A SEMINAR ON “SATELLITE DIGITAL RADIO”

CONTENTS SATELLITE RADIO SIRIUS SATELLITE RADIO WORLD SPACE BASIC COMPONENT OF SATELLITE RADIO XM SATELLITE RADIO GROUND REPEATERS THE SATELLITE RADIO RECEIVERS TECHNOLOGY FREQUENCY OF OPERATION EARTH ORBITS

SATELLITE RADIO Satellite radio is a subscriber based radio service that broadcast directly from satellites. It is an advanced form of mobile radio service where one can receive compact disc quality music and other entertainment channels. Even if the person is miles away from the radio station, the quality of the program is not affected

Sirius Satellite Radio Operated in the United States and Canada Provides 69 channels of music 65 channels of news, sports and entertainment Broadcast 24 hours a day commercial free from three satellites

WorldSpace Based in Silver Spring First stated by wanting to improve literacy in Africa Covers Asia, Europe, and Africa Licensed to serve Central and South America AfriStar (serves Africa) and AsiaStar (serves Asia and Europe) 3 transmission beams; 50 channels each WorldSpace satellite receivers are capable of receiving data at a rate of 128 kilobits per second (Kbps).

BASIC COMPONENTS OF SATELLITE RADIO The three satellite radio systems: Satellites Ground Repeaters Radio Receivers

XM Satellite Radio United States and Canada 73 music, 39 news, sports and entertainment, 29 regional traffic and weather, 23 play-by-play sports. XM Radio uses two Boeing HS 702 satellites, appropriately dubbed "Rock" and "Roll," placed in parallel geostationary orbit, one at 85 degrees west longitude and the other at 115 degrees west longitude. Geostationary Earth orbit (GED) is about 22.223 miles (35,764 km) above Earth, and is the type of orbit most commonly used for communications satellites

GROUND REPEATERS: Satellite radio reception, poses threats from weather, tall building_ and mountains that can potentially interfere with broadcasts. To avoid the interference caused by tall structures, both Sirius and XM Radio are supplementing their satellite coverage with terrestrial transmitters, called ground repeaters.

THE SATELLITE RADIO RECEIVER: Existing AM/FM car radio will not be able to receive satellite radio broadcasts. Replacement of the radio with a 3-band capable receiver (AM, FM, Sirius or XM Satellite).

Technology 25 MHz in S band 2.3 GHz 2 multichannel operators 2320-2332.5 MHz (Sirius) 2332.5-2345 MHz (XM) complementary terrestrial repeaters to overcome effects of satellite signal blockage and multipath interference AM/FM/SAT receivers Spring 2006

FREQUENCY OF OPERATION Digital radio is operated in a frequency range of between 215 - 230 MHz (Mega Hertz). This part of the radio spectrum is sometimes called Band III, or VHF, and was previously used for some television transmissions and by the military. The central frequency for the BBC National Multiplex is 225.648MHz.

Satellite Radio vs. Others Listening availability- SR very high, others are moderate to low Sound Quality-SR high, AM=very low, FM=High Variety-SR Highest, Variable due to economic factors

Earth Orbits

Orbits NGSO GSO Low Earth Orbits Height: 700-2000 km Rotation Period: 90 min. Time in LOS of earth station: 15 min. Medium Earth Orbits Height: 8000-12000 km Rotation Period: 5-12 hrs. Time in LOS of earth station: 2-4 hrs. Geostationary Orbits Height:35,780 km Rotation Period: 24 hrs. Time in LOS of earth station: 24 hrs. Spring 2006

Geosynchronous Orbit (GSO) Uses XM (85oW 115oW) Communications (DBS, data) Advantages 1 orbit per siderial day (23h56m) (geostationary) wide coverage Disadvantages round trip latencies exceed .5 seconds weak coverage inadequate elevation angles at high latitudes Congestion

Medium Earth Orbit (MEO) Uses Cellular telephone communications GPS (global positioning system) Advantages antenna size and power are relatively modest and the latency is still small Disadvantages Proximity to Van Allen belt creates hazards to electronic systems

Low Earth Orbit (LEO) Uses Advantages Disadvantages Data-communications (Little LEO) Data-and-voice communications (Big LEO) Advantages Low power requirements Short propagation delays Disadvantages Greater no. of satellites needed for coverage Big LEO req’d to provide continuous service to US

CONCLUSION It will be an intelligent communications device that will offer more services and conveniences than can be provided by conventional analog technology. For the broadcaster, digital radio is not just a way to stay competitive with other forms of digital sound, but one that offers numerous new business opportunities as well. It is a bright future for listeners and broadcasters alike: a future that truly promises to provide 'the best sound on the airwaves' for the world.

REFERENCES http://www.seminar.com/article/sdr_1.html, http://www.spinnakerlabs.com/Satellite digital radio.pdf  http://www.worldspace.com http://xmradio.com/whatisxm/index.xmc

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