I don’t know either, but I suppose that it is in Unproto (so not ARQ), as APRS.
Click on “Unproto”, prepare your message and when it is ready and the frequency free, send it either clicking on “Send” or typing the “Esc” key.
De : firstname.lastname@example.org [mailto:email@example.com] De la part de Andrew O'Brien
I'm new at communicating via 1200 baud packet and the International Space Station. As you can see by the attached screenshot, Multipsk works well for capturing the packet data. For those amateur operators using the software, how do you transmit on the uplink ? I am assuming astronauts are not sitting in their spacecraft typing replies , so if I transmit what should I be looking for to indicate I was heard? Another ham responding or just seeing my own text repeated back via the downlink ?