The wave distribution functions (WDFs) have been reconstructed by means of the maximum entropy inversion to the observed spectral matrix composed of the auto- and cross-power spectra among the three field components (Bx, By and Ez) in which the exactly right-handed circular polarization is taken in the integration kernels. The purpose of this paper is to investigate the properties of wave distribution functions reconstructed for wave sources whose central polarization is somewhat deviated from right-handed circular and to study (1) the WDF's by using the right-handed circular polarization in the kernels, (2) the effect of larger deviations for the polarization of elementary plane waves consituting the wave source, (3) the WDF's based on the elliptical polarization kernels and (4) the effect of limiting the number of eigenvalues. It is then found that changing the polarization model in the integration kernels would be helpful in finding out the polarization of the actually observed signals.

Low temperature experiments have been made to demonstrate the operation of LiNbO3 optical modulator with superconducting electrodes. The operation of the modulator for applied dc signals as well as microwave signals in the frequency range between 8 GHz and 12 GHz has been observed at temparatures as low as 4.2 K. The present results indicate a possibility of realizing high performance LiNbO3 optical modulators employing superconducting electrodes.

We have fabricated superconducting microwave passive components such as resonators, bandpass filters and delay lines with YBCO thin film conductors deposited on MgO substrates. Considerably high unloaded Q values of 12000 at 5.5 GHz was obtained with the YBCO microstrip resonator at 77 K, which indicated that the surface resistance of the YBCO thin film was 0.79 mΩ at that frequency and temperature. Excellent microwave properties were also demonstrated with the bandpass filter and the delay line. Considerably low insertion loss of about 1 dB was obtained with the 10 GHz YBCO bandpass filters at 77 K which have a various bandwidth from 0.5% to 10%. Also excellent microwave propagation was obtained with a 1.3 nsec YBCO coplanar delay line. Its insertion loss was less than 1 dB for the frequencies up to 4 GHz.

In order to provide a low profile wire antenna for mobile communication, we have developed a new type of the transmission line type antenna, which we call a Modified Transmission Line Antenna (MTLA). Analysis of a certain type of the modified transmission line antenna has revealed that the input impedance and the gain can be determined independently by appropriately choosing antenna configuration. In this paper, we first explain the fundamental characteristics of the modified transmission line antenna. We then introduce two types of MTLA, i. e. a zigzag MTLA and a double MTLA, for practical application of the MTLA to mobile communication. Their characteristics are also discussed theoretically and experimentally.

A 1/2 frequency divider using resonant-tunneling hot electron transistors (RHETs) has been proposed and demonstrated. The circuit make the best use of negative differential conductance, a feature of RHETs, and contains one half transistors than used in conventional circuits. The RHETs were fabricated using self-aligned InGaAs RHETs and WSiN thin-film resistors on a single chip. The RHETs have an i-InGaAlAs/i-InGaAs collector barrier that improves the current gain at low collector-base voltages. Circuit operation was confirmed at 77 K.

This paper describes on the transmission properties of the superconducting coplanar waveguide on LiNbO3 (LN) substrates, fabricated by YBa2Cu3Oy (YBCO) superconducting films. The films have been prepared by the reactive co-evaporation method and patterned by a wet etching process. The surface resistance of the obtained film was 0.04 Ω at 18 GHz and 77 K. It was confirmed from X-ray diffraction (XRD) that these films were highly oriented to the direction of c-axis without a secondary phase. The microwave transmission properties of these YBCO coplanar waveguides were investigated at frequencies up to 20 GHz and compared with that of the aluminum coplanar waveguide. The characteristic impedances of both coplanar waveguides were designed to be 50 Ω. It was found that the attenuation constants of these samples at 77 K were less than that of the aluminum coplanar waveguide for frequencies below 18 GHz.

This paper proposes a new design method of variable FIR digital filters. The method uses a multi-dimensional linearphase FIR filter as a prototype. The principle of the proposed method is based on the fact that the crosssectional characteristics of a 2-D filter along with a line vary if the intersection of this line is changed. The filter characteristics can be varied by recalculating all the filter coefficients from proposed equations, which leads to an advantage that the variable range is very wide. Another advantage is that the passband and stopband deviations are completely predetermined in the design procedures and that the passband edge can be accurately settled to a desired frequency while keeping the transition band width unchanged. First the proposed design method is explained and the effect of the transition band of 2-D filters is discussed. Then the calculation cost required in updating the filter coefficients are considered. Finally two design examples are presented and the proposed method is compared with the existing one, which shows the usefulness of our method.

