The dielectric resonator technique is commonly used for microwave surface resistance measurements of High Temperature superconducting (HTS) films. Thickness of super-conductors and its impact on measurement results has not been taken into consideration so far. A theoretical mode-matched solution analysis of a TE011 10 GHz sapphire resonator was performed. The results of this analysis demonstrate that the thickness of the films under test can significantly affect the resonant frequencies (fres) and quality factor Q of the resonant system, particularly when the thickness is less than three times the penetration depth (λ) of the films at the operating temperature. In such cases the microwave properties of the substrate affect fres and Q. For HTS films' thickness relatively small as compared to λ, measured quality factors and resonant frequency may also be affected by substrate thickness and the conductivity of the backing plates of the system. The presence of air gaps between the sapphire and the HTS films does not significantly influence surface resistance measurements. However they can markedly affect the surface reactance from which the penetration depth is calculated.

An experimental study on propagation characteristics in a room of a modern office building using a 57.5 GHz carrier is described. The objective of the study is to provide initial information about the path-loss and fading characteristics for millimeter-wave wireless indoor communication systems. The area of the floor of the room is about 90 m2 and the room was almost empty with no furniture except the experimental apparatus. A wide-beam scalar feed horn transmission antenna and an omnidirectional receiving antenna were used and set to be with the same height. The measured area was divided into many "squares" to characterize the propagation. The variation of square transmission loss was calculated, and the regions where the maximum square transmission loss was observed were pointed out. It became clear that the distance power law for square transmission loss was approximately of the order d-2 along the direct path. Rician distributions for fast fading were derived in almost all squares of this room. The spectra for the fast fading envelope were also derived. From the propagation point of view, the results show that no extreme difficulty seems to exist in developing wireless communication systems in the 60 GHz band.

This paper proposes a symbol rate controlled adaptive modulation/TDMA/TDD for future wireless personal communication systems. The proposed system controls the symbol rate according to the channel conditions to achieve wide dynamic range of the modulation parameter control as well as to improve the delay spread immunity. The main purpose of the proposed system is to increase the data throughput with keeping a certain transmission quality, especially in frequency selective fading environments. For this purpose, the proposed system predicts the C/N0 (carrier power-to-noise spectral density ratio) and the delay spread separately, and selects the optimum symbol rate that gives the maximum bit rate within a given bandwidth satisfying the required BER. The simulated results show that the proposed system can achieve higher transmission quality in comparison with the fixed symbol rate transmission system in both flat Rayleigh and frequency selective fading environments. The results also show that the proposed system is very effective to achieve higher bit rate transmission in frequency selective fading environments.

This paper proposes a human interface where a novel input method is used to substitute conventional input devices. It overcomes the deficiencies of physical devices, as it is based on image processing techniques. The proposed interface is composed of three parts: extraction of a person's handshape from a digitized image, detection of its fingertip, and interpretation by a software application. First, images of a pointing hand are digitized to obtain a sequence of monochrome frames. In each frame the hand is isolated from the background by means of gray-level slicing; with threshold values calculated dynamically by the combination of movement detection and histogram analysis. The advantage of this approach is that the system adapts itself to any user and compensates any changes in the illumination, while in conventional methods the threshold values are previously defined or markers have to be attached to the hand in order to give reference points. Second, once the hand is isolated, fingertip coordinates are extracted by scanning the image. Third, the coordinates are inputted to an application interface. Overall, as the algorithms are simple and only monochrome images are used, the amount of processing is kept low, making this system suitable to real-time processing without needing expensive hardware.

This paper presents an analytical study and computer-based model of radio wave polarization propagating through a microcell. It covers the following topics: the influence of random orientation of a handset terminal on the performance of communication systems using either a linearly or circularly polarized base-station antenna; an analysis of the computer-based simulation of the power response on different polarizations in a street-canyon microcell.

Future digital land mobile communication, for a moving picture, requires more transmission speed and less bit error rate than the existing system does for speech. In the system, the intersymbol interference may not be ignored, because of higher transmission speed. An adaptive equalizer is necessary to cancel intersymbol interference. To achieve low bit error rate performance on the mobile radio channel, trellis-coded modulation with interleaving is necessary. This paper proposes an interleaved trellis-coded modulation scheme combined with a decision feedback type adaptive equalizer of high performance. The reliable symbol reconstructed in the trellis decoder is used as the feedback signal. To make equalizer be free from decoding delay, deinterleaving is effectively utilized. The branch metric, for trellis-coded modulation decoding, is calculated as terms of squared errors between a received signal and an expected signal by taking the reconstructed symbol and the impulse response estimated by the recursive least squares algorithm into account. The metric is constructed to have good discrimination performance to incorrect symbols even in non-minimum phase and to realize path diversity effect in a frequency selective fading channel. Computer simulation results are shown for several channel models. On a frequency selective fading channel, average bit error rate is less than 1/100 of that of the RLS-MLSE equalizer for fdTs=1/1000 at average Eb/N0 beyond 15dB. Performance degradation due to equalization error is less than 1.8dB. Performance is greatly improved by the effect of the reconstructed symbol feedback.

