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Digital Audio Radio Service

Digital Audio Radio Service - The third part of our project...

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The third part of our project pertains to Satellite Radio’s and their implementation by the United States Military. Here I will explain how the three major corporations in the satellite radio industry affect military technology, and how this technology is used in the battlefield. The three major companies are: XM Satellite, Sirius Satellite, and World Space Corporation. Previously in this paper we discussed the technical specifications of how the satellites were used for commercial purposes. I’d like to start out by discussing the technical aspects of the three previously mentioned companies in relation to their interaction with the Military’s Digital Audio Radio Service (DARS) system. DARS is military jargon for satellite radio which includes the three fore mentioned companies, also DARS is a new service to consumers which use satellite to broadcast digital quality music, data, and information to a much larger coverage than AM and FM transmission. . From the three satellite providers, the military uses applications such as Moral Welfare Recreation (MWR), Satellite Weather Information Service (SWIS), psychological operations, propaganda, testing, and experimentation. X M Satellite Radio X M Satellite Radio delivered through two satellites mentioned above, Rock and Roll. These two satellites can cover the entire United States, Northern Mexico, and some parts of Southern Canada (Figure 1). They also have a design of about 12 to 15 years with an initial DC power of 15kw and that is twice the power of Digital Broadcast Satellite. X M satellite DARS, frequency allocation of 12.5 MHz (2332.5 to 2345.0 MHz) is divided into three sections each satellite transmits a pair of 2.5 MHz and the terrestrial repeaters use the remaining 2.5 MHz. Also each carrier signal has components with data rates gram 16 KBPS to 64 KBPS and the DTM carrier rates of 1.536 KBPS that allow multiplex up to 24 channels per carrier (XM Satellite Radio), DARS reception signal has to have a line of sight to the satellite that allows user to receive or continues signal without any interference. Then bandwidth of this repeater is 2.5 MGHz. Since this is half the width of the signal broadcast from the satellite only half the satellite transmitted bandwidth undergoes terrestrial repetition. X M with the help of ST Microelectronics developed the chipsets that can convert analog to digital and decrypt the signals from satellite and repeaters and then deliver it to the radio (XM Satellite Radio).
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Figure1 : Approximate coverage footprint of XM satellite, Rock and Roll Sirius Satellite Radio Sirius Satellite Radio uses the same concept as X M Radio but different satellite orbits and different number of satellite and capacity. Its programming delivered through three local FS 1300 satellite elliptical orbits with perigee of 24,469 KM and an apogee of 47,102 Km centered over the United States. Since elliptical orbit has higher elevation angels, therefore car antennas will have greater minimum gain from the direction of
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Digital Audio Radio Service - The third part of our project...

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