WSJT-X v1.8.0 released

Joe Taylor, K1JT, has announced the full General Availability release of version 1.8.0 of the popular WSJT-X software package.

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.

As we find ourselves slowly strolling toward the bottom of the solar cycle, HF propagation continues to decline. Many people are turning to these weak digital signal modes as a way to continue to be active, even under the worst conditions. Others enjoy these modes for use with QRP rigs or minimal antennas.  There’s a lot to be said about having the ability to get a signal from here to there at >20db below the noise floor.

This is a major update of WSJT-X, featuring the new FT8 mode and improvewd performance of JT65, QRA64 and MSK144 as well as many other performance enhancements, support for additional radios, a new and improved user guide and many other features.  Complete release notes are available here, or at the bottom of this post.

WSJT-X is a complex program. Be sure to read the online WSJT-X User Guide for Version 1.7.

WSTJ-X v1.8 is a free download and is available from the WSJT-X website here.



1. New mode called FT8: sensitivity down to -20 dB on the AWGN
channel; QSOs 4 times faster than JT65 or JT9; auto-sequencing
includes an option to respond automatically to first decoded
reply to your CQ.

2. New mode for accurate Frequency Calibration of your radio.

3. Improved performance of decoders for JT65, QRA64, and MSK144.
MSK144 includes facilities for amplitide and phase equalization
and an “SWL” mode for short-format messages.

4. Options to minimize screen space used by Main and Wide Graph

5. Enhanced management scheme for table of operating frequencies, and
a new set of default frequencies specific to the three IARU

6. Improved CAT control for many rigs, including those controlled
through Commander or OmniRig.

7. New keyboard shortcuts to set “Tx even/1st” ON or OFF.

8. A number of (mostly minor) bug fixes and tweaks to the user
interface. For example: new behavior for the audio level slider;
correctly logged QSO start times in certain situations; correct
control of FT-891/991 and some other radios via rigctld.

At the time of the v1.8.0-rc1 release the following tasks are yet to
be completed:

1. Updates to WSJT-X User Guide.
2. Sample files for FT8.
3. Enhanced decoding using AP (“a priori”) information.
4. Signal subtraction and multi-pass decoding.
5. Option to Auto-respond to the weakest responder to your CQ.


Installation packages for Windows, Linux, OS X, and Raspbian can be
downloaded from the WSJT web site:

Please send bug reports to either [email protected] or
[email protected]. Such reports should include a full
prescription of steps to reproduce the undesired behavior. You must
be a subscriber to post to either of these lists.


Brief Description of the FT8 Protocol

WSJT-X Version 1.8.0 includes a new mode called FT8, developed by K9AN
and K1JT. The mode name “FT8” stands for “Franke and Taylor, 8-FSK
modulation”. FT8 uses 15-second T/R sequences and provides 50% or
better decoding probability down to -20 dB on an AWGN channel. An
auto-sequencing facility includes an option to respond automatically
to the first decoded reply to your CQ. FT8 QSOs are 4 times faster
than those made with JT65 or JT9. FT8 is an excellent mode for HF
DXing and for situations like multi-hop E_s on 6 meters, where deep
QSB may make fast and reliable completion of QSOs desirable.

Some important characteristics of FT8:

– T/R sequence length: 15 s
– Message length: 75 bits + 12-bit CRC
– FEC code: LDPC(174,87)
– Modulation: 8-FSK, tone spacing 6.25 Hz
– Constant-envelope waveform
– Occupied bandwidth: 50 Hz
– Synchronization: 7×7 Costas arrays at start, middle, and end
– Transmission duration: 79*1920/12000 = 12.64 s
– Decoding threshold: -20 dB; several dB lower with AP decoding
– Multi-decoder finds and decodes all FT8 signals in passband
– Optional auto-sequencing and auto-reply to a CQ response
– Operational behavior similar to JT9, JT65

We plan to implement signal subtraction, two-pass decoding, and use of
a priori (AP) information in the decoder. These features are not yet
activated in v1.8.0.

We haven’t yet finalized what the three extra bits in the message
payload will be used for. Suggestions are welcome!

— Joe, K1JT, for the WSJT Development Team