1. Introduction

WSJT-X is a computer program designed to facilitate basic amateur radio communication using very weak signals. The first four letters in the program name stand for “Weak Signal communication by K1JT,” while the suffix “-X” indicates that WSJT-X started as an extended (and experimental) branch of the program WSJT.

WSJT-X Version 1.6 offers five protocols or “modes”: JT4, JT9, JT65 WSPR, and Echo. The first three are designed for making reliable 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 proven very effective for worldwide QRP communication on the HF bands. JT9 is optimized for the LF, MF, and lower HF bands. It is 2 dB more sensitive than JT65 while using less than 10% of the bandwidth. JT4 offers a wide variety of tone spacings and has proved very effective for EME on microwave bands up to 24 GHz. All three of these modes use one-minute timed sequences of alternating transmission and reception, so a minimal QSO takes four to six minutes — two or three transmissions by each station, one sending in odd UTC minutes and the other even. On the HF bands, world-wide QSOs are possible using power levels of a few watts and compromise antennas. On VHF bands and higher, QSOs are possible (by EME and other propagation types) at signal levels 10 to 15 dB below those required for CW.

WSPR (pronounced “whisper”) stands for Weak Signal Propagation Reporter. The WSPR protocol was designed for probing potential propagation paths using low-power transmissions. WSPR messages normally carry the transmitting station’s callsign, grid locator, and transmitter power in dBm, and they can be decoded at signal-to-noise ratios as low as -28 dB in a 2500 Hz bandwidth. WSPR users with internet access can automatically upload their reception reports to a central database called WSPRnet that provides a mapping facility, archival storage, and many other features.

Echo mode allows you to detect and measure your own lunar echoes, even if they are far below the audible threshold.

WSJT-X provides spectral displays for passbands up to 5 kHz, flexible rig control for nearly all modern radios used by amateurs, and a wide variety of special aids such as automatic Doppler tracking for EME QSOs and Echo testing. The program runs equally well on Windows, Macintosh, and Linux systems, and installation packages are available for all three platforms.

WSJT-X is an open-source project released under the GNU General Public License (GPL). If you have programming or documentation skills or would like to contribute to the project in other ways, please make your interests known to the development team. The project’s source-code repository can be found at SourceForge, and most communication among the developers takes place on the email reflector wsjt-devel. User-level questions and answers, and general communication among users is found on the WSJT Group email reflector.

1.1. New in Version 1.6

For quick reference, here’s a short list of features and capabilities added to WSJT-X since Version 1.5.0:

  • WSPR mode, including coordinated automatic band-hopping and a new two-pass decoder that can decode overlapping signals.

  • EME-motivated features including JT4 (submodes A-G), Echo mode, and automatic Doppler tracking. The JT4 decoder is more sensitive than that in the latest WSJT, and message averaging is fully automated. (Note that submodes JT65B and JT65C are also present in Version 1.6, but the high-sensitivity decoder required for EME with JT65 is not yet included.)

  • Tools for accurate frequency calibration of your radio, so you can be always on-frequency to within about 1 Hz.

  • Mode-specific standard working frequencies accessible from the drop-down band selector.

  • A number of corrections to the Hamlib library, fixing balky rig-control features. A few unreliable features peculiar to particular radios have been removed.

1.2. Future releases

Much work has already been done on Version 1.7 of WSJT-X. (Up to now this branch has been called v1.6.1.) More than 100 people have been building this version for themselves as development progresses, and reporting on their experiences. The next release will offer several “fast modes” intended for meteor and ionospheric scatter, including a new FEC-enhanced mode called JTMSK. It will also have a significantly improved JT65 decoder, especially advantageous when used in crowded HF bands. Starting with Version 1.7, WSJT-X will no longer use the patented, closed-source Koetter-Vardy algorithm.

