It was more than 10 years ago that the first map navigation system, as an example of invehicle information system, has appeared in the market in Japan. Today's navigation system has been improved to the level that the latest system has 10 micro-processors, 7 MBytes of memories, and 4 GBytes of external data storage for map database. From the viewpoint of the automobile driver, there are still some problems with the system. Major problems in general are a lack of traffic information, better human interface, and a need for cost-reduction. The introduction of application specific ICs (ASICs) is expected to make systems smaller, costless, and give higher speed response. Today's in-vehicle information systems are reviewed function by function to discover what functions need to be implemented into ASICs for future systems, what ASICs will be required, and what technology has to be developed. It is concluded that more integration technology is expected including high parformance CPUs, large capacity memories, interface circuits, and some analog circuits such as DA converter. To develop this technology, some, major problems such as power consumption, number of input/output signals, as well as design aid and process technology are pointed out.

In the present paper, we focus ourselves on the turning point (TP) algorithm proposed by Mueller and evaluate its performance when applied to a Gaussian signal with definite covariance function. Then the ECG wave is modeled by Gaussian signals: namely, the ECG is divided into two segments, the baseline segment and the QRS segment. The baseline segment is modeled by a Gaussian signal with butterworth spectrum and the QRS one by a narrow-band Gaussian signal. Performance of the TP algorithm is evaluated and compared when it is applied to a real ECG signal and its Gaussian model. The compression rate (CR) and the normalized mean square error (NMSE) are used as measures of performance. These measures show good coincidence with each other when applied to Gaussian signals with the mentioned spectra. Our results suggest that performance evaluation of the compression algorithms based on the stochastic-process model of ECG waves may be effective.

We propose a recognition method for HMM using a simultaneous generative histogram. Proposed method uses the correlation between two features, which is expressed by a simultaneous generative histogram. Then output probabilities of integrated HMM are conditioned by the codeword of another feature. The proposed method is applied to isolated digit word recognition to confirm its validity.

The performances of BPNN (neural network trained by back propagation) and PCANN (neural network which computes principal component analysis) for ECG data compression have been investigated from several points of view. We have compared them with an existing data compression method TOMEK. We used MIT/BIH arrhythmia database as ECG data. Both BPNN and PCANN showed better results than TOMEK. They showed 1.1 to 1.4 times higher compression than TOMEK to achieve the same accuracy of reproduction (13.0% of PRD and 99.0% of CC). While PCANN showed better learning ability than BPNN in simple learning task, BPNN was a little better than PCANN regarding compression rates. Observing the reproduced waveforms, BPNN and PCANN had almost the same performance, and they were superior to TOMEK. The following characteristics were obtained from the experiments. Since PCANN is sensitive to the learning rate, we had to precisely control the learning rate while the learning is in progress. We also found the tendency that PCANN needs larger amount of iteration in learning than BPNN for getting the same performance. PCANN showed better learning ability than BPNN, however, the total learning cost were almost the same between BPNN and PCANN due to the large amount of iteration. We analyzed the connection weight patterns. Since PCANN has a clear mathematical background, its behavior can be explained theoretically. BPNN sometimes generated the connection weights which were similar to the principal components. We supposed that BPNN may occasionally generate those patterns, and performs well while doing that. Finally we concluded as follows. Although the difference of the performances is smal, it was always observed and PCANN never exceeded BPNN. When the ease of analysis or the relation to mathematics is important, PCANN is suitable. It will be useful for the study of the recorded data such as statistics.

This paper describes our recent developments of ASICs for automotive multiplexing and data communications to implement in-vehicle networks. With the advancement of automotive electronics, there are ever growing needs for in-vehicle networks. One need is associated with solving the problem of an increasing number of electrical signal wires that inevitably accompany the increasing applications of automotive electronics. Another kind of need is concerned with sharing vehicle control data among several electronic control units such as engine, brake, suspension, and steering electronic control units to achieve an integrated vehicle control system for the purpose of obtaining higher performances in vehicle dynamics. In order to reduce the number of signal wires and share the control data, in-vehicle networks based on multiplexing and data communications are required. In this paper, two original communication protocols are presented to respectively cover low- and highi-speed multiplexing and data communications that are two most needed communication speed areas in our present and future automobiles. ASICs for the presented communication protoclos were designed and fabricated, using 2 µm COMS process. They have the chip size of 3.2 mm2.7 mm with 5,000 transistors and 6.9 mm4.9 mm with 18,000 transistors respectively for low- and high-speed multiplexing and data communications. An elaborate bus driver/receiver ASIC required for high-speed multiplexing and data communications was also designed and fabricated, using 35 V DC bipolar process. As one of its distinctive features, it can greatly suppress radio frequency noise radiated from a communication bus. It has the chip size of 4.8 mm3.8 mm that contains 570 device elements. The features of the protocols are given in detail with the descriptions of the developed ASICs.

