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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

DATV on ISS ?

How can this become a reality?

Wolf-Henning Rech DF9IC / N1EOW

Thomas Sailer HB9JNX / AE4WA

Wolf-Henning Rech DF9IC

d atv on iss
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

d atv on iss3
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

d atv on iss4
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

d atv on iss5
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

d atv on iss6
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

d atv on iss7
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

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D-ATV on ISS?

Source: ETSI TR 102 376

Wolf-Henning Rech DF9IC

d atv on iss9
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

d atv on iss10
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

d atv on iss11
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

d atv on iss12
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

d atv on iss13
D-ATV on ISS?
  • ... and what comes out of it

Wolf-Henning Rech DF9IC

d atv on iss14
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

d atv on iss15
D-ATV on ISS?
  • When and how does it happen?

Wolf-Henning Rech DF9IC

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