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