In this paper an approach to formal specification and verification of ISDN services in LOTOS is presented. As for specification, it is shown that LOTOS can be effectively applied to describe different levels of ISDN service specifications. At the higher level, only the external behaviour of the network is specified. On the other hand, at the lower level, specifications include the behaviour of network components such as switching systems, where each switching system can be specified independently of each other. Such specification style, proves suitable for verification of specifications by using the concepts of the simulation relation.

Telecommunication services are accomplished by cooperative networks of widely distributed communication processes and service users. Those specifications are often modeled by a set of possible message sequences among cooperating processes and users. The distributed and cooperative nature of telecommunication services results in a wide variety of message sequences and makes it more difficult for service designers to design such telecommunication services. To mitigate the difficulty, we propose a design support system with MSRs (message sequence rules) as design knowledge. The system supports the following two design activities: (1) specification of a typical message sequence that corresponds to a service behavior in a successful case, and (2) specification of incidentally possible message sequences that involve service behaviors in successful and unsuccessful cases. For the former activity, the system interacts with designers and identifies the messages they give with MSRs to understand the context of the message sequence and suggest possible subsequent messages. For the latter activity, the system applies MSRs to the typical message sequence and reasons possible messages from/to relevant processes and users under every state to suggest incidentally possible message sequences. Accordingly, designers may be relieved of investigating a wide variety of service behaviors in successful and unsuccessful cases. The system capability is based on MSRs equivalent to reusable message sequence components. MSRs can be obtained through abstraction of implementation-dependent messages and decomposition of those sequences into temporal relations among messages. The rule acquisition method provides MSRs with the potential to generate a wide variety of message sequences. In order to verify rule applicability, we have experimentally designed three kinds of services and conducted an experimental rule application to those specifications. The experimental evaluation results indicate that applicability is fairly high.

Weather conditions affect the performance of satellite broadcasting receiving systems. For example, snow accretion on antennas degrades G/T seriously because it reduces received signal power and also can increase antenna noise. We need a continuous measurement of G/T to evaluate the effect of the weather conditions to the satellite broadcasting receiving systems. However, a conventional method cannot perform the continuous measurement because the antenna under test must be oriented in a specific direction (to the zenith) to obtain a noise level in a satellite broadcasting channel. This paper presents the continuous measurement of G/T for the satellite broadcasting receiving systems. We describe details of the measurement method. In our measurement system, a standard antenna is placed at the inside of a room in order to prevent the weather conditions from affecting the gain of the standard antenna. The power flux density at the inside of the room is different from that at the outside where the antennas under test are placed. Employing the effective gain of the standard antenna, we take the difference of the power flux density into account. Moreover, we propose a method to estimate the noise level in the satellite broadcasting channel from the values at the outside of the channel, and clarify the accuracy of the noise estimation. Then, we show measurement results of the G/T values for several receiving systems. From these results, we show that the G/T measurement system has high precision. Also, from the specifications of the antenna gain and typical values of the noise figure, it is expected that the measurement system has a sufficient accuracy.

This paper analyzes the performance of an ATM cell multiplexer with a two level MMPP input on a discrete-time basis. We approximated the input process as a simple MMPP model. We developed an MMPP/D/1/K queueing model for the ATM cell multiplexer, and employed an analytic approach for the evaluation of cell loss probability. We verified the accuracy of the results using computer simulation. We applied the above analytic method to connection admission control (CAC) of the ATM network. The resulting connection admission control scheme employs the concept of the "effective bandwidth" and table-look-up procedure. We confirmed through a computer simulation that the proposed connection admission control scheme outperforms the peak bandwidth allocation scheme with respect to link utilization.

