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 . Look for the “Ham Video” link in the left sidebar. 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.
Gaston Bertels – ON4WF
PS: All Ham TV Bulletins are available at www.ariss-eu.org