A new positioning method for higher track density hard disk using embossed-servo-mark magnetic disks is proposed. An embossed-servo-mark medium with grooved-guard-band data tracks for 208 TPMM was developed using molded plastic substrate. The marks were magnetized so that conventional magnetic head can reproduce position signals. Simple analogy from optical disk track following to magnetic disk track following was taken and examined. A DSP controlled feed-forward servo was introduced to resolve the inherent eccentricity caused by mounting preformed tracks onto an independent spindle axis. The prototype drives with a form factor of 2.5 inches were designed introducing the disks, the servo scheme and the newly developed orthogonal MR head. As a result, an areal density of 650 kbits/mm2 (about 420 Mbits/in2) recording was successfully demonstrated on the media using 2.5-inch form factor prototype drives.

Circuit techniques for realizing fast cycle time of DRAM are described. 1) A high-speed and high-efficiency word-line level Vpp supply can be obtained by a unique static CMOS double-boosted level generator (SCDB) which controls the Vpp charge supply gate. 2) A new write-control scheme eliminates the timing overhead of a read access time after write cycle in a fast page mode operation. 3) A floor plan that minimizes the load of signal paths by employing the lead-on-chip (LOC) assembly technique. These techniques are implemented in an address-multiplexed 16 Mbit CMOS DRAM using a 0.5-µm CMOS technology. A 31-ns RAS cycle time and a 19-ns fast page mode cycle time at Vcc3.3 V, and also even at Vcc1.8 V, a 53-ns RAS cycle time and a 32-ns fast page mode cycle time were achieved. This DRAM is applicable to battery-operated computing tools.

To increase the accuracy of a near field antenna measurement system, it is necessary to know radiation characteristics of a probe to detect near field data. Open ended waveguide used as a near field probe in our system was analyzed using Transmission Line Matrix (TLM) method which is a time domain electromagnetic solver. Validity of this analysis has been confirmed by comparison with experimental data and existing theoretical approximation. Frequency dependence of a complex reflection coefficient at the waveguide aperture has been derived and is shown to agree with measured values. The radiation pattern of the open ended waveguide with mounting structure is also calculated. Ripples on both the amplitude and phase patterns are correctly predicted by our simulation. This method can be applied to accurately model the effect of probe antennas to enhance the accuracy of near field antenna range.

This paper describes the architecture and new circuit technologies of a proposed Pixel (bit) -Aligned Triple-port DRAM (PATDRAM). The PATDRAM has a 270 K word 16 b Random Access Memory (RAM), a 512 word 8 b Serial Access Memory-(a) (SAMa) and a 1024 word 4 b Serial Access Memory-(b) (SAMb). The random port, serial-a and serial-b port can be operated by three independent synchronous clocks. In these three ports, word data can be aligned to the location of an arbitrary bit position. Data transfer from SAMb to RAM can be individually masked by transfer mask data. The RAM operates by 33 MHz synchronous clock and two SAMs operate by 40 MHz clocks. Novel architecture of the PATDRAM accelerates graphics performance and simplifies in multimedia systems which manage both realtime video and computer graphics data, and also accelerates graphics performance in both two-dimensional (2D) and three-dimensional (3D) graphics systems. PATDRAM was designed using a 0.6 µ double metal, triple poly, stacked capacitor, CMOS process technology in a 10.98 mm9.88 mm die area integrated 4.4 Mb RAM, 8 Kb SAM, 4 Kb transfer mask register and 5 Kgate logic.

In the actual acoustic environment, the stochastic process exhibits various non-Gaussian distribution forms, and there exist potentially various nonlinear correlations in addition to the linear correlation between time series. In this study, a nonlinear ARMA model is proposed, based on the Bayes' theorem, where no artificially pre-established regression function model is assumed between time series, while reflecting hierarchically all of those various correlation informations. The proposed method is applied to the actual data of road traffic noise and its practical usefulness is verified.

