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DATV on ISS ?

DATV on ISS ?. How can this become a reality? Wolf-Henning Rech DF9IC / N1EOW Thomas Sailer HB9JNX / AE4WA. D-ATV on ISS?. Use open worldwide commercial broadcast standards - this ensures easy availability of receiving equipment DVB / ETSI standards: DVB-S (EN 300 431) since 1994

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DATV on ISS ?

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  1. DATV on ISS ? How can this become a reality? Wolf-Henning Rech DF9IC / N1EOW Thomas Sailer HB9JNX / AE4WA Wolf-Henning Rech DF9IC

  2. D-ATV on ISS? • Use open worldwide commercial broadcast standards - this ensures easy availability of receiving equipment • DVB / ETSI standards: • DVB-S (EN 300 431) since 1994 • DVB-S2 (EN 302 307) since 03/2005 • DVB-S FTA receiver costs 50-80 EUR (Germany, 2005) Wolf-Henning Rech DF9IC

  3. D-ATV on ISS? • Digital vs. analogue (FM) ATV: • scalable performance / bandwidth / RX sensitivity • multiple video and audio streams available • 10 - 20 dB better link performance • PA needs better linearity / has less efficiency • source encoder causes latency • hard degradation in presence of strong interference Wolf-Henning Rech DF9IC

  4. D-ATV on ISS? • Block diagramm of a DTV transmitter ... : • .... and a receiver: Video camera A/D converter Source Encoder Channel Encoder RF mo- dulator Upcon- verter Video monitor D/A converter Source Decoder Channel Decoder RF demo- dulator Down- converter Digital TV set-top box Wolf-Henning Rech DF9IC

  5. D-ATV on ISS? • Source Encoder: • removes redundant and irrelevant parts of the signal • trade-off between data rate and signal quality/latency • 1 ... 2 Mbit/s low quality - 4 ... 6 Mbit/s high quality for SDTV A/D converter Source Encoder Analog 5 MHz BW Digital 80 - 200 Mbit/s Digital 1 - 10 Mbit/s Wolf-Henning Rech DF9IC

  6. D-ATV on ISS? • Channel Encoder: • adds redundancy to the source coded signal for error correction capability • R = input data rate / output data rate = 7/8 ... 1/4 • trade-off between required Eb/N0 at receiver and bandwidth Source Encoder Channel Encoder Digital 120 Mbit/s Digital 1.5 Mbit/s Digital 1.7 - 6 Mbit/s Wolf-Henning Rech DF9IC

  7. D-ATV on ISS? • Source encoding: • MPEG-2 (DVB-S and DVB-S2) • MPEG-4 / H.264 (DVB-S2) for HDTV • Channel encoding and modulation • QPSK with R = 1/2 FEC with convolutional + Reed-Solomon coding (DVB-S) • QPSK with R = 1/2 - 1/4 FEC with BCH + LDPC coding (DVB-S2) Wolf-Henning Rech DF9IC

  8. D-ATV on ISS? Source: ETSI TR 102 376 Wolf-Henning Rech DF9IC

  9. D-ATV on ISS? • Required Eb/N0 incl. implementation loss: • 5 dB for DVB-S and 2 dB for DVB-S2 • compare to >20 dB for 1200 Baud AFSK=> 30...80 times better efficiency • Receiver noise level (N0): • T = 290 K => N0 = -174 dBm/Hz • Required signal power for 2 Mbit/s is -106 dBm for DVB-S and -109 dBm for DVB-S2 • compare to -120 dBm for FM voice signal at threshold and -115 dBm for 9600 Bd packet radio Wolf-Henning Rech DF9IC

  10. D-ATV on ISS? • „Quick and dirty“ link analysis (1): • assumed that the patch antenna at ISS is useable up to +-70° with 0 dBi gain (hopefully!) • then the minimum elevation at ground station is 10° and the maximum path length is around 1200 km ISS 70° 1200 km 300 km 10° Ground station SSETI Express Patch Antenna Wolf-Henning Rech DF9IC

  11. D-ATV on ISS? • „Quick and dirty“ link analysis (2): • 1200 km @ 2.4 GHz mean 162 dB path loss • TX EIRP assumed +40 dBm (+10 dBW, 10 W at the antenna feeding point with 0 dBi gain) • RX antenna assumed 1 m diameter dish with 40 % efficiency, 10° angle at -3 dB and 24 dBi gain • results in a received signal power of(+40 - 162 + 24) dBm = -98 dBm • 8 dB margin at -106 dBm RX sensitivity Wolf-Henning Rech DF9IC

  12. D-ATV on ISS? • Amateur radio hardware for DVB-S: 1.2 GHz 2.4 GHz Power Amplifier (DB6NT) DVB-S receiver Main unit withbaseband processor Video camera MPEG Encoder 2400 MHz modulator Wolf-Henning Rech DF9IC

  13. D-ATV on ISS? • ... and what comes out of it Wolf-Henning Rech DF9IC

  14. D-ATV on ISS? • Summary: • Digital video over 1200 km LOS path is possible with a 10 W EIRP transmitter and 24 dBi receiver antenna gain • Low cost transmitter technology is available to amateur radio and can be modified / adapted to the special needs at ISS • Ground station is more complex that for FM voice operation but within the capabilities of technically skilled hams Wolf-Henning Rech DF9IC

  15. D-ATV on ISS? • When and how does it happen? Wolf-Henning Rech DF9IC

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