Long term phase noises are characterized for network synchronization using two time domain measurement techniques: the Maximum Time Interval Error (MTIE) and Time Variance (TVAR). First, the characteristics of previously measured fiber delay variations are evaluated. The diurnal and annual delay variations and the long term noise feature of random walk phase modulation are well represented by the TVAR technique. The delay variation due to the AU pointer operation is then measured using commercial SDH demultiplexing equipment and compared with the simulation result; the simulation result agrees well with the experimental result. The delay variation in the SDH equipment is simulated using the thermal fiber delay variation measured in the actual network as the input phase of the equipment. It is shown that the SDH equipment sometimes generates delay steps of 617ns, which are larger than the normal pointer operations of 154ns. The long term delay variation, periods over 107s, due to the threshold spacing between the positive and negative stuffing is described. We also show that TVAR is suitable for evaluating the phase noise feature and MTIE can clearly show the peak value of phase noise. The long term phase noises evaluated in this paper are the dominant sources that degrade network synchronous performance. The results of this paper will be useful in designing the equipment synchronous specification.

We are studying a novel concept of the on-line hospital system using a virtual environment called Hyper Hospital," the Hyper Hospital" is a medical care system which is constructed in a distributed manner to the electronic information network using virtual reality (VR) as a human interface. In the present report, we studied the physiological and psychological responses of healthy subjects induced by the usage of the VR in terms of fatigue. Twenty healthy young male subjects were exposed to the virtual reality system and they performed some psychological tasks with a virtual nurse for 30 minutes. Several parameters of physiological, psychological, and subjective fatigue were measured. None of the physiological or psychological parameters such as urinary catecholamine release, ECG, etc. showed significant fatigue induced by our VR system. However, by using a standard questionnaire, some kinds of subjective fatigue were noted and they were thought to be indicating a direction of improvement for our VR system.

Error-correction techniques can be used to reduce the required carrier-to-noise ratio (C/N) in digital satellite news gathering (SNG) systems. The required e.i.r.p. of a digital SNG terminal is smaller than that of conventional analog SNG RF terminals. In this paper, a Ku-band portable SNG RF terminal using a flat antenna is proposed to make the best use of these digital systems. This portable terminal uses 16 planar microstrip subarray antennas, each with a solid-state power amplifier (SSPA) mounted on its backside. The proposed RF terminal is distinctly different from a conventional RF terminal with a parabolic antenna in two ways; it is portable and it has electronic tracking capability. Electronic antenna tracking reduces the terminal setup time because precise alignment of the antenna with the satellite is not required. This paper first describes the system concept and discusses the design concept. Secondly, it then explains phase shifters and feedback loops for electronic tracking. The tracking performance of a feedback system using four subarrays is also presented with some comparisons between theoretical and measured results. Experimental results for the low side-lobe flat antenna and the SSPAs are then presented. These are the most important components of the system. The flat antenna meets the design objectives specified by ITU-R Recommendations. By orthogonally exciting the rectangular patch antenna, the flat antenna is capable of operating dual polarizations and dual frequencies (transmit/vertical polarization: 14GHz; receive/horizontal polarization: 12GHz). The SSPAs have an efficiency of 21% and an output power of 5W.

This paper presents the results of a study made to determine the line length coverage of the high-bit-rate digital subscriber line (HDSL) present in NTT's local networks. The HDSL carries one bi-directional 784 kbit/s channel per pair and supports the digital interface at 1544kbit/s by using two cable pairs. The primary purpose of this study is to estimate the range limits for candidate transmission schemes considering line installation conditions, and to determine the most promising transmission scheme and its feasibility given the environment of NTT's local networks. Pulse amplitude modulation (PAM) and quadrature amplitude modulation (QAM) transmission schemes are compared for HDSL implementation. It is shown that 2B1Q-PAM and 16-QAM generally achieve better performance than the more complicated PAM and QAM given the presence intra-system crosstalk interference (interference between identical transmission systems). The range limits determined by inter-system crosstalk interference (interference between different transmission systems) with basic rate access (BRA) implementing a burst-mode transmission method are also estimated. This paper concludes that 2B1Q-PAM achieves the best overall performance in NTT's local networks. A feasibility study of 192-6144 kbit/s transmission is also described.