In digital control, it is essential to make the delay time for a large number of multiply-additions small because of sensor feedback. To meet the requirement, an architecture of the reconfigurable parallel processor using field-programmable gate arrays (FPGAs) is proposed. Although the performance is drastically increased in the full custom VLSI implementation, even the reconfigurable parallel processor using FPGAs becomes useful for many practical digital control applications. The performance evaluation shows that the delay time for the resolved acceleration cotrol computation of a twelve-degrees-of-freedom (DOF) redundant manipulator becomes about 70 µs which is about seventeen times faster than that of a parallel processor approach using conventional digital signal processors (DSPs).

In order to investigate the jitter characteristics of PLLs for practical applications, we have developed a computer simulation program of PLL, which can deal with arbitrary patterns both of data and jitters, as well as a conceivable nonlinearity of the circuit performance. We used a time-domain method, namely, we solved the state equation of a charge pump type PLL with a constant time step. The jitter transfer characteristics of a conventional PLL were calculated for periodic input data patterns with sinusoidal jitters. The result agreed fairly well with the corresponding experiments. And we have revealed that an ordinary PD (Phase Detector), which detects the phase difference between input and VCO signals at only rising edges, shows the folded jitter transfer characteristics at the half of the equivalent frequency of the input signal. This folded jitter characteristics increases the total jitter for long successive '1' or '0' data patterns, because of their low equivalent sampling frequency, and might increase the jitter even for the random data patterns. Based on simulation results, we devised an improved phase detector for PLL having a low jitter characteristics. And we also applied the simulation to an FDD (Frequency Difference Detector) type fast pull-in PLL which we have proposed recently, and obtained that the jitter of it was smaller than that of a conventional PLL by 25% for PRBS (pseudo random bit sequence) NRZ code.

The frequency characteristics of whole-body averaged specific absorption rates (SARs) in a human model exposed to a near field of an electric dipole or a magnetic dipole are calculated, using a finite-difference time-domain method. The dependences of the characteristics on the orientation of the dipole and on the distance from the source to the model are investigated. It is shown that the resonant peak of the SAR that appears in the E-polarized far-field exposure is observed only when the source is E-polarized and is located at 80cm, while the peak vanishes or is not noted when the source is located at 40cm and 20cm nor when it is H-polarized. The relationships between the whole-body averaged SARs and the incident electromagnetic field strengths are also investigated. It is suggested that the spatially-averaged value of the dominating component between the electric field and the magnetic field over the space where a human body would occupy provides a relevant measure to estimate the whole-body averaged SAR of a body in the vicinity of a small radiation source.

A semicylindrical microstrip applicator system is proposed and designed, both for microwave heating and for noninvasive temperature estimation, in application to hyperthermia treatment. The experimental results showed that the system functions both as a heating device and as a means of noninvasive temperature estimation. Therefore, electrical switching of these two functions makes the system realize both heating and temperature estimation. These functions reduce the pain of hyperthermia therapy for patients. The system is constructed of a water-loaded cylindrical applicator. Thus, the whole system can be made compact compared to conventional applicators. This improvement allows for various merits, such as realizing a surface cooling effect and decreased leakage of electromagnetic (EM) waves. When the applicator is set as an array arrangement, the system can be used as a microwave heating device. The penetration depth can be varied by adjusting phases of the EM wave radiated from each applicator. The experimental results at 430 MHz showed that semicylindrical microstrip applicators can be expected to be valid for tumor heating at depths within 55 mm. Moreover, by measuring transmission power between the two applicators, the system can be used to estimate temperature inside the medium. The transmission power which was measured in the frequency domain was converted in the time domain. By such a method, temperature distribution was calculated by solving simple simultaneous primary equations. The results of the temperature estimation show that the number of estimated temperature segments which have an error within 0.5 is 28 out of 36. The system can be easily used as a temperature measuring applicator as well as a heating applicator.

