The ARRL have suggested that new and evolving software-based digital modes over the past several years has altered the atmosphere of the HF bands
There have been suggestions that the popularity of modes that make it possible to contact stations neither operator can even hear has resulted in fewer CW and SSB signals on bands like 6 meters and 160 meters. Traditional modes require far more interaction and effort on the part of the operator; the newer digital modes not so much.
The recent advent of the still-beta “quick” FT8 mode, developed by Steve Franke, K9AN, and Joe Taylor, K1JT — the “F” and the “T” in the mode’s moniker — has brought this to a head. Some now wonder if FT8 marks the end of an era and the start of a new, more minimalist age.
“We’ve been as surprised as anyone about the rapid uptake of FT8 for making QSOs on the HF bands,” Taylor told ARRL this week. Rather than viewing FT8 as a total game-changer, he sees a dividing line between such digital modes and more traditional modes.
“SSB and CW are general-purpose modes,” Taylor asserted. “They are good for ragchewing, DXing, contesting, emergency communications, or whatever. FT8 and the other modes in WSJT-X are special-purpose modes. They are designed for making reliable, error-free contacts using very weak signals — in particular, signals that may be too weak for the more traditional modes to be usable, or even too weak to hear.”
Full Story - http://www.arrl.org/news/view/new-digital-modes-changing-complexion-of-bands-and-perhaps-of-ham-radio
WSJT-X weak signal modes software, covers FT8 - https://physics.princeton.edu/pulsar/k1jt/wsjtx.html