In current teleteaching systems, video conferencing systems have been used to transmit a motion video from a teacher's site. A video that captures a teacher or his or her chalkboard is transmitted to a remote site through a communication channel. Since the resolution of the video is not very high, a camera captures either a teacher or a chalkboard, but not both at the same time. Thus, remote students have difficulty in obtaining realistic sensation. Another approach to realizing teleteaching is to use a computer-based desktop conferencing system that supports a motion video and a computer-based shared chalkboard. In this approach, a teacher has to use a mouse or a handwriting tablet for input, and therefore cannot use a real chalkboard. Moreover, the teacher cannot use gestures to remote students. This paper presents a multimedia teleteaching system that integrates an electronic whiteboard with a multimedia desktop conferencing system for providing realistic sensation to remote students. The system provides two-way communication of a video and a computerized chalkboard. A teacher uses an electronic whiteboard as a real whiteboard using direct manipulation, and transmits his or her gestures to remote students by using video communication. The system provides dual views; one view is for teacher's gestures and the other is for chalkboard contents. By providing the dual views, the system can transmit teacher's gestures all the time. Since chalkboard contents are processed and displayed as computer data, students can see them clearly. With the computerized chalkboard, a teacher or a student can zoom contents, input data written on a paper using a scanner, or add annotation.

In the future satellite broadcasting system in 21GHz band, the rainfall attenuation is a most significant problem. To solve this problem, the hierarchical transmission systems have been studied. This paper analyzes the performance of the hierarchical modulation scheme from the view point of power assignment in the presence of the rainfall attenuation. This paper shows an optimum power assignment ratio to maximize the spectral efficiency and the signal-to-noise ratio of received image, and these optimum ratio is varied with the measure of system performance.

Mixed-signal LSIs promise to permit increased levels of integration, not only in voiceband but also in multi-GHz-band applications such as wireless communications and optical data links. This paper reviews the evolution of mixed-signal communications LSIs and discusses some of their design problems, including device noise and crosstalk noise. In the low-power and low-voltage designs emerging as new disciplines, the target supply voltage for voiceband LSIs is around 1 V, and even GHz-band circuits are approaching 2 V. MOS devices are expected to play an important role even in the frequency range over 100 MHz, in the area of wireless or optical communications circuits.

This paper presents a method, called reduced scan shift, which generates short test sequences for full scan circuits. In this method, scan shift operations can be reduced, i.e., not all but part of flip-flops (FFs) are controlled and observed. This method, unlike partial scan methods, does not decrease fault coverage. In the reduced scan shift, test vectors for the combinational part of a circuit are fistly generated. Since short test sequence will be obtained from the small test vectors set, test compaction techniques are used in the test vector generation. For each test vector in the obtained test set, it is found which FFs should be controlled or observed. And then a scan chain is configured so that FFs more frequently required to be controlled (observed) can be located close to the scan input (output). After the scan chain is configured, the scan shift requirement is examined for the essential faults of each test vector. Essential fault is defined to be a fault which is detected by only one test vector but not other test vectors. The order of test vectors is carefully determined by comparing the scan control requirement of a test vector with the scan observation requirement of another test vector so that unnecessary scan shift operations only for controlling or observing FFs can be reduced. A method of determining the order of test vectors with state transition is additionally described. The effectiveness of the proposed method is shown by the experimental results for benchmark circuits.

