I'm comparing tracking software options for serious linear transponder work on AO-7, FO-29, and AO-73. Currently using Gpredict with CAT control to my FT-847, but considering upgrading to Ham Radio Deluxe for better linear transponder support.

HRD claims to handle inverting transponder Doppler correction more accurately - it applies offsets from center frequencies then Doppler correction, rather than simple frequency tracking. The key difference seems to be proper handling of the inverted spectrum where LSB uplink becomes USB downlink.

For those running

• Linear transponder tracking with CAT control
• Multiple satellite operations
• Precision Doppler compensation for SSB/CW

What's your experience with software accuracy and ease of use?

I switched from Gpredict to HRD specifically for linear transponders and haven't looked back. The automatic frequency relationship handling between uplink/downlink is spot-on, especially for Mode B operations on AO-7.

Have you considered SatPC32? It's specifically designed for amateur satellite work and handles inverting transponder mathematics better than either Gpredict or HRD. The learning curve is steeper but the precision is worth it for serious linear satellite work.

For emergency communications, we've standardized on Gpredict because it's open source and runs on Linux systems. The GNU Radio integration for AO-73 telemetry is also a plus. HRD may be more accurate, but Gpredict's reliability and cross-platform support wins for emcomm applications.