Phase noise generation in varactor-tuned oscillators is analyzed by an asymptotic perturbation technique. It is found out that 1/f noise and AM noise are converted into phase noise by first- and higher-order nonlinearities of the varactor. The deduced formula can be utilized in CAD for circuit evaluation/optimization of varactor-tuned osicillators.

A new method for the compression of electrocardiographic (ECG) data is presented. The method is based on the orthonormal wavelet analysis recently developed in applied mathematics. By using wavelet transform, the original signal is decomposed into a set of sub-signals with different frequency channels corresponding to the different physical features of the signal. By utilizing the optimum bit allocation scheme, each decomposed sub-signal is treated according to its contribution to the total reconstruction distortion and to the bit rate. In our experiments, compression ratios (CR) from 13.5: 1 to 22.9: 1 with the corresponding percent rms difference (PRD) between 5.5% and 13.3% have been obtained at a clinically acceptable signal quality. Experimental results show that the proposed method seems suitable for the compression of ECG data in the sense of high compression ratio and high speed.

Electronics and automobiles were bound together by the introduction of emission regulations in the 1970's. The rapid progress of control technology and semiconductors that typify microcomputers has brought still closer relations between them. Without electronics, it would be impossible to realize features such as pursuit of comfort and environmental and safety measures which should be added to the automobile's fundamental features. In looking ahead to the future, the role of electronics in achieving electric automobiles and the ultimate goal of "automatic driving" is ever-increasing. Everyone knows that automobiles have become indispensable in our lives. In the future, the role of electronics will become increasingly important in order to evolve automobiles even further to allow harmonization with society.

A theoretical and experimental study of a thin card-sized antenna is presented. The method of moment with a wire-grid model is used to analyze this antenna. In order to validate numerical efficiency, measurements using Wheeler method are preformed on this antenna and its wire-grid models. The experimental and theoretical results are in good agreement if the wire conductivity is well chosen. And the noise reduction of measured Wheeler efficiency using least mean square method is also examined.

The relation between the radiation pattern and the dimension of the conducting box for a portable telephone is illustrated both theoretically and experimentally. The Galerkin-moment method using the Fourier series expansion for the surface current of the conducting box, which has a great advantage of having a high accuracy, is employed to obtain the radiation pattern. As an example of antennas, a quarter-wavelength monopole antenna having a sinusoidal current distribution is used. As a result, it is pointed out that the radiation pattern of a monopole antenna mounted on the box tends to tilt in a lower direction both in theory and in experiment as well. The relation between the radiation pattern and the location of the monopole antenna is also described. An asymmetrical, or distorted pattern is observed when the monopole antenna moves away from the center of the top plane.

A new superresolution technique is proposed for antenna pattern measurements. Unwanted reflected signals often impinge on the antenna when we measure it outdoors. A time-domain superresolution technique (a MUSIC algorithm) has been proposed to eliminate the unwanted signal for a narrow pass-band antenna. The MUSIC algorithm needs many snapshots to obtain a correlation matrix. This is not preferable for antenna pattern measurements because it takes a long time to obtain the data. In this paper, we propose to reduce a noise component (stochastic quantity) using the FFT and gating techniques before we apply the MUSIC. The new technique needs a few snapshots and saves the measurement time.

The invariant imbedding method combined with the time domain wave splitting technique is applied to the inverse problem for the telegraph equation t2u=(1/r)(pu)-btu+qu in a stratified half-space. The zeroth, second and fourth moments of the 3-D fields are used to reduce the three-dimensional problem to a set of one-dimensional problems. The imbedding equations for R0, R2 and R4, respectively the zeroth, second and fourth moments of the reflection operator, are derived. Numerical results for the reconstruction are presented using the reflection data on the surface.

This paper presents a method of translating natural language specifications of communication protocols into algebraic specifications. Such a natural language specification specifies action sequences performed by the protocol machine (program). Usually, a sentence implicitly specifies the state of the protocol machine at which the described actions must be performed. The authors propose a method of analyzing the implicitly specified states of the protocol machine taking the OSI session protocol specification (265 sentences) as an example. The method uses the following properties: (a) syntactic properties of a natural language (English in this paper); (b) syntactic properties introduced by the target algebraic specifications, e.g., type constraints; (c) properties specific to the target domain, e.g., properties of data types. This paper also shows the result of applying this method to the main part of the OSI session protocol specification (29 paragraphs, 98 sentences). For 95 sentences, the translation system uniquely determines the states specified implicitly by these sentences, using only (a) and (b) described above. By using (c) in addition, each implicitly specified state in the remaining three sentences is uniquely determined.

