Yes, no matter what I do, whether it's alt + f4, die, or save and quit normally, it always resets the signal. It goes down to 0% and turns off both frequency and polarity signals, as well as showing a big "NO SIGNAL" overlay, though it keeps the signal in there and you can still process it after
(attached is raw footage of me testing both saving/exiting and dying, the former of which still lets me save, and the latter not)