2. System Requirements

  • SSB transceiver and antenna

  • Computer running Windows (XP or later), Linux, or OS X

  • 1.5 GHz or faster CPU and 200 MB of available memory

  • Monitor with at least 1024 x 780 resolution

  • Computer-to-radio interface using a serial port or equivalent USB device for T/R switching, or CAT control, or VOX, as required for your radio-to-computer connections

  • Audio input and output devices supported by the operating system and configured for sample rate 48000 Hz.

  • Audio or equivalent USB connections between transceiver and computer

  • A means for synchronizing the computer clock to UTC within ±1 second

3. Installation

Installation packages for Windows, Linux, and OS X are found on the the WSJT Home Page. Click on the WSJT-X link at the left margin, and then select the appropriate package for your operating system.

3.1. Windows

Download and execute the package file wsjtx-1.6.0-win32.exe, following these instructions:

  • Install WSJT-X into its own directory rather than in the conventional location C:\Program Files\WSJTX. Suggested installation directories are C:\WSJTX or C:\WSJT\WSJTX.

  • All program files relating to WSJT-X will be stored in the chosen installation directory and its subdirectories.

  • Logs and other writeable files will normally be found in the directory C:\Users\<username>\AppData\Local\WSJT-X.

Important Note that your computer might be configured so that this directory is “invisible”. It’s there, however, and accessible. An alternative (shortcut) directory name is %LOCALAPPDATA%\WSJT-X\.
  • The built-in Windows facility for time synchronization is usually not adequate. We recommend the program Meinberg NTP (see Network Time Protocol Setup for downloading and installation instructions) or Dimension 4 from Thinking Man Software.

  • WSJT-X expects your sound card to do its raw sampling at 48000 Hz. To ensure that this will be so when running under recent versions of Windows, open the system’s Sound control panel and select in turn the Recording and Playback tabs. Click on Properties, then Advanced, and select 16 bit, 48000 Hz (DVD Quality).

  • You can uninstall WSJT-X by clicking its Uninstall link in the Windows Start menu, or by using Uninstall a Program on the Windows Control Panel.

3.2. Linux

Debian, Ubuntu, and other Debian-based systems:

  • 32-bit: wsjtx_1.6.0_i386.deb

    • To install: sudo dpkg -i wsjtx_1.6.0_i386.deb

    • Uninstall: sudo dpkg -P wsjtx

  • 64-bit: wsjtx_1.6.0_amd64.deb

    • To install: sudo dpkg -i wsjtx_1.6.0_amd64.deb

    • Uninstall: sudo dpkg -P wsjtx

You may also need to execute the following commands in a terminal:

sudo apt-get install libqt5multimedia5-plugins libqt5serialport5
sudo apt-get install libfftw3-single3

For Ubuntu 15.04 and similar systems, the above and also

sudo apt-get install libqt5opengl5

Fedora, Red Hat, and other rpm-based systems:

  • 32-bit: wsjtx-1.6.0-i686.rpm

    • To install: sudo rpm -i wsjtx-1.6.0-i686.rpm

    • Uninstall: sudo rpm -e wsjtx

  • 64-bit: wsjtx-1.6.0-x86_64.rpm

    • To install: sudo rpm -i wsjtx-1.6.0-x86_64.rpm

    • Uninstall: sudo rpm -e wsjtx

You may also need to execute the following commands in a terminal:

sudo yum install fftw-libs-single qt5-qtmultimedia qt5-qtserialport
KVASD Installation

All Linux users must install a companion program called kvasd, an implementation of the the Koetter-Vardy algebraic soft-decision decoder for the Reed Solomon (63,12) code. Users of Ubuntu and other Debian-based systems can install kvasd by executing the following commands in a terminal:

sudo add-apt-repository ppa:ki7mt/kvasd-installer
sudo apt-get update
sudo apt-get install kvasd-installer

The final screen of the installer should include the line

KVASD version 1.12 -- Decode test *** PASSED ***

which should also be displayed if the command

kvasd -v

is executed after installation is complete.

