Yuichi Otsu

Propagation Measurements and Tv-Reception Tests With the Japanese Broadcasting Satellite for Experimental Purposes

In July 1978, stationary experiments were commenced with the Japanese Medium-Scale Broadcasting Stellite for Experimental Purposes (BSE). In this BSE project, frequencies of 14/12 GHz are applied to the up and down links, respectively, and experiments have been carried out from the points of propagation and receiving. The analys is of the propagation measurements revealed statistics of rain attenuation in various parts of Japan. By the TV-reception tests, it has been confirmed that received power was generally coincided with the predicted one and received picture was excellent at each receiving location which was distributed all over Japan.

Experimental Program and Performance of Japan's Communication Satellite (CS) and Its First Results

Japans CS spacecraft was launched successfully in December 1977 and placed at 135°E longitude in a geostationary orbit. On-orbit performance of the satellite was verified quite well with the exception of two sets of K -band transponders. Substantial communication experiments have been conducted for more than half a year starting in May, 1978. In the satellite loop-back configuration at the Main Fixed Earth Station, 1872 and 972 channels of FDM-FM telephony signals can be transmitted through any K - and C -band transponder, respectively, with signal quality better than 50 dB in S/(N + D) . The quality of FM-TV signals is also good (more than 59 dB in unweighted S/N at K -band). Basic transmission characteristics of PCM-PSK signals with various modulation parameters were measured with good results. However, it became clear that spin modulation effects must be considered for estimating the BER performances, especially at K -band. DPCM-TV signal transmission tests were also conducted with satisfactory results. PCM-TDMA systems were verified to work well at K -band, including functions such as frame and burst synchronization, initial acquisition and so forth. Diversity switching functions will be tested in a later experimental phase. In propagation experiments, rainfall attenuation, excess noise temperature due to rain, and effects of the ionosphere have been studied. Although insufficient data have been accumulated, some estimation of the necessary link margin against the rainfall attenuation at K -band was obtained. In general, confidence has been attained that some CS-like system with K -band links will be suitable for practical use. The experiments are now being conducted and will continue through the nominal mission period of 3 years.

Development of on-board satellite communications equipment in the geostationary platform ERA☆

Abstract The evolving communications demands will accelerate the proliferation of geostationary communications satellites, as an essential element of communications infrastructure, growing pressures on arc/spectrum resources by the year 2000 and beyond. To offer relief from these pressures and to provide the capabilities needed for new services, concepts of geostationary communications platform (GPF) have been suggested by several organizations in the U.S.A. and Europe. Japan has also begun studies on communications payloads directed toward the GPF. This paper presents the projected activities of the study programs.

Propagation characteristics for millimeter and quasi-millimeter waves by using three Japanese geostationary satellites

Abstract Propagation experiments using the following geostationary satellites, Engineering Test Satellite-II (ETS-II), Medium-Capacity Communication Satellite for Experimental Purposes (CS), Medium-Scale Broadcasting Satellite for Experimental Purposes (BSE) and Experimental Communication Satellite (ECS), are being conducted by Radio Research Laboratories (RRL) with the co-operation of National Space Development Agency of Japan (NASDA), Nippon Telegraph and Telephone Public Corporations (NNT) and Japan Broadcasting Corporations (NHK). The Experimental Communication Satellite (ECS) will be launched into the geostationary orbit in February 1980. This satellite will then be used for further propagation experiments. The various and numerous propagation data obtained by using these satellites is being collected from many places all over Japan. The summary of the propagation experiments conducted at the main station is as follows. 1. (a) Experimental periods covered in this paper are about 1 year for ETS-II and CS, and six months for BSE. 2. (b) The percentages of time in which measured attenuation exceed 5, 10 and 15 dB are 0.7, 0.3 and 0.15% respectively at 34.5 GHz (ETS-II), 0.08, 0.016 and 0.008% respectively at 19.45 GHz (CS), 0.025, 0.0025 and 0.0009% respectively at 11.7125 GHz (BSE), and 0.02, 0.0023 and 0.001% respectively at 11.5 GHz (ETS-II). 3. (c) Duration of attenuation exceeding 30 dB at 34.5 GHz is less than 50 min with the occurrence probability of 0.013% for a one year period. Attenuation exceeding 6 dB at 11.5 GHz and the one exceeding 10 dB at 19.45 GHz are 0.0025% (8 min in a year) and 0.015% (10 min in three months). 4. (d) In the cumulative distributions of XPD (Cross Polarization Discrimination), values of XPD exceeding the percentages of time, 0.3, 0.1, 0.03 and 0.01% are 25, 22, 19 and 17 dB respectively at 34.5 GHz, 28, 23, 20 and 16.5 dB respectively at 19.45 GHz and 33, 29, 26 and 24 dB respectively at 11.5 GHz. This paper presents an outline of the propagation experiments carried out by using ETS-II, CS, BS and ECS, and propagation characteristics of radio waves mainly above 10 GHz at the main station (Kashima Branch, RRL).