If you've fallen behind on recent ham tech as far as I have, this might help (from the WSJT pdf [0]):<p>"WSJT-X is a computer program designed to facilitate basic amateur radio communication using very weak
signals.... JT65 and QRA64 were designed for
EME (“moonbounce”) on the VHF/UHF bands and have also proven very effective for worldwide QRP
communication on the HF bands.... JT9A is 2 dB more sensitive than JT65 while using less than 10% of the bandwidth.... These
four “slow” modes use one-minute timed sequences of alternating transmission and reception, so a minimal
QSO takes four to six minutes — two or three transmissions by each station, one sending in odd UTC minutes
and the other even."<p>[0] from the WSJT-X 2.2 User Guide PDF (offers 10 languages) at: <a href="https://physics.princeton.edu/pulsar/k1jt/wsjtx.html" rel="nofollow">https://physics.princeton.edu/pulsar/k1jt/wsjtx.html</a>