I do very much appreciate your reply! Thanks for trying to help.
Baud rate is not an issue, I'm talking to the radio just fine, and in receive mode Gpredict compensates for Doppler as expected. I'm personally having trouble getting the radio to operate in split mode and have Gpredict correct Doppler on the other VFO. I understand that Gpredict cannot adjust the radio's mode (FM, CW, SSB, etc.) or put the radio into split mode operation, this must be done manually. I've spent many hours trying different settings with no joy.
That's why it would be really helpful if someone with an FT-991 or 991A who has already been down this path could help with their configuration settings for Gpredict and also any tips about setup of the rig itself.
This is a completely brand new rig for me, and a fundamental change too - my previous radio was a 30+ year old Kenwood TS-430S. Eventually I plan on adding an SDR to the mix for panadapter and other uses, and when that happens I suspect this will become a much more straightforward operation as the SDR will be the receiver, the 991A will be the transmitter and this will be a full duplex setup - but that is some time away on my timeline, and I'd sure like to get this operational even in half duplex mode as soon as possible.