Thanks. I would like an AIS transmitter, the commercial AIS transmitters costs really a lot, while the receivers are cheap - and there are DIY-plans and open source software out there for the receiver thing, but for the transmitter ... very little. I thought that since "software defined radio" exists nowadays, this was "just" a software problem, but I was scolded by a professional radio engineer when suggesting so.
Thanks to this article, I now understand SDR a bit better, so I see clearly now that this is just a thing on the receiver side, and cannot be used on the transmitting side :-)
Yup, transmitting and receiving are two different things.
Thank you for reading and commenting.