Program Development


WSPR implements a protocol designed for probing potential propagation paths with low-power transmissions.  Normal transmissions carry a station's callsign, Maidenhead grid locator, and transmitter power in dBm.  The program can decode signals with S/N as low as -28 dB in a 2500 Hz bandwidth.  Stations with internet access can automatically upload their reception reports to a central database called WSPRnet, which includes a mapping facility.  To see a live version of the map pictured at top right, click here.

WSPR 2.0 introduces a number of new features including a  user-friendly setup screen with drop-down selection of audio devices and rig-control parameters, support for compound callsigns, fine selection of the fractional time for transmitting, and a Tune button.  A new Advanced setup screen offers optional CW identification and tools for frequency calibration and automated frequency corrections for your radio.  Full details are presented in the WSPR 2.0 User's Guide, which you will need to read in order to use the new features.  For the first time, a binary installation package is made available for Ubuntu Linux (versions 8.10 and later), Debian 5.03, and other Debian-based 32-bit Linux distributions.

WSPR 2.1 includes these enhancements:

  • Support for software-defined receivers and transceivers that use complex (I-Q) sampling, such as the popular SoftRock kits.
  • FMT, a package of command-line programs designed for use in the ARRL Frequency Measuring Test and similar frequency-measuring tasks.
  • WSPR 2.12 works with systems providing up to 100 audio devices or pseudo-devices.
WSPR-X  is a new experimental version that includes the slow mode WSPR-15. WSPR-15 uses 15-minute T/R sequences, rather than the standard 2-minute sequences; at MF and LF it is 9 dB more sensitive than WSPR-2, decoding signals as weak as -37 dB in the standard 2500 Hz reference bandwidth.  WSPR-15 is not recommended for use at HF: the tone spacing is only 0.183 Hz, less than the Doppler spreading typical of many HF paths. The main intended application for WSPR-15 is for very difficult paths at 137 kHz and the new 472 kHz band. It may be interesting to try on 160 meters, as well.  The recommended WSPR-15 sub-band is a 25 Hz slice just above the 200-Hz WSPR-2 sub-band, i.e., 1600-1625 Hz above the standard dial frequency on each band. This will be handled automatically if you set up WSPR-X in the normal way.

A brief online User's Guide for WSPR-X is posted at , and the Windows installation file is posted at .

WSPR-X does not presently do “band hopping” and does not support I/Q audio for use with direct conversion receivers and transceivers. Otherwise most familiar WSPR features are present and working well.

For software enthusiasts: Unlike older versions of WSPR, the user interface of WSPR-X is written in C++ and uses the Qt programming framework. My expectation is that this shift will make for easier development and program maintenance in the future. A click-to-install package is presently available only for Windows.  The program can also be compiled for Linux and OS X, but at present you're on your own for that task.  Source code for WSPR-X is available from the open-source SVN repository at SourceForge. Anonymous checkout of the full WSPR-X source code can be accomplished with the command

svn co svn://

User comments, suggestions, and bug reports on WSPR-X will be very welcome!



©2001-2018  by Joe Taylor, K1JT