Snart är det dags för amatörradio-video (Ham Video) att installeras och börja användas från ISS:
The ARISS DATV transmitter, dubbed “Ham Video”, already onboard the
International Space Station, will soon be installed in the Columbus module and
commissioned.
Commissioning will be done in several steps, each during a full pass of the
ISS over the Matera ground station (see Bulletin 2). It is not yet known if
these passes will be chosen in close succession, or if they will cover several
weeks. ARISS proposes ESA to operate so called “blank” transmissions during the
commissioning period. If this is accepted, it means that Ham Video will
transmit permanently without camera. The camera will not be used because it is
fed on batteries and servicing it would need prohibitive crew time.
Transmitting recordings is part of a future project, but not available
presently.
Although ground stations will receive a black image without audio, “blank”
transmissions contain all information needed for the setting up and the fine
tuning of the station. Moreover, collected data will be used for a performance
study of the ARISS L/S-band antennas as well as for an evaluation of the global
system.
For this launch campaign, ARISS addresses a call for collaboration to the
amateur radio community, especially to the operators interested in space
communications. Several satellite operators have shown interest.
Ham Video technical characteristics are available at www.ariss-eu.org .
Suggestions and useful addresses for the setting up of a Ham Video ground
station are also provided.
Among the components of a satellite ground station, the antenna system is the
most expensive. High gain antennas are needed, moved by azimuth and elevation
motors and driven by an appropriate computer program. For Ham Video reception,
a 1.2m dish with precision tracking is recommended. A station compliant with
the recommendations provided in the aforementioned reference text should be
capable of 3 to 4 minutes of DATV reception during a pass of the ISS. AO-40
operators who still have an S-band dish can now use it for Ham Video.
On the other hand, interesting data can be gathered by stations with a much
simpler setup. A dish with a self made helix feed could be used without motors.
This antenna could be positioned in a fixed direction, determined before a pass
of the ISS, pointing to the position of the ISS at closest approach, which
corresponds to the maximum elevation of the space station during the pass. With
the setup as described hereunder, 1 to 2 minutes of solid reception of the Ham
Video signal should be possible.
Call for participation to the Ham Video launch campaign
ARISS addresses a call to amateur radio experimenters who would like to
participate to the Ham Video launch campaign.
Data gathering during the initial “blank” transmissions is important and the
help of volunteering operators will be most appreciated.
More details to follow.
It is to be noted that builders of the hereunder proposed “Simple Station”
could later update their equipment and add tracking motors. Chained stations
will be needed for ARISS Ham TV school contacts. Video and audio from the ISS
will be web streamed to the schools over the Internet.
We will keep you informed of these developments. For the time being, as a
starter, let us concentrate on receiving “blank” transmissions.
All Ham TV Bulletins are available at www.ariss-eu.org
[ANS thanks Gaston Bertels, ON4WF, and AMSAT-UK, for the above information]