This paper describes some methods for interpolation of the topographical mesh-data in order to derive terrain profiles which are essential especially to predict the terrestrial radiowave propagation. The mesh-data provide ground heights at specific locations at regular intervals of 50m or 200m. Heights for intermediate locations must be obtained by interpolation of nearby heights. The interpolation is carried out first along a propagation path, and then across the path at key locations, such as mountain peaks. The two methods of interpolation, Everett-Newton's and Rectangle methods, are applied and compared. Both of them fairly meet our needs comparably.
This paper proposes a remedy for the rain attenuation by the use of multi-beam transmitter antenna, and describes how transmitter power is distributed to the individual beam. In order to simulate the rain attenuation, the use of rain data in the meteorological AMeDAS data is made. The rain data are converted to rain attenuation at 21GHz. The transmitter antenna is assumed to have 10 beams of which 3 beams are selected to be supplied additional power. The determination of the selection is made by comparing top 5% of attenuation in each beam, which includes averagely 1300 locations. By the use of this system % time of outage in a year is expected to be reduced to 0.4%, approximately.
When the climate of Kagoshima compare with some other area, it never rains but it pours through the year. I thought that it was much influence on availability of BS link. We understood rain characteristic at Kagoshima and we investigated that it was influence on availability of BS link. As a result, we could understand that 0.1% of rain time happened instantaneous degradation and availability of BS link cound not keep above 99.99% even if it use a big diameter antenna at 1993(worst year of last three years).
This paper describes prediction of attenuation of satellite wave at 22GHz in expectation of satellite broadcasting in the future, using with characteristic of relation between rain attenuation and one-minute rain rate (mm/h) of satellite wave observed at Kagoshima for Jul-Oct, 1995. To predict rain attenuation at 22 GHz, we evaluated effective distance from instant attenuation, using Olesen's aR^b relation with Laws and Parsons dropsize distribution (low). And, we also predicted rain attenuation characteristic at 12GHz, compared with measured one and evaluated the difference of each one.
This paper is concerned with a finite volume time domain (FVTD) method for electromagnetic wave propagetion in two dimensional tunnels. This method is based on the volume integrations of the Maxwell's eqations with respect to small rectangular solid cell. The electromagnetic fields in the rectangular solid cell are expressed in terms of the tangential electromagnetic fields on its surfaces, which are interpolatedby the former fields of the adjacent two cells. It is possible to solved the boundary value problem of arbitary shape which contains an inhomogeneous medium. It is found that numerical and experimental results are in good agreement regarding the electric field intensities in the tunnel.
This paper is concerned with a finite volume time domain (FVTD) analysis for the electromagnetic wave propagation in bended waveguides. FVTD method is based on the volume integrations of the Maxwell's equations with respect to regular hexahedron cell. The electromagnetic fields in the regular hexahedron cells are expressed in terms of the tangential electromagnetic fields on the surfaces of the cells, and the latter field components are given by the interpolation of the former fields of the adjacent two cells. The advantage of the FVTD method is that the impositions of the boundary condition are easy.
This paper is concerned with a finite volume time domain (FVTD) analysis for the plane wave scattering by an infinite plane grating. This method is based on the volume integrations of the Maxwell's eqations with respect to small rectangular solid cell. The electromagnetic fields in this are expressed in term of the tangential electromagnetic fields on the surfaces of the cells, and the latter field components are given by the interpolation of the former fields of the adjacent two cells. The advantage of the present method is that the impositions of the boundary coudition are easy. The PML absorbing boundary condition and periodic condition are used in this paper. The numerical results show that the present method provides us precise values as for transmitted power.
The extent of a rectangular ground plane for measuring electromagnetic interference with a pair of tuned half-wave dipole antennas is discussed. The effects of the four edges of the ground plane were considered by GTD, and the current distribution on dipole antennas was analyzed by using the method of moment. The calculations of the normalized site attenuation(NSA) were done for the case that measuring distance was 3m or 10m, and for both borizontal and vertical polarizations. These results are compared with NSA calculated for electrically small dipoles in place of half-wave dipoles.
The digital and mobile systems are expected in a future satellite broadcasting. The OFDM scheme improves an interference due to multi path propagation by using multi carrier. Therefor, OFDM scheme is useful in a mobile satellite broadcasting system. However, the OFDM scheme has the disadvantage of distortion by nonlinearity of satellite transponder due to multi carrier. This paper shows analysis of bit error performance including nonlinearity of satellite transponder and multi path propagation, and it shows the link budget in digital satellite broadcasting using OFDM scheme.
With a view to digital terrestrial television broadcasting systems, we developed a new OFDM modem. At most three constellations which vary in robustness can be used simultaneously to provide a system capable of graceful degradation. It became clear that using different constellations is more effective than using different powers in attaining minimum reception despite long signal delays.
OFDM system has been studying as a future Digital Terrestrial Television Broadcasting(DTTB) system which realizes the mobile recept on. This paper shows a DTTB system using 64DAPSK-OFDM which has robustness against bad receiving conditions. We also describe the result of the link design in fixed, portable and mobile conditions.
The next generation CATV system requires a Hybrid system of fiber and coaxial that uses digital modulation method. This paper presents the measurement results of transmission medium characteristics for a digital broadcasting and digital transmission characteristics with a COFDM equipment in a Hybrid-CATV system.
DTTB(Digital Terrestrial Television Broadcasting) has been studied for new TV services and efficient usage of frequency. The modulation method of DTTB should be OFDM (Orthogonal Frequency Division Multiplex) because of the robustness against ghost interferences. In this paper, theoretical study of BER (Bit Error Rate) degradation by ghost waves is described, and the result of experimental measurement is also mentioned.
We find out the fact that the quiality of the storage battery is decreasing. It comes from the character of putse electric discharge in the leaden storage battery. Therfore we report a debelopment of the Chacker which can check the decrease of storage battery
For the improvement of news programs production, as prototype we developed a skill-free, automated and new type of system, "DASUZOU-KUN". And it had been being in use for some news programs for about one year at NHK SAGA. It was set high value on. Then, for improving it more, we have developed a New "DASUZOU-KUN". It mixes that easy operations and merits of electronic script, and it can be used for all programs producted at local news studio. By our system, misslessly and efficiently everyone can product news programs.
Lately, the personal computers(PC) of inexpensive and high-powered has been introduced to TV stations, so the managements in any sections, like in program producing and the program datas, and the business infomation, the operation has been systemaized. This report is the example. Before broadcasting the recorded programs, previewing the tape is necessary, to clock the time between commercials and also, to check the quality of the picture and the sound. This time we have developed the preview system with PC to operate above with high efficiency. And we have connected this system and the upper system with LAN to preserve the preview datas and to acquire the program information, so the reliability of the data has been improved. Also, the communication between PC and the VTR is serial, the direct connection without using the VTR interface made the construction of the machinery very simple.
We, Fuji Television, developed wireless intercommunication system, which signal process is completely digital by using personal handyphone system. It is also available to telephone from personal station like codeless phone. We will be able to integrate all communication tools in studio.