The Amateur Radio on the International Space Station (ARISS) “Ham Video” digital transmitter has been conducting tests since May 1 in order to check reception of the signal by a network of ground stations in Europe. ARISS-EU Chairman Gaston Bertels, ON4WF, said the test transmissions will continue for as long as ISS on board operations permit. Ham TV has been sending a blank transmission signal, since the camera has not been powered on.
“The networked European ground stations are receiving excellent signals on 2395 MHz,” Bertels told ARRL. “The European network of ground stations is nearly complete. Six ground stations span the continent in an ‘X’ formation.” Bertels said that on each pass, the signal is analyzed with Tutioune software, developed by Jean Pierre Courjaud F6DZP.
Bertels said that four stations can receive about 10 minutes of solid copy during both ascending and descending passes over the continent. He said this comports with predictions. The networked ground stations have been streaming the blank digital video signal to the British Amateur Television Club (BATC) server. The BATC page shows all six video streams.
Once reliable ground station performance has been established, Bertels said, the Ham Video transmitter will be used to enhance ARISS school contacts, in conjunction with an audio-only VHF uplink. “This operational mode is dubbed ‘ARISS Ham TV,’” Bertels said. The Ham Video transmitter is located in the Russian Sector of the ISS Columbus module. It identifies as OR4ISS.
Although no Ham Video ground stations have been formally established in the US, Bertels said that Kerry Banke, N6IZW, in San Diego gets excellent results using a 1.8 meter dish. The European ground stations use 1.2 meter dishes.
“One of the mains challenges is the ISS tracking,” Bertels said. “S-band dishes have a small angular aperture, and the tracking needs precise calibration. This is done using the Sun as microwave source.”
Bertels said Piero Tognolatti, I0KPT, computed the maximum range of quasi error-free reception of the digital TV signals transmitted from the ISS at about 1000 km (625 miles). He said that range was taken into account when choosing the ground station locations. “Under optimal pass conditions, a single ground station achieves 6 minutes of error free reception,” Bertels told ARRL. “Experimentation continues on all aspects of the complex project: Mechanical construction of the precise tracking system, receiver electronics, decoding software, and signal streaming over the Internet.”
NASA Astronaut Mike Hopkins, KF5LJG, successfully installed and commissioned the ARISS) Ham Video system in March 2014. The following month, Japanese Astronaut Koichi Wakata, KC5ZTA, served as the host for a successful final commissioning pass for the Ham Video transmitter and camera. The S-band transmitter can use one of two ARISS patch antennas on Columbus. Radiated RF power is on the order of 10 W EIRP. Custody of the Ham Video transmitter was transferred from the European Space Agency to ARISS earlier this year. — Thanks to ARISS-EU Chairman Gaston Bertels, ON4WF