Coherent optical pattern recognition

Pattern-recognition systems, techniques, and applications using coherent optical systems are reviewed. Many optical pattern-recognition system architectures exist that include time-domain optical correlators and the optical joint transform correlators and refinements in the original optical matched spatial filter synthesis processor. Advanced optical pattern-recognition systems are also described such as hybrid optical/digital processors and diffraction-pattern sampling systems using specially shaped Fourier plane detector arrays. The optical space-variant pattern-recognition systems described are examples of the growing repertoire of operations now achievable in optical computers.     

Simulating power electronic systems—A new approach

The time-varying topology created by the switch-mode operation of power semiconductor devices in energy conversion systems presents difficulties in analysis. Presently available methods for simulating the behavior of these systems include the use of the digital computer, the conventional analog computer, and the breadboard. A new philosophically distinct technique called "parity simulation" produces a topologically isomorphic transformation of the system under study; that is, it exhibits a 1:1 correspondence, or parity, with the structure of the actual network. A parity simulator utilizes terminal equivalent representations of network elements. The microcomputer based interface is highly user oriented. Nonlinear or time-varying element parameters are easily incorporated. Several simulation examples are presented.     

A class of predictive analog filters for sensor signal processingand control instrumentation

A class of analog continuous-time filters is introduced, having predictive properties for specified narrow-band signal models, such as low-order polynomials or sinusoids. Such filters are designed by using model transfer functions designed in the discrete-time domain. Z-to-s-domain mapping is done using the inverse bilinear transformation. The analog filters are implemented with active-RC structures, using the state-variable structure for biquads and a single-op-amp structure for real poles and zeros. The application examples include a filter for zero-crossing detectors, polynomial predictors for sensor signal smoothing, and an optimized sixth-order ramp-tracking filter for anti-aliasing and anti-imaging in digital signal processor (DSP) systems where high selectivity is required     

Analysis of Digital Errors in Nonlinear PCM Systems

The effect of digital errors in linear pulse code modulation (PCM) systems has been considered by several authors for channels with independent errors. In this paper we present a general approach of analyzing digital errors in linear and nonlinear PCM systems with arbitrary channels. The examples given in this paper cover the different standard nonlinear PCM systems and independent channel errors. The technique used for the analysis leads to the conclusion that there are PCM codes less sensitive to digital errors than the standard binary folded PCM code. An example of such a PCM code is given in this paper.     

Discrete representation of signals

In processing continuous-time signals by digitalmeans, it is necessary to represent the signal by a digital sequence. There are many ways other than periodic sampling for obtaining such a sequence. The requirements for such representations and some examples are discussed within the framework of simulating linear time-invariant systems. The representation of digital sequences by other digital sequences is also discussed, with particular emphasis on the use of such representations to implement a nonlinear warping of the digital frequency axis. Some applications and hardware implementation of this digital-frequency warping are described.     

用虚拟技术分析和设计数字电路

本文介绍EWB（虚拟电子工作台）软件在分析和设计数字电路中的应用,列举了用该软件分析或设计组合电路、时序电路、脉冲电路及数字系统的几个实例。     

Emerging mobile and personal communication systems

The market demand for wireless communications has been demonstrated by the rapid growth of different second-generation wireless technologies that are optimized for particular applications and environments. Obvious examples include: digital cellular systems like GSM, ADC, PDC,and DCS1800 for widespread vehicular and pedestrian services, and cordless telecommunication systems based on CT2, DECT, and PHS standards for residential, business, and public cordless access applications. Efforts are also underway to consolidate the various radio environments and applications under a single standard for third generation wireless, i.e., FPLMTS. In the area of personal mobility, with the recent availability of “personal” numbers in various countries (e.g., 500 numbers in the United States), many fixed network operators are starting to offer such personal mobility services as “personal number service” and “number portability”. These services represent initial stages of full personal mobility that will be provided by UPT in both wireline as well as wireless environments. The expected heavy demand for PCS in the United States and the underlying market/regulatory forces are driving the standardization and business activity. A number of air interface standards for the 1900 MHZ PCS band are being considered, which are based on TDMA, CDMA, and FDMA technologies singly or in combination. Many are variations of existing digital cellular and cordless telecommunications technologies. PCS networking standards are also being developed; both for standalone systems and for systems that will utilize public switched network capabilities     

微型通用串行总线的研究动态和应用及传输模型

微型通用串行总线(Micro-USB)作为PC机及各类数码产品的主流接口,因其具有携带方便、传输速度快、易于扩展、总线供电等优点,尤其是其特殊的传输线模型,使其在通用计算机、嵌入式系统为主要应用领域的各种数字系统和设备中得到了广泛的应用,并获得制造商及用户的高度认可,具有广阔的发展前景.     

A real-time language for industrial process control

Industrial computer control systems require the economical production of efficient software including executive systems, maintenance programs, and both special and general purpose application programs for direct digital control. Moreover, the hardware configuration varies considerably from the single dedicated control computer to a general purpose multicomputer system. RTL, a real-time language developed cooperatively with industrial suppliers and users specifically for industrial control, is described with emphasis on those features peculiar to applications such as dedicated direct digital control, combined direct and supervisory control, operator interfaces, and interaction with plant management computer systems. The use of RTL for the production of special purpose executive systems and general purpose application programs for direct control, startup, etc., is emphasized. Details of the language discussed with examples include its file structure for communication of data bases between independent programs, and a variety of data types including character codes, strings, labels, lists, peripheral variables, and data structures. Peripheral variables are variables in the language associated with hard-ware features of the central processor and its input-output devices such as registers, interrupts, error indicators, and addresses all of which may be referenced in the language. Regular and peripheral variable data structures--combinations of different types of variables--are included and ease considerably the burden of real-time programming. The organization and performance of the existing compiler for RTL is explained.     

