Satellite Radio


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A seminar on Satellite Radio by Sagar Medikeri, April 2010.

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Satellite Radio

  1. 1. Satellite Radio – a technological overview<br />Sagar Medikeri,<br />2BV06EC060<br />
  2. 2. Radio – Analog and Digital<br />Introduction to Satellite Radio<br />Various Satellite Radio Technologies<br />Future of Satellite Radio<br />Seminar Overview<br />
  3. 3. <ul><li>Analog Radio</li></ul>Here, the audio signal is piggybacked on a carrier signal by means of analog modulation techniques like AM, FM<br /><ul><li>Digital Radio</li></ul>Here, the audio signal is digitized and then transmitted using digital modulation techniques like QPSK, QAM<br />Radio – Analog and Digital<br />
  4. 4. Analog vs. Digital Radio<br />
  5. 5. Satellite Radio - Market Players<br />
  6. 6. Large area coverage<br />CD quality audio<br />Subscription based<br />Commercial-free content<br />Lots of variety - 100s of channels<br />Programming includes music, news, talk radio, sports, humor<br />Audio associated metadata transmitted<br />Some channels broadcast in 5.1 surround sound format<br />FCC does not regulate content<br />Service features<br />
  7. 7. How Satellite Radio works?<br />Uplink Station, Satellite & Terrestrial Repeaters Control Room<br />Terrestrial Repeaters<br />Fixed Receivers<br />
  8. 8. Satellite Technology<br />
  9. 9. 1worldspace satellite spot beams<br />Asiastar<br />Afristar<br />
  10. 10. ATIS (Automatic Transmission Identification Service). In this scheme, there can be multiple uplink facilities. Each uplink facility has a station ID.<br />2 or 3 Parabolic or Unfurlable Antennas are used<br />The RF signal received by satellites is amplified by high power TWTAs operating in parallel<br />RF power transmitted is 12 – 15 KW<br />Satellites’ lifetime is 12 - 15 years<br />Satellite Technology<br />
  11. 11. Receiver Technology<br />2320 MHz<br />2332.5 MHz<br />Carrier 1<br />Carrier 2<br />Carrier 3<br />4 MHz<br />4 MHz<br />4 MHz<br />
  12. 12. Receiver Technology<br />Sirius 1<br />Carrier 1<br />Carrier 1<br />Sirius 2<br />Carrier 2<br />Carrier 3<br />75 MHz<br />IF<br />~ -50dBm<br />Maximal-Ratio Combining for Signal Diversity<br />Baseband <br />Processor<br />Antenna <br />Tuner<br />2.3 GHz<br />Digitize, Demodulate, Error correction, Decrypt<br />Down conversion<br />
  13. 13. Maximal Ratio Combining<br />Adder<br />Baseband 1<br />a1<br />Retrieve the 3 Baseband signals<br />75 MHz<br />IF<br />Baseband 2<br />a2<br />Best estimate of Baseband signal<br />Baseband 3<br />a3<br />
  14. 14. Perceptual Audio Coding<br />Entropy Coding<br />Filter Banks<br />Quantization & Encoding<br />MUX<br />Audio<br />Compressed Audio<br />Psychoacoustic Model<br />Bit Allocation<br />
  15. 15. Achieved by Hierarchical Modulation<br />QPSK is embedded into 16QAM<br />QPSK carries “High Priority” bits & QAM carries “Less Priority” bits<br />In poor link conditions, at least QPSK is resolved<br />Economizes Bandwidth<br />Link Adaptation<br />
  16. 16. Used to limit reception to legitimate subscribers<br />Integrity of content<br />Content Protection<br />Elliptical Curve Cryptography (ECC) is used for encryption. ECC provides RSA level security with a smaller key. This reduces transmission overhead.<br />Conditional Access<br />
  17. 17. Receivers ($120) and Subscriptions (>$7/month) costly<br />Stiff competition from iPod, Internet Radio, local FM<br />Steady Attrition Rates<br />Sirius & XM still in debt<br />But, the technology developed for Satellite Radio will pave the way for Satellite Digital Media Broadcasting (S-DMB)<br />Future of Satellite Radio<br />
  18. 18. Painter, T., and A. Spanias. "Perceptual coding of digital audio." Proceedings of the IEEE 88 (2000)<br />Wikipedia entries on,<br /> 1. Sirius Radio<br /> 2. XM Radio<br /> 3. Psychoacoustics<br />Gledhill J., MacAvock P., Miles R. Whitepaper on “Hierarchical Modulation”<br />References<br />
  19. 19. Thank You !!<br />