You can install kvasd on most Linux systems (including ARM-based systems) by downloading, unpacking, and executing the simple tools packaged in the kvasd-installer script. Your system will need the following standard tools already installed:

autoconf awk bash dialog libgfortran svn

Download the kvasd-installer tarfile to a convenient directory, then execute the following commands in a terminal there:

tar xzf kvasd-installer-1.12.14.tar.gz
cd kvasd-installer-1.12.14
sudo make install

As described above, the final screen of the installer should include the line

KVASD version 1.12 -- Decode test *** PASSED ***

3.3. Macintosh OS X

OS X 10.7 and later: Download the file wsjtx-1.6.0-Darwin.dmg to your desktop, double-click on it and consult its ReadMe file for important installation notes.

If you have already installed a previous version, you can retain it by changing its name in the Applications folder (say, from WSJT-X to WSJT-X_1.5). You can then proceed to the installation phase.

Take note also of the following:

  • Double-click on KVASD-Installer to insert the KVASD decoder into WSJT-X.

  • Use the Mac’s Audio MIDI Setup utility to configure your sound card for 48000 Hz, two-channel, 16-bit format.

  • Use System Preferences to select an external time source to keep your system clock synchronized to UTC.

  • To uninstall simply drag the WSJT-X application from Applications to the Trash Can.

4. Settings

Select Settings from the File menu or by typing F2. (On Macintosh select Preferences from the WSJT-X menu, or use the keyboard shortcut Cmd+,). The following sections describe setup options available on each of seven tabs selectable near the top of the window.

4.1. General

Settings Window

Select the General tab on the Settings window. Under Station Details, enter your call sign and 4-digit or 6-digit grid locator. This information will be sufficient for initial tests.

Meanings of remaining options on the General tab should be self-explanatory after you have made some QSOs using WSJT-X. You may return to set these options to your preferences later.

Important If you are using a callsign with an add-on prefix or suffix, or wish to work a station using such a call, be sure to read the section Compound Callsigns.

4.2. Radio

WSJT-X offers CAT (Computer Aided Transceiver) control of the relevant features of most modern transceivers. To configure the program for your radio, select the Radio tab.

Radio Tab
  • Select your radio type from the drop-down list labeled Rig, or None if you do not wish to use CAT control.

  • Alternatively, if you have configured your station for control by DX Lab Suite Commander, Ham Radio Deluxe, Hamlib NET rigctl, or OmniRig, you may select one of those program names from the Rig list. In these cases the entry field immediately under CAT Control will be relabeled as Network Server. Leave this field blank to access the default instance of your control program, running on the same computer. If the control program runs on a different computer and/or port, specify it here. Hover the mouse pointer over the entry field to see the required formatting details.

  • Select OmniRig Rig 1 or OmniRig Rig 2 to connect to an OmniRig server running on the same computer. Note that OmniRig is available only under Windows.

  • Set Poll Interval to the desired interval for WSJT-X to query your radio. For most radios a small number (say, 1 – 3 s) is suitable.

  • CAT Control: To have WSJT-X control the radio directly rather than though another program, make the following settings:

    • Select the Serial Port used to communicate with your radio.

    • Serial Port Parameters: Set values for Baud Rate, Data Bits, Stop Bits, and Handshake method. Consult your radio’s user guide for the proper parameter values.

    • Force Control Lines: A few station setups require the CAT serial port’s RTS and/or DTR control lines to be forced high or low. Check these boxes only if you are sure they are needed (for example, to power the radio serial interface).

  • PTT Method: select VOX, CAT, DTR, or RTS as the desired method for T/R switching. If your choice is DTR or RTS, select the desired serial port (which may be the same one as used for CAT control).

  • Transmit Audio Source: some radios permit you to choose the connector that will accept Tx audio. If this choice is enabled, select Rear/Data or Front/Mic.

  • Mode: WSJT-X uses upper sideband mode for both transmitting and receiving. Select USB, or choose Data/Pkt if your radio offers such an option and uses it to enable the rear-panel audio line input. Some radios also offer wider and/or flatter passbands when set to Data/Pkt mode. Select None if you do not want WSJT-X to change the radio’s Mode setting.

