Been struggling with CAT control on my IC-9700 for AO-73 linear transponder operations. Currently using SatPC32 but considering switching to Gpredict. The Doppler compensation seems to drift during high elevation passes - my uplink stays put but I can hear myself sliding across the downlink passband. Anyone using Gpredict with modern rigs notice better tracking accuracy?

Particularly interested in experiences with inverting transponder LSB/USB convention and how well the software handles the coordinated frequency adjustments during satellite approaches.

Had the exact same problem with SatPC32 on my 9700. The issue was the VFO locking setting in satellite mode - make sure you disable that. Also check your TLE update frequency, old elements will cause drift on high passes.

Gpredict user here with FT-991A. The CAT Doppler compensation works much better than SatPC32 in my experience, especially for linear birds. The interface takes getting used to but the tracking accuracy is noticeably tighter.

Check if your CAT polling rate is too fast - some rigs get overwhelmed. I run 500ms intervals on my 9700 and it's rock solid now. Even a few degrees error in elevation prediction can kill your signal strength.