This paper describes the multiple access performance of parallel combinatory spread spectrum (PC/SS) communication systems in nonfading and Rayleigh fading multipath channels. The PC/SS systems can provide the high-speed data transmission capability by transmitting multiple pseudo-noise sequences out of a pre-assigned sequence set. The performance is evaluated in terms of average bit error rate (BER) by numerical computation. In nonfading white gaussian channel, the PC/SS systems are superior to conventional direct sequence spread spectrum (DS/SS) systems under the identical spreading factor condition. In Rayleigh fading channel, the performance of the PC/SS system without diversity is poorer than that of the DS/SS system. By including the explicit and implicit diversity, the performance of the PC/SS system becomes better than that of conventional DS/SS systems. A longer spreading sequence is assignable to a PC/SS system having the spreading factor equal to that in the conventional DS/SS system. Hence, the error control coding is easily. It is found that the PC/SS systems including diversity and Reed-Solomon coding improves the multiple access performance.

Distributed computing over a network of workstations continues to be an illusive goal. Its main obstacle is the delay penalty due to network protocol and OS overhead. We present in this paper a low level hardware supported scheme for managing distributed shared memory (DSM), as an underlying paradigm for distributed computing. The proposed DSM is novel in that it employs a two-tier paging scheme that reduces the probability of false sharing and facilitates an efficient hardware implementation. The scheme employs a standard OS page and divides it into fixed smaller memory units called paragraphs, similar to cache lines. This scheme manages the shared data regions only, while other regions are handled by the OS in the standard manner without modification. A hardware extension of a traditional MMU, namely Distributed MMU or DMMU, is introduced to support the DSM. Shared memory coherency is maintained through a write-invalidate protocol. An analytical model is built to evaluate the system sensitivity to various parameters and to assess its performance.

In this paper performance of M-stage detection for DS/CDMA is considered in terms of near-far resistance. Asymptotic multiuser efficiency (AME) of M stage detection over fading multipath channel is calculated and it is shown that even in the fading case the detector is near-far resistant i.e., insensitive to the relative energies of the users. The idea is extended to cellular environment. The effect of power control imperfection is investigated. It is shown that capacity can be increased if near-far resistant technique is employed in conjunction with limited power control.

A generalized surface scattering radar equation for a near-nadir-looking pencil beam radar, which covers both beam-limited and pulse-limited regions, is derived. This equation is a generalization of the commonly used nadir-pointing beam-limited radar equation taking both antenna beam and pulse wave form weighting functions into account, and is convenient for the calculation of radar received power and scattering cross-section of the surface.

We propose an axially symmetrical Fabry-Perot multiple-device oscillator operating at an axially symmetrical TEM01n-mode, which has an excellent feature of uniform device-field coupling required for high efficiency power combining. By carrying out the boundary element analysis, it is shown that a plane-mirror output structure is remarkably advantageous compared with a concave-mirror output structure to obtain an adequate output coupling and to enable stable operation characteristic with respect to the axial mode number n. Experiments in X-band confirmed this excellent performance and achieved almost perfect power combining of efficiency as high as 106% and 99% for six- and eight-device case, respectively.

This paper presents a theoretically best algorithm within the framework of our image noise model for reconstructing 3-D from two views when all the feature points are on a planar surface. Pointing out that statistical bias is introduced if the least-squares scheme is used in the presence of image noise, we propose a scheme called renormalization, which automatically removes statistical bias. We also present an optimal correction scheme for canceling the effect of image noise in individual feature points. Finally, we show numerical simulation and confirm the effectiveness of our method.

A computer-based system for the automatic determination of the physical parameters of rainfall was developed. The measuring device consists of a light source and two TV cameras. Images of raindrops that fell through the slit were observed on a frosted glass plate as shadow images which were photographed simultaneously by two TV cameras with different shutter speeds and analyzed. The data indicated that the shape of raindrops were spheroid in case of small diameter but were slightly deformed into an oblate spheroid in case of larger diameter, and the fall velocity tends to increase with increasing size of raindrops. Rainfall rates calculated from the shape and velocity were compared with those measured directly and found to agree.