  • Split Operation: Significant advantages result from using Split mode (separate VFOs for Rx and Tx) if your radio supports it. If it does not, WSJT-X can simulate such behavior. Either method will result in a cleaner transmitted signal, by keeping the Tx audio always in the range 1500 to 2000 Hz so that audio harmonics cannot pass through the Tx sideband filter. Select Rig to use the radio’s Split mode, or Fake It to have WSJT-X adjust the VFO frequency as needed, when T/R switching occurs. Choose None if you do not wish to use split operation.

When all required settings have been made, click Test CAT to test communication between WSJT-X and your radio. The button should turn green to indicate that proper communication has been established. Failure of the CAT-control test turns the button red and displays an error message. After a successful CAT test, toggle the Test PTT button to confirm that your selected method of T/R control is working properly.

4.3. Audio

Select the Audio tab to configure your sound system.

WSJT-X Audio Configuration Screen
  • Soundcard: Select the audio devices to be used for Input and Output. Usually the Mono settings will suffice, but in special cases you can choose Left, Right, or Both stereo channels.

Important If you select the audio output device that is also your computer’s default audio device, be sure to turn off all system sounds to prevent transmitting them over the air.
Important Be sure that your audio device in configured to sample at 48000 Hz, 16 bits.
  • Save Directory: WSJT-X can save its received audio sequences as .wav files. A default directory for these files is provided; you can select another location if desired.

  • AzEl Directory: A file named azel.dat will appear in the specified directory. The file contains information usable by another program for automatic tracking of the Sun or Moon, as well as calculated Doppler shift for the specified EME path. The file is updated once per second.

4.4. Tx Macros

Tx Macros Screen

Tx Macros are an aid for sending brief, frequently used free-text messages such as the examples shown above.

  • To add a new message to the list, enter the desired text (up to 13 characters) in the entry field at top, then click Add.

  • To remove an unwanted message, click on the message and then on Delete.

  • You can reorder your macro messages by using drag-and-drop. The new order will be preserved when WSJT-X is restarted.

4.5. Reporting

Reporting Screen
  • Logging: Choose any desired options from this group.

  • Network Services: Check Enable PSK Reporter Spotting to send reception reports to the PSK Reporter mapping facility.

  • UDP Server: This group of options controls the network name or address and port number used by a program that will receive status updates from WSJT-X. Cooperating applications like JTAlert use this feature to obtain information about a running WSJT-X instance.

4.6. Frequencies

Frequency Screen

Working Frequencies: By default the Working Frequencies table contains a list of currently recommended dial frequencies for each mode. You can modify the frequency table as desired.

  • To change an existing entry, click to select it, type a desired frequency in MHz, and hit Enter on the keyboard. The program will format your frequency value appropriately and add a band designator.

  • To add a new entry, right-click anywhere on the frequency table and select Insert. Enter a frequency in MHz in the popup box and select the desired mode (or leave the Mode selection blank). Then click OK. The table may include more than one frequency for a given band.

  • To delete an entry, right-click it and select Delete.

  • Click the Reset button to return the table to its default configuration.

Frequency Calibration: If you have calibrated your radio using WWV or other reliable frequency references, or perhaps with the technique described here, enter the measured values for Intercept A and Slope B in the equation

Dial error = A + B*f

where “Dial error” and A are in Hz, f is frequency in MHz, and B is in parts per million (ppm).

Frequency values sent to the radio and received from it will then be adjusted accordingly so that frequencies displayed by WSJT-X are accurate.

Station Information: You can save Band, Offset and Antenna Description information for your station. The antenna information will be included in reception reports sent to PSK Reporter. By default the frequency offset for each band is zero. Nonzero offsets may be added if (for example) a transverter is in use.

  • For a simple setup approach you might want to delete any unwanted bands — for example, bands where you have no equipment. Then click on a Frequency entry and type Ctrl+A to “select all,” and drag-and-drop the entries onto the Station Information table. You can then add any transverter offsets and antenna details.

  • To avoid typing the same information many times, you can drag-and-drop entries between the lines of the Station Information table.

