时序险象基本判据

本文利用几个定义和限制,得到了一外部激励x,n个状态变量电位异步时序电路的任一状态的一般逻辑表达式特性方程.将此方程与状态表结合,导出了产生时序险象时的状态变量数和稳定状态数所满足的条件;给出了对时序险象研究特别有用的基本判定法则.     

时序险象基本判据

本文利用几个定义和限制，得到了一外部激励ｘ，ｎ个状态变量电位异步时序电路的任一状态的一般逻辑表达式－特性方程、将此方程与状态表结合导出了产生时序险象时的状态变量数和稳定状态数所满足的条件；给出了对时序险象研究特别有用的基本判定法则。     

参数不确定混沌系统的自适应同步控制

用同步误差最小化的自适应方法与替代状态变量的同步法相结合,来研究混沌系统的同步控制,并且估计驱动系统的未知参数,所需的信息只要一个这个系统的状态变量.未知参数可能显含在这个已知状态变量的发展方程中,也可能不显含在这个发展方程中,只要满足一定的条件,都可以实现参数估计与系统的混沌同步.以Lorenz系统为例,进行了具体分析与数值模拟,所得结果说明该控制策略是有效的.     

基于求解校验序列的(n,1,m)卷积码盲识别

伴随信息对抗和智能通信的快速发展,信道编码识别已成为信息恢复领域一个重要的课题。针对(n,1,m)卷积码盲识别问题,该文提出一种新的识别方法,该方法首先提出了校验序列的概念,通过改进后的矩阵模型求解出校验序列,进而由校验序列构造方程求解出生成多项式矩阵,完成识别。最后,通过实例仿真验证了该方法能够在参数n和码字起始位置都未知情况下有效识别出(n,1,m)卷积码。     

基于删余等效的高码率卷积码的低复杂度译码方法

根据删余卷积码具有较低的译码复杂度这一特征,提出了一种适用于普通高码率卷积码的低复杂度译码方法。通过多项式生成矩阵表示法,推导了删余卷积码的等效多项式生成矩阵,给出了等效多项式生成矩阵的计算准则。在分析删余卷积码与相同码率普通卷积码的等效关系和区别的基础上,提出了高码率卷积码的删余等效并给出了计算高码率卷积码删余等效后原始码和删余矩阵的方法。以原始码和删余矩阵构成的删余等效结构为译码基础,实现了高码率卷积码的低复杂度译码,其译码复杂度与原始码相当。仿真结果表明,删余等效译码方法相对于正常译码方法,其性能损失很小。     

卷积码的神经网络编码方法

根据卷积码的编码原理以及卷积码编码器的结构特点,结合BP神经网络的结构特征和工作原理,并将它们有机地结合起来,研究了卷积码的BP神经网络编码方法。利用BP神经网络输入和输出之间的非线性映射关系实现卷积码编码器的编码功能,为卷积码编码提供一条有效可行的实现途径。     

卫星通信中常用卷积码的识别方法研究

针对卫星通信系统中常用的系统卷积码和非系统卷积码进行识别研究,建立基于基本监督矩阵的识别方法,推广了码字同步方法适应各种编码率的卷积码起始位置的判定,给出了BPSK和QPSK调制下的相位模糊的处理方法,实现了卫星通信系统中常用卷积码的识别结果的判定,为卷积码识别技术的工程应用提供了技术基础。     

卷积码的Matlab仿真及其性能研究

信道编码是数字通信系统中的重要组成部分,他是保证信号可靠传输的一种重要方式。卷积码以其优越的性能被广泛使用在数字通信系统中。(2,1,7)卷积编码已经是国际卫星通信的标准。介绍了卷积码的特点以及卷积码的编码、译码原理,主要讨论了卷积码的Viterbi译码及其算法,最后通过Matlab仿真,对卷积码的性能进行了理论分析和实验仿真。     

维特比译码及其纠错能力的研究

在现代数字通信系统中,纠错编码技术的作用是很重要的,本文以卷积码为例,分析了纠错码的原理,并利用matlab实现了卷积码的编码和解码,对卷积码纠错原理进行了仿真研究。     

电力线通信系统中卷积码和Viterbi译码的FPGA设计实现

阐述了电力线通信系统中卷积码及其Viterbi译码的信道编码方法,给出了（2,1,6）卷积码编译码的设计以及采用VerilogHDL硬件描述语言完成卷积码编译码的FPGA实现方法。     

The dynamics of group codes: state spaces, trellis diagrams, andcanonical encoders

A group code C over a group G is a set of sequences of group elements that itself forms a group under a component-wise group operation. A group code has a well-defined state space Σ_k at each time k. Each code sequence passes through a well-defined state sequence. The set of all state sequences is also a group code, the state code of C. The state code defines an essentially unique minimal realization of C. The trellis diagram of C is defined by the state code of C and by labels associated with each state transition. The set of all label sequences forms a group code, the label code of C, which is isomorphic to the state code of C. If C is complete and strongly controllable, then a minimal encoder in controller canonical (feedbackfree) form may be constructed from certain sets of shortest possible code sequences, called granules. The size of the state space Σ_k is equal to the size of the state space of this canonical encoder, which is given by a decomposition of the input groups of C at each time k. If C is time-invariant and ν-controllable, then |Σ_k|=Π_1⩽j⩽v|F_j/F _j-1|^j, where F₀ ⊆···⊆ Fν is a normal series, the input chain of C. A group code C has a well-defined trellis section corresponding to any finite interval, regardless of whether it is complete. For a linear time-invariant convolutional code over a field G, these results reduce to known results; however, they depend only on elementary group properties, not on the multiplicative structure of G. Moreover, time-invariance is not required. These results hold for arbitrary groups, and apply to block codes, lattices, time-varying convolutional codes, trellis codes, geometrically uniform codes and discrete-time linear systems     

Counterexample in the least-squares inverse stabilisation of 2D recursive filters

A counterexample is presented disproving the conjecture that the planar least-squares inverse of a 2-variable polynomial is devoid of zeros when both variables are inside or on the unit circle.     

