Amateur Radio on the International Space Station

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Ham Video

A DATV (digital amateur television) transmitter is installed in the Columbus module of the International Space Station (ISS). This transmitter is dubbed "Ham Video".

Main characteristics :

  • Downlink frequencies: 2.422 GHz, 2.437 GHz
  • Contingency frequencies : 2.369 GHz, 2.395 GHz
  • DVB-S like signal (without PMT tables)
  • Symbol rates: 1.3 Ms/s, 2.0 Ms/s
  • FEC : ½
  • Video PID = 256
  • Audio PID = 257
  • Antennas: ARISS 41 and ARISS 43 patch antennas on the nadir of Columbus
  • RF radiated power : approximately 10 W EIRP

Ham Video operates with a Canon XF-305 camera.

 

Commissioning

Commissioning of the Ham Video transmitter is scheduled April - March 2014. The commissioning is performed in four steps. All four frequencies and two symbol rates are checked with each of the two antennas.

For each commissioning step, an astronaut transmits video and audio during a pass over the Matera ground station. The Matera VLBI station is located at the Italian Space Ageny’s ‘Centro di Geodesia Spaziale G. Colombo’ (CGS) near Matera, a small town in the south of Italy.

The commissioning steps extend over a period of several weeks.

 

Blank transmissions

Between the Commissioning steps, Ham Video transmits a continuous DATV signal with the camera turned off. Ground stations receive a black image and audio at zero level.

A « blank » DVB-S signal contains all the data of normal DVB-S. The information tables describing the content and the content itself, i.e. the video (black) and the audio (silence), are the same as for the image and the sound produced by a camera.

Receiving a black image and silent sound may seem uninteresting but, from a technical perspective, the digital signal offers an important source of information.

Even without decoding, several measurements of the received signal provide valuable information:

  • analogic HF signal strength (dBm)
  • analogic Signal/Noise ratio (dB)
  • digital Signal/Noise ratio = MER (dB)
  • error/correction ratio = Vber, Cber …
  • validation of the received transport stream = TS

 

 

Reception Reports

Ground stations with S-band capability can provide valuable information.

Basic data such as:

  • noise level without signal
  • AOS time (UTC)
  • maximum signal level during pass
  • LOS time (UTC)

can be reported by ground stations without the need of DATV hard- and software. A reporting facility is available here : Ham Video Reporting

Reception Reports of the blank transmissions provide precious information regarding the efficiency of the system in different configurations. The influence of the ground station environment is also evaluated.

These most needed reception reports are gratefully accepted.

 

Basic DATV Receiver

Some "Set Top Boxes” can be used for receiving Ham Video signals during a pass of the ISS.

More details on how to set up "Set Top Boxes" will be provided soon

 

Windows computer with TechnoTrend TT S2-1600 card and Tutioune software

A Windows computer with TT S2-1600 receiver card can be used for Ham Video reception.

The Tutioune software, developed by Jean Pierre Courjaud F6DZP, measures and records the Ham Video signals second per second:

  • HF signal level
  • digital Signal/Noise level = MER (dB)
  • error/correction = Vber
  • validation of the received transport stream = TS

The recorded file can be examined and forwarded to ARISS.

Better even, the data can be forwarded during an ISS pass to the TiouneMonitor on the www.vivadatv.org website. In other words, the data can be observed worldwide, real time.

Tutioune also shows the constellations during signal reception (see HamTV Bulletin #4). The TS stream can be recorded, but this is less interesting since richer information is already available.

Tutioune also decodes the DVB tables and provides the PIDs and the channel name (« HAMTV ») recovered from the SDT table.

 

Announcements

For the Blank Transmissions, different frequencies and both antennas are tested. The Symbol Rate is 1.3 Ms/s.

The frequency and antenna in use for the Blank Transmissions are announced per AMSAT Bulletin Board.

The exact days/times of the Commissioning steps at the Matera grond station are also announced.

Matera streams the received video over the BATC server, under the identification ISS1 - 5. The BATC server is available at http://www.batc.tv

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