As the size and complexity of network increases, the distributed systems management (DSM) will be vital in order to improve the availability of network management, to reduce the complexity of network operations, and to provide the high reliability. In this paper, we (1) describe general requirements required for systems management in distributed environment, (2) introduce the basic structure of distributed network management system (DNMS) for efficient network management, and also especially illustrate the concrete design of system management application process which is an important element among them, (3) propose the connectionless CMIP to accomplish for effectively managing the distributed management system, and indicate its efficiency; this protocol is available to manage dynamically changing DSM environment, to negotiate among the managing systems, to handle the dynamic informations etc. Finally, (4) the behavior and software structure of a suggested management system during negotiation to execute the received request for implementation are presented.

This paper describes the structure and properties of superconductive small antennas with thin-film matching circuits. These circuits make it possible to realize small antennas, 38 mm20 mm16 mm in size. This is one quarter the length of our previously reported ceramic antennas. The actual gain of this antennas was -4.5 dBi at 470 MHz. This value is 5.5 dB higher than that of Cu antennas with exactly the same structure.

Experimental results on the superconducting three-terminal devices Using Bi-system High-Tc Superconductors were reported. The VCJJ (Variabel critical-current-type Josephson junction devices) using the thermal effect (VCJJ) and a dual gate Josephson device of a new current-injection type are described. The basic technology and problems for high-Tc three-terminal devices are briefly discussed.

It often occurs in an environmental phenomenon in our daily life that a specific signal is partially or completely contaminated by the additional external noise. In this study, a digital filter for estimating a specific signal fluctuating impulsively under the existence of an actual external noise with various kinds of probability distribution forms is proposed in an improved form of already reported digital filter. The effectivenss of the proposed theory is experimentally confirmed by applying it to the estimation of an actual impulsve signal in a room acoustic.

This paper proposes a hierarchical Digital Signal Processor (DSP) Code Generator VIRGO for large scale general signal processing algorithms. Hierarchical structured Vectorized Signal Flow Graph (V-SFG) description is used as input specifications. Ths DSP independent optimization procedure for both the program size and the execution time is performed each module by each hierarchically with regard to operation order, memory assignment and register allocation. The efficient code generation is demonstrated by comparing both instruction steps and dynamic steps of a practical ADPCM encoder/decoder with a conventional method.

This paper describes the properties of non-dispersive and dispersive delay lines fabricated using EuBaCuO superconducting films. The 24 cm long stripline non-dispersive delay line showed a very low loss of 0.3 dB/nsec at 77 K and 10 GHz, and no dispersion at a delay time of 2.3 nsec at frequencies below 20 GHz. The 14 cm long microstrip dispersive delay line with modal dispersion exhibited a relative delay time of approximately 120 psec in the 118 GHz frequency range. The 26 cm long stripline dispersive delay line with structural dispersion due to coupling provided a relative delay time of 230 psec in the above frequency range and roughly the same loss as a non-dispersive delay line.

A ner trial of statistical evaluation for a nonstationary traffic flow and its traffic noise is proposed as a prediction method of its probability distribution function by considering the temporal change of distribution parameters especially from a structural viewpoint. First, a headway distribution of the nonstationary traffic flow passing through within a road segment is proposed on the basis of an Erlang distribution by reflecting a temporal change of its distribution parameters. Then, an initial phase density concerning with asynchronous counting method and the probability of counting n cars over a long time interval are derived from the above nonstationary expression of headway distribution. Thus, the statistics of noise intensity at an observation point has been predicted by combining the above probabilistic factors and deterministic factors related to noise propagation environment with use of a compound stochastic process model. Finally, te effectivenss of the proposed theory has been confirmed experimentally by applying it to the actual traffic flow on a highway.

In this letter, a generalized syndrome polynomial is proposed from which several decoding key-equations for Reed-Solomon codes can be derived systematically. These equations are always solved by the extended Euclidean algorithm.

Thin-film YBCO Josephson junctions were successfully fabricated by a pulsed excimer laser ablation, and the mixing experiments in the microwave region (820 GHz) were carried out at the temperature of 77 K. The IF output maximum was obtained at the bias voltage midway between the zero and the first Shapiro steps for the fundamental mixing. For the 2nd harmocic mixing, the IF output maximum was obtained at a zero bias voltage, and the conversion efficiency was -14 dB at the microwave frequency of 18 GHz. These results strongly suggest that the fabricated thin-film Josephson junctions work well at the temperature of 77 K as detectors and mixers in the microwave regions (820 GHz).