Pitch frequency is a basic characteristic of human voice, and pitch extraction is one of the most important studies for speech recognition. This paper describes a simple but effective technique to obtain correct pitch frequency from candidates (pitch candidates) extracted by the short-range autocorrelation function. The correction is performed by a neural network in consideration of the time coutinuation that is realized by referring to pitch candidates at previous frames. Since the neural network is trained by the back-propagation algorithm with training data, it adapts to any speaker and obtains good correction without sensitive adjustment and tuning. The pitch extraction was performed for 3 male and 3 female announcers, and the proposed method improves the percentage of correct pitch from 58.65% to 89.19%.

When measuring the ejection fraction for the evaluation of the ventricular pumping function by means of the thermodilution technique, the slow response a conventional thermistor has caused it to be considered unsuitable, and fast thermistors have been proposed as an alternative. However, in this paper we propose improving the time-domain response of a conventional thermistor using a signal processing technique composed of a series of first-order high-pass filters which is known as the natural observation system. We considered the rise time of the thermistor in response to a step temperature change to effect correction for the measurement of the ejection fraction. The coefficients of the natural observation system were calculated by minimizing the square error between the step-response signal of the thermistor and the band-limited reference signal. In an experiment using a model ventricle, the thermodilution curve obtained from a conventional thermistor was improved using the proposed technique, thus enabling successful measurement of the ejection fraction of the ventricles.

This paper presents an adaptive MLSE (Maximum Likelihood Sequence Estimator) suitable for TDMA cellular systems. The proposed MLSE has two special features such as handling wide dynamic range signals without analogue gain controls and fast channel tracking capability. In order to handle wide dynamic range signals without conventional AGCs (Automatic Gain Controller), the proposed MLSE uses envelope components of received signals obtained from a non-linear log-amplifier module which has wide log-linear gain characteristics. By using digital signal processing technique, the log-converted envelope components are normalized and converted to linear values which conventional adaptive MLSEs can handle. As a channel tracking algorithm of the channel estimator, the proposed MLSE adopts a QT-LMS (Quick-Tracking Least Mean Square) algorithm, which is obtained by modifying LMS algorithm to enable a faster tracking capability. The algorithm has a fast tracking capability with low complexity and is suitable for implementation in a fixed-point digital signal processor. The performances of the MLSE have been evaluated through experiments in TDMA cellular environments with π/4-shifted QPSK, 24.3k symbol/sec. It is shown that, under conditions of 65dB amplitude variations and 80Hz Doppler frequency, the MLSE successfully achieves less than 3% B.E.R., which is required for digital cellular systems.

This paper introduces some modelling methods of time-varying stochastic process and its linear/nonlinear adaptive identification. Time-varying models are often identified by using a least square criterion. However the criterion should assume a time invariant stochastic model and infinite observed data. In order to adjust these serious different assumptions, some windowing techniques are introduced. Although the windows are usually applied to a batch processing of parameter estimates, all adaptive methods should also consider them at difference point of view. In this paper, two typical windowing techniques are explained into adaptive processing. In addition to the use of windows, time-varying stochastic ARMA models are built with these criterions and windows. By using these criterions and models, this paper explains nonlinear parameter estimation and the property of estimation convergence. On these discussions, some approaches are introduced, i.e., sophisticated stochastic modelling and multi-rate processing.

This paper describes a 32-bit fully asynchronous microprocessor, with 4-stage pipeline based on a RISC-like architecture. Issues relevant to the processor such as design of self-timed datapath, asynchronous controller and interconnection circuits are discussed. Simulation results are included using parameters extracted from layout, which showed about the 300 MIPS processing speed and used 71,000 transistors with 0.5 µm CMOS technology.

