IN3LBQ on the Hühnerspiel (Amthorspitze) - photo by IN3OTD


glfer is a GTK+ application with a waterfall spectrum display and slow CW (QRSS) / dual-frequency CW (DFCW) transmitter control interface. It's composed of two main parts:

The signal to be analyzed can be acquired in real-time from the sound card or can be read from a WAV file.
Starting from release 0.3, it is possible to select a spectral estimator among several different types:

The spectrogram window includes also an Automatic Gain Control, which allow the output spectrogram to cover the entire palette to ensure the maximum visual contrast. In addition to this, there is also an automatic limiter which can be enabled to try to enhance the signal detection (based on an idea of RA9MB).

When using FFTW (see below) the number of points per FFT is not restricted to powers of two and is anyway user selectable up to about 65536 points. This limitations is mainly due to the maximum window size and could be (easily, or at least I think so) removed in the future. The sound card sampling rate is selectable to values depending on the capability of your particular hardware. For easier reading of the signals frequencies, you can automatically add an offset, with the usual convention of negative offsets meaning LSB reception.

The transmitter can be controlled using the serial or the parallel port; the pins used for PTT and key are the same as in Rik Strobbe QRS, i.e. RTS = key and DTR = PTT/DFCW for the serial port, DB0 = key, DB1 = PTT/DFCW for the parallel port.

A more detailed description is in the README file included in the glfer source distribution.

Here is a screenshot of glfer (click on the picture for a larger image [350 kB]):

glfer 0.4.0 screenshot

glfer is written using the GTK+ library (version > 2.0) for the graphical user interfaces, so please make sure that it is already installed on your system before trying to compile the program; the configuration script will anyway warn you if it will not be able to find the GTK+ libraries.
You can download the GTK+ library at the GTK+ home page

You may also use the FFTW library for greater speed and flexibility in FFT calculations; FFTW, by Matteo Frigo and Steven G. Johnson, is available at the FFTW home page; if FFTW is not available, glfer will use its own internal FFT routine.

You can here download the source code of glfer [167 kB], release 0.4.2; this release features a TX beacon mode, a news spectral estimator and several averaging modes for the spectrogram (added by Edouard Griffiths, F4EXB).
Version 0.4.2 allows to select any device in /dev as the control device for the TX.

To compile glfer, after extracting the tar archive, you should just need to type:


and at the end of the compilation you should have the executable file, named glfer, in the current directory, together with mixer, a small utility to set the input/output levels of the sound card.

Debian users should find a package for glfer at

openSUSE users can find a glfer package in the hamradio repositories for openSUSE 10.2, 10.3, 11.0 (and also 11.1, when this release will be published).

If you like glfer and would like to see some more features, or would like to tell your opinion about the program, please drop me a note.


[1] David J. Thomson, "Spectrum Estimation and Harmonic Analysis," Proc. IEEE, vol.70, no. 9, Sep. 1982.
[2] James A. Cadzow, "Spectral Estimation: An Overdetermined Rational Model Equation Approach," Proc. IEEE, vol.70, no. 9, Sep. 1982.