In the radio wave network systems for frequencies above 10GHz, it could be important to take into account for the attenuation due to rainfall. In order to obtain the attenuation by rain in the specific area, the estimation of rainfall rates is required for the time ratio of annual accuaulated time distributions of one minute rain rates. In this report. Morita and Karasawa-Matsudo methods for the estimation of accumulated time distributions of one minute rain rates have been evaluated on the basis of the experimental data for 20 years. As a result, it appears that accuracies in the methods could be improved by making minor corrections for conversion ratios and conversion coefficients. Furthermore, we discussed errors of the accumulated time distribution of rain rates.
This paper introduces Television Transmission System in Ogasawara islands via Communication Satellite. 8 on air programs are received at TOKYO TELECOM CENTER. These are transmitted via JCSAT3 Satellite, and received at Chichi-jima and Haha-jima in Ogasawara islands. This system applies skill of highly efficiency digital video compression using MPEG2 ENCODER, it is possible to use effectively for transponder.
We have measured multipath DU ratio (desired signal to undesired signal ratio) in present terrestrial analog broadcasting signals from the Tokyo Tower. On the base of measured data, we proposes a symple modeling method for delay profile and study on the length of gardinterval, one of paramater of OFDM for the future terrestrial television broadcasting.
A new scheme for adding digital data services over conventional NTSC broadcast is described. With the proposed approach, digital media contents are frequency-division-multiplexed between the FM sound carrier of own channel and picture carrier of adjacent upper channel by digital modulation technique. One of merits in this method is that the additional services can be implemented by means of attaching digital service equipment to existing broadcasting equipment, i.e. without making the existing broadcasting equipment obsolete. The result of veriflcation testing gives proof to this technology, which is also described in this paper. The result shows that approximately 400 kbit/s of additional digital services is made possible by the correct setup of multiplexing level and proper positioning of digital transmission carrier.
64QAM modulation has been adopted as a digital transmission standard for the cable television network. 64QAM characteristic with additive white noise has been well studied. The most distinctive difference in character of CATV network is its distortion. The distortion affects QAM signal as in-band interference. We have developed a prototype 64QAM equipment, and measured a characteristic of monotone interference and multitone interferences. We tried to theoretical analysis and found good agreement with the theory.
Designing of Microwave component is very difficult for many engineers, because we can not ignore the size of equipment against its wavelength. Now we mentioned the problem of high power micro wave design, and suggested one of the method to solve for this problem by using CAE for electric and magnetic field analysis. In this paper, we suggested how to use the electric and magnetic field analysis CAE for high power micro wave component design.
In recent years, air conditioners have let to high electricity consumption. We have therefore developed an air-conditioning system that uses a function of the refrigerant natural circulation (heat-pipe). This brings energy savings and low running costs because it needs no circulating power. Now, we suggest a new air-conditioning system without a refrigerator. It is very suitable for high heat density cabins (for example machine rooms of the broadcasting station) to decrease the temperature to somewhere near the temperature of the open air.