Accessibility of Fldigi for Linux


   Fldigi is an amateur radio digital modem program with versions for Windows, Mac OS X, and Linux. This article for vision-impaired hams describes the accessibility of the user interface of fldigi for Linux. The versions for Windows and Mac OS X are described in a separate article.

   Features of special interest include:

          • User-defined keyboard shortcuts
          • High visibility font and color options
          • Automatic scanning for signals on the waterfall
          • Co-operation with flrig for rig monitoring & control

   The fldigi user interface is not accessible for screen readers.


   Fldigi is freeware developed by W1HKJ. It includes software modems for the most popular amateur radio digital modes.

   The current version of fldigi for Linux is available from W1HKJ's Source Forge page. Links to packages for the major Linux distributions are at the bottom of the W1HKJ home page. These links include PPAs for Ubuntu in Kamal Mostafa's archive.

   Details on the installation and configuration of an Ubuntu PPA package from Kamal Mostafa's site are on a separate page of this Web site.

   Fldigi is in the Ubuntu Software Center. You can check the version number (by typing "fldigi" in the Software Center search box and clicking on the "More Info" button) and compare it with the current version number on W1HKJ's Download page.

   Also, fldigi is pre-installed along with a magnification utility on FldigiVI LiveUSB, which can boot most PCs with a 32-bit or 64-bit CPU.

Connecting the Radio to a Computer

   The basics of CAT serial interfaces are described in the article on rig monitoring. Many commercial interfaces work with Linux. For this review a MicroHam USB Interface III was used for the serial data connection. No custom device drivers are required by this device.

Rig Control

   Fldigi offers the options of push-to-talk via CAT control or hardware PTT.

   Optional rig tuning is also via CAT control. It enables you to enter a frequency manually and to select frequencies stored in computer memory. For rig tuning fldigi offers the option to use the HamLib radio control libraries. If HamLib does not include a profile for your rig, it may be possible to create one using the fldigi RigCAT system described in the online documentation.

   HamLib is not required if the flrig control program is running along with fldigi. A link to a list of radios supported by flrig is in the flrig Help file on the download page.

   Some examples of rig control settings for fldigi are included in the example of installation on an Ubuntu system.


   The main program window is compact (Figure 1), so a large screen and magnifier software may be helpful. Images are rendered with high resolution vector graphics. A wide range of high contrast colors is available for text, backgrounds, and indicator lights.

Figure 1. Fldigi Main Window.


   The main program window size is adjustable, and it does not affect the size of the text and controls. On a 15" screen the minimum window size is 4.9" H x 6.6" W. The maximum size is full screen. Fixed text is 0.08" high. A range of font/style/size options is available for received and transmitted text. The word-wrap option allows you to use large-size fonts without hidden text beyond the margin.

Keyboard Shortcuts

   Fldigi can use up to 48 macros, grouped in four rows of twelve control buttons. Each macro in the active row also has a corresponding function key in the range F1 - F12, so the macros also define keyboard shortcuts.

   Designating which of the four rows of macros is active requires you to use a mouse. Either click on the row-number indicator at the end of a row, or hover the mouse pointer over the row of buttons and use the mouse scroll-wheel, via an option in Configure menu > Macros.

   You can scan the waterfall automatically by creating a macro consisting of the <SRCHUP> tag and another macro with the <SRCHDN> tag. For example, pressing the function key for the <SRCHUP> macro causes fldigi to tune upward in audio frequency to the next signal on the waterfall.

   To modify or create a macro, configure fldigi (Configure menu > Macros) to "prompt you to save macro files when closing the program" and "load the last used macro file on startup." Right-clicking on a macro button opens the fldigi Macro Editor window.

Other Features

   Fldigi has a variety of other well documented features. For example:  An integrated logging program can be customized for contests as well as routine QSOs. Reed-Solomon identification codes can be sent and interpreted. Fldigi can do automatic call sign lookups and QSL notifications.

For More Information

   A link to the Fldigi Users Manual is on W1HKJ's home page.
   There is a Yahoo group for fldigi on Linux.
   Example of installing fldigi on an Ubuntu system.


   Fldigi is a multi-platform (OS X, Linux, Windows) program that vision-impaired hams can use for HF digital mode operation. The high-resolution display works well with magnifier software, but not with screen readers. Large font and high contrast color options are available. User-defined macros can be used as keyboard shortcuts, including automatic scanning for signals on the waterfall.

Author Information

   Peter DeNeef, AE7PD, is an Extra Class amateur radio operator in the U.S. This Web site has no ads or conflicts of interest.

rev. 1/26/2016

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