WSJT Home Page

  by K1JT

Program Development

Weak Signal Communication Software

WSJT, MAP65, WSPR, and WSJT-X are open-source programs designed for weak-signal digital communication by amateur radio.  Normal usage requires a standard SSB transceiver and a personal computer with soundcard.  SDR-style hardware including the SDR-IQ, Perseus, SoftRock, and FUNcube Dongle is supported by MAP65 and WSPRSimJT is a utility program that generates simulated signals for test purposes.  Ready-to-run Windows versions of all programs are available for free download, and the programs (except SimJT) can also be compiled and used under Linux, OS X, and FreeBSD.  For details about source code and operating systems other than Windows, see the Program Development page.

WSJT ("Weak Signal Communication, by K1JT") offers specific digital protocols optimized for EME (moonbounce), meteor scatter, and ionospheric scatter, at VHF/UHF, as well as for HF skywave propagation.  The program can decode fraction-of-a-second signals reflected from ionized meteor trails and steady signals 10 dB below the audible threshold.  Check the WSJT page and links therein for details about modes JTMS, FSK441, ISCAT, JT6M, JT65, and JT4. 

WSJT-X implements JT9, a new mode optimized for weak-signal communication on the LF, MF, and HF bands.  JT9 is about 2 dB more sensitive than JT65 and uses less than 10% of the bandwidth.  These modes are already highly popular, and further program enhancements are under active development.  Plans call for the eventual inclusion of other popular modes now supported in WSJT

MAP65 implements a wideband receiver for JT65 signals, optimized for EME on the VHF/UHF bands.  It can be used together with Linrad (by SM5BSZ) or SDR-Radio (by HB9DRV), or with direct input from a soundcard or FUNcube Dongle.  The program decodes all JT65 signals in a passband up to 90 kHz wide, producing a band map of callsigns sorted by frequency.  In a dual-polarization system, MAP65 optimally matches the linear polarization angle of each signal, thereby eliminating problems with Faraday rotation and spatial polarization shifts. 

WSPR (pronounced "whisper") stands for "Weak Signal Propagation Reporter." This program is designed for sending and receiving low-power transmissions to test propagation paths on the MF and HF bands.  Users with internet access can watch results in real time at WSPRnetVersion 2.11 of WSPR includes FMT, a package of command-line utilities that can help you make highly accurate frequency measurements without expensive laboratory equipment. Experimental version WSPR-X is also available, offering an optional mode WSPR-15 with 15-minute transmissions and better sensitivity by about 9 dB.

SimJT generates JT65 and CW test signals with user-specified signal-to-noise ratio.  It is useful for testing the JT65 decoder and the relative capabilities of these two modes.

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