Linux Ham Radio Digital Communications Software

lpsk31:
lpsk31 is a ncurses console application for ham radio communications in the popular PSK31 digital mode. lpsk31 uses only integer arithmetic for both signal detection and audio tone synthesis, so that it needs no floating point calculations for its operation. lpsk31 can keep a log of QSO's in text and ADIF format as well as a raw log of all that is typed in the transmit window or displayed in the receive window. Some QSO data (signal strength and frequency) can be acquired automatically via a CAT interface from the transceiver itself, if it is an FT847. Unfortunately there is no CAT for other types of transceiver since I had problems using Hamlib.

Manual Read more details on-line or download lpsk31's manual.

PackageDownload source package of lpsk31

xpsk31:
xpsk31 is a GTK+ graphical version of lpsk31, using the same basic signal decoding and encoding engine but controlled by the user via the GUI. In addition it has a FFT-derived "waterfall" display of the incoming signal and a "magniphase" display that shows the magnitude, phase and frequency error of the psk31 signal. It has similar QSO logging facilities and CAT control, for the FT847 and FT857 transceivers, which can be used to tune the transceiver to the appropriate carrier frequency by clicking on a signal trace.

Manual Read more details on-line or download xpsk31's manual.

PackageDownload source package of xpsk31

xpsk31

This a screen capture of xpsk31's window while receiving a CQ call. The longer line in the Magniphase window indicates the receiver tuning error and the smaller one the phase of the PSK31 signal.
Click on the thumbnail for the full sized image.

xfhell:
xfhell is a GTK+ application for the "fuzzy" digital communication mode known as Hellschreiber. xfhell has several different built-in fonts in Adobe BDF format, including a font set for Greek, and a special "short" font set that is 12 pixels high instead of the standard 14 of the original Hell fonts. Using this font set would make xfhell incompatible with other Hellschreiber programs, but the short fonts speed up operation and avoid wasted bandwidth, inherent in the original Hellschreiber design (an unavoidable problem of the original mechanical implementation of the mode). xfhell also has selectable lower baud rate operation (down to 7.6 Bd), which again make it incompatible with other Hellschreiber programs, but the lower speeds (especially combined with the 12-pixel fonts) would make this mode even more efficient and effective.

Another distinguishing characteristic of xfhell is its ability to compensate for slight differences in the clock frequency of sound cards, which produce the characteristic skew of decoded text, requiring double-row printing in order to make it legible. Hence xfhell prints received text on a single row, continuously compensating for clock skew and propagation path effects. This feature works well when capital letters are in use so that with lower-case letters, the printed text tends to wonder up-down in the screen - please avoid lower case letters, they are hard to read anyway!

xfhell has built-in CAT control for the FT847 and FT857 transceivers and a QSO logging facility similar to xpsk31. It also has a FFT-derived waterfall display of the incoming signal, with the ability to detect maximum signal level and tune the transceiver, via CAT, to the appropriate carrier frequency by clicking near the signal trace.

Manual Read more details on-line or download xfhell's manual.

PackageDownload source package of xfhell

xfhell This a screen capture of xfhell's window during a regular QSO in weak signal conditions.
Note the effect of lower case letters and propagation path changes on the text de-skewing function.
Click on the thumbnail for the full sized image.