Описание
WSJT-X implements communication protocols or "modes" called FST4, FST4W, FT4,
FT8, JT4, JT9, JT65, Q65, MSK144, and WSPR, as well as one called Echo for
detecting and measuring your own radio signals reflected from the Moon.
These modes were designed for making reliable, confirmed QSOs under extreme
weak-signal conditions.
JT4, JT9, and JT65 use nearly identical message structure and source encoding
(the efficient compression of standard messages used for minimal QSOs). They
use timed 60-second T/R sequences synchronized with UTC. JT4 and JT65 were
designed for EME ("moonbounce") on the VHF/UHF/microwave bands. JT9 is
optimized for the MF and HF bands. It is about 2 dB more sensitive than JT65
while using less than 10% of the bandwidth. Q65 offers submodes with a wide
range of T/R sequence lengths and tone spacings; it is highly recommended for
EME, ionospheric scatter, and other weak signal work on VHF, UHF, and microwave
bands.
FT4 and FT8 are operationally similar but use T/R cycles only 7.5 and 15 s long,
respectively. MSK144 is designed for Meteor Scatter on the VHF bands. These
modes offer enhanced message formats with support for nonstandard callsigns and
some popular contests.
FST4 and FST4W are designed particularly for the LF and MF bands. On these bands
their fundamental sensitivities are better than other WSJT-X modes with the same
sequence lengths, approaching the theoretical limits for their rates of
information throughput. FST4 is optimized for two-way QSOs, while FST4W is for
quasi-beacon transmissions of WSPR-style messages. FST4 and FST4W do not require
the strict, independent time synchronization and phase locking of modes like
EbNaut.
WSPR mode implements a protocol designed for probing potential propagation paths
with low-power transmissions. WSPR is fully implemented within WSJT-X,
including programmable "band-hopping".