WSJT-X implements communication protocols or "modes" called FT8, JT4, JT9,
JT65, QRA64, ISCAT, MSK144, and WSPR, as well as one called Echo for
detecting and measuring your own radio signals reflected from the Moon.
These modes were all designed for making reliable, confirmed QSOs under
extreme weak-signal conditions.
All but ISCAT use nearly identical message structure and "source encoding,"
the efficient compression of standard messages used to make minimal QSOs.
JT65 and QRA64 were designed for EME ("moonbounce") on the VHF/UHF bands;
JT65 has also proved very popular and effective for worldwide QRP
communication at HF. JT9 is optimized for the LF, MF, and HF bands.
It is about 2 dB more sensitive than JT65 while using less than 10% of the
bandwidth. With either JT9 or JT65, world-wide QSOs are possible with power
levels of a few watts and compromise antennas. JT4 and QRA64 are optimized
for EME on the VHF and higher bands, and especially the microwave bands
from 2.3 to 24 GHz. FT8 is operationally similar to JT65 but is much faster,
using T/R cycles only 15 s long. MSK144 is used for Meteor Scatter on the