In this letter, we introduce a predictor based least square (PLS) algorithm. By involving both order- and time-update recursions, the PLS algorithm is found to have a more stable performance compared with the stable version (Version II) of the RLS algorithm shown in Ref.[1]. Nevertheless, the computational requirement is about 50% of that of the RLS algorithm. As an application, the PLS algorithm can be applied to the fast Newton transversal filters (FNTF). The FNTF algorithms suffer from the numerical instability problem if the quantities used for extending the gain vector are computed by using the fast RLS algorithms. By combing the PLS and the FNTF algorithms, we obtain a much more stable performance and a simple algorithm formulation.

Transition coverage has been proposed as a measure of two-pattern test capabilities of TPG circuits for use in BIST. This paper investigates experimentally the relationships between transition coverages and actual stuck-open fault coverages in order to reveal what kind of circuits are appropriate for two-pattern testing. Fault simulation was performed using conventional (n-stage) LFSR, 2n-stage LFSR, and one-dimensional cellular automata (CAs) as TPG circuits and such sample circuits as balanced NAND tree and some ISCAS '85 benchmark circuits as CUTs. It was found that CAs which are designed so as to apply exhaustive transitions to any 3-dimensional subspaces can detect high rate of stuck-open faults. Influence of hazards of decreasing the fault coverage is also mentioned.

This paper presents the concept of k-FR circuits. The controllability of such a circuit is high due to its special structure. It is shown that all stuck-at faults and stuck-open faults in a k-FR circuit can be detected and located by k(k1)1 test vectors under the highly observable condition which assumes the output of every gate to be observable. k is usually two or three. This paper also presents an algorithm for converting an arbitrary combinational circuit into a k-FR circuit. A k-FR circuit is easy to test when using technologies such as the electron-beam probing, the current measurement, or the CrossCheck testability solution.

This paper deals with the problems in testing large mixed-signal ICs. To help generating test patterns of these larger mixed-signal circuits for a functional test, a fast fault simulation algorithm and a fault model voltage stuck-at fault" which the algorithm is based on, are proposed. A voltage stuck-at fault is that a signal line sticks its voltage level at a certain constant. Under an assumption that blocks in a circuit are designed as identically current-independent, i.e. their input impedance can be regarded as infinite and their output impedance as zero, fault simulation can be realized by the event driven method and the concurrent method and can detect voltage stuck-at faults. These methods are essential for digital fault simulation and very effective to high speed simulation, although they were impossible for an analog or mixed-signal circuit by a conventional algorithm. Furthermore, the efficiency of the simulation is improved because I/O relation of blocks is approximated to a stepwise linear function. The above techniques and methods make fault simulation for a mixed-signal circuit possible in practical use. Actually, a fault simulator was implemented, then some test circuits were simulated. The simulator is really faster than conventional simulation based on circuit simulation. Next, fault analysis was applied to several bipolar ICs to verify the validity of the fault model voltage stuck-at faults". Analyses of open and short faults between terminals of transistors and resistors show that this fault model has sufficient coverage (more than 50%) to test mixed-signal circuit.

This paper presents a new structure for noise and echo cancelers based on a combined fast abaptive algorithm. The main purpose of the new structure is to detect both the double-talk and the unknown path change. This goal is accomplished by using two adaptive filters. A main adaptive filter Fn, adjusted only in the non-double-talk period by the normalized LMS algorithm, is used for providing the canceler output. An auxiliary adaptive filter Ff, adjusted by the fast RLS algorithm, is used for detecting the double-talk and obtaining a near optimum tap-weight vector for Fn in the initialization period and whenever the unknown path has a sudden or fast change. The proposed structure is examined through computer simulation on a noise cancellation problem. Good cancellation performance and stable operation are obtained when signal is a speech corrupted by a white noise, a colored noise and another speech signal. Simulation results also show that the proposed structure is capable of distinguishing the near-end signal from the noise path change and quickly tracking this change.

The word error probability of linear block codes is computed for diversity systems with maximal ratio combining in mobile communications with three decoding algorithms: error correction (EC), error/erasure correction (EEC), and maximum likelihood (ML) soft decoding algorithm. Ideal interleaving is assumed. EEC gives 0.1-1.5dB gain over EC. The gain of EEC over EC decreases as the number of diversity channels increases. ML soft gives 1.8-5.5dB gain over EC.

A single bridging fault location technique for CMOS combinational circuits is proposed. In this technique, the cause of an error observed at the primary outputs in deduced using a diagnosis table constructed from the circuit under test and the given tests. The size of a diagnosis table is [the number of gates][the number of tests]2 bits, which is much smaller than that of the fault dictionary. The experimental results show that the number of possible bridging faults is reduced to less than 5 in several seconds, when using the tests to detect single stuck-at faults and considering only the bridging faults between physically adjacent nets.