I've just tried RTTY mode for the first time. The results are stunning. I could back the AGC Threshold down to the point where I could barely hear the station calling, and I could copy 100% -- I could widen the filter bandwidth to 1.5K and could hear almost no background noise.
Let me guess... RTTY mode implements a really-cool bi-modal filter of some type?
(sorry if this is in the docs or has already been discussed... I'm just so impressed, I had to post and ask).