  • When all settings have been configured to your liking, click OK to dismiss the Settings window.

4.7. Colors

WSJT-X uses colors to highlight decoded messages containing information of particular interest. Click on one of the buttons to select your preferred colors for any message category.

Reporting Screen

5. Transceiver Setup

Receiver Noise Level
  • If it is not already highlighted in green, click the Monitor button to start normal receive operation.

  • Be sure your transceiver is set to USB (or USB Data) mode.

  • Use the receiver gain controls and/or the computer’s audio mixer controls to set the background noise level (scale at lower left of main window) to around 30 dB when no signals are present. It is usually best to turn AGC off or reduce the RF gain control to minimize AGC action. If necessary you can also adjust the slider next to the dB scale, but note that the overall dynamic range will be best with this slider not too far from its mid-point.

Bandwidth and Frequency Setting
  • If your transceiver offers more than one bandwidth setting in USB mode, you should normally choose the widest one possible, up to about 5 kHz. This choice has the desirable effect of allowing the Wide Graph (waterfall and 2D spectrum) to display the conventional JT65 and JT9 sub-bands simultaneously on most HF bands. Further details are provided in the Basic Operating Tutorial. A wider displayed bandwidth may also be helpful at VHF and above, where JT4 and JT65 signals are found over much wider ranges of frequencies.

  • If you have only a standard SSB filter you won’t be able to display more than about 2.7 kHz bandwidth. Depending on the exact dial frequency setting, on HF bands you can display the full sub-band generally used for one mode (JT65 or JT9) and part of the sub-band for the other mode.

  • Of course, you might prefer to concentrate on one mode at a time, setting your dial frequency to (say) 14.076 for JT65 or 14.078 for JT9. Present conventions have the nominal JT9 dial frequency 2 kHz higher than the JT65 dial frequency.

Transmitter Audio Level
  • Click the Tune button on the main screen to switch the radio into transmit mode and generate a steady audio tone.

  • Listen to the generated audio tone using your radio’s Monitor facility. The transmitted tone should be perfectly smooth, with no clicks or glitches.

  • Open the computer’s audio mixer controls for output (“Playback”) devices and adjust the volume slider downward from its maximum until the RF output from your transmitter falls by around ten percent. This will be a good level for audio drive.

  • Alternatively, you can make the Tx audio level adjustment using the digital slider labeled Pwr at the right edge of the main window.

  • Toggle the Tune button once more to stop your test transmission.

Important Windows Vista and later incorrectly configure audio devices using the Texas Instruments PCM2900 series CODEC for microphone input rather line input. (This chip is used in many radios with built-in USB CODECs, as well as various other audio interfaces.) If you are using such a device, be sure to set the mic level in the Recording Device Properties to 0 dB.

6. Basic Operating Tutorial

Sections 6.1 through 6.4 cover basic operation for making two-way QSOs with modes JT9 and JT65 on the HF bands. Section 7 covers WSPR mode, and Section 8 covers VHF+ features. If you are a new user of WSJT-X we suggest that you go through the full HF-oriented tutorial while at your radio. It should take no more than 20 minutes. If your main interests are WSPR of VHF+, you may then proceed to Sections 7 and 8.

6.1. Main Window Settings

  • Click the Stop button on the main window to halt any data acquisition.

  • Select JT9 from the Mode menu and Deep from the Decode menu.

  • Set the audio frequencies to Tx 1224 Hz and Rx 1224 Hz.

Important Sliders and spinner controls respond to Arrow key presses and Page Up/Down key presses, with the Page keys moving the controls in larger steps. You can also type numbers directly into the spinner controls.
  • Select Tab 2 (below the Decode button) to choose the alternative set of controls for generating and selecting Tx messages.

6.2. Wide Graph Settings

  • Bins/Pixel = 4

  • JT65 …. JT9 = 2500

  • Start = 200 Hz

  • N Avg = 5

  • Palette = Digipan

  • Flatten = checked

  • Select Cumulative for data display

  • Gain and Zero sliders set near midscale

  • Use the mouse to adjust the width of the Wide Graph so that its upper frequency limit is about 2400 Hz.

6.3. JT9

For this step and the next, you may want to pretend you are K1JT by entering that callsign temporarily as My Call on the Settings | General tab. Your results should then be identical to those shown in the screen shot below.

Open a Wave File:
  • Select File | Open and select the file …\save\samples\130418_1742.wav. When the file opens you should see something similar to the to the following screen shot:

Main UI and Wide Graph
Decoding Overview

Decoding takes place at the end of a receive sequence and proceeds in two steps. The first decode is done at the selected Rx frequency, indicated by the U-shaped green marker on the waterfall scale. Results appear in both the left (Band Activity) and right (Rx Frequency) text windows on the main screen. The program then finds and decodes all signals in the selected mode over the displayed frequency range. The red marker on the waterfall scale indicates your Tx frequency.

Seven JT9 signals are present in the example file, all decodable. When this file was recorded KF4RWA was finishing a QSO with K1JT. Since the green marker was placed at his audio frequency, 1224 Hz, his message “K1JT KF4RWA 73” is decoded first and appears in the Rx Frequency window. The Band Activity window shows this message plus all decodes at other frequencies. By default lines containing CQ are highlighted in green, and lines with My Call (in this case K1JT) in red.

Decoding Controls

To gain some feeling for controls frequently used when making QSOs, try clicking with the mouse on the decoded text lines and on the waterfall spectral display. You should be able to confirm the following behavior:

  • Double-click on either of the decoded lines highlighted in green. This action produces the following results:

    • Callsign and locator of a station calling CQ are copied to the DX Call and DX Grid entry fields.

    • Messages are generated for a standard minimal QSO.

    • The Tx even box is checked or cleared appropriately, so that you will transmit in the proper (odd or even) minutes.

    • The Rx and Tx frequency markers are moved to the frequency of the CQing station.

    • The Gen Msg (“generated message”) radio button at bottom right of the main window is selected.

    • If you had checked Double-click on call sets Tx Enable on the Setup menu, Enable Tx would be activated and a transmission would start automatically at the proper time.

  • Double-click on the decoded message “K1JT N5KDV EM41”, highlighted in red. Results will be similar to those in the previous step, except the Tx frequency (red marker) is not moved. Such messages are usually in response to your own CQ, or from a tail-ender, and you probably want your Tx frequency to stay where it was.

  • By holding down the Ctrl key when double-clicking on a decoded line you can cause both Tx and Rx frequencies to be moved. This behavior can also be forced by checking Lock Tx=Rx.

  • Double-click on the message from KF4RWA in either window. He is sending “73” to K1JT, signifying that the QSO is over. Most likely you want to send 73 to him, so the message “KF4RWA K1JT 73” is automatically generated and selected for your next transmission. (Alternatively, you might choose to send a free text message or to call CQ again.)

  • Click somewhere on the waterfall to set Rx frequency (green marker on waterfall scale).

  • Ctrl-click on the waterfall to set both Rx and Tx frequencies.

  • Double-click on a signal in the waterfall to set Rx frequency and start a narrow-band decode there. Decoded text will appear in the right window only.

  • Ctrl-double-click on a signal to set both Rx and Tx frequencies and decode at the new frequency.

  • Click Erase to clear the right window.

  • Double-click Erase to clear both text windows.

6.4. JT9+JT65

Main Window:
  • Select JT9+JT65 on the Mode menu.

  • Toggle the Tx mode button to read Tx JT65, and set the Tx and Rx frequencies to 1718 Hz.

  • Double-click on Erase to clear both text windows.

Wide Graph Settings:
  • Set Bins/Pixel = 7

  • Adjust the width of the Wide Graph window so that the upper frequency limit is approximately 4000 Hz.