This paper presents an adaptive rate error control scheme for digital communication over time-varying channels. The cyclic code with majority-logic decoding is used in a cascaded way as an inner code to create a simple and powerful hybrid-ARQ error control scheme. Inner code is used only for error correction and the outer code is used for both error correction and error detection. When an error is detected, retransmission is required. The unsuccessful packets are not discarded as with conventional schemes, but are combined with their retransmitted copies. Approximations for the throughput efficiency and the undetectable error probability are given. A high reliability coupled with a simple high-speed implementation makes it suitable for high data rate error control over both stationary and nonstationary channels. Adaptive error control scheme becomes the best solution for time-varying channels when the optimum code is selected according to the actual channel conditions to enhance the system performance. The main feature of this system is that the basic structure of the encoder and decoder need not be modified while the error-correction capability of the code increases. Results of a comparative analysis show that the proposed scheme outperforms other similar ARQ protocols.

The technical trends of intelligent vehicles are discussed basing on the progress of technology of microelectronics, sensing and information processing. The concept of intelligent vehicles has started when the installation of computers on vehicles became possible in 1970s. The functions of computerized cars increased gradually with the progress of technology of microelectronics, sensing and information processing responding to the demands of the society. The first issues we had to challenge with the capability of electronic systems were the environmental and the energy resources problems. The R & D works of these purposes created many sophisticated computer control systems. Moreover, these works established the base of intelligent vehicles that contains various functions for drivability, safety, and information communications. On the other hand, many kinds of information and communication technology became useful to solve the issues on automobiles through infrastructure systems. United States, Europe, and Japan have started their own projects to realize such hierarchy management systems for traffic and vehicles. From the viewpoint of vehicle itself, it is the indispensable conditions and directions to implement the computer and telecommunications functions to the vehicles to establish clean, comfort, convenient, efficient and safe automobiles toward the next century.

In this article, the autocorrelation associative neural network that is one of well-known applications of neural networks is improved to extend its capacity and error correcting ability. Our approach of the improvement is based on the consideration that negative self-feedbacks remove spurious states. Therefore, we propose a method to determine the self-feedbacks as small as possible within the range that all stored patterns are stable. A state transition rule that enables to escape oscillation is also presented because the method has a possibility of falling into oscillation. The efficiency of the method is confirmed by means of some computer simulations.

This paper gives a model to explain one phenomenon found in the process of creative concept formation, i.e. the phenomenon that people often get trapped in some state where the mental world remains nebulous and sometimes suddenly make a jump to a new concept. This phenomenon has been qualitatively explained mainly by the philosophers but there have not been models for explaining it quantitatively. Such model is necessary in a new research field to study the systems for aiding human creative activities. So far, the work on creation aid has not had theoretical background and the systems have been built based only on trial and error. The model given in this paper explains some aspects of the phenomena found in creative activities and give some suggestions for the future systems for aiding creative concept formation.

A full-wave analysis for the scattering problem of infinite periodic arrays on dielectric substrates excited by a circularly-polarized incident wave is presented. The impedance boundary condition is solved by using the moment method in the spectral domain. Numerical results are given and scattering properties are discussed.

A two-cascaded image processing approach to enhance the subtle differences in X-ray CT image is proposed. In the method, an asymmetrical non-linear subfilter is introduced to reduce the noise inherent in the image while preserving local edges and directional structural information. Then, a subfilter is used to compress the global dynamic range of the image and emphasize the details in the homogeneous regions by performing a modular transformation on local image den-sities. The modular transformation is based on a dynamically defined contrast fator and the histogram distributions of the image. The local contrast factor is described in accordance with Weber's fraction by a two-layer neighborhood system where the relative variances of the medians for eight directions are computed. This method is suitable for low contrast images with wide dynamic ranges. Experiments on X-ray CT images of the head show the validity of the method.

A technique was developed to reduce ECG data efficiently within a controlled accuracy. The sampled and digitized data of the original waveform of an ECG is transformed in three major processes. They are the calculation of a beat-to-beat variation, a polygonal approximation and the calculation of the difference between consecutive node points. Then, an adaptive coding technique is applied to minimize redundancies in the data. It was demonstrated that the ECG waveform sampled in 200 Hz, 10 bit/sample, 5 µV/digit could be reduced with the bit reduction ratio of about 10% and within the reconstruction error of about 2.5%. A polygonal approximation method, called MSAPA, was newly developed as a modification of the well known method, SAPA. It was shown that the MSAPA gave better reduction efficiency and smaller reconstruction error than the SAPA, when it was applied to the beat-to-beat variation waveform. The importance of the low-pass filtering as a preprocessing for the polygonal approximation was confirmed in concrete examples. The efficiency of the proposed technique was compared with the cased in which the polygonal approximation was not used. Through these analyses, it was found that the redundancy elimination of the coding technique worked effectively in the proposed technique.