摘要:

AbstractThis paper describes an HDTV/TV compatible coding method based on lapped orthogonal transform (LOT). With this method, TV signals are obtained by performingN/2‐point inverse LOT to low‐orderN/2 coefficients. It is shown that the LOT domain decimation reduces the aliasing noise in TV images more efficiently than the DCT‐based method. In addition, intrafield/inter‐frame adaptive LOT coding is examined. The experimental results show that the coding efficiency of intrafield/interframe adaptive LOT coding is higher than that of intrafield/interframe adaptive DCT coding. LOT coding improves the SNR by 1 dB in fixed bit rate HDTV coding at 130 Mb/s. By using LOT as a decimation filter as well as a bit rate reduction algorithm in compatible HDTV coding, the quality of the TV images and the coding efficiency are better than with the DCT‐bas

ISSN:8756-6621    

DOI:10.1002/ecja.4410760401

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY

摘要:

AbstractTo eliminate the effect to the line in the transfer of the optical fiber cable when the line is not used, i.e., when the communication is not conducted. To achieve the transfer during the noncommunication state, there must be a system that can discriminate the communication status of the line. To realize such a system, a principle must be established for discrimination as well as a design based on the characteristics of the transmission equipment.This paper discusses the method of discriminating the communication and noncommunication status, using the most general coded mark inversion (CMI) code as the code to be propagated in the optical subscriber line. First, properties of the code that are generated in the communication and noncommunication states are discussed. It is shown to be most effective to use the ratio of the average powers of the line spectrum at 1/THz and the signal light as the discrimination data, whereT[s] is the period of the transmitted information. Then the design method is shown based on the actual transmission equipment.Finally, the result of evaluation is presented for the experimentally constructed communication/noncommunication discrimination equipment. It is shown that the correct discrimination is achieved down to the minimum ‐41 dBm of the average signal optical power, propagating in the optical fiber; and the proposed method is well applied to the actual transmission equipmen

ISSN:8756-6621    

DOI:10.1002/ecja.4410760402

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY

摘要:

AbstractIn ATM networks, it is necessary to control the quality of service because a large number of traffic classes with different statistical characteristics and required quality of service is handled uniformly in these networks.This paper evaluates the characteristics of the statistical multiplexing gain among the heterogeneous cell streams from voice and video media. It is considered that the information of picture elements that change between adjacent video frames are packetized and then transmitted into ATM networks. Therefore, when one scene finishes, all the information for the new scene appears as a sudden burst at the first frame of the next scene. This is an important characteristic of video traffic which is called scene change here.By considering scene change, the superposed arrival process is modeled on the heterogeneous cell stream from voice and video media using the phase‐type Markov renewal process. By analyzing the queueing model with this process, the characteristics of the statistical multiplexing gain are obtained. In particular, by using numerical computation, the effect of scene change on the statistical multiplexing gain is evaluate

ISSN:8756-6621    

DOI:10.1002/ecja.4410760403

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY

摘要:

AbstractThe NUCLEI (Nagasaki University codec using large interframe prediction errors as important parts) method is proposed in this paper as a new interframe coding method for the asynchronous transfer model (ATM). Characteristics of this method are as follows: 1) interframe predictions are done using a full band, considering the high coding efficiency during the normal state; 2) interframe predictions are done even after cell loss, considering the high coding efficiency after cell loss; and 3) utilizing the fact that the small moving areas are less important than the large moving areas in dynamic images (motion pictures), large moving areas or blocks with large interframe differences are allocated to priority (higher priority) cells as priority blocks and comparatively small blocks are allocated to nonpriority (lower priority) cells as nonpriority blocks. These characteristics are realized by assigning frame memories for storing priority block signals in addition to frame memories storing all images. It is shown by computer simulations that good interframe coding characteristics can be realized in both during the normal state and after a cell loss.

ISSN:8756-6621    

DOI:10.1002/ecja.4410760404

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY

摘要:

AbstractIn the multiple sub‐Nyquist sampling encoding (MUSE) system, stationary areas and moving areas of an image are processed differently from each other. These two processings are switched in accordance with the motion detection pixel by pixel. Since this motion detection is carried out independently on the encoder and the decoder, motion detection disagreement may occur between them [“motion detection disagreement”] due to transmission channel noise or particular image patterns.In this paper, the degradation of picture quality caused by the forementioned motion detection disagreement is analyzed. The analysis has made it clear that decoding an image which was encoded as a static image would generate picture degradation accompanied by flicker. However, when a static input image which was encoded as a moving image is decoded as a static image, the decoded image would only generate resolution degradation in its stationary areas but it would not produce any picture degradation through aliasing.This analysis conforms with the results of tests using the MUSE encoder and decoder. Thus, a prototype of a simplified encoder equipped with only a moving image processing was made. This prototype was combined with a MUSE decoder and images of good quality were obtained. The simplified encoder resolution in the stationary areas is somewhat inferior to that of conventional encoders. However, since it helps to reduce the machinery size by a third, or even smaller than that of conventional MUSE encoder, it may be used in consumer Hi‐Vision cameras if most of its devices are replaced wi

