such `pseudoperiodic' binary arrays with perfect correlation properties for all sizes p₁^a1×p ₂^a2 (p₁, p₂ odd prime, a₁, a₂=1, 2, 3...)     

等重码的一些新结果

本文给出两种构造二元非线性等重码的方法，这些方法是［１］文构造二元非线性循环等重码方法的改进。通过我们的构造方法可以得到几类二元最优等重码。我们进一步说明通过ＧＦ（ｑ）上的等重码和达到Ｐｌｏｔｋｉｎ界的最优码可以构造达到Ｊｏｈｎｓｏｎ上界的二元最优等重码     

Skeleton-based morphological coding of binary images

This paper presents new properties of the discrete morphological skeleton representation of binary images, along with a novel coding scheme for lossless binary image compression that is based on these properties. Following a short review of the theoretical background, two sets of new properties of the discrete morphological skeleton representation of binary images are proved. The first one leads to the conclusion that only the radii of skeleton points belonging to a subset of the ultimate erosions are needed for perfect reconstruction. This corresponds to a lossless sampling of the quench function. The second set of new properties is related to deterministic prediction of skeletonal information in a progressive transmission scheme. Based on the new properties, a novel coding scheme for binary images is presented. The proposed scheme is suitable for progressive transmission and fast implementation. Computer simulations, also presented, show that the proposed coding scheme substantially improves the results obtained by previous skeleton-based coders, and performs better than classical coders, including run-length/Huffman, quadtree, and chain coders. For facsimile images, its performance can be placed between the modified read (MR) method (K=4) and modified modified read (MMR) method.     

Error Rate Bounds for Digital PAM Transmission with Phase Jitter and Intersymbol or Cochannel Interference

A simple method is presented for computing upper and lower bounds for binary PAM signaling over channels with phase jitter. Other impairments to reliable communication are taken to be additive thermal noise and intersymbol or cochannel interference. The important cases of binary and quadrature phase shift keying are cases for which the analysis presented is valid. The method consists of finding upper and lower bounds conditioned on the phase jitter, φ, in a form in which the auguments of theQ-functions involved are linear incos phiandsin phi. When these functions are represented by a piecewise linear approximation, the average of these bounds can be given in closed form. In most cases 5 piecewise linear segments provides an error rate estimate that is accurate to at least 1 dB in system signal-to-noise ratio (SNR).     

基于正态散斑干涉的双随机幅-相编码光学加密技术

提出一种将散斑干涉应用于光学加密的方法.在任意一束散斑干涉光路中放置含二值信息的相位掩膜,由散斑干涉产生实振幅型加密图像,移去相位掩膜可得到解密密钥.该方法用双随机幅-相进行编码加密,提高系统安全性,更换密钥方便,解密图像信噪比高,可用于大信息量二值图像加密.加密图像是实值,便于显示或打印.本文给出了计算机仿真实验结果.     

并元互补二元序列族

本文首先提出了并元加族的概念,然后研究了并元互补二元序列族与并元加族的关系和并元互补二元序列族存在的条件.最后给出了并元互补二元序列族的计算机搜索方法.     

Blind identification and deconvolution of linear systems driven bybinary random sequences

The problem of blind identification and deconvolution of linear systems with independent binary inputs is addressed. To solve the problem, a linear system is applied to the observed data and adjusted so as to produce binary outputs. It is proved that the system coincides with the inverse of the unknown system (with scale and shift ambiguities), whether it is minimum or nonminimum phase. These results are derived for nonstationary independent binary inputs of infinite or finite length. Based on these results, an identification method is proposed for parametric linear systems. It is shown that under some mild conditions, a consistent estimator of the parameter can be obtained by minimizing a binariness criterion for the output data. Unlike many other blind identification and deconvolution methods, this criterion handles nonstationary signals and does not utilize any moment information of the inputs. Three numerical examples are presented to demonstrate the effectiveness of the proposed method     

An integer programming-based search technique for error-prone structures of LDPC codes

In this paper, an efficient, general framework is presented for finding common, devastating error-prone structures (EPS) of any finite-length low-density parity-check (LDPC) code. The smallest stopping set for the binary erasure channel (BEC), the smallest fully absorbing set, the smallest absorbing set, and the smallest elementary trapping set for the binary symmetric channel (BSC) are found and the dominant EPS are enumerated. The method involves integer programming optimization techniques, which guarantees that the results are provably optimal.     

Step-by-step decoding of the Bose-Chaudhuri- Hocquenghem codes

A new and conceptually simple decoding procedure is developed for all of the cyclic Bose-Chaudhuri-Hocquenghem codes. Iftis the number of errors guaranteed correctable by the Bose-Chaudhuri bound, then any pattern oftor fewer errors can be corrected in a step-by-step manner using this procedure. In the binary case, the method requires only the determination of whether at times tmatrix is singular. In the general case, the method requires only the determination of whether at times tmatrix and a(t+1) times (t+1)matrix are simultaneously singular. Circuits to implement the algorithm are developed and two detailed examples are given. Finally, the step-by-step procedure is compared to other known methods for decoding the Bose-Chaudhuri-Hocquenghem codes.     

Subband domain coding of binary textual images for documentarchiving

In this work, a subband domain textual image compression method is developed. The document image is first decomposed into subimages using binary subband decompositions. Next, the character locations in the subbands and the symbol library consisting of the character images are encoded. The method is suitable for keyword search in the compressed data. It is observed that very high compression ratios are obtained with this method. Simulation studies are presented.     

Construction of efficient error-limiting variable length codes

A novel method for generating an optimal binary prefix condition code is described. The proposed code generation method generates optimal variable length codes that have short average error spans compared to the existing self-synchronising codes. A technique for calculating the expected error spans of variable length codes are also presented     

高速Berlekamp-Massey算法结构及电路实现

介绍了两种用于二进制BCH解码器的高速Berlekamp—Massey算法实现方案。在加入寄存器以减少关键路径的延时从而提高电路速度的基础上，一种方法是采用有限域乘法器复用的方法降低电路的复杂度；另一种方法则通过对有限域乘法器进行流水线设计，进一步提高电路的工作速度，实现超高速应用。设计中充分利用了二进制BCH码中Berlekamp—Massey算法迭代计算时修正值间隔为零的性质，用超前计算的方法减少了运算周期的增加。提出的方案可用于设计高速光通信系统的信号编解码芯片。     

Hierarchical enumerative coding of first-order Markovian binarysources

A lossless adaptive compression algorithm for compressing first-order Markovian binary sources is presented. The method is a customised version of the recently introduced hierarchical enumerative coding. Experimental results indicate that it has good compression performance, especially when the transition probabilities are time-varying