It's not entirely clear to me from the write-up, but it seems some of the problems that the author had with the "tracker" come from attempting to do carrier phase synchronization (with the Costas loop) before any kind of clock recovery.
Whoa, thank you! I don't know much about RF and learned ad-hoc for this project, and it seems perfectly plausible to me that someone knowledgeable would be able to look at this and identify a root cause - I certainly didn't do anything special for clock recovery, and based on the name I would have blindly assumed that synchronising the carrier wave _would_ be tantamount to recovering the satellite clock. I haven't researched clock recovery yet, and will do so. Once again, thank you!