ISSN:8756-6621    

DOI:10.1002/ecja.4410760405

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY

摘要:

AbstractThis paper clarifies the radiation characteristics of a tension truss‐type deployable antenna based on measurements made on its solid model and presents its experimental method. The main reflector of the model antenna is constructed by many triangular plates approximating a paraboloid. As the aperture shape of a tension truss‐type deployable antenna is a hexagon, the difference between the circular aperture of the model antenna and the hexagon is covered with radiowave absorbers. The distribution of mechanical reflector errors which are projected on the aperture plane is formulated and their relations to electrical errors is shown. Data on reduction of gain and grating lobes in the radiation pattern arising from periodic reflector errors are obtained. The measured results are compared with calculated values of radiation characteristics and good agreement is obtained. It is shown that radiation characteristics can be estimated by the aperture integration method by neglecting the disturbance of current distribution at seams of fac

ISSN:8756-6621    

DOI:10.1002/ecja.4410760406

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY

摘要:

AbstractPreviously, the authors have proposed a design method of a shaped dual‐reflector contoured‐beam antenna with virtual multihorns with a view to applications to the broadcast satelliteBS‐3. In such a design, there were discontinuities on the main reflector.In this paper, a method for eliminating these step discontinuities is studied for the dual‐reflectors. The current distribution on the main reflector corresponding to the desired radiation pattern is determined by optimization depending on the constraint gain of the far field. Note that the optimization method for the aperture phase distribution was known for a single smoothly shaped contoured‐beam antenna. Also, in this paper, an optimization method for the amplitude distribution is proposed anew. Further, by adding a restriction to the phase difference between the adjacent elements in the optimization of the phase distribution, the step discontinuity on the reflector is eliminated. By means of this method, an antenna made of a main reflector with an aperture diameter of 2.3 m is designed at 12 GHz which is the frequency of the downlink of the broadcast satellite.Most of Hokkaido, Honshu, Shikoku, Kyushu, and Okinawa is covered by a radiation pattern with more than 40 dBi and other remote islands with more than 28 dBi. A one‐half scale model is fabricated and the radiation pattern is measured at 22 GHz. The results agree well with the numerical results. Also, the sidelobe and the cross‐polarization characteristics of this antenna sufficiently satisfy the technical standard

ISSN:8756-6621    

DOI:10.1002/ecja.4410760407

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY

摘要:

AbstractA millimeter‐wave imaging array is proposed in which many Yagi‐Uda antennas are placed on a dielectric lens. By changing the dimensions of these antennas, the impedance matching with the detector is optimized. At the same time, a radiation pattern matched to the incident beam from the focusing optics is realized. The crosstalk between the adjacent detectors on the array is measured. An optimum spacing is derived and a good imaging property is realized. The present imaging array is suitable for MMIC and is applied in practice for plasma measurement for nuclear fusion resea

ISSN:8756-6621    

DOI:10.1002/ecja.4410760408

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY

摘要:

AbstractThis paper presents an analysis method based on the point matching method for the reflection characteristics of a metal cylinder with mirror‐symmetrical cross section coated with a wave absorber. By means of this method, various design charts and the numerical results of the reflection characteristics are shown for wave absorbers that are optimum for the elliptical and oval‐shaped cross sections. The effectiveness of this method was confirmed by a model experim

ISSN:8756-6621    

DOI:10.1002/ecja.4410760409

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY

摘要:

AbstractA method for broadbanding and dual banding of the microstrip antennas (MSA) is proposed and discussed. The effect of errors at the time of fabrication of the MSA also is studied. The method described in this paper combines a transformer made of a distributed circuit with the MSA. The design consists of three steps. Since the radiating element and the transformer are separated completely by the ground plane in the present method, the technique can be applied to an MSA with an arbitrary shape without applying any fabrication on the radiating element. Broadbanding can be accomplished rather easily, and the dual‐banding can be accomplished with a slight modification in the design. The prototype stub‐loaded MSA demonstrated with a bandwidth of 1.3 percent with a VSWR ≤ 2 can be increased to 3.4 percent (2.6 times). For the dual‐banding, the separation rate of two frequencies with respect to the fundamental resonant frequency can be controlled by about 2 to 5

ISSN:8756-6621    

DOI:10.1002/ecja.4410760410

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY