WSJT-X v1.7 released

Joe Taylor, K1JT, has announced the release of version 1.7 of the popular WSJT-X software package.

WSJT-X implements digital communication protocols or “modes” called JT4JT9JT65QRA64ISCATMSK144, 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 several new modes including modes: ISCAT, MSK144 and QRA64 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 v1.7 is a free download and is available from the WSJT-X website here.

Copyright 2001 - 2016 by Joe Taylor, K1JT.

Release: WSJT-X Version 1.7.0

Short list of new features since Version 1.6
1.  New modes: ISCAT, MSK144, QRA64.
2.  Newly implemented submodes: JT65B-C, JT9B-H (wide and fast).
3.  FT decoder replaces KV decoder for JT65; KVASD is no longer used.
4.  Improvements to JT4, JT9, and JT65 decoders.
5.  Multi-pass decoding now implemented for JT65 as well as WSPR.
6.  Many improvements to Rig Control.
7.  Improved convenience features for EME Doppler tracking.
8.  Multiple configurations can be saved and restored.
9.  Sample-file download facility.
10. Optional auto-sequencing for Fast modes.
11. Contest Mode for MSK144.
12. Power settings optionally remembered for Transmit and Tune on a
    band-by-band basis.
13. WSJT-X User Guide enhanced and extended in many ways.

New Modes

1. MSK144 is intended for meteor scatter at 50 MHz and higher.  It
uses a low-density parity check code (LDPC) designed by Steve Franke,
K9AN.  The mode is a direct descendant of the now-defunct experimental
mode JTMSK, with a number of improvements for better performance on
weak and short meteor pings.  The effective character transmission
rate is about 250 cps, compared with 147 cps for FSK441.  Like JT4,
JT9, JT65, and QRA64, MSK144 uses strong forward error correction.
Message decoding is "all or nothing": partial decodes do not occur,
and you will see little or no garbage on your screen.

Standard MSK144 message frames are 72 ms long, compared with about 120
ms for an equivalent FSK441 message.  The MSK144 waveform allows
coherent demodulation, allowing up to 3 dB better sensitivity.  After
QSO partners have exchanged callsigns, MSK144 can use even shorter
messages with frames only 20 ms long.  As in all the fast modes in
WSJT-X, the 72 ms (or 20 ms) messages are repeated without gaps for
the duration of a transmission cycle.  For most purposes we recommend
a T/R cycle duration of 15 s, but 5 s and 10 s sequences are also

Short ("Sh") messages in MSK144 are intended primarily for 144 MHz and
higher frequencies, where most underdense pings are very short.  These
messages do not contain full callsigns; instead, they contain a hash
of the two callsigns along with a report, acknowledgement, or 73.
Short messages are fully decodable only by the station to whom they
are addressed, as part of an ongoing QSO, because only then will the
received hash match that calculated using the known strings for "My
Call" and "DX Call".  If you are monitoring someone else's QSO, you
will not be able to decode its Sh messages.

MSK144 includes a "Contest Mode" in which grid locators replace
signal reports in ths standard QSO exchange.

An MSK144 signal occupies the full bandwidth of a typical SSB
transmitter, so transmissions are always centered at an offset of
1500Hz.  For best results, selectable or adjustable Rx and Tx filters
should be set to provide the flattest possible response over at least
300 - 2700 Hz.  The maximum permissible frequency offset between you
and your QSO partner is 200 Hz, and less is better.

2. QRA64 is a intended for EME and other weak-signal use.  Its
internal code was designed by Nico Palermo, IV3NWV, and implemented in
WSJT-X by K1JT.  The protocol uses a "Q-ary Repeat Accumulate" code --
along with LDPC, another one of the latest research areas in
communication theory.  The QRA64 code is inherently better than the
Reed Solomon (63,12) code used in JT65, yielding already a 1.3 dB
advantage.  QRA64 uses a new synchronizing scheme based on 7 x 7
Costas arrays, so you will not see a bright sync tone at the lowest
tone frequency.  This change yields another 1.9 dB advantage.

In most respects our implementation of QRA64 is operationally similar
to JT65.  QRA64 does not use two-tone shorthand messages, and it makes
no use of a callsign database.  Rather, additional sensitivity is
gained by making use of "already known" information as a QSO
progresses -- for example, when reports are being exchanged and you
have already decoded both callsigns in a previous transmission.  QRA64
presently offers no message averaging capability, though that may be
added.  In our early tests, many EME QSOs have already been made using
submodes QRA64A-E on bands from 144 MHz to 10 GHz.  We hope to make
further improvements to the QRA64 decoder as we gain experience with
the mode.

3. ISCAT is essentially the same as in recent versions of program
WSJT.  The mode is useful for signals that are weak but more or less
steady in amplitude over several seconds or longer. Aircraft scatter
at 10 GHz is a good example. ISCAT messages are free-format and may
have any length from 1 to 28 characters. This protocol includes no
error-correction facility.

Program Setup

Many of the new program capabilities are enabled when you check
"Enable VHF/UHF/Microwave features" on the Settings | General tab.
For MSK144 mode, we suggest setting "T/R 15 s" and "F Tol 100 Hz".
Check "Sh" to enable the use of short messages and "Auto Seq" for
auto-sequencing.  For QRA64 mode, set Tx and Rx frequencies to 1000 Hz
(600 Hz for submode E).

Final Comments

As always, we will be grateful for any and all reports from users;
these will surely help us to make further improvements to WSJT-X.  The
most helpful bug reports describe the problem clearly and include a
complete recipe to reproduce it.  Feature requests are also welcome.
Send your reports to, or to the developers