Microprocessors and digital ICs for motion control

This paper reviews the developments in microprocessors and digital ICs with a special attention to applications to motion control. First, the use of microprocessors and digital ICs in the control of electric motor drives is considered. General-purpose microprocessors and microcontrollers are then presented with emphasis on features that are necessary for the implementation of real-time control systems. High-performance advanced processors such as digital signal processors (DSPs), reduced-instruction-set computing (RISC) processors, and parallel processors are studied. Development and debugging tools required for developing sophisticated microprocessor-based control systems are considered. The capabilities of application-specific integrated circuits (ASICs) in motion control and their design process are examined. Typical application examples illustrating research work in digital motion control using microprocessors and digital ICs are presented. The potentials of new devices are considered for application to high-performance drive systems. Trends for future development of the microprocessor technology for motion control applications are projected     

Video conferencing systems

In this paper several video conferencing systems are discussed. These include single person-camera, voice-switched, split-screen, continuous presence, and virtual space systems. Special emphasis is placed on the more recent video conferencing systems, i.e., the continuous presence and the virtual space systems. The role of digital signal processing in the video conferencing environment is discussed. The interaction between service definition, the video conferencing system, and the digital signal processing requirements is highlighted.     

Bioinspired Artificial Eyes: Optic Components,Digital Cameras,and Visual Prostheses

The diverse vision systems found in nature can provide interesting design inspiration for imaging devices, ranging from optical subcomponents to digital cameras and visual prostheses, with more desirable optical characteristics compared to conventional imagers. The advantages of natural vision systems include high visual acuity, wide field of view, wavelength‐free imaging, improved aberration correction and depth of field, and high motion sensitivity. Recent advances in soft materials, ultrathin electronics, and deformable optoelectronics have facilitated the realization of novel processes and device designs that mimic biological vision systems. This review highlights recent progress and continued efforts in the research and development of bioinspired artificial eyes. At first, the configuration of two representative eyes found in nature: a single‐chambered eye and a compound eye, is explained. Then, advances in bioinspired optic components and image sensors are discussed in terms of materials, optical/mechanical designs, and integration schemes. Subsequently, novel visual prostheses as representative application examples of bioinspired artificial eyes are described.     

Digital modulation techniques for mobile and personal communicationsystems

The paper describes in detail various digital modulation techniques for mobile and personal communication systems. Among others, these include π/4-shift quadrature phase-shift keying (QPSK), used in the second generation digital cellular mobile systems in North America and Japan, and Gaussian minimum-shift keying (GMSK), employed in the GSM system in Europe. It then briefly discusses the current research activities in modulation schemes for future systems     

A simulation tool for dynamically reconfigurable field programmablegate arrays

The emergence of static memory-based field programmable gate arrays (FPGAs) that are capable of being dynamically reconfigured, i.e., partially reconfigured while active, has initiated research into new methods of digital systems synthesis. At present, however, there are virtually no specific CAD tools to support the design and investigation of digital systems using dynamic reconfiguration. This paper reports on an investigation of new CAD tools and the development of a new simulation technique, called dynamic circuit switching (DCS), for dynamically reconfigurable systems. The principles of DCS are presented and examples of its application are described     

数字邻频双工器在CMMB 发射系统的应用

在无线发射系统频率资源稀缺和发射塔安装条件受限的情况下,CMMB发射系统可采用数字邻频双工器将CMMB信号与模拟电视信号无损耗地合成后共用一副天线发射。阐述数字邻频双工器的工作原理及其在金湖发射台的应用,并说明数字邻频双工器的安装、使用注意事项。     

Entwurf gemischt analog-digitaler Systeme

Today mainly submicron CMOS and BiCMOS technologies are used for the design of mixed analogue-digital applicationspecific integrated circuits (ASIC). This allows to integrate complete systems. Overall system costs are reduced and the reliability of the complete system can be improved. Today’s electronic systems often contain sensors to convert non-electric signals followed by electronic amplifiers, filters, analogue-to-digital converters and digital signal processing. The advantages of analogue and digital signal processing can be integrated on a single IC and for some applications it is even possible to include the sensor on the silicon chip.     

A digital library for biomedical imaging on the Internet

Traditional medical image management systems, such as picture and archiving communication systems, are based on specialized workstations and closed systems architecture. Internet technology is being explored for the efficient and cost-effective distribution of biomedical images. This article discusses new issues of a digital library for medical imaging, presents two different architectures for a Web-based medical imaging library, and illustrates their utilization with implemented examples     

R&D activities on wireless systems in China

Various wireless systems and the research preceding their practical use in China are described. The topics discussed include research establishments, research and development projects underway, challenges inherent to digital radio, and expansion opportunities afforded by satellite communications     

Chaotic frequency hopping sequences

This letter describes a novel family of frequency hopping sequences generated by chaotic systems. The sequences give a uniform spread over the entire frequency bandwidth. In addition to having good Hamming correlation properties, they possess ideal linear span. The sequences produce almost as good performance as random hopping patterns when used in frequency hopping code-division multiple-access (FH/CDMA) systems. Many numerical examples based on a digital chaos generator are presented     

The bilinear transformation

The bilinear transformation (BLT) is useful to instrumentation and design engineers in many settings. Two examples are: in the modeling of continuous-time (CT) systems via digital computer and in the design of digital infinite-impulse-response filters that are to have response characteristics similar to those of a selected CT filter. An introduction to the BLT is presented along with a discussion of how to obtain the BLT numerically