WSJT-X implements communication protocols or "modes" called JT4, JT9, JT65, and
WSPR, as well as one called Echo for detecting and measuring your radio signals
reflected from the Moon. The JTxx modes were all designed for making reliable,
confirmed QSOs under extreme weak-signal conditions. They use nearly identical
message structure and "source encoding," the efficient compression of standard
messages. JT65 was designed for EME ("moonbounce") on the VHF/UHF bands, and
has also proved very popular and effective for worldwide QRP communication at
HF. In contrast, JT9 is optimized for the LF, MF, and HF bands. JT9 is about 2
dB more sensitive than JT65 while using less than 10 procent of the bandwidth.
With either JT9 or JT65, world-wide QSOs are possible with power levels of a few
watts and compromise antennas. JT4 is particularly optimized for EME on the
microwave bands from 2.3 to 24 GHz. Finally, as described more fully on its
own page, WSPR mode implements a protocol designed for probing potential
propagation paths with low-power transmissions. WSPR has now been fully
implemented within WSJT-X, including automatic band-hopping, so all modes are
available in a single program.

• Anton Midyukov

• Anton Midyukov
• Eve R. Ybody

• wsjtx
• wsjtx-data
• wsjtx-debuginfo