An Ultra-high-speed (higher than 60 MHz) Viterbi decoder VLSIC with coding rates from one-half to fifteen-sixteenth and a constraint length of seven for forward error correction (FEC) has been developed using 0.8-µm semicustom CMOS LSIC technology and a newly developed high-speed ACS circuit. To reduce power consumption of the one-chip Viterbi decoder, a universal-coding-rate scarce-state-transition (SST) Viterbi decoding scheme and low-power-consumption burst-mode-selection (BMS) path memory have been proposed and employed to the developed VLSIC. In addition, a new maximum-likelihood-decision (MLD) circuit for the SST Viterbi decoder has been developed. The total power consumption of the developed chip is reduced to 75% of the conventional one and the developed Viterbi decodar VLSIC achieves a maximum operation speed of 60 MHz. It achieves near theoretical net coding-gain performance for various coding rates.

This paper describes the circuit design and experimental results of a video-rate 10-b analog-to-digital converter (ADC) suitable for consumer video products, such as high-definition TV sets. Triple-stage conversion scheme combined with two new conversion methods, "Dynamic Sliding Reference Method" and "Triangular Interpolation Method," and an internal Bi-CMOS Sample/Hold circuit have been developed. These conversion methods require no adjustment circuit to fit reference voltages between conversion stages and realize small active area. As a result, a maximum conversion frequency of 16 MHz, acceptable SNRs of 56 dB and 48 dB for 10 kHz and 8 MHz input frequency respectively and small DNLE of 0.75 LSB have been achieved. This ADC is fabricated with 1.2 µm Bi-CMOS technology and integrates very small number of bipolar transistors of 2 K on a small active area of 2.52.7 mm2 and consumes 350 mW.

In this paper, chaos synchronization in coupled discrete-time dynamical systems is studied. Computer results display the interesting synchronization behaviors in the mutually coupled systems. As possible applications of chaos synchronization, parameter estimations and secure communications are proposed. Furthermore, a modified OGY method is given, which converts a chaotic motion into a periodic motion.

In an image fiber containing a large number of cores, a certain class of crosstalk has been found to decrease with the distance along the fiber axis. This crosstalk is absolutely distinguished from the usual crosstalk that increases with the distance. A theoretical model is presented based on the power transfer between three groups of modes supported by each core. The process of power transfer is described by coupled power equations. Values of the coupling coefficients can be determined from the measurement of the crosstalk. The equations are solved numerically for the transmission of a point image. The results are in good agreement with measurement results.

This paper discusses the characteristics of the nonlinearly amplified spread–spectrum (SS) signals. We evaluate the symbol error–rate performance with the conventional receiver, changing the length of the spreading sequence. In addition, we also propose the receiver with MLSE. The configuration of the MLSE for the nonlinearly amplified signals is generally complicated; however we show that the complexity of the MLSE receiver can be reduced, as the number of required reference sequences in the receiver for an SS signal is small. As the result, it is shown that the error rate performance of the nonlinearly amplified SS signal can be improved by this proposed receiver and that the degradation caused by the nonlinear amplification can be made negligibly small with a sufficiently long spreading sequence.

Multimedia services based on broadband ISDN (B-ISDN) technology need a network architecture that satisfies the requirements of users, carriers, and vendors. This paper describes a new network architecture for B-ISDN service control and management based on INA. We list general requirements, and present implementation issues of INA. A network architecture and main components, which resolve implementation issues, is then proposed. We also describe a video-on-demand service based on our proposed architecture.

A particle trajectory estimation method from far electromagnetic fields are discussed in this paper. Authors have already presented a trajectory estimation method for single particle system and good agreements between a source particle trajectory and an estimated one have been obtained. For this, this paper discusses twin particles system as an examples of multi-particles systems for simplicity. First of all, it is pointed out that far electromagnetic fields from the twin particles system show quite different aspect from the single particle system using an example, radiation patterns produced by two particles which carry out circular motion. This result tells us that any trajectory estimations for general multi-particles system are almost impossible. However, it is shown that when the distance between the particles is small, the estimation method for the single particle system can be applied to the twin particles system, and that twin particles effects appear as disturbance of estimated trajectory.

