Antennas, Satellite Broadcasting, and Emergency Preparedness for the Voice of America (1988) / Chapter Skim
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Satellite Direct Audio Broadcasting and Reception
Satellite Direct Audio Broadcasting and Reception
Pages 24-37
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From page 24... ...
with a roadmap for introducing satellite audio broadcasting technology, and the improved services which it allows, into its operations to compensate for many of the transmission and reception limitations of its terrestrin1 ~ hi ~hfrequency (HF) , relay network.
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From page 25... ...
terrestrial systems and people invest in such technologies as audio-cassette players, portable personal radios, compact-disk players, and video-cassette recorders, their expectations of broadcast signal quality and reliability will increase. This seems to require that the VOA consider supplementing HF with other transmission systems, and DBS-A is an obvious choice.
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From page 26... ...
In detailed and quantitative terms, the report showed that present receiver populations are very unevenly distributed around the globe because of different economic conditions and national, political regulation. Technically, the receiver characteristics in various regions depend directly on the types of signals locally available, medium wave (MOO)
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From page 27... ...
Changes in the transmitter frequency and corresponding, required retuning of the receiver by the listening audience throughout the day, to offset the variations in ionospheric reflection or to counteract jamming 8. Technical complexity and high costs, both for initial acquisition and installation and for continuing operation and maintenance, of the many high-power transmitting stations distributed around the world to achieve the desired audience coverage 9.
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From page 28... ...
Numerous studies (Bachtell et al., 1985; Horstein, 1985; National Research Council, 1986) have shown that satellite broadcasting in the HF band to achieve compatibility with the existing, short-wave, receiver population would require satellite power levels and antenna diameters that are beyond the current state of the art, as illustrated in Figure 3-1.
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From page 29... ...
29 i l ll ~ , ,~ , a,_ o 1 -~=14 / ~ _ it.
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From page 30... ...
However, the relative magnitudes can be estimated based on the known history and projections of the VOA and the histories of satellite communications systems already in use for domestic and international fixed service. Table 3-1 summarizes the capitalization and operating costs of one VOA relay site, one international satellite, and one domestic satellite over a ten-year period.
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From page 31... ...
Item Terrestrial HF International Satellite Domestic Satellite Initial cost per relay 100-150 105 site or satellite plus launch vehicle Initial cost per satellite control station Annual operation and main- 8 tenance per site or satellite Equipment lifetime (years) Total equivalent annualized cost Total equivalent annualized cost for global coverage 95 21 2 20 7_ 20b 18 130-155C 72d 10 2 1Oa 20b 12 48d Space segment round segment CTen stations dPour satellites
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From page 32... ...
By contrast, a satellite can transmit hundreds of audio signals simultaneously, depending on its design, with no time constraints and potential coverage of 90 to 120 degrees of longitude and +70 degrees of latitude. Thus for total VOA coverage comparisons, there would be a large, per-channel cost difference in favor of four geostationary satellites over a total of 10 to 15 terrestrial HE sites.
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From page 33... ...
clearly recognized that replacement of the VOA's HE, terrestrial, broadcast facilities with direct-broadcast satellites transmitting at HE is neither technically nor economically feasible for the very near future. However, the state of the art of satellite technology does offer several options for introductory use of satellite transmitters by the VOA and others for limited broadcasting or auxiliary functions.
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From page 34... ...
CONCLUSIONS The potential advantages to the VOA (and to all the other international, audio broadcasters throughout the world) of DBS-A in terms of reliability, service-area coverage, signal quality, reduction of installation and operating costs, channel capacity, and reduction of the likelihood of jamming are compelling.
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From page 35... ...
, to do so with the excellent quality and reliability offered by satellite communications circuits today in the provision of radio and television distribution services and to do so at a lower unit cost than that of surface-based HF. The following four recommendations constitute the major milestones in a roadmap for the VOA's introduction of satellite direct audio broadcasting.
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From page 36... ...
delegation position in concert with the National Aeronautics and Space Administration and the Departments of Commerce and State for the forthcoming 1988 Space World Administrative Radio Conference concerning allocation of frequencies for direct satellite broadcasting of audio programming, and participate in the delegation's activities at the Conference.
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From page 37... ...
Spaced-Based Broadcasting: The Future of Worldwide Washington: National Academy Press. Worldwide direct audio broadcasting from space Space Policy 3(August)
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