基于敏感位置识别的状态化简技术研究

 模型构建是模型检验的基础,在微控制器代码模型构建过程中面临状态爆炸的问题。由于生成模型的状态数量与代码规模密切相关,通过简化代码可以有效缩减生成的状态数量。该文提出了敏感变量和敏感位置的概念,并以此为基础提出了结合子程序摘要信息的敏感位置识别算法;该算法从待验证的性质出发,提取敏感变量,识别代码中与敏感变量相关的敏感位置;模型构建过程中只对敏感位置对应代码进行建模,从而实现对模型状态的缩减。实验结果表明所提的方法能够有效缓解微控制器代码模型生成过程中的状态爆炸问题。     

LUT应用于快速确定CDMA长码状态的性能分析

介绍了一种基于LUT表的CDMA长码状态快速算法,并与传统的MSRG结构或SSRG结构CDMA长码状态算法进行了比较和分析。通过将部分运算结果预先存储在LUT表中,新方法将巨大的运算量(最多可能出现242-1次的长码发生器运算)降为不超过4242次长码发生器操作和42次4242阶矩阵模2相乘运算,极大地提高了确定当前时刻长码状态的实时性能。     

DPCM encoding of regenerative composite processes

Fixed (nonadaptive) and forward adaptive differential pulse code modulation of regenerative composite sources is investigated. In the fixed code, an approximate formula is given for the optimal value of the prediction coefficient. This is then used as an initial guess to optimize the code (predictor and quantizer) through a numerical method. In the forward adaptive scheme, the state of the switch in the composite source is estimated using a MAP sequence estimation algorithm, and the code is then matched to the mode process corresponding to the estimated switch state. The performance of the two systems is evaluated with quantizers of 4, 8, and 16 levels. The results show that the forward adaptive scheme significantly outperforms optimized fixed DPCM in the sense of mean-squared error. Stochastic stability of the code is also established for the fixed DPCM scheme as well as for an adaptive scheme which receives the switch state as side information     

Design of 2-D recursive digital filters satisfying prescribed magnitude and constant group delay response

Generation of the 2-variable very-strictly-Hurwitz polynomial (VSHP) using properties of derivatives of even or odd parts of Hurwitz polynomials and their applications in designing 2-D recursive digital filters satisfying prescribed magnitude and constant group delay response is described.     

Minimal syndrome formers for group codes

Given a controllable group code, it has been shown by Forney (1970, 1973), Trott, and Loeliger (1994) that it is possible to construct a canonical encoder whose state space coincides with the canonical state space of the code, that is the essential element determining the minimal trellis of the code. The construction of such an encoder is based on the concept of controllability granule. In this paper the construction of a syndrome former for an observable group code is proposed. This syndrome former exhibits analogous properties of the above mentioned canonical encoder and, in particular, its state space coincides with the canonical state space of the code. The proposed construction is based on the concept of observability granule, introduced by Forney and Trott (1993), which dualizes the concept of controllability granule. Similarly to what happens for the encoders, each observability granule produces a map and all these maps together provide the syndrome former. The main difference is that here, to achieve the right state-space dimension, the automata associated with these maps do not evolve independently from each other, but are coupled according to a triangular structure     

Secure FSM-based arithmetic codes

Recently, arithmetic coding has attracted the attention of many scholars because of its high compression capability. Accordingly, in this paper, a method that adds secrecy to this well-known source code is proposed. Finite state arithmetic code is used as source code to add security. Its finite state machine characteristic is exploited to insert some random jumps during source coding process. In addition, a Huffman code is designed for each state to make decoding possible even in jumps. Being prefix-free, Huffman codes are useful in tracking correct states for an authorized user when he/she decodes with correct symmetric pseudo-random key. The robustness of our proposed scheme is further reinforced by adding another extra uncertainty by swapping outputs of Huffman codes in each state. Several test images are used for inspecting the validity of the proposed Huffman finite state arithmetic coding (HFSAC). The results of several experimental key space analyses, statistical analyses, key and plaintext sensitivity tests show that HFSAC with a little effect on compression efficiency provides an efficient and secure method for real-time image encryption and transmission.     

On (n, n-1) convolutional codes with low trellis complexity

We show that the state complexity profile of a convolutional code C is the same as that of the reciprocal of the dual code of C in case that minimal encoders for both codes are used. Then, we propose an optimum permutation for any given (n, n-1) binary convolutional code that will yield an equivalent code with the lowest state complexity. With this permutation, we are able to find many (n, n-1) binary convolutional codes which are better than punctured convolutional codes of the same code rate and memory size by either lower decoding complexity or better weight spectra     

Bounds on the state complexity of codes from the Hermitian functionfield and its subfields

An upper bound on the minimal state complexity of codes from the Hermitian function field and some of its subfields is derived. Coordinate orderings under which the state complexity of the codes is not above the bound are specified. For the self-dual Hermitian code it is proved that the bound coincides with the minimal state complexity of the code. Finally, it is shown that Hermitian codes over fields of characteristic 2 admit a recursive twisted squaring construction