WSPR
Weak Signal Propagation Reporter is meant to be used with the least power (around 5 watts). The protocol can detect signals well below what we can hear. You can read more at the ARRL WSPR site. It is part of the WSJT suite, which you can read about here.
By participating in WSPR, you assist with HF propagation studies.
How we would use it
As this is a mode designed for propagation, the only use we would have for it in emergency communication is in the propagation. That is, by looking at reports of signals we can match up just the VT stations.
Overall, I believe JS8 would be a better mode for this.
