Vojtech and Patrick thanks you for the reply. I effectively didn't realize synchronization was so critical too. Interesting.
Just a comment/question to both, since you are both developers of widely used programs (and I take this opportunity to thank you both for that), I discovered the THOR mode as release by Dave in Fldigi and I have to say based on the preliminary test that I have done (and echoed by tests done by Rein developer of the PSKmail system), that I am very impressed by the performance I get. It is also an ifsk mode like DominoEx but for some reason performs much better at least as implemented in fldigi. Not sure if it is the permanent FEC but is seems quite robust in my tests between VK and ZL. Have you had any comments or request for implementation in your software or is it just too new, or not different enough? 73s, John VK2ETA (And for Patrick, Ex FK8DV. Merci)