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Basic data

Maintainer Joseph Hooton Taylor, Jr. (K1JT)
developer Joseph Hooton Taylor Jr.
Publishing year 2001
Current  version 2.2.0
(June 4, 2020, is not backwards compatible with MSK144 and the obsolete 75-bit protocol of FT8)
operating system Windows , Linux , FreeBSD , OSX
category Amateur radio software, communication protocol
License Open source
Basic data

Maintainer Joseph Hooton Taylor, Jr. (K1JT)
developer Joseph Hooton Taylor Jr.
Publishing year 2005
Current  version 10.0
( February 18, 2014 )
operating system Windows , Linux , FreeBSD , OSX
category Amateur radio software, communication protocol
License Open source

WSJT ( W eak S ignal communications, by K1 JT ) and WSJT-X as the current version is a set of communications protocols and a free ham radio - software for communication using weak signals . They were developed by radio amateur and Nobel laureate in physics Professor Joseph Hooton Taylor, Jr. ( amateur radio call sign K1JT). The digital signal processing by WSJT makes it much easier for radio amateurs to use certain types of propagation such as meteor scatter and earth-moon-earth . On VHF, it has replaced the Morse code previously used for very poor transmission paths.


Joe Taylor had the idea of using a PC's sound card as an analog-to-digital converter , for example to convert analog radio signals into digital data for processing in a computer or to generate analog audio signals with various modulation schemes for transmission. As an alternative to the Morse method , he developed WSJT, a simple method for digital text communication that works with significantly lower transmission strengths.

WSJT was originally published in 2001. Since then there have been several major revisions in which more communication modes have been added or removed. Since 2005, the software has been released as open source software under the GNU General Public License . Although Joe Taylor is still the maintainer as the original developer, several programmers are currently involved in the further development of the software.

The first program version dates from 2001. The operating modes FSK441, JT65 (in older versions JT44) and, since beta version 7.01, Weak Signal Propagation Reporter (WSPR) in QSO mode are supported. WSJT is an open source project. There are software variants for Windows , Linux and FreeBSD . The executable program parts, source codes and program descriptions are freely available and can be ported to other platforms.


The current version WSJT-X implements the new operating modes FT8 , FT4, JT4, JT9, JT65, QRA64 and ISCAT as well as MSK144 and WSPR . WSJT-X thus covers all operating modes developed by K1JT for long, medium, short, ultra-short and centimeter waves , including the JT65 and QRA64 preferred for earth-moon-earth as well as the optimized operating mode JT4. This means that no additional software such as WSPR or WSPR-X is required for WSPR either .

Version 2.0 was published on December 10, 2018 (current version 2.2.1), which brought improvements in the operating modes FT8 and MSK144 in particular. Since the version of February 26, 2019 is not backwards compatible with previous versions in the operating modes mentioned and they cannot communicate with one another, it is recommended that the older version no longer be used.

Variants of the transmission method

WSJT for meteor scatters

FSK441 was developed for high-speed meteor scatter connections and uses the short 'pings' that are caused by reflections on ionized meteoroid orbits about 100 kilometers above the earth. These 'pings' are usually a few decibels above the noise floor and can last from 10 to a few 100 milliseconds. Radio amateurs usually use this operating technique during meteor showers . FSK441 thus enables connections of around 800 to 2200 kilometers on the VHF bands (50 MHz and 144 MHz). The walking speed is 441 baud .

WSJT for earth-moon-earth and short wave

JT65, on the other hand, was developed for decoding very quiet signals with an almost constant signal strength. It uses MFSK with 65 different tones. The method is able to transmit signals that are 10 decibels and more below the level required for a telegraphy connection. This makes the JT65 the ideal operating mode for troposcatter , ionoscatter and EME connections. Smaller amateur radio stations in particular benefit from this, as EME connections can be made with significantly less effort than with the previous methods. Since 2006, JT65A has also been used successfully by numerous QRP stations on shortwave (e.g. on 14076 kHz USB). The variants JT65A, JT65B and JT65C differ in the transmitted tone intervals 5.4 Hz, 10.8 Hz or 21.6 Hz.

The WSJT mode JT65 has a special feature that is helpful when decoding extremely weak signals, the so-called "deep search" mode. This mode can be set for reception and enables the received signals to be compared using a known signature database. In WSJT, Taylor limited himself to a limited search area of ​​the known signature database, since due to the limited computing power of commercially available PCs, trying out all possible combinations takes a very long time. With the implemented search routine it is possible to decode the desired information within a short time even on low-performance PCs.

The signature database can be expanded in the WSJT software or with a text editor, taking into account the syntax rules set there.

WSJT on the 6-meter tape

JT6M is optimized for meteor and ion scatters in the 6 meter band .

WSJT for medium and long wave

The JT9 mode is similar to JT65, but is designed for the amateur radio bands on medium and long wave, where there is more noise. The transmission intervals last 1, 2, 5, 10 or 30 minutes. In the operating mode with a 30-minute transmission interval, the bandwidth is only 0.4 Hz.


  • Joe Taylor, K1JT: WSJT: New Software for VHF Meteor-Scatter Communication . In: QST . December, 2001, ISSN  0033-4812 , p. 36-41 .
  • Wolfgang Bedrich, DL1UU: WSJT - a new digital operating mode for VHF DXers . In: radio amateur . No. 10 , 2001, ISSN  0016-2833 , p. 1088 .
  • A. Kearns: Interview: Joe Taylor, K1JT, Nobel Prize winner and inventor of the popular WSJT software. RadCom 2006, Volume 82, No. 4, p. 18.
  • Bernd J. Mischlewski, DF2ZC: WSJT revolutionized the VHF range as a radio process 10 years ago . In: radio amateur . No. 8 , 2012, ISSN  0016-2833 , p. 812 .
  • David Witkowski, Tomas Hood: Communicating under the noise: JT65A on HF - Part I. In: CQ Amateur Radio Magazine, October 2010, 32–38.
  • David Witkowski, Tomas Hood: Communicating under the noise: JT65A on HF - Part II. In: CQ Amateur Radio Magazine, November 2010, 18-25.

Web links

Individual evidence

  1. Steve Ford: ARRL VHF Digital Handbook. American Radio Relay League Publisher, Newington CT 2008, ISBN 0-87259-122-0
  2. ^ Joseph Hooton Taylor, Jr .: WSJT-X User Guide. 1. Introduction. December 19, 2016, accessed January 29, 2017 .
  3. WSJT-X 2.0.1 published , Funkamateur from February 26, 2019, , accessed on June 26, 2019.
  4. ^ Joe Taylor: The JT65 Communications Protocol. In: QEX, September 2005, p. 3 ff.
  5. Steve Ford: A new digital mode for low frequencies. In: QST, March 2013, p. 66.