In this paper, we develop a unified synthesizing approach for the cloning templates of Cellular Neural Networks (CNNs). In particular, we shall consider the case when the signal processing problem is complex, and a multilayered CNN with time-variant templates is necessary. The method originates from the existence of correspondence between the cloning templates of Cellular Neural Network and its discrete counterpart, Discrete-Time Cellular Neural Network (DTCNN), in solving a prescribed image processing problem when time-variant templates are involved. Thus, one can start with calculating the cloning templates from DTCNN, and then translating the cloning templates to those for CNN operations. As a result, the mathematical tools being used in the synthesis of Discrete-time Cellular Neural Network can also be applied to the analog type Cellular Neural Network. This inevitably helps to simplify the design problem of CNN for signal processing. Examples akin to contour drawing and parallel thinning are shown to illustrate the merits of our proposed method.

This paper investigates the properties of synchronized alternating one-way multicounter machines (lsamcm's) which operate in real time (lsamcm-real's) and whose leaf-sizes are bounded by a constant or some function of the length of an input. Leaf-size reflects the number of processors which run in parallel in scanning a given input. We first consider the hieracrchies of lsamcm-real's based on the number of counters and constant leaf-sizes. We next show that lsamcm-real's are less powerful than lsamcm's which operate in linear time when the leaf-sizes of these machines are bounded by a function L(n) such that limn[L(n) log n/n]0 and L(n)2.

In order to construct a high-capacity and high-reliable indoor wireless communications system, it is essential to design the modulation/demodulation, coding and access schemes with high and variable data rate transmission capabilities, which meet the technical requirements inherent to wireless communications, i.e., high frequency utilization efficiency and robustness for fading. In this paper, we propose the frequency and time division multiple access with demand-assignment (FTDMA/DA) using multicarrier modulation as a frequency and time synchronous answer to meet the requirements, and analyze the performance of the FTDMA/DA system, taking account of teletraffic characteristics of multimedia information sources.

This paper describes the formation of ultra-thin tantalum oxide capacitors, using rapid thermal nitridation (RTN) of the storage-node polycrystalline-silicon surface prior to low-pressure chemical vapor deposition of tantalum oxide, using penta-ethoxy-tantalum [(Ta(OC2H5)5) and oxygen gas mixture. The films are annealed at 600-900 in dry O2 atmosphere. Densification of the as-deposited film by annealing in dry O2 is indispensable to the formation of highly reliable ultra-thin tantalum oxide capacitors. The RTN treatment reduces the SiO2 equivalent thickness and leakage current of the tantalum oxide film, and improves the time dependent dielectric breakdown characteristics of the film.

A new approach to the problem of optimal software testing time is described. Most models implicitly assume the testing is terminated at the end of a prescribed period of time without user's approval. It means the release time and the in-service reliability are determined unilaterally by the developer. If software developer uses and maintains it, the assumption is appropriate. But, it may be inappropriate, if a software requiring more stringent reliability is developed by second party on a contract basis. In this case, the time of release is usually determined with the user's approval. To overcome the weaknesses of the assumption, a two stage testing with failure-free release policy is proposed. A software, after being tested by the developer for some time (in-house testing), is transferred to acceptance testing performed jointly with the user. During the acceptance testing, it is released when τ units of time specified by user is observed to be failure-free for the first time. The policy may be attractive to a user because he can determine the time of release, and extend the testing time by increasing τ. A software cost model for the policy is developed. For the software developer, an optimal in-house testing time minimizing software cost, and various quantities of interests, such as expected periods of acceptance testing, are derived based on the Jelinski-Moranda software reliability model. Finally, numerical examples are shown to illustrate the results.

There has been growing interest in Broadband ISDN (B-ISDN) based on ATM (Asynchronous Transfer Mode) technologies, since ATM is expected to support a wide range of applications through high-speed and flexible multimedia communication capabilities. This paper reviews and discusses technical issues on multimedia communication protocols and services from the integration points of view of computer and communication technologies. An ISDN-based distributed multimedia and multi-party desktop conference system called MERMAID is introduced as an example which offers highly-sophisticated functions for remote collaborations among multiple users. This system, which was developed in early 1989 and has been used for daily research work since then, involves B-ISDN key technologies related to multimedia and multicast protocols, and computer architecture for groupware applications.