Open a Wave File:
  • Select File | Open and navigate to …\save\samples\130610_2343.wav. The waterfall should look like this:

Wide Graph Decode 130610_2343
Important Notice the BLUE marker on the waterfall scale, here set at 2500 Hz. Its position is set by the spinner control JT65 nnnn JT9, where nnnn is a frequency in Hz. In JT9+JT65 mode the program will automatically decode JT9 signals only above this frequency.

JT9 signals appear in the Cumulative spectrum as nearly rectangular shapes about 16 Hz wide. They have no clearly visible sync tone like the one at the low-frequency edge of all JT65 signals. By convention the nominal frequency of both JT9 and JT65 signals is taken to be that of the lowest tone, at the left edge of its spectrum.

This sample file contains 17 decodable signals — nine in JT65 mode (flagged with the character # in the decoded text windows), and eight in JT9 mode (flagged with @). On multi-core computers the decoders for JT9 and JT65 modes run simultaneously, so their results will be interspersed. The Band Activity window contains all decodes (you might need to scroll back in the window to see some of them). A signal at the frequency specified by the green marker is given decoding priority, and its message is displayed also in the Rx Frequency window.

  • Confirm that mouse-click behavior is similar to that described earlier, in Example 1. WSJT-X automatically determines the mode of each JT9 or JT65 message.

Important When you double-click on a signal in the waterfall it will be properly decoded even if on the “wrong” side of the JT65 nnnn JT9 marker. The Tx mode automatically switches to that of the decoded signal and the Rx and Tx frequency markers on the waterfall scale resize themselves accordingly. When selecting a JT65 signal, click on the sync tone at its left edge.
  • Double-click on the waterfall near 815 Hz: a JT65 message originating from W7VP will be decoded and appear in the Rx Frequency window. Between the UTC and Freq columns on the decoded text line you will find dB, the measured signal-to-noise ratio, and DT, the signal’s time offset in seconds relative to your computer clock.

UTC dB DT Freq Mode Message







  • Double-click on the waterfall at 3196 Hz. The program will decode a JT9 message from IZ0MIT:

UTC dB DT Freq Mode Message







  • Scroll back in the Band Activity window and double-click on the message CQ DL7ACA JO40. The program will set Tx mode to JT65 and Tx and Rx frequencies to that of DL7ACA, 975 Hz. If you had checked Double-click on call sets Tx Enable on the Setup menu, the program would configure itself to start a QSO with DL7ACA.

  • Double-click on the decoded JT65 message CQ TA4A KM37. The program will set Tx mode to JT9 and the Rx and Tx frequencies to 3567 Hz. The program is now configured properly for a JT9 QSO with TA4A.

Reopen the First Sample File:
  • Select File | Open and navigate to …\save\samples\130418_1742.wav.

Taking full advantage of the wide-band, dual-mode capability of WSJT-X requires a receiver bandwidth of at least 4 kHz. These data were recorded with a much narrower Rx bandwidth, roughly 200 to 2400 Hz. If you have no Rx filter wider than about 2.7 kHz, you will be using data like this. For best viewing, adjust Bins/Pixel and the width of the Wide Graph so that only the active part of the spectrum shows, say 200 to 2400 Hz. Re-open the example file after any change of Bins/Pixel or Wide Graph width, to refresh the waterfall.

The signals in this file are all JT9 signals. To decode them automatically in JT9+JT65 mode you’ll need to move the JT65 nnnn JT9 delimiter down to 1000 Hz or less.

Waterfall Controls

Now is a good time to experiment with the Start control and the sliders controlling gain and zero-point of the waterfall and spectrum plots. Start determines the frequency displayed at the left side of the waterfall scale. Sliders set the baseline level and gain for the waterfall and the several types of spectra. Good starting values should be close to mid-scale. You might want to uncheck Flatten when adjusting the sliders. Re-open the wave file after each change, to see the new results.

Important When finished with this Tutorial, don’t forget to re-enter your own callsign as My Call on the Settings | General tab.

7. WSPR Mode

  • Select WSPR-2 from the Mode menu. The main window will reconfigure itself to the WSPR interface, removing some controls not used in WSPR mode.

  • Configure the Wide Graph as suggested in the screen shot below.