The Paper describes a comprehensive system for image recognition based on the technique of boundary spline matching. It can be used to accurately compare two objects and determine whether they are identical or not. The result is extremely satisfactory for comparing planar objects as revealed from the illustrative example presented in this paper. In real practice, images of the same scene object can easily be considered as belonging to different objects if the objects are viewed from different orientations and ranges. Thus, image recognition calls for choosing the proper geometric transformation functions to match images as the initial step so that recognition by template matching can be done as the second step. However, there are a large variety of transformation functions available and the subsequent evaluation of transformation parameters is a highly nonlinear optimisation procedure which is both time consuming and not solution guaranteed, making real-time estimation impossible. This paper describes a new method that represents the boundary of each of two image objects by B-splines and matches the B-splines of two image objects to determine whether they belong to the same scene object. The algorithm developed in this paper concentrates on solving linear simultaneous equations only when handling the geometric transformation functions, which takes almost negligible computational time by using the standard Gaussian Elimination. Representation of the image boundary by B-splines provides a flexible and continuous matching environment so that the level of accuracy can be freely adjusted subject to the requirement of the user. The non-linear optimisation involves only one parameter, i.e. the starting point of each boundary under B-spline simulation, thus guaranteeing a very high speed computational system. The real time operation is deemed possible even there is a wide choice of proper transformation functions.

This paper describes a new method for pose estimation of human face moving abruptly in real world. The virtue of this method is to use a very simple calculation, disparity, among multiple model images, and not to use any facial features such as facial organs. In fact, since the disparity between input image and a model image increases monotonously in accordance with the change of facial pose, view direction, we can estimate pose of face in input image by calculating disparity among various model images of face. To overcome a weakness coming from the change of facial patterns due to facial individuality or expression, the first model image of face is detected by employing a qualitative feature model of frontal face. It contains statistical information about brightness, which are observed from a lot of facial images, and is used in model-based approach. These features are examined in everywhere of input image to calculate faceness" of the region, and a region which indicates the highest faceness" is taken as the initial model image of face. To obtain new model images for another pose of the face, some temporary model images are synthesized through texture mapping technique using a previous model image and a 3-D graphic model of face. When the pose is changed, the most appropriate region for a new model image is searched by calculating disparity using temporary model images. In this serial processes, the obtained model images are used not only as templates for tracking face in following image sequence, but also texture images for synthesizing new temporary model images. The acquired model images are accumulated in memory space and its permissible extent for rotation or scale change is evaluated. In the later of the paper, we show some experimental results about the robustness of the qualitative facial model used to detect frontal face and the pose estimation algorithm tested on a long sequence of real images including moving human face.

This letter proposes the method using a filter to suppress the very large noise obstructive to the radio pulsar surveys. This noise suppression filter is constructed from the average of the amplitude spectrum of pulsar signal for each channel. Using this method, the dispersion measure, one of the important parameters in the pulsar surveys, can easily be extracted.

A new polarization splitter at optical frequencies is proposed. The basic structure of the device is a tapered velocity coupler which is composed of a straight and a dimensionally tapered slab waveguide on a LiNbO3 substrate. The numerical results obtained with the finite difference method indicate that extinction ratios of polarization less than 2% for both TE and TM modes are possible of realization under moderate control voltages and that the splitting characteristics are stable over a wide range of frequencies.

We are developing GENESIS, a new seamless total environment for designing, developing, installing, and operating various types of telecommunication networks as extremely large distributed processing applications in the future network integrated by ATM. Similar uniform architectures for quick introduction and easy management of service or operation applications have been proposed, such as by TINA, but there has been insufficient study on how to operate and con figure those applications. This paper discusses the implementation model and execution environment in GENESIS from the viewpoint of flexible operation according to network conditions. The implementation model can describe detailed configurations under various conditions on design or operation, independently of the execution environment. To achieve the goals of GENESIS, our execution environment provides message handling functions and a transparent interface for controlling network resources independently of the configuration, and dynamic reconfiguration functions that are independent of the execution. This paper also reports the prototype system GENESIS-1. The GENESIS-1 message handling mechanism and the effect of the reconfiguration functions are described.