I recently bought an FT-818 to accompany my FT-817 to work portably on linear satellites. In this article I will show you how to set up Gpredict properly.
At home I use Gpredict for doppler correction under Windows. Gpredict is free software, but requires Hamlib/rigctl(d) for cat control. Hamlib is not self-explanatory because it is not a ready-made software. You have to create the individual parameters yourself. The necessary information can be found in Hamlib's Gitlab.
So you have to create a command for each transceiver. Since I use 2 transceivers for full-duplex, I have to create 2 commands.
The most important thing is to find out the ID of your transceiver. The list can be found here: https://github.com/Hamlib/Hamlib/wiki/Supported-Radios
For me it is ID 1020 for Yaesu FT-817 and 1041 for Yaesu FT-818.
FT-817 and FT-818 have slight differences in the CAT commands. Therefore there are 2 profiles. (This is also the reason why the current version of SatPC32 currently does not work with the FT-818. Only the FT-817 is supported there.)