Program Development


WSJT-X implements JT9, a new mode designed especially for the LF, MF, and HF bands, as well as the popular mode JT65.  Both modes were designed for making reliable, confirmed QSOs under extreme weak-signal conditions.  They use nearly identical message structure and source encoding.  JT65 was designed for EME (“moonbounce”) on the VHF/UHF bands and has also proved very effective for worldwide QRP communication at HF; in contrast, JT9 is optimized for HF and lower frequencies.  JT9 is about 2 dB more sensitive than JT65A while using less than 10% of the bandwidth.  With either mode, world-wide QSOs are possible with power levels of a few watts and compromise antennas.  A 2 kHz slice of spectrum is essentially full when occupied by ten JT65 signals.  As many as 100 JT9 signals can fit into the same space, without overlap.

WSJT-X offers a "bi-lingual" operating mode in which you can transmit and receive JT65 and JT9 signals, switching between modes automatically as needed.  Displayed bandwidth can be as large as 5 kHz.  If your receiver has as upper-sideband filter at least 4 kHz wide, you can have all the typical JT65 and JT9 activity on screen at once, available for making QSOs with a click of the mouse.  Even with standard SSB-width IF filters, switching between JT65 and JT9 modes is quick and convenient. 

The current release of WSJT-X is Version 1.5.0.  It offers many advantages over previous releases including faster and better decoding performance, more convenient handling of messages with compound callsigns, and many improvements in rig control. A log of changes since version 1.4 is available here.  Upgrading from WSJT-X v1.4 will be seamless; there is no need to uninstall a previous version or move any files.  If you are upgrading from WSJT-X v1.3 you will need to copy your log files into a new location and re-enter your setup information.  Release notes for Version 1.5 (including details for upgrading from v1.3 and v1.4) are provided here.

Future plans

Future versions of WSJT-X will include other popular modes from WSJT and its sister programs, starting with WSPR and JT4.


Be sure to refer to the online WSJT-X User Guide for Version 1.5.

Installation instructions for Linux can be found here in the User Guide.  Download the package file appropriate for your system, from the lilst below.  (Versions installable with "apt-get" and "yum" will be made available as soon as our package maintainers create the packages.)
Macintosh OS X: 
Installation instructions for version 1.5 can be found here in the User Guide.  Download the package file appropriate for your system: 
Source Code:
Communication among contributing developers takes place on the wsjt-devel email reflector.  The package posted here contains all source code for WSJT-X as well as a snapshot of the Hamlib 3 sources and a CMake script to build WSJT-X on any supported platform.

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